Selection of a peptide mimicking neutralization epitope of hepatitis E virus with phage peptide display technology.

AIM: To select the peptide mimicking the neutralization epitope of hepatitis E virus which bound to non-type-specific and conformational monoclonal antibodies (mAbs) 8C11 and 8H3 fromed 7-peptide phage display library, and expressed the peptide recombinant with HBcAg in E.coli, and to observe whether the recombinant HBcAg could still form virus like particle (VLP) and to test the activation of the recombinant polyprotein and chemo-synthesized peptide that was selected by mAb 8H3. METHODS: 8C11 and 8H3 were used to screen for binding peptides through a 7-peptide phage display library. After 4 rounds of panning, monoclonal phages were selected and sequenced. The obtained dominant peptide coding sequences was then synthesized and inserted into amino acid 78 to 83 of hepatitis B core antigen (HBcAg), and then expressed in E.coli. Activity of the recombinant proteins was detected by Western blotting, VLPs of the recombinant polyproteins were tested by transmission electron microscopy and binding activity of the chemo-synthesized peptide was confirmed by BIAcore biosensor. RESULTS: Twenty-one positive monoclonal phages (10 for 8C11, and 11 for 8H3) were selected and the inserted fragments were sequenced. The DNA sequence coding for the obtained dominant peptides 8C11 (N'-His-Pro-Thr-Leu-Leu-Arg-Ile-C', named 8C11A) and 8H3 (N'-Ser-Ile-Leu-Pro- Tyr-Pro-Tyr-C', named 8H3A) were then synthesized and cloned to the HBcAg vector, then expressed in E.coli. The recombinant proteins aggregated into homodimer or polymer on SDS-PAGE, and could bind to mAb 8C11 and 8H3 in Western blotting. At the same time, the recombinant polyprotein could form virus like particles (VLPs), which could be visualized on electron micrograph. The dominant peptide 8H3A selected by mAb 8H3 was further chemo-synthesized, and its binding to mAb 8H3 could be detected by BIAcore biosensor. CONCLUSION: These results implicate that conformational neutralizing epitope can be partially modeled by a short peptide, which provides a feasible route for subunit vaccine development.

[Significance of serological markers and virological marker for hepatitis E in rhesus monkey model].

OBJECTIVE: To evaluate the serological markers and biological marker in the diagnosis of hepatitis E infection in a rhesus monkey model. METHODS: 86 rhesus monkeys had been infected with different doses of HEV. Hence, they were taken sequential blood samples at intervals up to 86 weeks for 4 hepatitis E virus (HEV) specific antibody assays (E2-IgM, E2-IgG, GL-IgG, and YES-IgG), and nucleic acid assay. RESULTS: All the animals produced E2-IgG and all but one also produced E2-IgM and excreted the virus in stool, whereas positive rate of GL-IgG and YES IgG were low and correlated with virus level. Hepatitis occurred over a period of 4 weeks (between 3 an 7 weeks) after infection. Virological marker occurred mainly during incubation period and declined rapidly after onset of hepatitis. Seroconversion of E2-IgM occurred before onset of hepatitis in 70% monkeys and declined rapidly up to 50% of peak value after 4 weeks. E2-IgM seroconversion was closely paralleled by E2-IgG; however, E2-IgG persisted in all animals for the entire duration of experiment of up to 86 weeks. Production of GL-IgG and YES-IgG was delayed by one week after the E2 antibodies, these antibodies showed a transient occurrence and seroprevalence declined to 50% of the peak value over a period of 12 weeks. CONCLUSION: E2-IgM might be used as a suitable acute hepatitis E marker, and E2-IgG as a suitable epidemiological marker. The seroconversion or titer elevation of GL-IgG and YES-IgG antibodies probably used to confirm the infection. The viral markers are optional for early diagnosis.

[Construction of highly effective artifical miRNA targeted to HIV-1 vif and the lentiviral-mediated antiviral research in vitro].

Effective and specific RNA interference (RNAi) elements are essential for the RNAi-based anti-HIV-1 research which has achieved extensive application. vif37 targeted to HIV-1 vi f is a highly effective and conserved RNAi target obtained from the previous study on screening. In this study, we explored the construction of artificial miRNAs to induce RNAi targeted to vif37, which had advantages on inhibition efficiency and flexibility of promoter selection. Three artificial miRNA targeted to vif37 were constructed by walking method using native miR-155 as a backbone and expressed by RNA polymerase II promoter. Then, expression vectors of artificial miRNA were co-transfected with HIV-1 infectious clone pNL4-3 to score its inhibition ability and showed that only miR-vif37 had the significant inhibition efficiency similar to shRNA-vif37. Subsequently, co-transfections with luciferase reporter plasmids into which different target sequences were inserted proved the specificity of miR-vif37 H. The replication of HIV-1 was inhibited in MT-4-miR37 H cells which could express miR-vif37 H stably and were cloned from MT-4 cells transducted with recombinant lentiviral vectors containing the miR-vif37 H expression element. Real-time RT-PCR revealed that miR-vif37 H had much lower expression level than shRNA-vif37. Results also showed that intracellular miR-181 and miR-16 expression levels and stat1 mRNA levels were not effected by the expression of miR-vif37 H in MT-4-miR37 H cells. We conclude miR-vif37 is a specific and highly effective artificial miRNA which will promote the further application of vif37 target.