HIV vaccine offers hope in defeating ‘cleverest virus in the world’

Scientists are optimistic that an HIV vaccine on trial in SA could hold the key to outwitting “the cleverest virus in the world”.

South Africa – the biggest host of HIV-prevention studies and the country with the largest antiretroviral programme – is one of the 11 nations involved in studying whether “broadly neutralising antibodies” (BNAbs) can avert HIV infection.

These antibodies‚ which neutralise more than 90% of HIV strains‚ develop naturally in about 25% of HIV-positive people.

Last week‚ researchers from the US-based HIV Vaccine Trials Network and HIV Prevention Trials Network said they had completed enrolling about 4‚600 participants at 21 clinical sites across Africa‚ South America and the US.

Two studies — one on men‚ the other on women — are “precedent-setting”‚ according to delegates attending the HIV Research for Prevention (HIVR4P) conference in Madrid‚ Spain.

No fewer than 14 HIV-prevention studies are being conducted in SA‚ including those testing the efficacy of pre-exposure prophylaxis (PreP)‚ antiretroviral microbicide vaginal rings and whether hormonal contraceptives play any role in increasing the risk of HIV.

Speaking at the conference‚ prevention trials network principal investigator Larry Corey said the new trials would determine whether these potent antibodies are able to latch better on the evasive virus and kill it before it destroys the body’s most powerful infection-fighting cells – CD4 T-cells.

The CD4 cells – which act as “commander” cells and instruct other immune or “sniper” CD8 cells and other “foot soldier cells” to kill the invading virus – are often the first to be killed by HIV‚ making infected individuals prone to opportunistic infections.

“We need to know if these antibodies will protect against HIV infection‚” said Corey.

“By now we have established that it’s incredibly safe to use them on humans‚ but we want to know what works best‚ which dose of antibodies is the right amount. We hope that these two studies will give us some answers to the puzzle and provide us with the mark to shoot at.”

Some 1‚900 HIV-negative women aged between 18 and 24 are involved in the female study‚ being carried out in Gauteng‚ KwaZulu-Natal‚ the Western Cape‚ Botswana‚ Kenya‚ Malawi‚ Mozambique‚ Tanzania and Zimbabwe.

The male study‚ involving 2‚700 HIV-negative men — including transgender individuals and men who have sex with men — is being done in Brazil‚ Peru‚ Switzerland and the US.

While a vaccine teaches the body to make antibodies on its own‚ existing HIV vaccine candidates have failed because the virus mutates‚ making it unrecognisable to antibodies.

The new studies entail administering antibodies directly every two months for two-and-a-half years.

Nyaradzo Mgodi‚ from the University of Zimbabwe‚ said: “I’m very optimistic because whatever answers we get will lead us to another investigation.”