Smallpox Vaccine May Protect Against HIV

MONDAY May 17, 2010 -- Vaccination with the smallpox vaccine called "vaccinia" may boost a person's ability to resist infection with HIV, new research suggests.

If true, the finding could link the rapid, late 20th-century spread of HIV to the simultaneous vanquishing of smallpox disease and the removal of the smallpox vaccine -- and possible HIV firewall-- from worldwide distribution.

The notion stems from recent work by researchers at the University of California, Los Angeles, and George Mason University in Manassas, Va. The findings were published May 17 in BMC Immunology.

"There have been several proposed explanations for the rapid spread of HIV in Africa," Dr. Raymond Weinstein of George Mason U. said in a news release. These include "wars, the reuse of unsterilized needles and the contamination of early batches of polio vaccine," he said.

"However, all of these have been either disproved or do not sufficiently explain the behavior of the HIV pandemic," he said. "Our finding that prior immunization with vaccinia virus may provide an individual with some degree of protection to subsequent HIV infection suggests that the withdrawal of such vaccination may be a partial explanation."

The study authors noted that the vaccine for smallpox was gradually removed from use between the 1950s and the 1970s, following global elimination of the disease.

They point out that HIV began spreading faster in more or less the same time frame.

To get a closer look at how the two occurrences might be associated, Weinstein and his colleagues analyzed the behavior of white blood cells sampled from patients recently immunized with the smallpox vaccine.

They found that after exposure to HIV, cells from immunized individuals were five times less likely to allow for HIV replication than the same cells taken from non-immunized patients.

The research team theorized that administration of the smallpox vaccine might trigger long-term changes in the immune system that guard against HIV infection. They further highlighted a certain receptor on the surface of white blood cells -- called "CCR5" -- as one possible target of such a beneficial change.

"While these results are very interesting and hopefully may lead to a new weapon against the HIV pandemic, they are very preliminary and it is far too soon to recommend the general use of vaccinia immunization for fighting HIV," said Weinstein.

More information

For more on HIV transmission, visit the U.S. Centers for Disease Control and Prevention.

Posted: May 2010


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