The trial was carried out by an international group of
researchers - including a team from Case Western Reserve
University (CWRU) in Cleveland, OH - and is reported in the
journal Clinical Infectious Diseases.
The investigators found - contrary to previous studies - that the commonly used herpes drug valacyclovir (known under the brand name Valtrex) reduced levels of HIV-1 even in patients
that did not have herpes.
HIV-1 is the predominant strain of human immunodeficiency virus (HIV) that causes acquired immune deficiency syndrome (AIDS). When people refer to HIV without saying which type of virus, they usually mean HIV-1.
Previously it was thought that the herpes simplex virus 2
(HSV-2) had to be present for valacyclovir to be effective
against HIV.
Co-senior author Benigno Rodriguez, associate professor of medicine and infectious diseases at CWRU School of
Medicine, says: "These results demonstrated that the mechanism by which valacyclovir acts against HIV is not only through
the presence of HSV-2."
The results of the trial suggest not only that valacyclovir is
effective for more HIV patients than previously thought, but
they also point to new avenues for developing HIV drugs.
Such news will be most welcome given that some forms of HIV-1 are now resistant to current drugs.
Prof. Rodriguez says their work also reveals important clues
about how the drug decreases HIV-1 levels.
Valacyclovir reduces viral load by blocking HIV-1 replication
The findings suggest that valacyclovir reduces viral load
because once it activates inside HIV-infected cells, it stops the
virus from replicating.
There is a known link between HIV-1 and HSV-2 in that herpes causes periodic outbreaks of genital lesions that make herpes-infected people more likely to contract HIV through
intimate contact.
Outbreaks of herpes are treated either with acyclovir or its
newer sibling valacyclovir, which can be given in less frequent doses.
Earlier work with acyclovir had already suggested that the drug
blocked HIV-1 reproduction, even in the absence of HSV-2.
This prompted the new trials of valacyclovir in HIV-infected
patients.
The study reports the results of two trials that ran between
2009 and 2012. One trial was in the US and the other in Peru.
Altogether, 18 HIV-1 infected patients who tested negative for
HSV-2 were enrolled. They had low CD4 cell counts and they
were not taking antiretrovirals.
The patients were randomly assigned to one of two groups. In one group, the treatment began with the active drug, in the other group, it began with a placebo. The study was double-blind, meaning that throughout, neither the patients nor the clinicians who gave them the treatment knew whether they were receiving the active drug or the placebo.
The patients took the drug (active or placebo) twice daily for 12 weeks. The trial was also a crossover trial, so after a 2-week break with no medication, the groups switched - the placebo was replaced by active drug and the active drug was replaced by placebo. Another 12 weeks of taking the drug twice a day followed.
HIV viral loads were down with valacyclovir, and up with placebo
The results showed that when the patients were on valacyclovir, their HIV viral loads went down, and when they were on placebo, their HIV viral loads went up.
Co-senior author Michael M. Lederman, a professor of
medicine at CWRU, says: "Our most recent clinical study demonstrates that acyclovir
blocks HIV replication directly.
The anti-HIV activity of
valacyclovir does not depend on blocking the inflammation
caused by herpes simplex virus 2."
The CWRU team believes the study offers valuable clues to new anti-HIV drug development, using agents based on the molecular structure of valacyclovir, as Prof. Lederman explains: Funds for the study came from various institutes and programs with the National Institutes of Health (NIH).
Meanwhile, Medical News Today recently learned about a study presented at a conference that showed the antiretroviral
Truvada reduced HIV infection risk by 86%. The researchers found that taking the drug daily was highly effective at preventing HIV infection in men who have sex with men.
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