Viral replication modulated by synthetic peptide derived from hepatitis B virus X protein.
OBJECTIVE
A strategy for viral vaccine design is the use of conserved peptides to overcome the problem of sequence diversity. At present it is still unclear whether conserved peptide is safe as a candidate vaccine. We reported it here for the first time not only to highlight the biohazard issue and safety importance for viral peptide vaccine, but also to explore the effect of a fully conserved peptide on HBV replication within the carboxyl terminus of HBx.


METHODS
We synthesized the fully conserved peptide (CP) with nine residues, FVLGGCRHK. HBV-producing 2.2.15 cells were treated with or without 3.5 microM CP for 36 hours. Quantitative detection of viral DNA was performed by real-time PCR. HBV antigens were determined by enzyme-linked immunoadsorbent assay (ELISA). Quantitative analyses of p53 and Bax proteins were based on immunofluorescence. Flow cytometry was performed to detect cell cycle and apoptosis.


RESULTS
Both extracellular and intracellular copies of HBV DNA per ml were significantly increased after incubation with 3.5 microM of CP. HBsAg and HBeAg in the cultured medium of CP-treatment cells were as abundant as untreated control cells. CP influenced negatively the extracellular viral gene products, and 3.5 microM CP could significantly inhibit intracellular HBsAg expression. In response to CP, intracellular HBeAg displayed an opposite pattern to that of HBsAg, and 3.5 microM CP could efficiently increase the level of intracellular HBeAg. Flow cytometric analyses exhibited no significant changes on cell cycle, apoptosis, p53 and Bax proteins in 2.2.15 cells with or without CP.


CONCLUSIONS
Together with the results generated from the synthetic peptide, we address that the conserved region, a domain of HBx, may be responsible for modulating HBV replication. As conserved peptides from infectious microbes are used as immunogens to elicit immune responses, their latent biological hazard for human beings should be evaluated.
Song
Chang-Zheng
CZ
Laboratory of Immunobiology, College of Life Sciences, Shandong University, Jinan 250100, Shandong Province, China. songcz@life.sdu.edu.cn
Wang
Qing-Wei
QW
Song
Chang-Cheng
CC
Bai
Zeng-Liang
ZL
D045744:Cell Line, Tumor; D017124:Conserved Sequence; D006515:Hepatitis B virus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000235:genetics; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D054334:Viral Regulatory and Accessory Proteins; D014779:Virus Replication / Q000187:drug effects*
D010446:Peptide Fragments; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein