Wason Biotech Inc. ( Diagnostic Reagent Materials and Rapid Test: Zika, Dengue, MP, TB, HIV, HCV): Varicella-zoster Virus

Wason Biotech Inc. ( Diagnostic Reagent Materials and Rapid Test: Zika, Dengue, MP, TB, HIV, HCV): Varicella-zoster Virus: Varicella-zoster virus Introduction The varicella-zoster virus (VZV) can cause two diseases: chickenpox (varicella) and shingles (herpe...

Varicella-zoster virus

Introduction

The varicella-zoster virus (VZV) can cause two diseases: chickenpox (varicella) and shingles (herpes zoster).

Before a vaccine was developed in 1994, chickenpox was a common contagious childhood disease that produced itchy blisters, but rarely caused serious problems. However, if adults who did not have the disease as children contract it, it could cause more serious complications.

Shingles is caused by the same virus that causes chickenpox. Once you have had chickenpox, the varicella-zoster virus lies dormant in your nerves and can re-emerge as shingles. Shingles, which is characterized by a rash of blisters, can be very painful. But it is not life threatening. Some people who develop shingles also develop a condition caused postherpetic neuralgia, which causes the skin to remain painful even after the rash is gone. Shingles is most common in people over age 60, or in those with weakened immune systems. There is a vaccine that reduces your risk of getting shingles.

Signs and Symptoms

Chickenpox

The typical rash of chickenpox is made up of groups of small, itchy blisters surrounded by inflamed skin. The rash usually starts on the face, scalp, or chest, and quickly spreads throughout the body. It usually appears a few days after you have been exposed. Over 4 days, each blister tends to dry out and form a scab, which then falls off 9 to 13 days later.

The rash may be preceded or accompanied by:

· Fever, usually low grade

· Fatigue

· Headache

· Flu-like symptoms

Shingles

The typical shingles rash starts as redness followed by blisters that usually cover only one side of your body. The rash follows the path of the nerve where the virus has lain dormant. About 50 to 60% of people with shingles have the rash on their trunk. The next most common site is one side of the face, which may even include the tongue, eye, or ear.

Before the rash appears, you will have warning symptoms of pain, usually a sharp, aching, piercing, tearing, or burning sensation, on the part of your body where the rash appears 1 to 5 days later. That area may also feel itchy, numb, and unbearably sensitive to touch, even just from your clothes touching your skin.

Other symptoms may include:

· Fever

· Malaise (feeling unwell) and other flu-like symptoms, including muscle aches

· Headache

· Swollen lymph nodes

· Upset stomach

Causes

Chickenpox

Both chickenpox and shingles are caused by the varicella-zoster virus (VZV), a type of herpes virus. The virus is spread when you come into contact with the rash, or by sneezing, coughing, and breathing. In other words, when someone with chickenpox sneezes or coughs, there are droplets with the VZV virus in the air. The person is contagious from 2 days before the rash appears until all of the blisters have crusted over.

Shingles

While shingles is caused by the same virus that leads to chickenpox, the way you develop this painful skin condition is different. After you have had chickenpox, the virus lives in a dormant state, as if it is hibernating, in nerve cells along your spine. Later in life, when it "wakes up", usually from a weakened immune system, aging, or other risk factor, the virus travels down the path of the particular nerve where it was "hibernating," causing pain followed by the rash. About 30% of people who have had chickenpox will develop shingles. Getting vaccinated can reduce your risk.

Risk Factors

Chickenpox

· Exposure to the virus if you have not had chickenpox nor received the vaccine

· Being under 10 years of age

· Time of year: late winter and early spring is the most common time that the virus is spread

Shingles

· Age (most common in people over 60)

· Stress

· Weakened immune system (for example, people with HIV/AIDS, or those taking drugs to suppress the immune system due to autoimmune diseases or organ transplants)

· Having had chickenpox before age 1

Diagnosis

Your doctor can usually diagnose chickenpox easily because of its characteristic rash. However, if there is any doubt, the doctor may view a scraping from one of the blisters under the microscope.

If you have shingles, your doctor can usually make a diagnosis from the history of pain and other symptoms and the rash itself. He or she may take a scraping from one of the blisters for a laboratory test.

Preventive Care

Chickenpox

· The chickenpox vaccine (Varivax) is given to children over 1 year old. If a person receives the vaccine before age 13, then he or she only needs one dose. If a person receives the vaccine when he or she is older than 13, a second dose is needed 1 to 2 months later.

· If you have never had chickenpox or the vaccine, avoid contact with anyone who has chickenpox.

· Children with chickenpox should be kept out of school or daycare until their doctor says otherwise to avoid spreading the virus.

Shingles

· If you have never had chickenpox, the chickenpox vaccine can reduce your risk of getting chickenpox and shingles. Even if you do get the disease, having had the vaccine reduces the risk of complications.

· The shingles vaccine (Zostavax) can reduce the risk of getting shingles among people who are over 60 and have had chickenpox. It does not completely ensure you will not get shingles. If you do develop shingles, being vaccinated reduces the severity and the risk of postherpetic neuralgia.

The shingles vaccine is not recommended for people who:

· Have ever had a reaction to gelatin or neomycin

· Have a weakened immune system

· Take drugs to suppress the immune system (such as corticosteroids)

· Have tuberculosis

· Have a history of lymphatic or bone marrow cancer

One study found that older adults who regularly practice tai chi had a better immune response to the varicella virus, and their immunity increased even more when they had the shingles vaccine.

Treatment Approach

Both chickenpox and shingles generally get better by themselves, unless you are at high risk for complications. The goal of treatment is to reduce pain and itching.

Lifestyle

You can reduce symptoms of chickenpox and shingles with some simple steps:

· Apply cool water compresses to your skin or soak in a bathtub filled with cool water

· Add finely ground oatmeal (there are special brands sold in drugstores) to the bathtub

· Apply calamine or an over-the-counter hydrocortisone lotion to the affected areas

· Trim your fingernails to avoid infection

· For small children with chickenpox, cover hands with loose fitting, soft cotton or flannel mittens to prevent scratching

Medications

Chickenpox

· Antihistamine. If itching is severe, your doctor may suggest an antihistamine (such as Benadryl).

