Quantitative hepatitis B core antibody and quantitative hepatitis B surface antigen:Novel viral biomarkers for chronic hepatitis B management

The management of hepatitis B virus(HBV)infection now involves regular and appropriate monitoring of viral activity,disease progression,and treatment response.Traditional HBV infection biomarkers are limited in their ability to predict clinical outcomes or therapeutic effectiveness.Quantitation of HBV core antibodies(qAnti-HBc)is a novel non-invasive biomarker that may help with a variety of diagnostic issues.It was shown to correlate strongly with infection stages,hepatic inflammation and fibrosis,chronic infection exacerbations,and the presence of occult infection.Furthermore,qAnti-HBc levels were shown to be predictive of spontaneous or treatment-induced HBeAg and HBsAg seroclearance,relapse after medication termination,re-infection following liver transplantation,and viral reactivation in the presence of immunosuppression.qAnti-HBc,on the other hand,cannot be relied on as a single diagnostic test to address all problems,and its diagnostic and prognostic potential may be greatly increased when paired with qHBsAg.Commercial qAnti-HBc diagnostic kits are currently not widely available.Because many methodologies are only semi-quantitative,comparing data from various studies and defining universal cut-off values remains difficult.This review focuses on the clinical utility of qAnti-HBc and qHBsAg in chronic hepatitis B management.

A Co-expression System Based on Phage and Phagemid to Select Cognate Antibody-antigen Pairs in vivo

A modified selectively infective phage (SIP) is developed to facilitate the selection of interacting antibody antigen pairs from a large single chain antibody (scFv) library in vivo. The system is constructed with a modified helper phage M13KO7 and phagemid pCANTAB 5 E. The antigen fused to the C terminal of N1 N2 domain and the scFv to the N terminal of CT domain of the gIIIp of filamentous phage are encoded on the phage and phagemid vectors respectively. The phages produced by co transformants restore infectivity via interaction between antigen and antibody fusions in the cell periplasm. In a model system, the scFv fragment of the anti hemagglutinin 17/9 antibody and its corresponding antigen are detected in the presence of a 10 5 fold excess of a non interacting control pairs, which demonstrates this system to be very sensitive and facile to screen a large single chain antibody library.

Screening and evaluation of human single-chain fragment variable antibody against hepatitis B virus surface antigen

BACKGROUND: Phage display technology has become a vital tool in studies aimed at identifying molecules binding to a specific target. It enables the rapid generation and selection of high affinity, fully human antibody product candidates to essentially any disease target appropriate for antibody therapy. In this study, we prepared the recombinant single-chain fragment variable ( ScFv) antibody to hepatitis B virus surface antigen (HBsAg) by the phage display technology for obtaining a virus-targeting mediator. METHODS: mRNA was isolated from B-lymphocytes from a healthy volunteer and converted into cDNA. The fragment variables of heavy and light chain were amplified separately and assembled into ScFv DNA with a specially constructed DNA linker by polymerase chain reaction. The ScFv DNA was ligated into the phagmid vector pCANT-AB5E and the ligated sample was transformed into competent E. coli TG1. The transformed cells were infected with M13K07 helper phage to form a human recombinant phage antibody library. The volume and recombinant rate of the library were evaluated by bacterial colony count and restriction analysis. After two rounds of panning with HBsAg. the phage clones displaying ScFv of the antibody were selected by enzyme-linked immunosorbant assay ( ELISA) from the enriched phage clones. The antigen binding affinity of the positive clone was detected by competition ELISA. HB2151 E. coli was transfected with the positive phage clone demonstrated by competition ELISA for production of a soluble form of the anti-HBsAg ScFv. ELISA assay was used to detect the antigen binding affinity of the soluble anti-HBsAg ScFv. Finally, the relative molecular mass of soluble anti-HBsAg ScFv was measured by SDS-PAGE. RESULTS: The variable heavy ( VH ) and variable light (VL) and ScFv DNAs were about 340bp, 320bp and 750bp, respectively. The volume of the library was up to 2 × 106 and 8 of 10 random clones were recombinants. Two phage clones could strongly compete with the original HBsAb for binding to HBsAg. Within 2 strong positive phage clones, the soluble anti-HBsAg ScFv from one clone was found to have the binding activity with HBsAg. SDS-PAGE showed that the relative molecular weight of soluble anti-HBsAg ScFv was 32 kDa. CONCLUSION: The anti-HBsAg ScFv successfully produced by phage antibody technology may be useful for broadening the scope of application of the antibody.

