HIV replicates in the body even when undetectable in the bloodstream
Finding is fundamental to completely eradicate the virus10/03/2015
A HIV patient can reduce the viral load to undetectable levels by continuous use of powerful medications. However, when the treatment is interrupted, the virus quickly returns to the bloodstream. How is this possible? The answer to this mystery was recently found in a study lead by researchers from NorthWestern University, in the USA and published on Nature.
According to the research, the HIV persists in the body in a reservoir in lymphoid tissue. This tissue is found in the spleen, tonsils, appendix and other components of the lymphatic system. And the virus is not latent: it can replicate, move and even evolve. The papers authors believe this is the reason the viral infection is reactivated whenever the therapy is interrupted.
To reach this hypothesis, scientists assessed viral sequences from lymph node cells and blood from three HIV patients whose viral load was already undetectable in the bloodstream. “We noticed these reservoirs were constantly refilled with low-replication viruses in the infected lymphoid tissue, and then, migrating from these protected sanctuaries to the bloodstream”, said doctor Steven Wolinsky, one of the papers authors, interviewed by the Brazilian Society of Tropical Medicines communication department.
Until now, most scientists believed the reservoir only contained infected cells in a latent state for several reasons. First, no one had ever seen the virus with the new genetic mutations that inevitably take place when the HIV completes its growth cycles. Second, most patients do not develop the resistance mutations to the treatment, especially with the presence of antiretroviral drugs in the body.
The results offer a new perspective on how the HIV remains in the body, despite the powerful antiretroviral therapy. The study also explains why the development of drug resistance is not inevitable, once the virus multiplication takes place in a place where the drug concentrations are very low.
The finding is fundamental to completely eliminating the HIV from the body, because it highlights the importance of creating ways to distribute the drug concentrations in all the lymphoid tissue. “Eliminating the infected cells in the reservoirs that protect the viruses from antiretroviral drugs in the key to reach a functional cure”, said doctor Wolinsky.…