· Acyclovir (Zovirax). An antiviral drug prescribed for children who are at high risk of complications from chickenpox, or for adults who have chickenpox.

· Pain relievers. Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) can help reduce pain. DO NOT give aspirin to children under 19 because of the risk of a rare but serious illness called Reye syndrome.

Shingles

Antiviral drugs. Most effective when started within 72 hours of the first sign of a rash, these drugs are often given to people who are at risk of postherpetic neuralgia. They include:

· Acyclovir (Zovirax)

· Famciclovir (Famvir)

· Valacyclovir (Valtrex)

Corticosteroids. Used with Zovirax to reduce inflammation.

Pain relievers. For pain associated with shingles, an over-the-counter pain reliever, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) may be effective. For severe pain, or pain associated with postherpetic neuralgia, your doctor may prescribe a narcotic (opioid) pain reliever.

For postherpetic neuralgia

Capsaicin. Contains a pain reliever derived from chili peppers that produces a burning sensation when applied to the skin. It is available as an ointment (Zostrix) or a patch. A 2003 study reported that the patch reduced pain by 33% in about half of people with postherpetic neuralgia.

Lidocaine patch (Lidoderm). Applied to the skin to reduce pain.

Tricyclic antidepressants. Low doses of tricyclics, especially nortiptyline (Pamelor), may help reduce pain.

Gabapentin (Neurontin). An anticonvulsant (antiseizure) medication that may also help reduce pain.

Nutrition and Dietary Supplements

Since supplements may have side effects or interact with medications, you should take them only under the supervision of a knowledgeable health care provider.

· Adenosine monophosphate (AMP). An early study looked at injections of AMP, a compound that is made by the body, for treating the initial symptoms of shingles, as well as preventing postherpetic neuralgia. Researches gave people with shingles injections of either 100 mg of AMP or placebo. At the end of 4 weeks, 88% of those who got AMP were pain free compared to 43% who got placebo. The study used injections of AMP, so researchers do not know if taking AMP orally would have any effect. People who take dipyridamole (Persatine) or carbamazepine (Tegretol) should not take AMP. People with heart disease or gout should not take AMP.

· Vitamins B-12 and E. A few studies suggest that vitamin E (1,200 to 1,600 mg per day) and injections of B-12 (but not oral B-12) might help reduce symptoms of postherpetic neuralgia. But the studies were not good quality, and more research is needed.

Herbs

The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, under the supervision of a health care practitioner.

· Cayenne (Capsicum frutescens/Capsicum spp.). Capsaicin cream made from cayenne pepper can relieve pain when applied to the skin. Capsaicin may help relieve the pain of post herpetic neuralgia, and an over-the-counter ointment is approved for this treatment (see Medications). Capsaicin causes burning when applied to the skin, so use sparingly and do not use around eyes, nose, or mouth.

· German Chamomile (Matricaria recutita). Traditionally, this herb has been used topically to treat skin conditions and childhood illnesses like chickenpox. However, no scientific studies have examined whether chamomile is helpful in treating chickenpox. Chamomile interacts with a number of medications, so ask your doctor before taking it. People who are allergic to ragweed, chrysanthemums, daisies, and other members of the aster family, should not take chamomile.

· Licorice (Glycyrrhiza glabra). Traditionally, licorice gel has been used topically (applied to the skin) to treat shingles and postherpetic neuralgia. In test tubes, one of the constituents of licorice, called glycyrrhizin, stops the varicella zoster virus from reproducing. However, no scientific studies have examined whether licorice gel is helpful in treating either shingles or postherpetic neuralgia. Licorice, if absorbed systemically, interacts with a number of medications, and can potentially aggravate certain medical conditions, such as hypertension. Ask your doctor before using it.

Acupuncture

Although the results of scientific studies have been mixed, acupuncture may help relieve the nerve pain associated with shingles, especially when combined with traditional medications. Acupuncturists treat people based on an individualized assessment of the excesses and deficiencies of qi (or energy) located in various meridians. In the case of shingles, a qi deficiency is usually detected in the liver meridian and an excess in the gallbladder meridian. Acupuncturists will often provide needle or moxibustion treatment (a technique in which the herb mugwort is burned over specific acupuncture points) around painful areas.

Homeopathy

Few studies have examined the effectiveness of specific homeopathic therapies, however, professional homeopaths may consider the following remedies for the treatment of chickenpox and shingles based on their knowledge and experience. Before prescribing a remedy, homeopaths take into account a person's constitutional type. Your physical, emotional, and psychological makeup. An experienced homeopath assesses all of these factors when determining the most appropriate treatment for each individual.

Chickenpox:

· Antimonium crudum. For irritable children who are extremely sensitive to touch and may have a thick white coating on the tongue.

· Antimonium tartaricum. For large, slowly-appearing pox lesions accompanied by cough.

· Mercurius. For large, pus-filled pox which may ooze; this remedy is most appropriate for individuals who sweat profusely and may have enlarged lymph nodes.

· Pulsatilla. For fever associated with chicken pox; children who tend to be whiny, clingy, and weepy but have little thirst despite the fever.

· Rhus toxicodendron. For severe itching that worsens at night and improves with warm compresses or a bath; this remedy is the most commonly prescribed.

· Sulphur. For extremely itchy lesions that worsen with heat or bathing, and which children will often scratch to the point of bleeding.

Shingles:

· Arsenicum. For intense burning sensation that improves with warmth and worsens with cold.

· Lachesis. For particularly dark, sometimes purple, lesions on the left side of the body.

· Mezereum. For burning, sharp pains that worsen with touch; this remedy is most appropriate for individuals who are naturally chilly and sensitive to cold.

· Ranunculus bolbosus. For lesions located on the chest or back; pain worsens with touch and movement.

· Rhus toxicodendron. For intense itching and pain that may be relieved by touch.

