VIRAL INFECTION IN BATS 



20 



30 40 50 60 7C 80 90 



DAYS AFTER. /NOCULATlON 



Figure 3. Schematic representation indicating suppressive effect of simulated hiber- 

 nation on progress of infection and immunologic response of bats (Eptesicus f. fuscus) 

 following intramuscular inoculation of Japanese B encephalitis virus (150 weanling 

 mouse i. c. LD^q). Shaded areas refer to periods in simulated hibernation (10° C). Solid 

 bars indicate virus demonstrated by intracerebral inoculation of weanling mice. Clear 

 bar indicates no virus recovered. Log neutralization index (LNI) indicated by curves. 



response in animals held at room temperature from time of inocu- 

 lation. Some animals become viremic as early as 24 to 48 hours 

 after receiving 150 LD5Q doses of virus, whereas virus is seldom 

 isolated from brown adipose tissue before the 3rd or 4th day post- 

 inoculation. We indicate demonstration of virus in blood and brown 

 fat over a period of approximately 25 days. It is difficult to define 

 precisely the duration of active infection, since there appears to be 

 much individual variation. We do know that virus can be demon- 

 strated in brown fat and/or blood of virtually all animals tested 7 to 

 12 days after receiving virus and that subsequently, the number of 

 infected animals and the concentrations of virus in their tissues 

 gradually diminish. This decrease in viral proliferation coincides 

 with the time when neutralizing antibodies first become detectable, 

 and it is at this point that we have demonstrated on occasion low 

 concentrations of virus inthebloodof animals with positive neutral- 

 ization indices. A significant number of animals have positive LNI 

 30 to 50 days post- inoculation, although some infected animals never 

 develop antibody detectable by the methods used. Studies on the 



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