Researchers report cats may be the key to human HIV vaccine

October 2, 2013

(Medical Xpress)—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, report University of Florida and University of California, San Francisco researchers.

Their findings appear in the October issue of the Journal of Virology. This discovery 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, a professor of retroviral immunology at the UF College of Veterinary Medicine and the study's corresponding author.

The researchers are working on a T-cell-based HIV vaccine that activates an immune response in T from HIV-positive individuals against the feline AIDS virus. T-cell 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.

"In humans, some peptides stimulate immune responses, which either enhance HIV infection or have no effect at all, while others may have anti-HIV activities that are lost when the virus changes or mutates to avoid such immunity," she said. "So, we are looking for those viral peptides in the cat AIDS virus that can induce anti-HIV T-cell activities and do not mutate."

In previous studies, scientists have combined various whole HIV proteins as vaccine components, but none have worked well enough to be used as a commercial vaccine, Yamamoto 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," she said.

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 (FIV) peptides to what they found using HIV-1 peptides.

"We found that one particular peptide region on FIV activated the patients' T cells to kill the HIV," Yamamoto said.

This feline viral region identified by human cells appears to be evolutionarily conserved—it is present in multiple AIDS-like viruses across animal species, she added.

"That means it must be a region so essential that it cannot mutate for the survival of the virus," she said.

Yamamoto and her team believe that 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 want to stress that our findings do not mean that the feline AIDS virus infects humans, but rather that the cat virus resembles the human virus sufficiently so that this cross-reaction can be observed," said study collaborator Dr. Jay A. Levy, a professor of medicine at UCSF.

To date, a T-cell-based vaccine has not been used to prevent any viral diseases, Yamamoto said.

"So we are now employing an immune system approach that has not been typically utilized to make a vaccine," she said. "The possible use of the cat virus for this is unique."

Michael Murphey-Corb, a professor in the department of microbiology and molecular genetics at the University of Pittsburgh, has known Yamamoto since she discovered the feline AIDS virus.

"Dr. Yamamoto has identified the immunological Achilles' heel of HIV," Murphey-Corb said.

Levy, along with Dr. Mobeen Rathore, director of the UF Center for HIV/AIDS Research, Education and Service in Jacksonville, and the University of South Florida in Tampa provided the blood from HIV-infected subjects. Other collaborators include the UF College of Medicine, the Clinical and Translational Science Institute at UF, and LifeSouth Community Blood Centers of Gainesville.

Explore further: AIDS vaccine candidate appears to completely clear virus from the body

Related Stories

AIDS vaccine candidate appears to completely clear virus from the body

September 11, 2013
An HIV/AIDS vaccine candidate developed by researchers at Oregon Health & Science University appears to have the ability to completely clear an AIDS-causing virus from the body. The promising vaccine candidate is being developed ...

Harnessing immune cells' adaptability to design an effective HIV vaccine

March 21, 2013
In infected individuals, HIV mutates rapidly to escape recognition by immune cells. This process of continuous evolution is the main obstacle to natural immunity and the development of an effective vaccine. A new study published ...

HIV/AIDS vaccines: Defining what works

July 18, 2013
Designing an effective HIV/AIDS vaccine is something of a paradox: a good vaccine would be safe and look enough like HIV to kick-start the immune system into neutralizing the virus – but the problem is that this is exactly ...

New target to fight HIV infection identified

October 1, 2013
A mutant of an immune cell protein called ADAP (adhesion and degranulation-promoting adaptor protein) is able to block infection by HIV-1 (human immunodeficiency virus 1), new University of Cambridge research reveals. The ...

Study explores barriers to HIV vaccine response

September 20, 2013
Researchers at The Scripps Research Institute (TSRI) discovered that an antibody that binds and neutralizes HIV likely also targets the body's own "self" proteins. This finding could complicate the development of HIV vaccines ...

New HIV-1 replication pathway discovered

September 18, 2013
Current drug treatments for HIV work well to keep patients from developing AIDS, but no one has found a way to entirely eliminate the virus from the human body, so patients continue to require lifelong treatment to prevent ...

Recommended for you

New injectable antiretroviral treatment proved to be as effective as standard oral therapy

August 3, 2017
Intramuscularly administered antiretroviral therapy (ART) may be as effective for HIV treatment as current oral therapies. This is the main conclusion of a Phase II clinical trial carried out by 50 research centers around ...

Research finds home-based kit would increase HIV testing

July 31, 2017
Research led by William Robinson, PhD, Associate Research Professor of Behavioral & Community Health Sciences at LSU Health New Orleans School of Public Health, has found that 86% of heterosexuals who are at high risk for ...

Scientists divulge latest in HIV prevention

July 25, 2017
A far cry from the 1990s "ABC" campaign promoting abstinence and monogamy as HIV protection, scientists reported on new approaches Tuesday allowing people to have all the safe sex they want.

Girl's HIV infection seems under control without AIDS drugs

July 24, 2017
A South African girl born with the AIDS virus has kept her infection suppressed for more than eight years after stopping anti-HIV medicines—more evidence that early treatment can occasionally cause a long remission that, ...

Meds by monthly injection might revolutionize HIV care (Update)

July 24, 2017
Getting a shot of medication to control HIV every month or two instead of having to take pills every day could transform the way the virus is kept at bay.

Candidate AIDS vaccine passes early test

July 24, 2017
The three-decade-old quest for an AIDS vaccine received a shot of hope Monday when developers announced that a prototype triggered the immune system in an early phase of human trials.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.