Mind-Body Medicine

The following relaxation techniques may help reduce the pain and stress associated with shingles and postherpetic neuralgia:

· Meditation

· Breathing exercises

· Progressive muscle relaxation

· Biofeedback

People with post herpetic neuralgia have reported some relief from using hypnosis.

Other Considerations

Pregnancy

If you get chickenpox when you are pregnant, the infection may spread to the baby.

Special Populations

If you have a weakened immune system, shingles blisters may spread to other parts of your body and it will likely take longer for the symptoms to heal, maybe lasting for months. Conditions that weaken your immune function include:

· HIV or AIDS

· Organ transplant recipient

· Cancer, especially leukemia, Hodgkin's disease and other lymphomas, or undergoing chemotherapy

· Having an autoimmune disease (such as rheumatoid arthritis, lupus, multiple sclerosis, and Crohn's disease)

· Taking drugs that suppress your immune system

Warnings and Precautions

· Do not give aspirin to children under 19 due to the risk of a rare but serious illness called Reye's syndrome.

· Call your doctor if you experience confusion, vomiting, or weakness, even paralysis, of the arms, legs, trunk, or face during or soon after a chickenpox or shingles infection.

Prognosis and Complications

While chickenpox usually goes away on its own, severe and sometimes fatal infections may occur, particularly in newborn infants, adults, and people whose immune systems are weakened. Potential infections include:

· Encephalitis, a brain infection

· Myocarditis, an infection of the heart muscle

· Pneumonia

· Secondary bacterial skin infection

Shingles usually clears up in 2 - 3 weeks. Your chance of getting another bout of shingles is only 1 - 5% if you have a healthy immune system. If you have a weakened immune system (see Special Populations), your risk for recurrence is higher.

Potential complications from shingles include:

· Shingles lesions involving the mouth or eye; the latter may lead to blindness if not treated.

· Postherpetic neuralgia, persistent pain for months to years even after the skin lesions have cleared up.

· Secondary bacterial skin infections.

· Encephalitis (a brain infection) or sepsis (an infection in your blood stream, affecting many organs in the body).

A growing body of research suggests that VZV may lead to a variety of neurologic complications, including encephalitis and meningitis.

Wason biotech Inc. already researched our the anti-VZV neutralizing antibody ELISA aSSAY, for more information pls contact with us,

Diagnostic Reagent, Antibody,Antigen,Blocking Agents,Serum/Plasma: Mycobacterium Tuberculosis Polyproteins

Diagnostic Reagent, Antibody,Antigen,Blocking Agents,Serum/Plasma: Mycobacterium Tuberculosis Polyproteins: Enhanced serodiagnostic utility of novel Mycobacterium tuberculosis polyproteins Xiaoyan Feng a , k , Bingshui Xiu a , k , Kun C...

Mycobacterium Tuberculosis Polyproteins

Enhanced serodiagnostic utility of novel

Mycobacterium tuberculosis polyproteins

Xiaoyan Feng ^a,k, Bingshui Xiu ^a,k, Kun Chen ^a, Xiqin Yang ^a, Hongtao Zhang ^b, Jun Yue ^c, Yaoju Tan ^d, Hongmin Li ^e, Russell A. Nicholson ^f, Albert W. Tam ^g, Ping Zhao ^h, Li Zhang ⁱ, Jing Liu ^j, Xiaoguo Song ^a, Guohua Wang ^a,

Heqiu Zhang ^a,*

a Department of Bio-diagnosis, Beijing Institute of Basic Medical Sciences, 27, Taiping Road, Beijing 100850, China

b Beijing Chest Hospital, Beijing 101149, China

c Shanghai Pulmonary Hospital, Shanghai 200030, China

d Guangzhou Chest Hospital, Guangzhou 510095, China

e 309th Hospital of the Chinese People’s Liberation Army, Beijing 100091, China

f Department of Biological Sciences, Simon Fraser University, Burnaby, B.C. V5A 1S6, Canada

g Fastgen Corporation, Foster City, CA 94404, United States

h Chaoyang District Centre for Disease Control and Prevention, Beijing 100029, China

i Tianjin Haihe Hospital, Tianjin 300350, China

j China Nation Center for Biotechnology Development, Beijing 100039, China

Accepted 22 October 2012

Available online 2 November 2012

KEYWORDS		Summary  Objectives: The detection of Mycobacterium tuberculosis specific antibodies in
Tuberculosis;		human sera has been a rapid and important diagnostic aid for tuberculosis (TB) control and
Serodiagnosis;		prevention. However, any single antigen is not enough to be used to cover the antibody profiles
Polyproteins		of all TB patients.
		Methods: Seven single antigens (38 kDa, ESAT-6, CFP10, Mtb8.4, MPT64, TB16.3 and Mtb8) were
		evaluated serodiagnostically. Two novel M. tuberculosis polyproteins, 38kD-ESAT6-CFP10 (38F)
		and Mtb8.4-MPT64-TB16.3-Mtb8 (64F), were expressed and the novel 38Fe64F indirect ELISA
		assay used to analyze antibody responses to polyproteins in serum samples.
		Results: The sensitivity of the novel 38Fe64F indirect ELISA alone was much higher than that of
		the sputum culture test (86.91% vs. 50.62%) and that of the sputum smear test (78.64% vs.
		47.57%). The novel 38Fe64F indirect ELISA had a sensitivity of 74.16% with sera from

 

extrapulmonary TB patients and a sensitivity of 37.14% with sera from LTBI. The specificity of the novel 38Fe64F indirect ELISA was 90.36% with the sera from healthy blood donors and 94.15% with the sera from non-TB patients.

