AIDS Trial Narrowed, Research Progresses

The NIH narrowed an AIDS vaccine trial planned for U.S. testing. The trial, called Partnership for AIDS Vaccine Evaluation (PAVE 100) will be pared down to focus on the question of whether the vaccine lowers amount of HIV virus in the blood of those who are subsequently infected after vaccination. Scientists questioned the sense of moving forward with this larger trial last year in light of the failure of the multi-country Merck vaccine trials, as we commented in "New Directions for AIDS Research Funding".

In other AIDS research news,Weijing He and a team of colleagues in the US and UK found that a protein called DARC (Duffy antigen receptor for chemokines), that makes some African people resistant to malaria may influence HIV infections and AIDS outcomes. The small study published by Cell Host & Microbes shows that the existence of certain DARC mutations enables resistance to some malaria parasites -- though not Plasmodium falciparum, the most prevalent and deadly parasite.

The DARC mutation that prevents infection by some malaria parasites also seems to influence how successfully HIV invades and attacks the immune system. DARC codes a receptor on the surface of red blood cells that binds or tethers the HIV virus. The researchers found that a particular mutation of DARC increases the odds of acquiring HIV-1.

However the mutation also seems to increase the DARC protein's interactions with chemokines. Chemokines are proteins in the immune system that trigger inflammation, and they interact with HIV virus. Researchers have shown that the DARC protein acts by scavenging, retention, or transporting chemokines, and mutated DARC protein seems to lower levels of chemokines. In this study, once infected, people with the mutated DARC lived 2 years longer than those with the normal copy of the protein. While the study helps pave an outline of these interactions the authors predict (with understatement) that future research will show "the net effect of the relationship between DARC and chemokines on HIV disease in vivo is likely to be much more complex."

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