Prevention of de novo HBV infection by the presence of anti-HBs in transplanted patients receiving core antibody-positive livers

AIM： To analyze whether the presence of anti-HBs in liver transplant recipients is effective in preventing HBV infection. METHODS： Twenty-three patients receiving anti-HBc positive liver were studied. Nine recipients were anti-HBc positive as a result of previous HBV infection. Of them, one also received HBV vaccine during the pre-liver transplantation period. Fourteen recipients were anti-HBs positive due to HBV vaccine administered during the pretransplant period. Liver biopsy was obtained in 10/14 anti-HBc negative/anti-HBs positive recipients and in 4/9 anti-HBc positive recipients. RESULTS： After a mean foUow-up period of 46 months, 1 recipient with protective serum anti-HBs levels developed de novo HBV infection as a consequence of immune escape HBV mutants. Among the 14 vaccinated anti-HBc negative/anti-HBs positive recipients, 1/10 patients with available liver biopsy （10%） had liver HBV-DNA at 13 mo post-liver transplantation without serum viral markers and did not develop de novo HBV infection.The vaccinated anti-HBc positive recipient without HBV vaccine response was HBV-DNA positive in serum and liver, viral DNA was continuously negative in the following tests, so a spontaneous seroconversion was diagnosed. CONCLUSION： The presence of anti-HBs as a result of HBV vaccine or past HBV infection seems to be effective at protecting patients receiving livers from anti-HBc positive donors. However, the emergence of immune escape HBV mutants, which can evade the anti-HBs protection, should be considered as a risk of HBV infection.

<i>Blastomyces dermatitidis</i>Antibody Responses in Serial Serum Specimens from Dogs with Blastomycosis: Comparison of Different Yeast Lysate Antigens

The systemic fungal organism, Blastomyces dermatitidis causes blastomycosis in animals and hu-mans. This study was designed to evaluate antibody detection in 55 serial serum specimens from 9 dogs with blastomycosis using B. dermatitidis yeast lysate antigens produced from two human isolates (B5896;B5931) and two dog isolates (ERC-2;T-58) with the indirect enzyme linked im-munosorbent assay (ELISA;peroxidase system) to determine an optimal lysate antigen(s) for use in the ELISA to detect antibody in the dog serum specimens. The mean absorbance values when the lysate antigens were compared with respect to their ability to detect antibody in the day 0 sera from the 9 dogs were 1.024 (ERC-2), 1.351 (B5896), 1.700 (B5931) and 2.084 (T-58) respectively. All of the reagents exhibited a high level of sensitivity and in all instances the amount of antibody declined as the time interval post-treatment increased, but the T-58 lysate prepared from the dog isolate from Tennessee was the optimal reagent. We continue to evaluate antigens for B. derma-titidis antibody detection in different immunodiagnostic assays.

Antigen Detection in Canine Blastomycosis: Comparison of Different Antibody-Antigen Combinations in Two Competitive ELISAs

This present study was designed to evaluate four different Blastomyces dermatitidis antibody-antigen combinations (B5896 and T-58 antibodies and B5896 and WI-R antigens) for the detection of antigen in 36 urine specimens from dogs with blastomycosis using a standard indirect ELISA (STD) and a biotin-streptavidin ELISA (B-SA). The antigen detection sensitivity values ranged from 81% (B-SA: T-58 Ab + WI-R Ag) to 100% (STD and B-SA: B5896 Ab + WI-R Ag;B5896 Ab + B5896 Ag) with the antibody-antigen combinations in the two assays. Optimal detection was evidenced when the B5896 Ab was allowed to react with the urine specimens for 30 min at 37?C and then placed in the B-SA ELISA plates containing the B5896 Ag. The greatest absorbance value obtained with this antibody-antigen com-bination was 0.903 (range of 0.596 - 0.903) as compared to the control value of 1.246. The difference between the control absorbance and the test absorbance values was 0.343 which was considerably greater than the control-test values with the other combinations. This study thus showed that the results obtained in antigen detection assays are dependent upon the antibody used to react with the urine specimens as well as the antigen used in the enzyme immunoassay.

