ABSTRACT
Western blot, capture-PCR, blocking ELISA and synthetic polypeptides were used to systematically study the recognition epitopes on HEV ORF2 of 23 anti-HEV monoclonal antibodies(McAbs) which were previously generated in our laboratory directed against HEV ORF2. Results showed that seven McAbs recognized linear epitopes that located at aa408-458 of HEV ORF2 and 16 conformation-dependent McAbs, most of which recognized the surface epitopes of native HEV, located at aa459-606 of HEV ORF2. The systematical study of the recognition epitopes of anti-HEV McAbs on HEV ORF2 provides important information for the investigation of virus receptor and HEV infection mechanism, as well as its vaccine and diagnostics development.
Subject(s)
Animals , Mice , Antibodies, Monoclonal , Allergy and Immunology , Enzyme-Linked Immunosorbent Assay , Epitopes , Hepatitis Antibodies , Allergy and Immunology , Hepatitis E virus , Allergy and Immunology , Mice, Inbred BALB C , Viral Proteins , Allergy and ImmunologyABSTRACT
In this study, a new combined enzyme immunoassay(NRAg ELISA) for detection of HBV PreS1 and core antigens which was highly consistent with serum HBV DNA test was established. The serial serum dilution test indicated that the average sensitivity of the assay was 10(3.2) genome copies/mL (95% CI: 10(2.2-4.2) genome copies/mL), which was notably higher than the test performed on Pre S1 or core antigen alone. The test with sera from 994 blood donors whose HBsAg were negative demonstrated that the specificity of this assay was 99.7% (95% CI: 99.1%-99.9%). 271 serum samples from chronic hepatitis patients were also examined and the result showed that the total consistent rate between NRAg ELISA and HBV DNA was 96.3% (95% CI: 93.3%-98.2%). The NRAg ELISA S/CO(signal/cutoff) was closely correlated with HBV genome copies (R = 0.9158, n=231). Furthermore,by using this assay,we found a patient whose HBsAg was negative but HBV DNA was positive. Sequencing result showed that HBV genome from this patient had a point mutation in the "a"epitope of S gene. Our results indicate that HBV NRAg ELISA has a high relativity with HBV DNA test, and can effectively detect the mutation of HBsAg,it is expected to be a potent tool for screening HBsAg mutant and is a convenient method for substituting HBV DNA test.
Subject(s)
Humans , DNA, Viral , Blood , Genetics , Enzyme-Linked Immunosorbent Assay , Methods , Hepatitis B Antigens , Blood , Hepatitis B Core Antigens , Blood , Hepatitis B virus , Genetics , Allergy and Immunology , Polymerase Chain Reaction , Reproducibility of ResultsABSTRACT
HEV is classified into H (human) group and Z (zoonosis) group according to its compatible host. H group contains genotype 1 and genotype 2 HEV isolates which infect human only; Z group contains genotype 3 and genotype 4 HEV isolates which infect both human and animals. After analysis of amino acid sequences between ORF2 aa368 and aa606, four group-conserved sites that were all located in the neutralization region of ORF2 were identified. They are aa483, aa492, aa497 and aa599. Mutation analysis and capture PCR were then performed on these sites with a group of monoclonal antibodies. Results showed that the difference of the aa497 between H and Z groups was responsible for the maintenance of their group-specific immunodominant epitopes, probably through confirmation-dependent epitope changes. Thus, aa497 and its related change on the surface structure of HEV may play important roles in host selection by H and Z groups of HEV.