Conclusions: The novel 38Fe64F indirect ELISA assay had effective diagnostic performance and would make meaningful contribution to the diagnosis of TB disease in developing countries. ª 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

 

Introduction Materials and methods

Tuberculosis (TB) is one of the greatest problems impacting human health. According to the World Health Organisation, approximately 9 million people become sick every year, and this leads to 1.7 million deaths.¹

Mycobacterium tuberculosis is the causative agent of TB. The tuberculin skin test has long been used for the di-agnosis of TB. However, this test is the recommended diag-nosis test for latent TB infection and requires standardized application and interpretation, and a positive result de-pends on an adequate immune response.² Even though the sputum culture test has far been considered the gold standard for TB diagnosis, it can take at least one week to obtain results and requires extensive biosafety labora-tory facilities.³ The most widely used diagnostic test is the sputum smear test, which has a sensitivity of 34e80%.⁴ Immunocompromised patients often present with lower bacterial loads, which are easily missed by the sputum smear testing owing to its detection threshold of 10⁴ bacilli per milliliter.⁵ The usefulness of the IFN-g-re-lease assays (IGRAs) in the diagnosis of active TB remains questionable.⁶ A recently developed gene amplification test (GeneXpert MTB/RIF) can be used to diagnose tubercu-losis within two hours with excellent sensitivity.⁷ However, its use is restricted because this assay requires dedicated and expensive equipment.

Serological tests are based on the detection of circulat-ing antibodies against M. tuberculosis-specific antigens and are the attractive diagnostic methods because they are rapid, easy to perform, and easily implemented under the conditions commonly encountered in developing countries. The detection of M. tuberculosis-specific antibodies in hu-man sera has emerged as a useful aid in the diagnosis of TB. In recent years considerable progress has been made in the identification of serological antigens.^8e10 However, the detection of antibodies against a single antigen usually offers low sensitivity in TB diagnosis, and no commercially available serological test has so far shown useful levels of sensitivity and specificity,¹¹ a problem likely due to the great heterogeneity of the antibody response in TB pa-tients.^12,13 It is therefore generally accepted that it will be necessary to include several antigens in a future serodi-agnostic assay. The necessary improvements in sensitivity can most likely be achieved by the use of cocktails of differ-ent proteins and genetically engineered fusion molecules containing the best antigens.

In this study, two novel M. tuberculosis polyproteins, 38kD-ESAT6-CFP10 and Mtb8.4-MPT64-TB16.3-Mtb8, were expressed as antigens with multiepitopes, and evaluated for serodiagnosis of TB.

Ethics statement

The study was approved by the ethics committee of the Beijing Chest Hospital, the Shanghai Pulmonary Hospital, the Guangzhou Chest Hospital, the 309th Hospital of the Chinese People’s Liberation Army, Chaoyang District Centre for Disease Control and Prevention, and Tianjin Haihe Hospital. Written informed consent was obtained from all participants.

Study population

For evaluating the serodiagnostic performance of the seven individual antigens, serum samples were collected from two groups. (i) Sera were collected from 94 pulmonary TB patients. The diagnosis of pulmonary TB in these patients was based on X-ray and/or clinical findings and/or patient history. (ii) Samples from healthy blood donors (n Z 91) were obtained from the Beijing Red Cross Blood Center.

For evaluating the serodiagnostic utility of the two novel M. tuberculosis polyproteins, serum samples were col-lected from six different groups of individuals. (Ⅰ) Pulmo-nary TB group, including 205 sputum culture positive TB patients, 200 were culture negative, 49 smear positive TB patients, 54 were smear negative, and 41 smear negative but culture positive TB patients. (Ⅱ) Extrapulmonary TB group, including 89 extrapulmonary TB patients, regardless of sputum culture and smear microscopy results. The diag-nosis of extrapulmonary TB for these patients was based on X-ray and/or clinical findings. (Ⅲ) Thirty-five serum sam-ples were collected from the Latent TB infection (LTBI) subjects. The population with positive results of the PPD skin test and without clinical symptoms was often consid-ered as LTBI in China. (Ⅳ) To evaluate the specificity of the two novel polyproteins, the fourth group comprised 523 healthy blood donors without TB contract history. (Ⅴ) The fifth group comprised 171 non-TB patients, including 38 with pneumonia, 31 with fever, 13 with tracheitis, 10 with upper respiratory tract infection, 9 with diabetes mel-litus, 8 with laryngitis, 6 with hematologic diseases, 4 with abdominal pain, 3 with coronary heart disease, 3 with asthma, 2 with respiratory failure, 14 with urinary system disease, 7 with nervous system disease and 23 with other diseases. (Ⅵ) Twelve serum samples were collected from the nontuberculous mycobacterial lung disease (NTM) pa-tients group. The diagnosis of NTM patients was based on clinical findings and/or the identification of nontuberculous mycobacteria.

368 X. Feng et al.

B-cell epitope prediction

The BioSun Version 3.0 was used for B-cell epitope pre-diction. The software was developed by the Center of Computational Biology, Beijing Institute of Basic Medical Sciences. The “B-cell epitope prediction” section of the software allows the user to predict candidate B-cell epitopes from protein sequence of antigens. Based on the epitope curve, the fragment containing the dominant B-cell epitopes with higher peak value was selected as the target fragment.

Three dimensional structure modeling of the 38F polyprotein

Based on the crystal structures of 38 kDa, ESAT-6 and CFP10, the theoretical 3-D structure of the fused 38F polyprotein was obtained using the HOMOLOGY module on the SGI Indigo 2 workstation (R4400 at 150 Mhz).

Construction, expression, and purification of the recombinant protein

Coding sequences of each dominant antigen fragment of seven single antigens (38 kDa, ESAT-6, CFP10, Mtb8.4, MPT64, TB16.3 and Mtb8) were amplified from M. tubercu-losis H37Rv genomic DNA by PCR with specific endonuclease restriction sites (Xho I and Xba I) and then inserted into the prokaryotic expression plasmid pBVIL1. For the fused poly-proteins, 38kD-ESAT6-CFP10 (38F) and Mtb8.4-MPT64-TB16.3-Mtb8 (64F), the recombinant plasmid was con-structed using the Xho I, Xba I, Spe I and BamH I sites. The recombinant plasmids were transformed into Escheri-chia coli HB101 respectively. The purification of the re-combinant proteins was conducted by ion exchange and gel filtration. The purity of fusion protein was analyzed by Gel-Pro Analyzer Version 3.1.00.00 (Media Cybernetics, Silver Spring, MD). The protein concentration was deter-mined by the Bradford method (Pierce, Rockford, IL).

