Evolution Of HIV In Lemurs
Researchers at the Stanford University School of Medicine have discovered a virus related to HIV in the genetic makeup of the Madagascar grey mouse lemur, a finding that could provide new evidence about the origins of HIV, according to a study recently published in the Proceedings of the National Academy of Sciences, IRIN/PlusNews reports. According to the researchers, the study suggests that lentiviruses -- the family of viruses to which HIV belongs -- have been present in primates for more than 14 million years.
Madagascar was last linked with mainland Africa about 14 million years ago, and this allowed lentiviruses to pass to lemurs. According to IRIN/PlusNews, it was widely believed that HIV-1 and HIV-2 were passed to humans from primates in mainland Africa and that the primates have harbored the virus for about one million years at the most. However, the study's findings contradict this theory. One of the two senior authors of the study, Robert Shafer, called the discovery "one of the most important missing links" needed to understand the evolutionary history of HIV-related viruses.
Robert Gifford, another lead author of the study, said that the lentivirus material found in the genetic makeup of the lemur will aid scientists in understanding the functions of different genes within the virus and the limit to which the virus can adapt. This information could be used to help develop HIV/AIDS treatments and prevention methods for humans, IRIN/PlusNews reports.
Gifford said, "Our discovery means that primate lentiviruses have been present in Madagascar historically and may still be circulating there. Since Madagascar has been very isolated throughout evolutionary history, it's not clear how we could have these viruses present both there and in Africa, unless they are in fact many millions of years old." He added, "If we are ever going to properly understand the relationships between lentiviruses and disease, assess the risk of new epidemics occurring, and harness the body's natural defenses to prevent and control HIV infections, we need to establish the proper ecological and evolutionary contexts." According to IRIN/PlusNews, some scientists now believe that lentiviruses could be at least 50 million years old and that they could be present in primates worldwide.
Although the findings are unlikely to dramatically alter the course of HIV/AIDS research in the immediate future, they are expected to affect scientists' understanding of the disease, IRIN/PlusNews reports (IRIN/PlusNews, 12/16). Shafer said, "If we understand how hosts have controlled infection over millennia, then that opens the way to developing new drugs or to other ways of encouraging innate resistance," London's Guardian reports.
In addition, the study's findings also indicate that the lemurs might have survived an epidemic similar to HIV/AIDS before developing immunity, "promising important insights into how the human epidemic might unfold," according to the Guardian (Beaumont, Guardian, 12/18).
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