AIDS vaccine tested on apes shows promising results

Scientists are excited by the reaction of monkeys injected with an AIDS vaccine similar to that which is due to be tested in South Africa within months.  

The monkey study, which has not yet been published, involved eight monkeys, four of which were vaccinated with a vaccine modified to include the genetic material of monkey HIV, or Simian-immuno Virus.

All eight were then exposed to a lethal dose of a combination of the Simian-immuno and Human Immuno Viruses (SHIV). The four monkeys that were not vaccinated died, while the four vaccinated monkeys survived.

“Two of the monkeys developed an undetectable viral load [of SHIV] almost immediately. The third monkey developed an undetectable viral load after a few months, while the viral load of the fourth monkey was detectable but very low,” said Professor Salim Abdool Karim, deputy vice-chancellor of the University of Natal, this week.

While the response is exciting, we cannot extrapolate the findings to humans as monkeys and humans have different immune responses,” said Karim, who is co-chair of the protocol committee overseeing the AIDS vaccine initiative.

The candidate vaccine contains a portion of the genes of HIV which are harmless to humans as they cannot replicate. It is designed to train a human’s immune system to recognise and defend the body against HIV.

Meanwhile, the coalition of organisations involved in the AIDS vaccine trial have started to prepare the way for Phase One of the vaccine trial.

They have presented both the KwaZulu-Natal Cabinet and the Medicines Control Council’s ethics committee with a draft of the protocol that will govern the country’s first ever AIDS vaccine trial.

The Medical Research Council’s Neetha Morar said the draft protocol, “which sets out the who, what, how and when” of the trial, would be reviewed next month by the US and South African scientists collaborating on the vaccine.

Once the protocol was finalised, it would be submitted to the Medicines Control Council (MCC) along with an application to proceed with the trial.

The MCC has promised to fast track its response to the application.

This process, along with the fact that copies of the vaccine prototype were still being manufactured in the US, means that the phase one trial was likely to begin next year.  

“We had a candidate vaccine ready in the laboratory late last year,” said Karim. “But this is a first for us, and the process is complex and will take time.”

Morar said RK Khan Hospital in Chatsworth had been chosen as the site of the Phase One trial as scientists had recently completed a two-year trial of a possible microbicide – a vaginal gel aimed at preventing HIV transmission.

“The hospital community is aware of what is involved in running a trial, and they support us,” said Morar. “In addition, we have developed some of the infrastructure in terms of the laboratories and special wards.”

Phase one trials will also be held at the Chris Hani Baragwanath Hospital in Gauteng.

Dr Efthyia Vardas of the HIV/AIDS   Vaccine Division at Chris Hani Baragwanath said four floors of the nurses’ residence had been converted for use in Phase one trials.

This included the establishment of two laboratories and a clinical ward had been set in which the small group of volunteers for Phase one trials could be observed overnight.

She said they would be recruiting anything between 10 and 50 low risk” volunteers who are either sexually abstinent of in low risk relationships, for the Phase one trials.

Interestingly Vardas said that an overwhelming number of politicians and religious leaders had volunteered.

Volunteers would also be screened and observed for six months before the vaccine is administered.  

The Phase one trial, which will involve 48 South African volunteers and take 12 to 18 months, will only test the safety of the vaccine and not whether it can prevent HIV. The efficacy of the vaccine will only be tested in Phase Three.


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