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New Hope for West Nile Virus Vaccine

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Aug. 19, 2003 — A promising vaccine for West Nile Virus could be soon available for humans. Scientists say they’ve created a vaccine — by combining a related virus with West Nile virus — that effectively protects monkeys from the infection.

Aug. 19, 2003 — A promising vaccine for West Nile Virus could be soon available for humans. Scientists say they’ve created a vaccine — by combining a related virus with West Nile virus — that effectively protects monkeys from the infection. The vaccine has generated a lot of excitement in the science community. Last week, the CDC reported that the number of West Nile virus cases doubled for the year — in that week alone. “We’re optimistic that our engineered virus vaccine will provide long-term immunity to West Nile virus, but the human clinical trials will give us the definitive data,” says researcher Brian Murphy, MD, of the National Institute of Allergy and Infectious Diseases, in a news release. Vaccine Triggers Strong Immune Response The research, appearing in the September issue of Virology, details how Murphy’s team replaced genetic material in a distant-cousin virus — called dengue type 4 — with corresponding West Nile virus genetic material. Researcher Alexander Pletnev, PhD, and colleagues created the strategy of mixing parts of one virus with another to use as vaccines in 1991. They discovered that this formula could cripple the disease-causing virus but still trigger a strong immune response against it. Scientists tested two versions of the West Nile/dengue 4 virus vaccine in monkeys – one combined West Nile virus proteins with the entire dengue virus’ genetic material, and the other combined West Nile virus proteins with a modified dengue virus. Researchers gave the monkeys the combination vaccine, and other monkeys were injected with either West Nile virus or dengue 4 virus for comparison. Humans Are Next After six weeks, the monkeys that received the combination vaccine showed either a reduced level of virus or no signs of the virus present in the blood. The vaccine containing the modified dengue virus was more potent in eliminating viruses from the blood; in monkeys receiving this vaccine no West Nile virus infection was found. The combination vaccines also produced high levels of antibodies that successfully fought the infection. Researchers say the West Nile/dengue 4 virus vaccine with the modified dengue virus will be the first tried on humans for two reasons. First, it produces many antibodies against West Nile virus, and second, it does not create measurable levels of the virus in monkeys. They say the vaccine could eventually provide lifelong immunity against West Nile virus. Birds carry West Nile virus, but it is spread to humans by mosquitoes that have bitten infected birds. Typically, infections are at their highest from late August to September. The virus first appeared in the U.S. in 1999 in New York. Last year, West Nile virus spread to 44 states, infecting more than 4,000 people and killing 284. (Source: WebMD, Aug 19 2003, Cherie Berkley)


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Dates

Posted On: 12 September, 2003
Modified On: 5 December, 2013


Created by: myVMC