Scientists at the Ohio State University have discovered a hitherto unknown mechanism by which cells fight against the invasion of the HIV/AIDS virus. It was found that two proteins that help in the repair of injured DNA also destroy the DNA of the HIV virus, which is vital for its survival once it enters the cell.
The report published in the Proceedings of the National Academy of Sciences says that this discovery might lead to newer treatments targeting the virus. "Our findings identify a new potential drug target, one that involves a natural host defence," said lead researcher Professor Richard Fishel. "HIV treatments that target cellular components should be far less likely to develop resistance." Current treatments involve a battery of drugs, which prevent the virus from replicating itself. But doctors fear that the virus might mutate to develop resistance to this combination therapy. In the current study, it was found that cells with high levels of proteins XPB and XPD has lower levels of HIV provirus in their chromosomes. Before HIV enters the cell its genetic material is in the form of ribonucleic acid or RNA, which gets converted into cDNA once it enters the cell. The researchers at Ohio introduced mutations of the two proteins into cells and found that there were higher levels of HIV provirus in the chromosomes of these cells. Then they exposed the cells infected with HIV to a drug known to destroy cDNA. It was found that the virus was destroyed rapidly in cells with normal XPB and XPD than in those with the mutant proteins. "Overall, our results indicate that these two DNA repair proteins participate in the destruction of HIV cDNA in cells," Professor Fishel said. "This process reduces the pool of HIV cDNA that can integrate into host chromosomes, thereby protecting cells from infection."