Susceptibility of the Mongolian gerbil (Meriones unguiculatus) to Western equine encephalitis

Abstract

The Mongolian gerbil (Meriones unguiculatus) was highly susceptible to peripheral infection with Western equine encephalitis virus. Small doses of virus ranging from 0.1 to 10 intracerebral 3-week-old mouse LD50 which induced no clinical response in 3-week-old mice when inoculated subcutaneously, caused death in 4-week-old gerbils. At this age, a standard dose of virus produced uniform viremia patterns between individuals. Peak virus concentration approaching 105.0 intracerebral 3-week-old mouse LD50 per 0.03 milliliter of blood, was attained at 48 h post inoculation. Resistance to infection increased with age but 10-week old gerbils remained susceptible and exhibited marked clinical signs of encephalitis during the course of infection. Brains from animals, which died within 10 days of infection, yielded large amounts of virus.