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Vpr, an auxiliary protein of HIV-1(Human immunodeficiency virus type 1), exerts important functions to promote viral replication and AIDS progression. In this study, we performed a yeast two-hybrid screening assay using human cDNA library to further investigate the molecular mechanism of various functions of Vpr RelB, a key protein in NF-kappaB signaling pathway, was identified as a Vpr interaction protein by co-immunoprecipitation. Further investigations indicated that RelB not only promoted the Vpr-mediated activation of NF-kappaB reporter gene, but also enhanced the transactivation of HIV LTR. Moreover, the results showed that RelB promoted Vpr-induced cell cycle G2/M arrest. Collectively, these results indicated that RelB might interact with Vpr and regulate its transcriptional activation and cell cycle arrest.

Aim: To explore the possibility of the replacement of the gag gene between human immunodeficiency virus and bovine immunodeficiency virus, to achieve chimeric virions, and thereby gain a new kind of AIDS vaccine based on BHIV chimeric viruses., Methods: A series of chimeric BHIV proviral DNAs differing in the replacement regions in gag gene were constructed, and then were transfected into 293T cells. The expression of chimeric viral genes was detected at the RNA and protein level. The supernatant of 293T cell was ultra centrifuged to detect the probable chimeric virion. Once the chimeric virion was detected, its biological activities were also assayed by infecting HIV-sensitive MT4 cells., Results: Four chimeric BHIV proviral DNAs were constructed. Genes in chimeric viruses expressed correctly in transfected 293T cells. All four constructs assembled chimeric virions with different degrees of efficiency. These virions had complete structures common to retroviruses and packaged genomic RNAs, but the cleavages of the precursor Gag proteins were abnormal to some extent. Three of these virions tested could attach and enter into MT4 cells, and one of them could complete the course of reverse transcription. Yet none of them could replicate in MT4 cells., Conclusion: The replacement of partial gag gene of HIV with BIV gag gene is feasible. Genes in chimeric BHIVs are accurately expressed, and virions are assembled. These chimeric BHIVs (proviral DNA together with virus particles) have the potential to become a new kind of HIV/AIDS vaccine.

Objective: Chimeric human/bovine immunodeficiency virus (HBIV) cDNA was constructed by replacing HIV tat and LTR with bovine immunodeficiency virus (BIV) tat and LTR to study the activity of BIV tat and LTR in the chimerae., Methods: The target fragments of BIV tat, LTR and HIV gag, pol, env were respectively amplified by using PCR and sequentially inserted into pBluescript SK(+) vector. The chimeric clone was transfected into human MT4 cells. The transcript and gene expression of the HBIV chimeric virus were detected by using RT-PCR and a reverse transcriptase assay, respectively., Results: BIV tat mRNA and HIV gag mRNA were detected. The reverse transcriptase activity of the chimeric virus was analyzed in the fluctuation curve., Conclusions: In chimeric HBIV cDNA transfected MT?4 cells, BIV tat and HIV gag were transcripted. The reverse transcriptase of the chimeric virus had biological activity. These data suggest that in MT4 cells, BIV LTR had promoter activity and BIV tat had the function of transactivation in the chimeric virus. The study of the chimeric virus with infectivity is in progress.