ELISA

Microplates were coated with individual antigens at 5 mg/ml (100 ml/well) in coating buffer (0.1 M carbonate/

bicarbonate, pH 9.6) and stored at 4 C overnight. For polyproteins, microplates were coated with 3 mg/ml 38F and 1.5 mg/ml 64F. The plates were washed three times with phosphate-buffered saline (PBS) containing 0.05% Tween 20 (PBST). Two hundred microliters of PBST containing 1% bovine serum albumin was added to each well, and the plates were sealed and incubated at 37 C for 1 h. The plates were washed three times. One hundred microliters of serum diluted at 1:10 in PBST containing 1% BSA was added to the antigen-coated well. The plates were sealed and incubated at 37 C for 30 min and then washed three times. One hundred microliters of horseradish peroxidase-conjugated anti-human IgG antibody (Sigma) was added to each well, and the plates were sealed and incubated at 37 C for 30 min. The plates were washed three times. The bound enzyme was detected by freshly-prepared tetramethyl benzidine (TMB) substrate. After 20e30 min incubation in room temperature, the stop solution (0.1 N sulfuric acid) was added and the optical density was determined at 450 nm using an automatic microplate reader (Bio-Rad, USA).

Statistical analysis

Data processing was performed using GraphPad Prism 4.0 (GraphPad Software Inc., San Diego, CA) and SPSS 16.0 software package (SPSS Inc., Chicago, IL). The diagnostic value of the novel 38Fe64F indirect ELISA was evaluated by the receiver operating characteristic (ROC) curve analysis.

Results

The screening of the fragment containing the dominant B-cell epitopes

The seven individual antigens (38 kDa, ESAT-6, CFP10, Mtb8.4, MPT64, TB16.3 and Mtb8) were selected in present study due to their reactivity with a subpopulation of sera from TB patients (Table 1). Based on the epitope curve, the fragment containing the dominant B-cell epitopes with higher peak value for each antigen was determined, which was 21e374 aa for the 38 kDa antigen, 20e95 aa for ESAT-6, 55e100 aa for CFP10, 20e85 aa for Mtb8.4, 25e178 aa for

Table 1 Sensitivities and specificities of 7 individual fragment antigens and 2 polyproteins with sera from TB patients and

healthy controls.

	Protein name	Rv no.	Reference(s)	Epitope	Sensitivity [95% CI]	Specificity [95% CI]		Cutoffa	Serab
		of gene		fragment
	38 kDa antigen	Rv0934	14,15	21e374 aa	40.43% [30.4%e51.1%]	97.80%	[92.3%e99.7%]	0.251	7
	ESAT-6	Rv3875	16	20e95 aa	46.81% [36.4%e57.4%]	98.90%	[94.0%e100.0%]	0.229	2
	CFP10	Rv3874	9,16	55e100 aa	44.68% [34.4%e55.3%]	100.00%	[96.0%e100.0%]	0.267	6
	Mtb8.4	Rv1174c	17,18	20e85 aa	27.67% [18.9%e37.9%]	96.70%	[90.1%e99.3%]	0.144	2
	MPT64	Rv1980	9	25e178 aa	26.60% [18.0%e36.7%]	96.70%	[90.7%e99.3%]	0.148	2
	TB16.3	Rv2185c	19	32e144 aa	36.17% [26.5%e46.7%]	98.90%	[94.0%e100.0%]	0.176	1
	Mtb8	Rv0379	20	23e86 aa	40.43% [30.4%e51.1%]	98.90%	[94.0%e100.0%]	0.472	4
	38F	e	e	e	70.11% [59.4%e79.5%]	95.56%	[89.0%e98.8%]	0.227	11
	64F	e	e	e	64.37% [53.4%e74.4%]	96.67%	[90.6%e99.3%]	0.184	9

a  The cutoff was calculated as the mean for the control plus 3 standard deviations.

  ^b  The sera from TB patients contained antibodies against only one specific antigen or one polyprotein.

Serological reactivity of individual antigens

The indirect ELISA assay was conducted using individual antigens respectively and the sensitivity and specificity of individual fragments containing the dominant B-cell epi-topes were evaluated. The results are shown in Fig. 2 and the sensitivities and specificities of the 7 individual frag-ment antigens are summarized in Table 1. The sensitivities of the 7 individual fragment antigens were from 26.60% to 46.81%. All antigens had a specificity of 96.7% or greater. A total of 85.11% of sera (80 of 94) from TB patients con-tained antibodies against at least one antigen. But, only 5.32% (5 of 94) of the patient serum samples recognized all antigens. Sera from 24 TB patients contained antibodies against only one specific antigen, among of them, 7 serum samples contained antibodies against the 38 kDa antigen alone, 6 contained antibodies against CFP10 alone, 4 con-tained antibodies against Mtb8 alone, 2 contained anti-bodies against MPT64 alone, 2 contained antibodies against ESAT-6 alone, 2 contained antibodies against Mtb8.4 alone, and 1 contained antibodies against TB16.3 alone. These observations indicated that when appropriate antigens are used, specific antibody responses to antigens of M. tuberculosis can be measured in the vast majority of individuals with active TB.

Assembly of 38F and 64F polyproteins

It is already known that a single antigen can never adequately diagnose TB. Thus, strategies using multiple antigens either individually or as fusion polyproteins have been recommended.²¹ However, when the seven fragment antigens were mixed together and tested as one for each patient, sensitivity decreased (data not shown). Thus, two novel M. tuberculosis polyproteins, 38F and 64F, were ex-pressed as antigens with multiepitopes in a way described in the Materials and Methods. The B-cell epitope curves of fused polyproteins were analyzed by the BioSun Version 3.0 and the 3-D theoretical structure of the fused 38F polyprotein was obtained using the HOMOLOGY module on the SGI Indigo 2 workstation (Fig. 3). The results showed that the three fragment antigens of the fused 38F polypro-tein retained the spatial structure of the original epitope, which suggested that the 38F still had good antigenicity. The 3-D theoretical structure of the 64F was not modeled because crystal structures of Mtb8.4, TB16.3 and Mtb8 were not available. But the B-cell epitope curve of the 64F showed that the B-cell epitopes of the fusion antigen included dominant epitopes of each individual fragment antigen. The diagnostic performance of the 38F and 64F polyproteins was thoroughly examined in the present study.

