Variable Resistance to Ectromelia (Mousepox) Virus Among Genera of Mus

Abstract

Ectromelia virus, an orthopoxvirus, is a member of the poxvirus family. It replicates in the cytoplasm of infected cells producing progeny virions which are “brick-shaped” with dimensions of approximately 200 by 300 nm, and contain a double-stranded DNA genome of 130–140×l0₆ daltons MW. (Mackett and Archard 1979). The virus naturally infects M. m. domestieus in animal colonies causing a severe disease (mousepox) in certain strains (A/J, DBA/2J, BALB/cByJ), and a subclinical infection in others (AKR/J, C57BL/6J, C57BL) (Schell 1960; Wallace and Buller 1985). Much speculation has centered on the question of a potential wildlife host for ectromelia virus. Fenner examined 150 wild mice from the area of Melbourne, Australia without finding evidence for prior exposure to this virus (Fenner 1949). Kaplan et al. (1980) have presented serologic evidence suggesting that field mice (Apodemus) and voles (Microtus and Clethrionomys) can be infected with an orthopoxvirus, but no direct evidence that these species are natural reservoirs for ectromelia virus is available. Thus it was of interest to study closer relatives of M. m. domesticus for susceptibility to ectromelia virus.