Investigations of Attenuated Strains of Group A Arboviruses.
Annual summary rept. no. 2, 1 Jul 73-30 Jun 74,
VIRGINIA COMMONWEALTH UNIV RICHMOND
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Reported is a study to develop attenuated strains of Eastern Equine Encephalitis EEE Virus and Western Equine Encephlaitis WEE virus, which would be suitable candidates for human vaccines. The clone 15 strain of WEE virus has been utilized to prepare a chicken embryo cell culture vaccine as a candidate for human use. Preliminary studies on the purity, potency, and safety of the vaccine indicate that the virus does not produce clinical disease in monkeys, guinea pigs, or hamsters when inoculated intracerebrally and systemically. Preliminary studies to date, indicate the vaccine is free of advintitious agents, however, the vaccine does produce two distinct plaque types of WEE virus. Studies with the Arth 167 strain of EEE have indicated that this attenuated strain is neurovirulent for monkeys, guinea pigs, mice, and hamsters when inoculated intracerebrally, but is not neuro-tropic when inoculated peripherally. From these results, it has been concluded that the Arth 167 SPM strain of EEE is unsuitable as a vaccine candidate.