BBC World News

SÃO PAULO — Despite 25 years of research, a vaccine against HIV remains stubbornly out of scientists’ reach. There are, however, around 30 HIV vaccines in clinic trials around the world, and many others at different stages of development, both building on past experience and experimenting with new concepts.

Scientists at the University of São Paulo in Brazil have been working on their HIVBr18 vaccine since 2002. The team claims their vaccine is the only one in development which aims to trigger  CD4+ T-cells — special immune system helper cells vital to coordinating the body’s immune defence system.

Preliminary results from a new technique, tested on animals earlier this year, have proved extremely encouraging.

As part of a BBC Health Check special on HIV, our reporter in São Paulo, Ben Tavener, has been finding out how a vaccine in Brazil is progressing.

Rhesus monkeys at Butantan Institute, São Paulo, are involved in the development of USP's HIV vaccine.

Rhesus monkeys at the Butantan Institute, São Paulo, are involved in the development of USP’s HIV vaccine. (Photo: Ben Tavener)

Scientists from the University of São Paulo (USP) say that a preliminary test on primates given a experimental anti-HIV vaccine being developed by the university has produced unexpectedly good results.

The study on rhesus monkeys gave three separate doses of the vaccine, prepared by USP scientists at the Faculty of Medicine, at varying intervals since last November at the university’s Butantan Institute, a world leader in pioneering vaccines and anti-venoms.

The immunising component of the vaccine has been developed and patented by the leading Brazilian university.

We tested the immune response of the [monkeys] and the results were excellent,” lead vaccine developer Edécio Cunha Neto was quoted by Folha de S.Paulo newspaper as saying.

The results surprised scientists by how intense the response was in primates, after more muted results from tests on rats. Vaccine responses are usually expected to be lower in primates than in rodents, but in this case the primate responses were up to ten times higher.

HIV vaccine for humans?

The scientists’ goal is to create a safe and effective human vaccine that will immunise people against the virus which, if not kept at bay by antiretroviral drugs, leads to AIDS.

Figures from the World Health Organization says AIDS killed around 1.6 million people worldwide in 2012, and that 35 million people are currently living with HIV/AIDS.

Researchers developing the vaccine since 2002 first looked at human patients whose own immune systems were capable of recognising and fighting HIV, allowing them to work out which peptide components of the virus were triggering a response from the body.

This breakthrough gave rise to a targeted DNA vaccine, which has been tested on rodents modified to replicate human immune responses, and now on primates.

Researchers are looking to put the vaccine technology into a host virus which would be unable to infect the individual with HIV but would give greater immunisation.

The next stage for the vaccine will see it given to 28 of the rhesus monkeys to compare immune responses depending on a set of variables over two years. This development phase on monkeys is expected to last until 2016.

Financial and ethical cost

The first dose of the HIV vaccine was given to the healthy primates at the beginning of November 2013 in conjunctive with a flu-like virus, which scientists say catalyses a greater immune response.

The enclosure housing the monkeys at the Butantan Institute has been subject to tighter security since the beginning of trials due to increased activity by animal rights campaigners, who have questioned why the tests have to be carried out on primates.

However, researchers say that the final human destination for the vaccine means primates must be used in its development, given their genetic closeness to humans, but have stressed that the animals taking part in the experiments are well treated.

Eventually it is hoped to move the study onto a human testing phase, although the university is still looking for private investors as such a phase is expected to cost some R$250 million (US$105 million at today’s rate) to develop.

The study has so far cost around R$1 million (US$419,000), reports say.

Other HIV vaccines are in different phases of development across the world, and hundreds of millions of dollars are being spent annually on this medical holy grail.

(Report written for Anadolu Agency)