Analysis of sperm membrane antigens relevant to antisperm antibody using Western blot

To identify the sperm membrane antigens associated with antisperm antibody. Methods: The antisperm antibody in serum was tested by ELISA. Antisperm antibody positive sera from 18 infertile men and 15 infertile women were used. The molecular weight (MW) of sperm membrane antigens associated with the antisperm antibody was analyzed with antisperm antibody positive serum using Western blot. Results: Eight kinds of MW of sperm membrane antigens were identified. The ratio of identification on the 78 KD(60.7 %), 60KD (71.4 %), 51 KD (14.9 %) and 23 KD (14.29 %) sperm antigen was higher than others. Conclusion: Sperm membrane antigens with MW of 78 KD, 60 KD, 51 KD and 23 KD were associated with antisperm antibody and immunological infertility. (Chin J Andro12002; 16: 345)

PURIFICATION AND IDENTIFICATION OF THE ANTIGEN ASSOCIATED WITH MONOCLONAL ANTIBODY 3H_(11) AGAINST GASTRIC CANCER CELL

The object of this study is to investigate the properties of gastric cancer assoiciated antigen by McAb3H11 against gastric cancer cell line. Antigen purified by affinity chromatography and further charac- terized by biochemical and immunological techiques. Results showed that assoiciated antigen of McAb 3H11 was mainly located on the membrane of target cells. It was sensitive to heat and digestion of proteases,but resistant to treatment with sodium periodate. Schiff’s reagent staining was negative. SDS-PAGE and IEF- analysis showed that the antigen was a 210 kD molecular weight with pl of 8. 5 protein. The molecular weight of antigen extracted from target cell with tunicamycin was not changed. We concluded that the cor- responding antigen of McAb 3H11 might be an alkaline protein.

Comparison of Antibody Detection with Yeast Lysate Antigens Prepared from Blastomyces dermatitidis Dog Isolates from Wisconsin and Tennessee

Blastomyces dermatitidis, the causative agent of blastomycosis, a potentially lethal dimorphic fungal disease of humans and animals has been difficult to diagnose in the clinical laboratory. We are attempting to develop and improve immunodiagnostic assays by producing novel yeast lysate reagents for the detection of antibodies in blastomycosis. The objective of this study was to use lysate antigens prepared from four B. dermatitidis antigens isolated from dogs infected with blastomycosis from two different endemic areas (Wisconsin and Tennessee) testing for the detection of antibodies in serum specimens from immunized rabbits and infected dogs using the indirect ELISA. In the dog sera, absorbance values ranged from 0.774 to 1.350, while the rabbit sera values ranged from 0.533 to 1.191. Antigen T-58 appeared to lack any geographical specificity in antibody detection, which could prove useful in future immunodiagnostic detection of blastomycosis infections.

Comparison of antibody detection with <i>Blastomycesdermatitidis</i>yeast lysate antigens in serum specimens from immunized rabbits and infected dogs

This present study was designed to evaluate B. dermatitidis antigens, prepared from two isolates (B5896, 597), when the yeast cells were allowed to lyse in distilled water for one day or seven days. The indirect enzyme-linked immunosorbent assay (ELISA) was used to determine the ability of the lysate reagents to detect antibodies in 30 rabbit and 30 dog serum specimens. Mean absorbance values with B5896 lysate antigen ranged from 1.637 (day 1) to 1.461 (day 7) and absorbance values with 597 antigen ranged from 1.579(day 1) to 1.396 (day 7) with the serum specimens from immunized rabbits. Serum specimens from infected dogs yielded absorbance values ranging from 1.672 (day 1) to 1.763 (day 7) with the B5896 and values ranging from 1.909 (day 1) to 1.224 (day 7) with the 597. Optimal reactivity was obtained with the day 1 lysate using both lysate antigens against the rabbit sera and with the 597 antigen against the dog sera. Slightly greater reactivity was evidenced with the day 7 B5896 antigen when the dog sera was tested. Comparative studies are continuing in order to produce an optimal anti-genic preparation for antibody detection in blastomycosis.

