Alternate Routes to West Nile Virus Vaccine

Date: Wed, 13 March 2002
Posted by: Environmental Risk Analysis Program (envrisk@cornell.edu)

Forwarded from ProMED-Mail (http://www.promedmail.org), a program of the International Society for Infectious Diseases (http://www.isid.org):

Source: Newsday.com, Tue 12 Mar 2002 [edited by ProMED]
(http://www.newsday.com/news/health/ny-dsbelow2621105mar12.story?coll=ny%2Dhealth%2Dheadlines)

Alternate Route to a Hybrid West Nile virus Vaccine
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In the race for an effective vaccine against West Nile virus, 2 independent research teams have taken similarly promising pathways toward the finish line. In both efforts, scientists swapped genes from the potentially fatal West Nile virus into the "backbone" genome of a distantly related virus. Researchers have reached 2 main conclusions with the resulting vaccines created by using the hybrid viruses: They are dramatically weakened, but they protect laboratory animals against lethal doses of the West Nile strain that first swept across the New York region in 1999.

The most recent research, published last week in the Proceedings of the National Academy of Sciences, details the efforts of scientists from the National Institute of Allergy and Infectious Diseases in Bethesda, MD and Walter Reed Army Institute of Research in Silver Spring, MD. The collaborators spliced 2 genes for West Nile coat proteins into a dengue virus backbone stripped of its own corresponding genes. West Nile virus and dengue virus belong to the flavivirus family of tick- and mosquito-borne viruses, a family that also includes yellow fever virus and Japanese encephalitis virus. [This research was summarised previously in the ProMED-mail post archived as "West Nile virus, candidate human vaccine 20020306.3695". - Mod.CP]. Dr. Robert Chanock, a senior investigator and mentor to the Infectious Diseases Institute coauthors, stated that the hybridization process between these distantly related viruses greatly reduces the amount of replicating hybrid virus, but allows enough of it to reproduce so that its coat proteins can induce a strong protective immune response against West Nile virus.

Thomas Monath, a vice president at the vaccine development company Acambis in Cambridge, MA, called the report an "excellent study," but he cautioned that the research is still in its early stages. Monath's company has taken a similar approach to developing a West Nile virus vaccine, by swapping the same 2 West Nile virus genes into the backbone genome of [an attenuated] yellow fever virus. Monath said that researchers currently have much more experience with the yellow fever virus backbone, which they've used to successfully present the West Nile virus coat proteins to animal immune systems. Acambis has already demonstrated that its hybrid vaccine protects horses and primates from West Nile virus infection, he said, including current trials with rhesus monkeys and baboons. The company hopes to start human clinical trials by this summer.

Acambis has already completed 3 human clinical trials using a hybrid vaccine with a yellow fever virus backbone and genes for the coat proteins of Japanese encephalitis virus, a close relative of West Nile virus. Monath said the latest of these trials, reported in the January issue of the journal Vaccine, was a "spectacular success. If we can do it for Japanese encephalitis, we're very confident we can do it for West Nile."

[Byline: Bryn Nelson]

[In accordance with the standard policy of ProMED-mail to avoid comment on vaccines under development, this thread is now cut until the results of the projected human trials for both vaccines become available. - Mod.CP]

[see also:
West Nile virus, candidate human vaccine 20020306.3695
West Nile virus, goose vaccine 20020206.3493
2001
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West Nile virus, equine vaccine 20010804.1533
West Nile virus, equine vaccine (02) 20010808.1867
West Nile virus, vaccine research 20010607.1117]

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