New Delhi, May 19: Smallpox vaccination reduces replication of HIV by five times, according to a study. It says that ending smallpox vaccination may have contributed to the rapid spread of HIV in the mid- twentieth century.
The link has been claimed by scientists from the George Mason University and George Washington University in the US. The team studied white blood cells from 10 people immunised by smallpox virus and compared it with those extracted from another 10 people not immunised.
The scientists found lower HIV replication in the blood of people vaccinated by the smallpox vaccine.
“ There are several proposed explanations for the rapid spread of HIV in Africa, including wars, reuse of unsterilised needles and the contamination of early batches of polio vaccine. However, all of these have either been disproved or do not sufficiently explain the behaviour of the HIV pandemic. Our finding that prior immunisation 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,” Raymond Weinstein from George Mason University said. “ The duration of such protection remains to be determined.” The study has been published in the journal BMC Immunology . Smallpox vaccine consists of a virus called vaccinia, which is closely related smallpox causing virus called variola.
Both types of virus exploit the same ‘ receptor’ molecule on the surface of white blood cells.
At the end of the 1960s, smallpox was still an endemic in Africa and Asia. Smallpox immunisation was gradually withdrawn from the world during 1950s to the 1970s following the worldwide eradication of the disease.
HIV has been spreading exponentially since approximately the same time period. This relatively sudden appearance and explosive spread of HIV throughout Africa and around the world beginning in the 1950s have never been adequately explained.
“ While these results are very interesting and hopefully may lead to a new weapon against the HIV pandemic, they are preliminary and it is far too soon to recommend the general use of vaccinia immunisation for fighting HIV,” the team said.
—Agencies