Investigations of Attenuated Strains of Group A Arboviruses.
Final rept. Jul 71-Dec 75,
MEDICAL COLL OF VIRGINIA RICHMOND HEALTH SCIENCES DIV
Pagination or Media Count:
These investigations were designed to isolate mutant strains of Eastern Equine Encephalitis EEE virus which could serve as a potential vaccine candidate strain and to characterize the Clone-15 strain of Western Equine Encephalitis WEE virus to determine its potential as a human vaccine virus. The Clone-15 strain was used to prepare chicken embryo cell culture vaccine as a candidate for human use. About 150,000 doses of final vaccine were prepared and stored in bulk. About 3,500 doses were lyophilized as a final package vaccine. The vaccine does elicit antibody production in laboratory animals. The final WEE vaccine contains 2 plaque types of virus a large plaque which resembles the parental strain and a small plaque which is genetically unstable and gives rise to the large plaques. The vaccine appears to be safe in laboratory animals it does not produce clinical evidence of disease in adult guinea pigs, hamster, or rhesus monkeys when inoculated both parenterally and into the nervous system. The vaccine does produce clinical disease in newborn mice and in young hamsters when inoculated into the nervous system. As the result of studies undertaken to develop an attenuated vaccine candidate strain of EEE virus using both BeAn 221 strain and the Arth 167 strain, it was concluded that EEE virus is a very stable virus and difficult to attenuate by the methods attempted.
- Medicine and Medical Research