The sensitivity and specificity of 38F and 64F polyproteins

The purity of 38F and 64F polyproteins was 96.02% and 96.22% respectively. The indirect ELISA assay was conduct-ed using 38F and 64F polyprotein respectively and the

sensitivity and specificity of each polyprotein was evalu-ated. The results are shown in Table 1 and Fig. 2. The sen-sitivities of the 38F and 64F polyprotein were 70.11% and 64.37%, which were higher that of each antigen. The spec-ificities of the 38F and 64F polyprotein were 95.56% and 96.67% respectively.

ELISA sensitivity and specificity of MTb polyproteins

The indirect ELISA assay was conducted using the novel 38F and 64F polyproteins, and the assay was then used to analyze serological antibody responses to the fusion protein in patients with pulmonary TB, extrapulmonary TB, LTBI, non-TB patients, NTM patients and healthy blood donors.

ELISA sensitivity

In order to evaluate the sensitivity of the novel 38F and 64F polyproteins in indirect ELISA, the antibody responses of pulmonary TB serum samples were examined. The results were shown in Fig. 4A, indicating that 92.20% of culture-positive pulmonary TB patients (95% confidence interval [CI], 89.5%e94.3%) and 81.50% of culture-negative pulmo-nary TB patients (95% CI, 75.4%e86.6%) were detected, with a statistically significant difference with healthy blood donors (p < 0.01). A combination of the 38Fe64F indirect ELISA and the sputum culture test for 405 pulmonary TB pa-tients that performed the sputum culture test had a sensi-tivity of 90.86% (368 of 405 samples) compared to 86.91% (352 of 405 samples) for novel 38Fe64F indirect ELISA alone and 50.62% (205 of 405 samples) for sputum culture alone, demonstrating the significantly improved sensitivity when both test or the novel 38Fe64F indirect ELISA alone were (was) used. For pulmonary TB patients performed the spu-tum smear test, 81.63% of smear-positive pulmonary TB pa-tients (95% CI, 68.0%e91.2%) and 75.93% of smear-negative pulmonary TB patients (95% CI, 62.4%e86.5%) were de-tected, with a statistically significant difference with healthy blood donors (p < 0.01). A combination of 38Fe64F indirect ELISA and sputum smear test for 103 pul-monary TB patients that performed the sputum smear test had a sensitivity of 87.38% (90 of 103 samples) compared to 78.64% (81 of 103 samples) for novel 38Fe64F indirect ELISA alone and 47.57% (49 of 103 samples) for sputum smear alone, demonstrating the significantly improved sensitivity when both test were used. Importantly, 75.93% of smear-negative pulmonary TB patients were detected by the novel 38Fe64F indirect ELISA. The sensitivity of the novel 38Fe64F indirect ELISA assay in sera of smear negative but culture positive pulmonary TB patients was 78.05% (95% CI, 62.4%e89.4%; p < 0.01). To further evaluating the serodiagnostic value of the novel 38Fe64F indirect ELISA, serum samples from 89 extrapulmonary TB patients and LTBI subjects were evaluated respectively (Fig. 4A). The results showed that 66 of 89 samples were positive, with the sensitivity of 74.16% (95% CI, 63.8%e82.9%), with a statistically significant difference with healthy blood do-nors (p < 0.01). For LTBI subjects, 13 of 35 serum samples were positive, with the sensitivity of 37.14% (95% CI, 21.5%e55.1%).

370

  

Figure 1 Display of epitope curves for the seven individual M. tuberculosis proteins. The fragment between the right arrow and left arrow was the fragment determined to contain the dominant B-cell epitopes.

Figure 2 Normalized levels of antibodies to the seven individual fragment antigens and two polyproteins for TB patients and for healthy controls. Arbitrary units (A.U.) represent the OD for the sample test divided by the cutoff, based on the mean for a defined panel of 91 healthy controls plus 3 standard deviations.

ELISA specificity

To evaluate the specificity of the novel 38F and 64F polyproteins in indirect ELISA, the antibody responses of three group serum samples were examined. The first group comprised 523 healthy blood donors, the second group included 171 non-TB patients, and the third group included 12 NTM patients. The results were shown in Fig. 4A. For healthy blood donors, the specificity was 90.63% (95% CI, 87.8%e93.0%). For non-TB patients, the overall specificity was 94.15% (95% CI, 89.5%e97.2%), without a statistically significant difference with healthy blood donors (p > 0.05). Among the group of non-TB patients, 69 sera samples were from patients suffering from a variety of re-spiratory diseases, including pneumonia, tracheitis, upper respiratory tract infection and laryngitis. Whereas in the 10 ELISA-positive sera, 8 samples were from respiratory dis-eases patients, only 2 ELISA-positive samples were from non-respiratory diseases patients. So, the novel 38Fe64F indirect ELISA had a specificity of 88.41% with sera from re-spiratory disease patients, whereas it had a much higher specificity of 98.04% with sera from non-respiratory disease patients. For NTM patients, the specificity of the novel 38Fe64F indirect ELISA assay in sera of NTM patients was 83.33% (95% CI, 51.6%e97.9%; p > 0.05).

ROC curve of the novel 38Fe64F indirect ELISA assay

The ROC curve of the novel 38Fe64F indirect ELISA assay performance for serodiagnosis was mapped with all TB patients and healthy controls (See Fig. 4B). The area under the curve (AUC) of the novel 38Fe64F indirect ELISA assay was 0.884. The value of AUC usually indicates diagnostic ac-curacy, with those closer to 1.0 possessing better discrimi-natory power. The ROC analysis indicated that the novel 38Fe64F indirect ELISA assay had a better overall diagnos-tic performance.

