VIRAL INFECTION IN BATS 



and upon transfer to room temperature 3 months after the initiation 

 of the original infection may experience a second cycle of infection 

 and antibody response. 



DISCUSSION AND SUMMARY 



Our primary interest in studyingthe influence of low temperature 

 on experimental viral infections in bats has been to accumulate in- 

 formation which would help in understanding how periods of winter 

 hibernation could affect natural virus infections in these animals. 

 As might be expected, the depressed metabolic state and the low 

 body temperature of bats held at 5° C or 10° C are not conducive to 

 active viral multiplication. Of far greater interest is the observation 

 that bats in simulated hibernation are able to sustain viral infections 

 during this period of inactivity. Although virus does not appear to 

 replicate at a readily measurable rate during this period, viability 

 is maintained. Upon transfer to a warmer environment simulating 

 spring arousal, virus lying dormant in brown adipose and/or other 

 tissues begins to multiply and active infection, demonstrable by con- 

 ventional assay methods, ensues. This sustenance of viral particles 

 in the hibernating bat seems more remarkable when accomplished 

 in animals placed at lowtemperature immediately after virus inocu- 

 lation. In our studies with rabies virus, animals were inoculated 

 intramuscularly and placed immediately at 5° C or 10 C, allowing no 

 time for virus to attach to or penetrate the cells of the animals at 

 room temperature or the higher temperatures believed to be opti- 

 mum for this animal virus; yet some bats transferred to a warm 

 environment even a month or more later were subsequently shown 

 to develop rabies infection. During the periods inoculated animals 

 were held at low temperature, only an occasional animal could be 

 proved infected upon sacrifice, and in all cases rabies virus was 

 demonstrated in low titer, indicating that virus was not multiplying 

 very rapidly in these bats. Evidence was obtained, however, in an 

 experiment with a bat rabies virus strain in little brown Myotis, 

 that some t)Ape of viral activity occur red during the period the inocu- 

 lated animals were held at 5° C which resulted in what appears to 



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