Could Smallpox Vaccination Combat HIV?

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Reported May 19, 2010

Could Smallpox Vaccination Combat HIV?

(Ivanhoe Newswire) -- Could the end of smallpox vaccination in the mid-20th century have caused a loss of protection that contributed to the rapid spread of HIV in the years since then? Researchers have found the same immunization given to prevent the spread of smallpox, called vaccinia, produces a five-fold reduction in HIV replication in the laboratory.

Weinstein, a family doctor turned laboratory scientist at Mason University, Manassas, VA, worked with a team of researchers from Washington University and UCLA to test the ability of white blood cells taken from people recently immunized with vaccinia to support HIV replication. The researchers found significantly lower viral replication in blood cells from vaccinated individuals.

"There have been several proposed explanations for the rapid spread of HIV in Africa, including wars, the reuse of unsterilized needles and the contamination of early batches of polio vaccine,” Weinstein was quoted as saying. “However, all of these have been either disproved or do not sufficiently explain the behavior of the HIV pandemic. 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."

From the 1950s to the 1970s, smallpox immunization was gradually withdrawn following the worldwide eradication of the disease. HIV has been spreading exponentially since approximately the same time period.

Weinstein and his colleagues propose that vaccination may confer protection against HIV by producing long term alterations in the immune system, possibly including the expression of a certain receptor, CCR5, on the surface of a person's white blood cells which is exploited by both viruses. Weinstein concluded, "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."

SOURCE: BMC Immunology, May 17, 2010