VIRAL INFECTION IN BATS 



blood of an animal sacrificed 21 days after virus inoculation. The 

 passage history of the virus strain seems to deter mine its degree of 

 infectivity for the Mexican free- tailed bat, where the recently iso- 

 lated strain is much more infective than the laboratory- adapted 

 strain. Similar results were obtained with two strains of St. Louis 

 encephalitis virus. This bat species is quite resistant to infection 

 with the high mouse passage Hubbard strain, but is quite susceptible 

 to infection with a strain recovered from a flicker bird and in its 

 seventh mouse brain passage. Virus was first demonstrated in blood 

 one to two days after virus inoculation, increased to levels of 4.0 

 log units by the seventh day, and was still detectable in animals 

 sacrificed about one month post- inoculation. In addition, virus was 

 demonstrated with much greater frequency in brown fat than in 

 brain or kidney. In a few instances virus was demonstrated in tissue 

 preparations from animals that were not viremic at the time of 

 sacrifice. 



The little brown bat is highly susceptible to the OCT-541 strain of 

 Japanese B encephalitis virus. Virus was widely distributed in the 

 various tissues assayed during an observation period of about one 

 month; virus was demonstrated in the blood and in brown fat with 

 about equal frequency, and in several instances virus was demon- 

 strated in the brown adipose tissue and not in blood or other tissues 

 tested. This bat species is only slightly susceptible to infection with 

 the flicker bird strain of St. Louis encephalitis virus. The big brown 

 bat ( Eptesicus f, fuscus) is highly susceptible to infection with the 

 OCT-541 strain of Japanese B encephalitis virus. All animals devel- 

 oped widespread infection during the first 12 days following virus 

 inoculation, titers in the blood and brown fat reaching more than 

 3.0 log units in many instances. Subsequent to the twelfth day, the 

 infection seemed gradually to subside; only 2 of 10 animals tested 

 had a detectable viremia by the twenty- fifth day. The susceptibility 

 of this bat species to the other virus strains has not yet been 

 determined. • 



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