Drug improves vaccine response in HIV patients

The drug maraviroc could help some vaccines work more effectively in people with HIV infection

The drug maraviroc could help some vaccines work more effectively in people with HIV infection, according to a study by Imperial College London researchers.

HIV causes a progressive weakening of the immune system, which results in patients responding poorly to vaccinations and becoming increasingly vulnerable to infectious diseases.

Maraviroc is already used in combination with other treatments for HIV as it prevents the virus from entering white blood cells, but now a clinical trial has found that it also enhances the body’s response to immunisation. The findings are published in the journal Molecular Medicine.

Forty-seven patients with HIV were given either maraviroc or a placebo in addition to their normal combination of antiretroviral drugs in a trial at Chelsea and Westminster Hospital, sponsored by St Stephen’s AIDS Trust. The patients were given vaccinations against meningitis, tetanus and cholera, and the researchers measured their biological responses.

After being given an injected meningitis vaccine, the levels of antibodies in the blood rose in the maraviroc group, but did not rise significantly in the placebo group. The maraviroc group also showed an increased response to an HIV protein, unlike the placebo group.

After a tetanus booster, the patients given maraviroc produced an increased amount of interferons – chemical signals that activate immune defences – and their tetanus-specific immune cells began to multiply at an earlier stage than those given a placebo.

Paradoxically, the maraviroc patients, unlike the placebo group, did not respond to the cholera vaccine, which contains killed cholera bacteria and is taken orally. The researchers believe a possible explanation is that the drug resulted in less of the vaccine crossing from the gut into the blood, but further investigation is needed to  determine if this was the case.

Dr Samantha Westrop, the study’s first author, from the Department of Medicine at Imperial College London, said: “People with HIV are vulnerable to infectious diseases and they don’t respond as well to vaccinations, so there is interest in how to improve their immune response. The outcomes of our trial using maraviroc were very encouraging and we think as a result clinicians may, in future, be interested in prescribing maraviroc in conjunction with certain vaccines."

Reference

SJ Westrop et al. 'CCR5 antagonism impacts vaccination response and immune profile in HIV-1 infection.' Molecular Medicine, 7 August 2012.