HIV update - 2nd September 2014

Encouraging vaccine news

A relatively simple vaccine that works in an unusual way has managed to completely block infection with SIV, the monkey equivalent of HIV, in monkeys. This finding gives new hopes for the development of a vaccine which could prevent HIV infection.

But the research is also encouraging in terms of a vaccine for people who have already acquired HIV – in other words, a therapeutic vaccine to suppress the replication of HIV. When the vaccine was given to monkeys who were previously infected with SIV, their viral load was rapidly suppressed.

The vaccine works in a very different way to other HIV vaccines that have been tested. The French and Chinese scientists who developed it were themselves surprised by the positive results of their unconventional approach. They say the results suggest a new approach for developing an HIV vaccine in humans.

The vaccine appears to work by stimulating the production of a previously unknown group of CD8 T-cells that stopped the monkeys’ CD4 cells from recognising SIV as a foreign invader, thereby preventing an immune response to SIV. This suppressant effect means that the SIV is deprived of the SIV-specific immune-activated CD4 cells it needs in order to proliferate and establish an infection in the body.       

The vaccine consisted of inactivated SIV administered alongside doses of bacteria that are already familiar to scientists – either BCG, an anti-tuberculosis vaccine or gut bacteria that are used in probiotic supplements.

Although the study is small, involving a few dozen animals, around half of those vaccinated were completely protected from infection, while some others were infected but soon had an undetectable viral load. In contrast, all monkeys that were not vaccinated were infected.

Other scientists should now check that they get the same results when using the same technique. But it remains to be seen whether the approach will work in humans – previous HIV vaccines have looked promising in animal studies but have failed to work in humans.

As a first step to finding out, two safety trials are planned in humans. In one, HIV-negative volunteers at low risk of HIV will be given the vaccine to see if it stimulates the same immune- and virus-suppressant responses. In the other, HIV-positive volunteers on fully suppressive HIV treatment will be given the vaccine and then taken off treatment six months later if test tube results suggest the vaccine has produced such responses.

If you are interested in taking part in vaccine trials in the UK, or encouraging people in your networks to find out about volunteering for trials, visit the Help make history website. It has information on HIV vaccine trials that are currently recruiting participants, and you can register your interest in future trials.

Talking about HIV status before having a baby

A study in South Africa has found that over 40% of women who had recently been pregnant and a third of men whose partner had been pregnant did not know what their partner’s HIV status was. The respondents included both HIV-positive people who did not know whether their partner also had HIV, and HIV-negative people whose partners could have been living with HIV.

People living with HIV who are married or have a long-term sexual partner sometimes think that their partner will inevitably also have HIV. However, this is not necessarily the case – many partners remain HIV negative, for a period of time at least. The only way to be sure of your partner’s status is through HIV testing.

When a couple knows that they have different HIV statuses, they can take steps to avoid HIV transmission within the couple. This could include using condoms, taking pre-exposure prophylaxis (PrEP) and taking HIV treatment.

And if they would like to have a child they can also take steps to become pregnant and give birth, without either the baby or the partner acquiring HIV. But to benefit from these measures, individuals need to be aware of their own HIV status and that of their partner.

The researchers were especially interested in whether people had discussed HIV status before becoming pregnant. They say that more needs to be done to help couples with HIV testing and disclosure.

NAM has created an interactive tool for women which provides information on pregnancy and having a baby. For women who are not pregnant yet, there is detailed information on the safest ways to become pregnant. The information is personalised to your situation, including your partner’s HIV status. The tool can be used both by women living with HIV and by HIV-negative women who have HIV-positive male partners. The tool is available on a computer or a smartphone by visiting www.aidsmap.com/pregnancy

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