GENE ENGINEERING EB VIRUS MEMBRANE ANTIGEN IN DETECTION OF MA-IgA ANTIBODY(COMPARISON WITH VCA-IgA AND EA-IgA ANTIBODIES)

With gene engineering EB virus membrane antigen as the diagnostic antigen, indirect immunofluo-rescence (IF) assay was used to detect IgA antibody against EB virus membrane antigen (MA-IgA) in sera from 202 nasopharyngeal carcinoma (NPC) patients and 315 controls (normal and patients with other tumors). MA-IgA antibody was positive in 96.8% of the pretreatment NPC patients with a GMT of 1:36.3. MA-IgA detection by this method was more sensitive than EA-IgA detection by IE. In contrast, patients with tumors other than NPC were negative for MA-IgA antibody. 9.1% of VCA-IgA positive persons were MA-IgA positive with a GMT of less than 1:5. No MA-IgA positive was found in VCA-IgA negatives. The results indicated that this method was relatively specific. In the treatment group, the positive rate and GMT of MA-IgA antibody declined with increase in survival time and the decline was faster than VCA-IgA. When recurrence or distant metastasis developed, similar to VCA-IgA and EA-IgA antibodies, the positive rate and GMT of MA-IgA antibody increased to its pretreatment level. Therefore, MA-IgA detection might be valuable in the early diagnosis and monitor of NPC.

CHARACTERIZATION OF MONOCLONAL ANTIBODY CL58 AGAINST CARCINOEMBRYONIC ANTIGEN(CEA)AND STUDY OF ITS BIODISTRIBUTION

Objective: To study the preparation and characterization of monoclonal antibody (McAb) against carcinoembryonic antigen (CEA). Methods: CEA antigen was extracted from metastasized liver of patients with colorectal cancer and used for the preparation of McAb against CEA by hybridoma technique. Immunoreactivity of McAb to CEA antigen was evaluated using ELISA. Mouse ascites was purified by two steps, high performance liquid chromatography (HPLC) using protein A and high performance hydroxylapatite (HPHT). Normal adult tissues and tumor specimen were used for immunohistochemical evaluation of the McAb. Isotope 99mTc labeled CEA McAb was used for biodistribution in tumor-bearing mouse. Results: Purified CEA antigen was a glycoprotein of 180 kD. Anti-CEA McAb affinity constant was 7.4×109/M. The McAb showed positive staining in 54–88% of colorectal cancer, gastric cancer and lung cancer, while negative for normal tissues. 24 hours after injection of 99mTc labeled McAb, tumor ID%/g was higher than 15% and tumor/blood, tumor/kidney and tumor/liver were 1.82, 1.51 and 2.92 respectively. T/NT ratios of other viscera were over 3.0. Conclusion: Purified CEA antigen had very good immunogenicity. The anti-CEA McAb was highly specific. 99mTc labeled McAb was stabled both in vivo and in vitro. In vivo distribution result was satisfactory. McAb CL58 may be useful for RII and RIGS.

Comparison of Two Enzyme Immunoassays and Four Lysate Antigens for the Detection of Antibody in Canine Blastomycosis

Blastomycosis, the systemic fungal disease of humans and animals caused by Blastomyces dermatitidis and the cryptic species Blastomyces gilchristii, is often misdiagnosed as a bacterial or viral pulmonary disease. Therefore, the development of improved immunodiagnostic assays for this disease has been the primary focus of research in our laboratory. The present study was designed to evaluate four Blastomyces yeast-phase lysate antigenic preparations (human, 597, Eagle River, WI;dog, ERC-2, WI;Human, B5927, Mountain Iron, MN;soil, 85, Georgia, ATCC 56920) for their ability to detect antibody in 48 serum specimens from dogs with diagnosed blastomycosis using an indirect ELISA (STD) compared to a biotin-streptavidin ELISA (B-SA). All four lysate antigens were able to detect antibodies in the specimens with mean absorbance values ranging from 0.930 (B5927) to 1.142 (ERC-2) with the STD ELSA and from 1.395 (B5927) to 1.775 (85) with the B-SA ELISA. The results indicated that both ELISA methods could be utilized for antibody detection, but the B-SA ELISA exhibited greater sensitivity than the STD ELISA with all four of the lysates.

