The viral reservoir of HIV, the dormant cache of the virus that can stay hidden for years and survives even the toughest regimen of anti-retroviral therapy, establishes itself in the body within days of infection and earlier than scientists previously thought, according to a study published on Sunday.
Scientists from the Beth Israel Deaconess Medical Center (BIDMC) in Boston and the U.S. Military HIV Research Program infected rhesus monkeys with simian immunodeficiency virus (SIV) — thought to be a predecessor of the human strain — and started giving them anti-retroviral drugs within three, seven, 10 and 14 days.
While the monkeys who received anti-retrovirals (ART) within three days of infection initially didn’t show any SIV-related immune response or even any evidence of the virus in the blood, all the monkeys showed signs of SIV within six months.
"Our data show that in this animal model, the viral reservoir was seeded substantially earlier after infection than was previously recognized," Dr. Dan Barouch, director of the BIDMC’s Center for Virology and Vaccine Research and one of the authors of the study, said in a release. "We found that the reservoir was established in tissues during the first few days of infection, before the virus was even detected in the blood."
Their research was published Sunday in the journal Nature.
Scientists know very little about how and when HIV’s viral reservoir becomes inextricably established in the body.
The hopes that early treatment with HIV drugs could reverse the course of the virus and eradicate the viral reservoir were recently dashed when the child known as the Mississippi baby — who was believed to be functionally cured of HIV after starting ART within days of her birth — began showing detectable signs of the virus again.
The authors of the Nature paper pointed out that starting the monkeys on ART within a few days of infection delayed signs of SIV in the blood.
Still, they said the fact that they still couldn’t eradicate the viral reservoir means that far more research needs to be done about strategies to wipe it out.
"The strikingly early seeding of the viral reservoir within the first few days of infection is sobering and presents new challenges to HIV-1 eradication efforts," the authors wrote. "Taken together, our data suggest that extremely early initiation of ART, extended ART duration and probably additional interventions that activate the viral reservoir will be required for HIV-1 eradication."