In a rare incident, a patient has cleared functional HIV infection without outside help. This may the first known instance of a spontaneous cure. According to reports, over 1-5 billion cells of this patient was analysed and it showed no functional HIV copies in any of them. However, the person still has some non-functional copies of the virus.
Another patient had just one functional copy of HIV in more than 1 billion blood cells. This HIV copy was stuck in a genetic supermax prison, as reported by Science News.
These two people are among the rare group of people are able to maintain very low or undetectable levels of HIV without antiretroviral drugs. This group of people is known as elite controllers.
These people have no symptoms or clear signs of damage from the virus. “It’s not even that we’re talking about a few months or a few years. It’s extremely long-term,” says Satya Dandekar, an HIV researcher at the University of California, Davis School of Medicine who was not involved in the study. In contrast, for 99.5 percent or more of the world’s 35 million people infected with the virus, drugs are the only way to keep the virus down.
HIV is a retrovirus, which means that it stores its genetic information as RNA. An enzyme called reverse transcriptase copies those RNA instructions into DNA, which can then insert into the host’s DNA. Reverse transcriptase is error prone, often resulting in defective or incomplete copies of the virus. So the researchers went into the study thinking that elite controllers might be loaded with these nonfunctional versions, which can’t make infectious virus, says Xu Yu, an immunologist at the Ragon Institute of MGH, MIT and Harvard in Boston.
Yu and colleagues investigated whether elite controllers have a propensity for steering the virus to heterochromatin. But in lab dishes, the guide proteins in elite controllers’ cells still direct HIV insertions in or near genes, just like what happens in the cells of other people.
“It’s probably not that [elite controllers] just got lucky at the beginning of the infection” to get HIV trapped in heterochromatin, says Yu’s Ragon Institute colleague, Mathias Lichterfeld, a virologist and infectious diseases physician. Instead, the researchers think elite controllers’ immune systems eliminated cells producing functional virus, leaving behind only broken copies of the virus and intact versions locked in heterochromatin. Exactly how the immune system manages that feat isn’t known.
The researchers have submitted the findings in Nature's August 26 report.