HLA antigens and anti-sperm antibody production in Iranian vasectomized men

Dear Editor： Anti-sperm antibodies （ASAs） are composed of numerous antibodies interacting with multiple sperm antigens that play a role in fertility. In males, ASAs cause ＇immune infertility＇ by decreasing sperm counts and normal forms, as well as reducing sperm motility and viability, markedly reducing the likelihood of natural conception. The development of ASA in the male depends on the release of sequestered antigens on germ cells following the disruption of the blood-testis barrier.

Antigen Gene Cloning and Expression of HIV-1 for AIDS Vaccine Design Ⅲ. HIV-1 Antigen Gene Cloning, in Vitro Expression and Antibody Induction

Objective: To evaluate the humoral immune induction in rats of a candidate AIDS vaccine expressing the gag p24 gene froma subtype B HIV-1 isolate. Methods: The amplified p24 gene was inserted into aneukaryotic expression vector to form the supercoiled DNAvaccine. The linearized expressed DNA vaccine was preparedfrom the expression plasmid by polymerase chain reaction(PCR). The antigen gene expression in rats of the linearizedand supercoiled DNA vaccines were in vitro and in vivodetected. Results: In vitro transcription and Northern hybridizationshowed that the linearized DNA vaccine could synthesizeamounts or p24 mRNA similar to the supercoiled DNA vaccine.Antibody assays of inoculated rats confirmed that thelinearized expression DNA could induce a slightly higherantibody titer than the expression plasmid, while the highestautibody titer had been induced by plasmid plus adjuvantinoculation. Conclusion: The construction of a candidate AIDS vaccinebased on the p24 gene could shed light on a potential IV vaccine, meriting evaluation in a rhesus macaque SHIV-AIDSmodel.

Recognition of HBV antigens and HBV DNA by dendritic cells

BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic, noncytopathic, DNA virus which can cause acute and chronic infection. Viral persistence is associated with a weak or absent specific immune responses to HBV, particularly the cellular immune response. Dendritic cells (DCs) are professional antigen-presenting cells with a unique T cell stimulatory aptitude that play a crucial role in the instruction of adaptive immune responses upon infection. An impaired function of DCs was suggested by recent studies to account for the T and B cell hyporesponsiveness in chronic HBV infection. This review summarizes recent insights into the recognition of HBV antigens by DCs. DATA SOURCES: Studies were identified by searching MEDLINE and/or PubMed for articles using the key words 'hepatitis B virus (HBV)', 'dendritic cells', 'C-type lectins', 'mannose receptor', 'toll-like receptor', and 'dendritic cell-specific intercellular-adhesion-molecule-3 grabbing nonintegrin (DC-SIGN)' up to December 2009. Additional papers were identified by a manual search of the references from the key articles. RESULTS: DCs play an important role in the progress of hepatitis B, especially in the recognition of HBV. There are three main ways of recognition of HBV antigens by DCs. First, HBV DNA can be recognized by DCs through toll-like receptor 9 (TLR9) which activates the NF-kappa B signal pathway and p38 MAPK to up-regulate the expression of interferon (IFN) regulatory factor 7 (IRF-7) in a manner independent of type I IFN signaling, resulting in secretion of type I IFN and inflammatory cytokines, and induction of DC maturation and the adaptive immune response. Second, HBc/HBeAg cannot be recognized by DCs, but DNA or ssRNA encapsulated within HBcAg can be internalized by DCs through TLRs. Third, HBsAg can be internalized by DCs through the mannose receptor, which lacks the ability to induce DC maturation without the assistance of DC-SIGN. Meanwhile, there is some cross-talk among the three mechanisms, which induces an effective anti-viral response or HBV persistence. CONCLUSIONS: On the basis of these recognition processes, methods have been used to enhance the efficacy of DC-based vaccine against HBV and have been useful in the clinical application of HBV vaccine therapy. But the interactions between HBV antigens/HBV DNA and DCs are not clear, and cross-talk between TLRs and various ligands makes HBV antigen recognition by DCs more complicated. More efforts should be made to define the mechanisms and develop effective vaccines and therapies. (Hepatobiliary Pancreat Dis Int 2010; 9:584-592)

