BARCELONA (Reuters Health) - Researchers in Italy and the US will soon begin human trials with a "therapeutic" AIDS vaccine designed to help people infected with HIV control the infection in combination with drugs, they said on Tuesday.

The vaccine is supposed to be applied to the skin and has already been shown to benefit monkeys chronically infected with an HIV-like virus in laboratory studies, Dr. Franco Lori told Reuters Health at the International AIDS Conference.

Dr. Juliana Lisiewicz, co-founder with Lori of the Research Institute for Genetic and Human Therapy based in Washington and Pavia, Italy, is presenting details of the monkey study on Thursday at the Barcelona meeting.

Lori told Reuters Health that while they were developing the vaccine, the researchers studied the case of a man in Berlin whose immune system spontaneously controlled HIV. They concluded that they needed to stimulate "killer" T cells, white blood cells that are responsible for destroying infected cells.

"We do this by using a novel DNA vaccine that contains most of the HIV proteins," he said. "In this way we guarantee a wide spectrum of action, and do not target a specific protein."

He continued, "We gently rub the skin so that we expose a network of Langerhans cells, part of the immune system. When the vaccine gets in contact with the Langerhans cells, they signal the danger to the closest lymph node, propelling it to recognize the...virus, and activate HIV-specific killer cells that can eliminate infected cells."

In the monkey trials, seven chronically infected rhesus macaques were given antiretroviral therapy 3 weeks on and 3 weeks off, while seven others were given the drugs on the same schedule plus the vaccine.

The monkeys who did not receive the vaccine saw virus levels rebound each time there was a break in drug therapy. The seven that received the vaccine progressively controlled the rebound in viral levels from an average of 33,860 copies per milliliter of blood to less than 200 copies.

A separate group of monkeys with AIDS saw viral load drop from a mean of 4,292,260 copies per milliliter to less than 200 copies when given the drug-vaccine combination.

"The vaccine is designed to work with the drugs. Drugs can control the virus when people take them as directed but the bad news is that when patients stop--either because they can't afford them or because they simply forget them--the virus rebounds immediately. In this case, the vaccine would come into action, keeping the virus in check." Lori said.

"Our preliminary animal data provided promising results where, for the first time, a vaccine therapy suppressed the virus in chronic infection. We are optimistic that we will demonstrate similar results in humans," he told Reuters Health.

The group hopes to begin human trials at the end of this year both in Italy and in the United States. First results are expected at the end of 2003.

Reference Source 89

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