A Quantitative Assay for Measuring of Bovine Immunodeficiency Virus Using a Luciferase-based Indicator Cell Line

In order to quantitate the bovine immunodeficiency virus line （BIVL） was established by transfecting baby hamster kidney （BIV） cells infection in vitro, a BIV indicator cell with reporter plasmids containing the firefly luciferase gene driven by a BIV long terminal repeat promoter. The BIV activates promoter activity of the LTR to express luciferase upon infection. BIV infection could therefore by quantified by detection of luciferase activity. Compared to standard assays used to detect BIV infection, the BIVL-based assay is 10 times more sensitive than the the CPE-based assay, and has similar sensitivity with the viral capsid protein Western blot assay BIV indicator cell line could detect BIV infection specifically. Luciferase activity of BIV infected BIVL cells showed a time dependent manner, and 60 h post infection is the optimal time to detect BIV infection. Luciferase activity of BIVL cells correlates with the BIV capsid protein expression. Moreover, a linear relationship was found between MOI and the activated intensity of luciferase expression. In brief, the BIV indicator cell line is an easy, robust and quantitive method for monitoring BIV infection.

Construction and characterization of chimeric BHIV (BIV/HIV-1) viruses carrying the bovine immunodeficiency virus gag gene

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.

An Experimental Model for Screening Anti-AIDS Drugs with Bovine Immunodeficiency Virus

The assays for bovine immunodeficiency virus (BIV) induced syncytium formation and BIV long terminal repeat (LTR) directed luciferase (Luc) gene expression were applied to screen and evaluate anti AIDS drugs. Frequency of the syncytium formation and BIV LTR directed Luc activity were in proportion to the number of input BIV infected cells. AZT inhibited the syncytium formation and the BIV LTR directed Luc gene expression level. Its inhibitory effects were dosedependent with the IC 50 being 0.24 and 0.052 mmol / L, respectively.

Crystal structures of catalytic core domain of BIV integrase: implications for the interaction between integrase and target DNA

Integrase plays a critical role in the recombination of viral DNA into the host genome.Therefore,over the past decade,it has been a hot target of drug design in the fight against type 1 human immunodeficiency virus(HIV-1).Bovine immunodeficiency virus(BIV)integrase has the same function as HIV-1 integrase.We have determined crystal structures of the BIV integrase catalytic core domain(CCD)in two different crystal forms at a resolution of 2.45Åand 2.2Å,respectively.In crystal form I,BIV integrase CCD forms a back-to-back dimer,in which the two active sites are on opposite sides.This has also been seen in many of the CCD structures of HIV-1 integrase that were determined previously.However,in crystal form II,BIV integrase CCD forms a novel face-toface dimer in which the two active sites are close to each other.Strikingly,the distance separating the two active sites is approximately 20Å,a distance that perfectly matches a 5-base pair interval.Based on these data,we propose a model for the interaction of integrase with its target DNA,which is also supported by many published biochemical data.Our results provide important clues for designing new inhibitors against HIV-1.