HIV “can never be cured”
A controversial news commentary in the subscription-only journal Nature on 14th February (Happy Valentine’s Day) reports on
HIV’s status as an ‘incurable’ infection, although in many cases doctors are able to stave off the onset of full-blown AIDS by giving patients sustained courses of drugs.
This item was based on an article published in May 2007:
Decay of the HIV reservoir in patients receiving antiretroviral therapy for extended periods: implications for eradication of virus.
J Infect Dis. 2007 195:1762-1764
The persistence of latently infected resting CD4+ T cells has been clearly demonstrated in human immunodeficiency virus (HIV)-infected individuals receiving effective antiviral therapy. However, estimates of the half-life of this viral reservoir have been quite divergent. We demonstrate clear evidence for decay of this HIV reservoir in patients who initiated antiviral therapy early in infection. The half-life of this latent viral reservoir was estimated to be 4.6 months. It is projected that it will take up to 7.7 years of continuous therapy to completely eliminate latently infected resting CD4+ T cells in infected individuals who initiate antiviral therapy early in HIV infection.
which was recently backed up by a second publication from the same research group:
Persistence of HIV in Gut-Associated Lymphoid Tissue despite Long-Term Antiretroviral Therapy.
J Infect Dis. 2008 Feb 8
Human immunodeficiency virus (HIV) persists in peripheral blood mononuclear cells despite sustained, undetectable plasma viremia resulting from long-term antiretroviral therapy. However, the source of persistent HIV in such infected individuals remains unclear. Given recent data suggesting high levels of viral replication and profound depletion of CD4(+) T cells in gut-associated lymphoid tissue (GALT) of animals infected with simian immunodeficiency virus and HIV-infected humans, we sought to determine the level of CD4(+) T cell depletion as well as the degree and extent of HIV persistence in the GALT of infected individuals who had been receiving effective antiviral therapy for prolonged periods of time. We demonstrate incomplete recoveries of CD4(+) T cells in the GALT of aviremic, HIV-infected individuals who had received up to 9.9 years of effective antiretroviral therapy. In addition, we demonstrate higher frequencies of HIV infection in GALT, compared with PBMCs, in these aviremic individuals and provide evidence for cross-infection between these 2 cellular compartments. Together, these data provide a possible mechanism for the maintenance of viral reservoirs revolving around the GALT of HIV-infected individuals despite long-term viral suppression and suggest that the GALT may play a major role in the persistence of HIV in such individuals.
Many HIV patients can manage their infection with a cocktails of antiretroviral drugs which can reduce their “viral load” – the amount of virus circulating in the blood plasma – to undetectable levels. But this work shows that even in such “non-infectious” patients HIV is still lurking in gut tissues, and still infecting other immune cells in the blood. It might not ever be possible to completely eradicate the virus from the body, even though people are doing well, says Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases.
Tags: Biology, Health, HIV/AIDS, Medicine, Microbiology, Science, Vaccines, Virology
This is a piece of good news in what is otherwise an unremittingly gloomy picture of HIV/AIDS: the fact that the viral reservoir can actually be depleted over time is wonderful; given that ARV therapy can keep people healthy and viral load low AND deplete the productive reservoir means that people put on therapy early can have a cautiously optimistic prognosis.
And, of course, there is the chance that innovative therapeutic vaccines now under development could help – in combination with ARVs – to eradicate the virus in infected people completely.
We in the HIV vaccine field could do with some good news!!