Brazil To Test New HIV Vaccine on Rhesus Monkeys
Brazilian scientists announced that they would begin testing a new HIV vaccine on monkeys later this year. Known as the HIVBr18, the vaccine works by maintaining a viral load so low that it will keep an HIV-positive person from developing an immunodeficiency or transmitting the virus to an uninfected person.
The vaccine was developed and patented by a team from the Medicine Faculty of the University of Sao Paolo, the Sao Paulo State Research Foundation (FAPESP), who also funded the study. The research team is made up of Edecio Cunha Neto, Jorge Kalil and Simone Fonseca.
"Our goal is to test various immunization methods to select the one capable of inducing a stronger immunological response and thus be able to test it on humans," said Neto, according to the FAPESP.
Even though the vaccine will not totally rid the virus from an infected patient, it is expected to stop transmission between an infected and uninfected person, and may also lead to further understanding of new ways to stall HIV's progression in people who are positive.
The trial is expected to last two years. Rhesus monkeys, provided by Sao Paulo's state's Butantan biomedical research institute, were chosen as test subjects because their immune system is similar to a human being's. Rhesus monkeys can contract SIV or simian immunology virus; it is believed when SIV crossed the species barrier it led to the first case of HIV in humans.
Beginning in 2001, the research team worked for 12 years on the HIVBr18 vaccine, with the hope of effectively curing a global pandemic that affects 33 million people today.
Provided they receive adequate funding, at the conclusion of the monkey trials, the scientists hope to begin the first clinical trials of HIVBr18 in humans.
An HIV Vaccine Eludes Researchers
Creating a vaccine for HIV is complicated by many factors. While vaccines for illnesses like polio work by mimicking the body’s natural immunity against reinfection, this can’t work for HIV, as AIDS patients’ recovery is almost zero.
Also, while most vaccines protect against diseases, people can live with HIV infection for years before getting AIDS. And while most vaccines work within the mucosal surfaces of respiratory or gastrointestinal tract infections, HIV infection primarily occurs through the genital tract. It is also highly immutable, and evades the immune system.
Earlier this year, researchers at the Aarhus University Hospital in Denmark began conducting clinical trials on humans using a "novel strategy" proven effective in laboratory tests.
According to a New York Daily News article, the study uses a therapy that flushes the virus from so-called reservoirs that it forms within DNA cells, whereupon the body’s immune system, with help from a vaccine, can hunt and destroy. Though the therapy appeared effective when using human skin cells in the lab, efficacy in the human body remains unproven, according to Dr. Ole Sogaard, a senior researcher in the department of infectious disease.
"The challenge will be getting the patients’ immune system to recognize the virus and destroy it. This depends on the strength and sensitivity of individual immune systems," said Sogaard.
The small study would involve 15 people with funding from the Danish Research Council of $2.1 million, as British researchers conduct similar research through a consortium of five universities. Both studies would cure those already infected with the virus, but wouldn’t prevent HIV or AIDS.
The Danish study began just days after the U.S. government announced failure in a large study to develop a possible HIV vaccine. The U.S. HVTN 505 HIV vaccine trials were halted this April when they failed to reduce the amount of HIV in the blood, according to the National Institutes of Health.
"It’s disappointing, but there was important information gained," said Dr. Anthony Fauci, head of the U.S. National Institute of Allergy and Infectious Diseases.
That study enrolled 2,504 volunteers -- mostly gay men -- in 19 U.S. cities in 2009. It tested a one-two vaccination involving a genetically modified vaccine and a separate booster vaccine comprised of the same material. The strategy, known as "prime-boost," involves a DNA-based vaccine given to prime the immune system to attack the AIDS virus, followed by a second vaccine encasing the same material inside a shell made of a disabled cold virus acting as a booster shot to strengthen the response.
In that study, one half of the group received dummy shots, and the other received the two-part experimental vaccine. All were given free condoms and extensive counseling about the risk of HIV.
With the cancellation of that vaccine trial, researchers are now looking to attack the virus before it ensconces itself within host T-cells. They will try to create powerful antibodies that could beat the T-cell attack to the punch.
"We know that these trials, even those that do not achieve their goals, play an important role in informing HIV vaccine development," said International AIDS Vaccine Initiative CEO Margie McGlynn. "The world needs an AIDS vaccine, and in order to develop one we must persist in the clinical evaluation of promising vaccine strategies."