Methodological aspects of anti-human leukocyte antigen antibody analysis in solid organ transplantation

Donor human leukocyte antigen(HLA)-specific antibodies(DSA) play an important role in solid organ transplantation. Preexisting IgG isotype DSA are considered a risk factor for antibody mediated rejection, graft failure or graft loss. The post-transplant development of DSA depends on multiple factors including immunogenicity of mismatched antigens, HLA class Ⅱ typing of the recipient, cytokine gene polymorphisms, and cellular immunoregulatory mechanisms. De novo developed antibodies require special attention because not all DSA have equal clinical significance. Therefore, it is important for transplant clinicians and transplant immunologists to accurately characterize DSA. In this review, the contemporary immunological techniques for detection and characterization of anti-HLA antibodies and their pitfalls are described.

Identification of a gene engineering antibody against cystic echinococcosis in liver

OBJECTIVE: To identify a gene engineering antibody against cystic echinococcosis in liver. METHODS: A single chain of variable fragment of human antibodies (ScFvs) was selected from the library by using affinity selection technique with the recombinant antigen on solid surface. The positive clones were demonstrated by ELISA and their DNA sequences were also determined. RESULTS: The DNA sequence data showed that the antibody gene is composed of 768bp. In addition, a specific combination capacity with recombinant Echinococcus granulosus antigen B (r-EgB) was demonstrated by ELISA. CONCLUSION: The obtained gene engineering antibody against r-EgB may have potential implications in immunological treatment and drug targeting delivery.

Development of Anti-Isoproturon Polyclonal Antibody

A competitive enzyme-linked immunosorbent assay （ELISA） suitable for the determination of the urea herbicide isoproturon, 3-（4-isopropylphenyl）-l,l-dimethylurea, in food and environmental samples was developed. Two haptens named 1-（3- carboxypropyl）-3-（4-isopropylphenyl）-1-methylurea （hapten 4C） and 1-（5-carboxypentyl）-3-（4-isopropylphenyl）-1- methylurea （hapten 6C） were synthesized. The haptens were coupled to bovine serum albumin （BSA） and ovalbumin （OVA）, respectively, using the N-hydroxysuccinimide reaction. The hapten 6C-BSA conjugate was used as the immunogen, with which a high-titer anti-isoproturon polyclonal antibody （pAb） was successfully obtained by immunization of New Zealand white rabbits. The hapten 4C-OVA conjugate was used as coating antigen and a method of the indirect competitive ELISA for isoproturon was established. The haptens were confirmed with TLC, IR, and 1H NMR. The conjugation molar ratios of hapten 4C to OVA and hapten 6C to BSA were 36：1 and 46：1, respectively, as calculated by a UV spectrophotometry. The highest titer of the anti-isoproturon sera determined by a non-competitive indirect ELISA procedure was 1.6 × 10^5. The optimal concentrations of the coating antigen and the dilution of the anti-isoproturon sera used in the ELISA were 0.1 mg·L^-1 and 1.0 × 10^5, respectively. The concentration of isoproturon that inhibits 50% of antibody-antigen binding （IC50） was 0.07 mg·mL^-1. The cross-reactivities of six urea herbicides including chlorbromuron, fluometuron, monolinuron were lower than 0.1%. Isoproturon is a small molecule without immune activity and active functional group for attaching to carrier protein. To produce an antibody against isoproturon with high titer and high specificity is the most important step in the development of an immunochemical method for the determination of isoproturon in food and environmental samples. The two haptens synthesized in this study have carboxyl groups and accommodate different lengths of spacer arms, and the phenyl and isopropyl groups are fully exposed. An anti-isoproturon polyclonal antibody with high titer and high specificity was successfully obtained by immunization of rabbits with the conjugate of the hapten attached to the protein carrier.