Researchers have made a breakthrough in the search for a vaccine that could protect people from acquiring HIV after preliminary studies on monkeys showed a 50 percent chance of protection against the virus. Speaking at the 13th Aids Vaccine Conference under way in Barcelona, Spain yesterday, researcher Dr Louis Picker from the Oregon Health and Science University, US, said this time he was confident that the vaccine could also work in humans as well.
“The stars are aligned and we feel we have a very good shot,” said Dr Picker.
This new vaccine was made from modifying another virus with just enough Simian Immunodeficiency Virus (SIV) to be able to trigger an immune response in the monkeys’ immune system.
SIV is a virus which affects monkeys in a similar way HIV affects humans by destroying the immune system thereby making the body prone to any disease.
Scientists report that the SIV is 100 times deadlier than HIV. Dr Picker said following results of this study, they were now working towards conducting more research, this time on humans to see if it can protect humans the same way it did in monkeys.
“I think we have found a good candidate and we are currently in the process of preparing a similar study for humans,” he said.
“It could take at least two years before we go through the regulation procedures and secure enough funding for the clinical trial for humans to take place.”
Clinical trials normally take up to five years to be completed but others could be stopped midway if no sign of effectiveness is witnessed during the five-year study period.
If some form of protection is found in human trials, further confirmatory trials are conducted to ensure that the vaccine really works before it goes through the licensing and distribution process.
If the vaccine tested on the monkeys gets the nod to be tried on humans, it would be the sixth Aids vaccine efficacy trial on humans in the past 30 years.
Of the five trials conducted before, only one conducted in 2009 in Thailand proved a modest protection from HIV by 31 percent. Four other trials failed to protect people from acquiring HIV.
Further clinical trials to confirm the Thailand results have been scheduled for Thailand and South Africa soon. About 36 other studies still in their infancy are under way to establish if they can protect people from acquiring HIV.
These studies have not been tested in humans yet. Meanwhile, the director of the National Institute of Allergy and Infectious Diseases with the National Institutes of Health, US, Dr Anthony Fauci who failed to attend the conference in person because of the US government shutdown said, basing on the Thailand study, scientists now had a pathway to creating a preventive vaccine for HIV.
“This pathway will involve a vaccine design strategy that necessitates an in-depth understanding of cell lineage involved in the natural evolution of broadly neutralising anti-bodies observed over time in HIV -infected individuals,” said Dr Fauci through a video call.
A vaccine for HIV has been difficult to develop because the nature of HIV is such that it is constantly making copies of itself and constantly changing its form to a point where it becomes unrecognisable by the immune system.
The difference between this and other viruses is that bacteria remain the same and recognisable – making it possible and easier for vaccines to be made that work well all the time.
In addition to a prevention vaccine, scientists are also looking at finding a therapeutic vaccine that can be given to people already infected with HIV with a view to eliminate the virus.
“We are also exploring whether developing an effective therapeutic vaccine for HIV-infected individuals might help achieve a functional cure- that is, no measurable viral load even after discontinuing antiretroviral therapy,” said Dr Fauci.
Zimbabweans, like anyone else in the world, are eagerly waiting for a vaccine and subsequent cure for HIV as the virus continues to claim more lives.
About 1.2 million people are estimated to be living with HIV in the country, many of whom have no access to treatment.