Discussion

Over 90% of the worldwide burden of tuberculosis is in low-income and middle-income countries where the diagnosis of tuberculosis still relies heavily on sputum smear micros-copy and chest radiology. There is a great need for rapid point-of-care tests that can be readily used at all levels of the health system and in the community.^22,23 Biological, molecular and immunological studies of the MTB complex have resulted in identification of different useful antigens, some of which are specific to the MTB complex. In this study, we used the ELISA technique to evaluate the

        

of the novel 38F and 64F fused polyprotein. A is the epitope curve for the 38F polyprotein and B is the	of the original B-cell epitopes of each fragment antigen. C is the three-dimensional structure of the novel	indicates the ESAT-6 antigen fragment, Green indicates the CFP10 antigen fragment and Blue indicates the
Figure 3   Display of epitope curves and three-dimensional structure	epitope curve for the 64F polyprotein. The fused polyprotein remained	fused 38F polyprotein. Red indicates the 38 kDa antigen fragment, Pink	linker between each antigen fragment.

serological responses of seven single antigens, 38 kDa, ESAT-6, CFP10, Mtb8.4, MPT64, TB16.3 and Mtb8, to pulmo-nary TB patients. The 38 kDa antigen is the most frequently investigated serological antigen and is a key component in commercial kits for TB identification.²⁴ Unfortunately, the recognition frequency reported for the 38 kDa antigen varies in sensitivity (40e89%) and specificity (44e100%), largely depending on the smear status and disease manifes-tation,^14,15 which limits the implementation of these assays in clinical practice. ESAT-6 and CFP10 are the most immu-nodominant MTB antigens hitherto identified, and their di-agnostic specificity stems from their genomic location within the region of difference 1 (RD1), a part of the MTB genome absent from all Mycobacterium bovis BCG vaccine strains.²⁵ The sensitivity with ESAT-6 antigen for diagnosis of tuberculosis varied from 5% to 76% with a specificity ranging from 51% to 100%. But some studies show that the accuracy of tests based on ESAT-6 is not very satisfactory in countries where there is high prevalence of TB.²⁶ CFP10 has been identified to be amongst the earliest pro-teins produced by M. tuberculosis during culture in bacteri-ological media. With this antigen the sensitivity varied from 9% to 78% with specificity range 55e100%.⁹ Mtb8.4 was iden-tified through biochemical purification of immunodominant T-cell antigens from TB culture filtrates and capable of elic-

iting proliferation and IFN-production in PBMCs from PPDþ donors.^17,18 MPT64 is highly immunogenic and one of the

major antigens from TB bacteria.²⁷ With MPT64 the sensi-tivity varied from 7% to 78% with 82e100% specificity, and the positivity in HIV positive tuberculosis patients was higher.⁹ TB16.3 was the single most frequently recognized antigen in patients both from regions where TB is endemic and regions where TB is not endemic, as well as from TB pa-tients coinfected with HIV, with levels of recognition of 46e98% and maintenance of a specificity of 97%.¹⁹ Mtb8, most likely a cell wall-associated transporter protein, re-acts with the rabbit anti-soluble protein antiserum but also reacts with a small but discrete population of pulmo-nary TB sera.²⁰

In present study, in order to improve the sensitivity and specificity of TB diagnosis, the fragments containing the dominant B-cell epitopes of seven M. tuberculosis proteins were screened and selected. The antibody responses of TB patients to these seven individual fragment antigens have not been investigated previously. The sera from TB patients frequently recognized these antigens, with levels of recogni-tion of 26.60e46.81% and maintenance of the specificity from 96.7 to 100%. This was consistent with previous find-ings.¹² The number and the species of serologically reactive antigens varied greatly from individual to individual. Al-though only 5.32% of the patient serum samples recognized all antigens, a total of 85.11% of sera from TB patients con-tained antibodies against at least one antigen, and a total of 24 of serum samples from TB patients contained antibodies against only one specific antigen, which indicating that sero-diagnostic assays for TB must be based on rational design of antigen combinations to achieve high diagnostic accuracy. Accordingly, in this study, two novel polyproteins, 38F and 64F, were expressed, and the indirect ELISA assay using the novel 38F and 64F polyproteins was established.

Through clinical evaluation the novel 38Fe64F indirect ELISA assay showed some advantages. The first was the

Serodiagnosis for tuberculosis	373

 

Figure 4 The serodiagnosis performance of the novel 38Fe64F indirect ELISA assay. (A) Antibody responses to 38Fe64F polypro-teins by indirect ELISA assay. Arbitrary units (A.U.) represent the OD for the sample test divided by the cutoff. The cutoff value was derived from the mean OD of healthy blood donors plus 3 standard deviations. When the ratio is greater than 1, the sample was antibody-positive. When the ratio is less than 1, the sample was antibody-negative. (B) ROC curve of the novel 38Fe64F indirect ELISA assay performance for serodiagnosis of TB patients and healthy controls. The area under the curve (AUC) of the novel 38Fe64F indirect ELISA assay was 0.884.

advantage of the ELISA technique in diagnosing TB. ELISAs theoretically represent attractive serodiagnostic methods because they are simple, rapid, inexpensive and do not require much training or sophisticated equipment. Espe-cially in developing countries and areas where TB is endemic, the ELISA method has advantages over other methods. But, no commercially available serological test has so far shown useful levels of sensitivity and specificity, which may be due to the great heterogeneity of the antibody response in TB patients.²⁸

