Vaccine Research

Summaries from the CDC HIV/STD/TB Prevention News Update
and links to Kaiser HIV/AIDS Reports on the Kaisernetwork and other sources

Winter 2010 News Headlines and Briefly

THAILAND:
"AIDS Vaccine Effects May Wear Off, Researchers Say"
Reuters , (02.18.2010) Maggie Fox
An AIDS vaccine candidate previously reported to have partial efficacy may have been most useful during a short timeframe, researchers announced Thursday at the 17th Conference on Retroviruses and Opportunistic Infections in San Francisco. The vaccine’s temporary protection may have waned after a year or so, making it more difficult to assess its effects, reported Dr. Nelson Michael, of the Walter Reed Army Institute of Research, and colleagues.

“It is very likely that this vaccine only worked for a short period of time,” Michael said. The trial in Thailand showed a 31 percent cut in infection risk over a longer timeframe of three years. “It is a weak, a modest effect but something that we can build on.”

The vaccine is a combination of Sanofi-Pasteur’s ALVAC canarypox/HIV vaccine and AIDSVAX, made by VaxGen and now owned by the nonprofit Global Solutions for Infectious Diseases.

Though the trial enrolled 16,000 volunteers, they were not individuals at particularly high risk of HIV infection, Michael said. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, and Michael will work together to design a trial in Asia or Africa to better determine whether the vaccine can be useful.

“Is [short-term protection] ideal? No,” said Michael. “But it is true there are vaccines like the flu vaccine where you have to get them every year.”

Researchers next will examine the blood of trial participants to look for clues as to why the vaccine worked. Labs around the world will be searching for correlates of efficacy, such as measurements of antibodies that indicate some immune system response, Michael said. Those results could take roughly a year.

"US Company Virxsys Says Using AIDS to Fight AIDS"
Reuters , (02.18.2010) Maggie Fox   CDC NPIN Summary
Early results presented to the 17th Conference on Retroviruses and Opportunistic Infections in San Francisco suggest a gene therapy approach to controlling HIV could be effective. Maryland-based Virxsys Corp. said two products in development have shown promise.

A gene therapy treatment called VRX496 takes a patient’s CD4 T-cells, the cells that HIV infects, and treats them with an RNA antisense product. RNA is the genetic material retroviruses such as HIV use, and antisense approaches involve a type of mirror image of the genetic sequence to block genetic activity. A crippled HIV virus genetically engineered with the antisense sequence then is used to infect the T-cells.

“VRX496 lies inactive in a patient’s white blood cells (specifically the CD4 cells), waiting for HIV to enter that cell,” said Virxsys. “When HIV does enter, replication of HIV within that cell activates VRX496, which then binds to and destroys the HIV.”

A team at the University of Pennsylvania School of Medicine is conducting a Phase I/II trial of 65 HIV-infected volunteers who are currently taking breaks in their AIDS drug regimens. While on the breaks, participants are treated with VRX496. At least one patient is showing a strong effect, said Garry McGarrity, head of science at Virxsys.

In another study, Virxsys said its genetically engineered vaccine VRX1023 was given to 15 monkeys at three different doses. Though it did not prevent infection, it did reduce viral load. The vaccine is made using a crippled HIV strain. The company is now seeking permission to conduct human trials.

“I think the vaccine is more the interesting one because it is far more doable in the end,” said Dr. Joep Lange, head of the Amsterdam Institute for Global Health and Development and a member of Virxsys’ medical advisory board. “It doesn’t prevent infection, but it does give good reduction in viral load,” said Lange, also a former president of the International AIDS Society.

 

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