SA SPEAR­HEADS GLOBAL HUNT FOR ELU­SIVE HIV VAC­CINE

SA women will lead the way to find the ‘first elu­sive global vac­cine’

CityPress - - Front Page - VUYO MKIZE [email protected]­press.co.za

You strike a woman, you strike a rock is a say­ing that is tak­ing on new mean­ing with a new HIV vac­cine trial.

The trial, also known as “Im­bokodo” (HVTN 705/HPX2008), which will be con­ducted on 2 600 women in south­ern Africa, will eval­u­ate whether an in­ves­ti­ga­tional mo­saic HIV-1 pre­ven­tive vac­cine is safe and able to re­duce the in­ci­dence of HIV in­fec­tion among them.

South­ern African women will now lead the way in the quest to find the “first elu­sive global vac­cine” for HIV.

Janssen Phar­ma­ceu­ti­cals – with the Bill & Melinda Gates Foun­da­tion and the Na­tional In­sti­tutes of Health – made the an­nounce­ment about the start of the trial on the eve of World Aids Day, com­mem­o­rated yes­ter­day.

This year marks 30 years since the world started mark­ing World Aids Day. And, while there have been great ad­vances in HIV treat­ment and pre­ven­tion, around the world, and in South Africa in par­tic­u­lar, nearly 2 mil­lion peo­ple still be­come in­fected with HIV world­wide each year. HIV and Aids con­tinue to be one of the world’s most press­ing global health chal­lenges.

In South Africa alone there are 270 000 new HIV in­fec­tions a year, with 7.2 mil­lion peo­ple liv­ing with HIV, ac­cord­ing to UNAids. And the quest to find a vac­cine, let alone a cure, has been be­set by prob­lems – start­ing with the virus it­self.

Pro­fes­sor Glenda Gray, chair­per­son of the Im­bokodo study and the chief ex­ec­u­tive and pres­i­dent of the SA Med­i­cal Re­search Coun­cil, told City Press this week: “It’s a dif­fi­cult virus to un­der­stand be­cause no hu­man has been ex­posed to it and cured. We don’t have a hu­man model for that nor what it takes to be pro­tected against HIV. And what­ever we learn in pri­mates may not work in hu­mans, so we don’t have a good an­i­mal model ei­ther.

“An­other chal­lenge is that the virus repli­cates all the time so the im­mune sys­tem is al­ways play­ing catch-up. The out­er­most struc­ture of the virus is so tight that it is hard for the im­mune sys­tem to de­velop an­ti­bod­ies that can cling to the virus. So it’s like an arms race.”

The Im­bokodo study is the sec­ond vac­cine ef­fi­cacy study to be launched in more than a decade. An­other study, HVTN 702, was launched in 2016 and is un­der way to eval­u­ate a dif­fer­ent can­di­date vac­cine.

The HVTN 702 study was mod­elled on a study done in Thai­land in 2009 which showed that a par­tic­u­lar vac­cine regime could re­duce HIV trans­mis­sion by 30% and so it proved to be a mod­er­ately ef­fec­tive vac­cine. But a year af­ter the vac­cine was ad­min­is­tered, it showed to be only 60% ef­fec­tive in pro­tect­ing against HIV. It was op­ti­mised with new anti­gens and the re­sults should be known around 2020.

Gray said: “We have three strate­gies un­der way in tack­ling HIV. The one is a neu­tral­is­ing an­ti­body study, also hap­pen­ing in south­ern Africa, called AMP in which we are look­ing to see whether the po­tent neu­tral­is­ing an­ti­bod­ies we cloned from a few in­di­vid­u­als can pro­tect against HIV.

“This study is fully en­rolled and we will know in around 2020 if these neu­tral­is­ing an­ti­bod­ies work.” The Im­bokodo study aims to en­rol 2 600 sex­u­ally ac­tive women aged be­tween 18 and 35 in five south­ern African coun­tries. The first par­tic­i­pants have be­gun re­ceiv­ing vac­ci­na­tions at clin­i­cal re­search sites in South Africa. Reg­u­la­tory ap­provals are now be­ing sought to con­duct the study at ad­di­tional sites in Malawi, Mozam­bique, Zam­bia and Zim­babwe.

On the lat­est probe, Jo­han van Hoof, Janssen Vac­cines & Pre­ven­tion and Ther­a­peu­tic area head, said: “Hav­ing a pre­ven­tive vac­cine would be a vi­tal tool in a com­pre­hen­sive global strat­egy to end the HIV pan­demic.

“Our in­ves­ti­ga­tional vac­cine is based on mo­saic anti­gens that have been en­gi­neered us­ing genes from a wide range of dif­fer­ent HIV sub­types. The ul­ti­mate goal is to de­liver a global vac­cine that could be de­ployed in any geo­graphic re­gion to help pro­tect vul­ner­a­ble pop­u­la­tions at risk of in­fec­tion.”

Gray said they were start­ing in south­ern Africa be­cause it was the re­gion hard­est hit by the epi­demic. “The beau­ti­ful thing is we have three vac­cine strate­gies, in ad­vanced stages, all hap­pen­ing mostly in south­ern Africa and, very soon, they will give us insight as to what is or isn’t work­ing. We are hope­fully on the brink of ma­jor dis­cov­er­ies,” she said.

PI­O­NEER Pro­fes­sor Glenda Gray

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