title: Homegeneity of Venezuelan encephalitis virion populations of hamster-virulent and benign strains, including the attenuated TC83 vaccine.
abstract: A hamster-virulent strain of Venezuelan encephalitis virus (BeAn8, subtype III) and a benign strain (BeAr35645, subtype IV) each yielded 100 clones with virulence properties like those of the parental virion population. Another hamster-virulent strain (63U2, subtype I, variety E) was heterogeneous since 2 out of 100 clones were less virulent for hamsters than the other 98 clones or the parental virus population. The attenuated TC83 vaccine strain, (a derivative of subtype I, variety A), although over 99% homogeneous with respect to hamster virulence, was unstable since virulent virions could be selected from the parental population by passage through hamsters.
mesh_terms: D000367:Age Factors; D000818:Animals; D000917:Antibody Formation; D002642:Chick Embryo; D002999:Clone Cells; D006224:Cricetinae; D004666:Encephalitis Virus, Venezuelan Equine / Q000145:classification / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D006168:Guinea Pigs; D007106:Immune Sera; D009500:Neutralization Tests; D010948:Viral Plaque Assay; D014765:Viral Vaccines; D014774:Virulence
chemical_list: D007106:Immune Sera; D014765:Viral Vaccines