In our study, through the use of polyproteins containing seven antigens fragments, we demonstrate that the neces-sary improvement in sensitivity can be achieved. This was the second advantage of the novel indirect ELISA assay using the novel 38F and 64F polyproteins. The sensitivity of the novel 38Fe64F indirect ELISA alone (86.91%) was much higher than that of the sputum culture test (50.62%) and very near to the sensitivity when both tests were used (90.86%). Similarly, the sensitivity of the novel 38Fe64F indirect ELISA alone (78.64%) was much higher than that of the sputum smear test (47.57%). However, more impor-tantly, 81.50% of culture-negative pulmonary TB patients and 75.93% of smear-negative pulmonary TB patients were detected by the novel 38Fe64F indirect ELISA. It was evident that the novel 38Fe64F indirect ELISA would significantly improve the detection rate for the culture-negative or smear-negative pulmonary TB patients. Thus, the sensitivity would improve significantly when the novel 38Fe64F indirect ELISA was used alone or combination with the culture test or the smear test. It is well known that the diagnosis of extrapulmonary TB is more difficult. The results showed the sensitivity of the novel 38Fe64F indirect ELISA in extrapulmonary TB patients was 74.16%. Latent infection with M. tuberculosis indicates the

presence of live M. tuberculosis organisms in a human host who is asymptomatic. But, the bacteria exist in a quies-cent state and M. tuberculosis-specific antibodies are in low level or undetectable.²⁸ Thus, the novel 38Fe64F indi-rect ELISA showed the lower sensitivity (37.14%) for LTBI subjects. In China, the majority of patients with active tu-berculosis go to the doctor because of the onset of symp-toms. So, when used in hospitals, due to the better sensitivity and specificity, the novel 38Fe64F indirect ELISA could contribute to the clinical diagnosis of TB patients having active diseases. When used to medical screening of healthy people, some of healthy LTBI persons could be de-tected using the novel 38Fe64F indirect ELISA, which re-mind of regular monitoring or preventive treatment. Thus, the novel 38Fe64F indirect ELISA is very suitable for the majority of economically less developed countries with high TB burden.

Good diagnostic reagents must take into account both sensitivity and specificity. The third advantage of the novel 38Fe64F indirect ELISA was the higher specificity. For the group of 523 healthy blood donors, the specificity of the novel 38Fe64F indirect ELISA was 90.63%. This value is slightly lower, in part due to the fact that China is a country with a huge TB burden and has a policy of routine BCG vaccination. Since BCG vaccination, environmental myco-bacteria, and other respiratory diseases may influence the results of the serodiagnosis of TB, the real value of a good diagnostic reagent should be tested through cross-sectioned studies.²⁹ For respiratory diseases patients, the novel 38Fe64F indirect ELISA had a specificity of 88.41%, whereas had a much higher specificity of 98.04% with sera from non-respiratory diseases patients. The presence of higher false positive results in respiratory disease patients could be ascribed to cross reaction with other respiratory

disease-related pathogens or the presence of incipient TB. On one hand, the selected Mtb8, Mtb8.4 and TB16.3 were not M. tuberculosis specific genes that show some homol-ogy with other mycobacteria, including M. avium, M. kan-sassi, and M. intracellulare. So, 2 of 12 NTM patients were detected positive, indicating cross reaction with non-tuberculous mycobacteria. On the other hand, progression from LTBI to active TB is likely a dynamic process between resolution and progression in the early stages of the dis-ease, and some of respiratory disease patients may be un-derlying incipient or culture-negative TB.³⁰

Based on present diagnostic methods, pulmonary TB and smear-positive TB are often easily recognized, whereas the diagnosis of extrapulmonary TB and smear-negative TB is more difficult. It is estimated that 55.6% of patients with active TB are smear- and culture-negative, and samples for the verification of pathological changes can be difficult or impossible to obtain in these cases. Therefore, the de-velopment of such systems is very urgently needed due to the pressure for strengthening earlier diagnosis of diseases in the paucibacillary stage, including pulmonary tubercu-losis with negative sputum smears of adults, extrapulmo-nary tuberculosis, childhood tuberculosis and tuberculosis patients with HIV coinfection.³¹ At the same time, the test system must be operationally simple for use at the point of care in the developing world and must be rapid, in addition to providing diagnostic accuracy in terms of sensitivity and specificity. The novel 38Fe64F indirect ELISA assay has po-tential to achieve this purpose. The ROC analysis indicated that the novel 38Fe64F indirect ELISA assay had a better overall diagnostic performance. The serodiagnostic value of the novel 38Fe64F indirect ELISA assay in special popula-tions, such as children and individuals with concurrent HIV infection, needs further study.

Currently, the sensitivity and specificity of commercial serological tests in the clinical was unsatisfactory and, the selected samples in clinical trials with the serological tests

were not standardized. Therefore, the WHO, based on laboratory evaluation,³² meta-analysis^33,34 and cost-effec-

tiveness,³⁵ has issued a recommendation against the use of currently available serological tests for the diagnosis of tuberculosis. It is believe that, course of TB patients, im-mune status, whether or not the patient was treated, and the selected antigen of the tests will affect the sensitivity of serological tests, and thus if a standardized sample li-brary is established and correct antigens are selected, the establishment of serological tests with excellent diagnostic performance is possible. Most importantly, the serological tests have the inherent advantages of simplicity, cheapness and rapid detection, and the established serological tests with excellent diagnostic performance will help to control the prevalence of TB epidemic.

Authors contributions

The conception and design of the study: Feng XY, Xiu BS, Zhang HQ;

Acquisition of data: Chen K, Yang XQ, Zhang HT, Yue J, Tan YJ, Li HM, Zhao P, Zhang L, Liu J, Song XG, Wang GH; Analysis and interpretation of data: Feng XY, Xiu BS,

Zhang HQ;

Drafting the article or revising it critically for important intellectual content: Feng XY, Nicholson RA, Tam AW;

Final approval of the version to be submitted: Feng XY, Zhang HQ.

Conflict of interests

We declared that there is no conflict of interest with respect to this manuscript.

Acknowledgment

This work was supported by the grants from the National Natural Science Foundation of China [30772067], National S&T Major Project for Infectious Diseases Control [2009ZX10004-718] and the National High Technol-ogy Research and Development Program of China [2011AA02A120].

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