A virus with nine lies

UF researchers explore possible use of cat AIDS virus for human HIV vaccine

By Sarah Carey

Blood from HIV-infected human subjects shows an immune response against a cat AIDS virus protein, a surprise finding that could help scientists find a way to develop a human AIDS vaccine, UF and University of California, San Francisco researchers have found.

This discovery, published in the Journal of Virology, supports further exploration of a human AIDS vaccine derived from regions of the feline AIDS virus.

“One major reason why there has been no successful HIV vaccine to date is that we do not know which parts of HIV to combine to produce the most effective vaccine,” said Janet Yamamoto, Ph.D., a professor of retroviral immunology at the UF College of Veterinary Medicine and the study’s corresponding author. “The possible use of the cat virus for this vaccine is unique.”

The researchers are working on a T-cellbased HIV vaccine that activates an immune response in T cells from HIV-positive individuals against the feline AIDS virus. T-cell peptides are small pieces of protein that can prompt the body’s T cells to recognize viral peptides on infected cells and attack them. However, not all HIV peptides can work as vaccine components, Yamamoto said.

“We are looking for those viral peptides in the cat AIDS virus that can induce anti-HIV T-cell activities and do not mutate,” she said. “Surprisingly, we have found that certain peptides of the feline AIDS virus can work exceptionally well at producing human T cells that fight against HIV.”

The researchers isolated T cells from HIV-positive individuals and incubated these cells with different peptides that are crucial for survival of both human and feline AIDS viruses. They then compared the reactions they got with feline immunodeficiency virus, or FIV, peptides to what they found using HIV-1 peptides.

Yamamoto and her team believe the feline AIDS virus can be used to identify regions of the human AIDS virus that might be more effectively used in a vaccine-development strategy for HIV.

“We found that one particular peptide region on FIV activated the patients’ T cells to kill the HIV,” Yamamoto said, adding that this feline viral region is present in multiple AIDS-like viruses across animal species. “It must be a region so essential that it cannot mutate for the survival of the virus.”