Research into finding the elusive cure for HIV, the virus that leads to AIDS, has been ongoing ever since the virus was first identified in humans in the early 1980s. Though treatment with highly active antiretroviral therapy (HAART) has dramatically improved such that the disease can be relatively effectively managed, HIV remains incurable and persistent.
Approximately 33 million people in the world are HIV positive, the majority of these in developing countries, particularly in sub-Saharan Africa. The virus, which is passed on through blood and semen, is able to cleverly evade the body’s immune system – hiding, in fact, within the white blood cells, the very cells that are supposed to seek and destroy viruses and other foreign bodies. Infection with the virus is practically symptomless, but left untreated, as the virus gradually proliferates inside the body, it overpowers the immune system and leaves the body susceptible to opportunistic infections that the patient is unable to shake off. It is this Acquired Immune Deficiency Syndrome (AIDS) that leads to death, via secondary infectious diseases such as TB, pneumonia or viral cancers.
Antiretrovirals – drugs which attempt to slow the replication of virus particles inside the body – have improved the quality of life and life expectancy for HIV positive people (who have access to these drugs) no end. Though someone with HIV will, likely, ultimately die of an AIDS-related disease, they can be expected to live a long and relatively healthy life, as opposed to a death sentence within a few short years as was previously the case. Recently, a research team from the National Institute of Allergy and Infectious Diseases (NIAID) in the US has demonstrated another important benefit of antiretroviral therapy – that starting HAART as soon as HIV infection is diagnosed, rather than when AIDS begins to become apparent, can actually reduce the ability of HIV to spread from person to person.
From a huge randomised clinical trial that began in 2005 and spanned 13 countries around the world, it was found that cross infection with HIV to a non-HIV positive partner was 96% less likely if the HIV positive partner began taking HAART while their immune system was still healthy, compared to patients who began HAART only when their CD4 T-cell count fell to below 250 cells/mm3. In fact, in the first study group, only 1 new HIV infection occurred, compared to 27 in the latter group.
And NIAID are on a roll, it seems. Another research group investigating the possibility of a vaccine for HIV infection have made a very significant breakthrough using a monkey model of infection. A potential vaccine for SIV – the simian equivalent of HIV – was trialled by giving half of a healthy study population of monkeys an injection containing the vaccine, and half a placebo. The monkeys were then injected with one of two strains of SIV. Unfortunately, the vaccine failed to protect against those given the SIVmac251 strain, but of those given the SIVsmE660 strain, 50% did not develop SIV infection.
Though of course, it is too soon to tell whether this vaccine will work equally well in humans with HIV, the results are very promising. By studying the blood cells of monkeys used in the study, the researchers were able to identify the effect of ”neutralising” antibodies that helped to prevent the SIV virus from replicating, and so affirm that this line of enquiry into an HIV vaccine is valuable. The best previous vaccination results were from a study carried out in Thailand, and that particular vaccine conferred only 31% protection against the virus, so it is clear that while a cure or a fully protective vaccination for HIV is still far away, we are certainly moving in the right direction.
Lisa A. Martin - Freelance science copywriter/editor 