( In one of the first molecular studies o...)Fragment of yellow fever virus may hold key to safer vaccine

The findings may help scientists improve the existing vaccine, which has rare but severe side effects, said Jan ter Meulen, an HHMI international research scholar and associate professor of virology at Leiden University Medical Center in The Netherlands.

The group has identified a specific region on one of the viral proteins that elicits an immune response. Antibodies produced by the immune system interact with this part of the protein, known as a neutralizing epitope, to fight off infection. To protect people from the disease, yellow fever vaccines must contain this essential fragment of instruction to the immune system, said ter Meulen, senior author of a study published in the July 5, 2005, issue of the journal Virology and published early online.

These days, the horror of Ebola or Marburg hemorrhagic fever grabs more attention, but yellow fever is the original viral hemorrhagic fever. It strikes more than 200,000 people a year, mostly in Africa, killing about 30,000 of them, the World Health Organization estimates. No drug treatment is effective against the virus.

Since yellow fever is spread by mosquitoes, much of America has been safe from the disease thanks to control efforts aimed at the insects and a highly effective vaccine that has been available for 60 years. Vaccination is the key strategy for people living in and traveling to tropical Africa, South America, and several Caribbean Islands, where yellow fever is endemic.

In the last 20 years, however, yellow fever has been on the rise, mostly due to the lapse of immunization programs in high risk areas. More recently, serious and potentially fatal side effects from the vaccine have been r
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Source:Howard Hughes Medical Institute