Biomaterial Database

Virulence heterogeneity of a predominantly avirulent Western equine encephalitis virus population. 1976

P B Jahrling

Selective removal of small plaque (SP) Western equine encephalitis (WEE) virus from a population heterogeneous with respect to virulence and plaque morphology permitted direct detection of a small sub-population of virulent large plaque (LP) WEE virus. Selective removal of SP-WEE virus was achieved by intracardiac (i.c.a.) inoculation of hamsters; plasma obtained 60 min after inoculation was proportionately enriched for LP-WEE virus since only the SP-WEE virus was cleared. By this method, the proportion of LP- to SP-WEE virus, in a population of SP-WEE virus which appeared to be homogeneous by conventional plaquing methods, was calculated to be 1 LP- to 250000 SP-WEE virions. The presence of a virulent LP-WEE virus sub-population explains why a single passage of a high but not low dose of SP-WEE virus in hamsters resulted in the emergence of an LP-WEE virus population with enhanced virulence.

UI	MeSH Term	Description	Entries
D010949	Plasma	The residual portion of BLOOD that is left after removal of BLOOD CELLS by CENTRIFUGATION without prior BLOOD COAGULATION.	Blood Plasma,Fresh Frozen Plasma,Blood Plasmas,Fresh Frozen Plasmas,Frozen Plasma, Fresh,Frozen Plasmas, Fresh,Plasma, Blood,Plasma, Fresh Frozen,Plasmas,Plasmas, Blood,Plasmas, Fresh Frozen
D004667	Encephalitis Virus, Western Equine	A species of ALPHAVIRUS that is the etiologic agent of encephalomyelitis in humans and equines in the United States, southern Canada, and parts of South America.	Encephalomyelitis Virus, Western Equine,WEE Virus,Western equine encephalitis virus,Encephalitis Viruses, Western Equine,Virus, Western Equine Encephalitis,Viruses, Western Equine Encephalitis,Western Equine Encephalitis Viruses,WEE Viruses
D006224	Cricetinae	A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.	Cricetus,Hamsters,Hamster
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014644	Genetic Variation	Genotypic differences observed among individuals in a population.	Genetic Diversity,Variation, Genetic,Diversity, Genetic,Diversities, Genetic,Genetic Diversities,Genetic Variations,Variations, Genetic
D014774	Virulence	The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.	Pathogenicity
D046508	Culture Techniques	Methods of maintaining or growing biological materials in controlled laboratory conditions. These include the cultures of CELLS; TISSUES; organs; or embryo in vitro. Both animal and plant tissues may be cultured by a variety of methods. Cultures may derive from normal or abnormal tissues, and consist of a single cell type or mixed cell types.	Culture Technique,Technique, Culture,Techniques, Culture