Bats in Relation to Arthropod-Borne Viruses: An Experimental Approach with Speculations

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Abstract
Experimental arbovirus infection in Chirop-tera strongly indicates that the bat could participate in every facet of the year-round persistence of arboviruses in nature. Infection in the active bat is characterized by a long-term initial viremia and viral invasion and proliferation in brown fat, brain, and kidney in the absence of overt signs of encephalitis. Pregnancy does not enhance the susceptibility of the Mexican freetailed bat to infection with certain strains of Japanese B (JBE) and St. Louis (SLE) encephalitis viruses. JBE virus was found to cross the placenta and invade and multiply in fetuses of infected bats in the absence of gross pathology, suggesting a means of perpetuation of the virus in nature in the absence of a vector. Bats can sustain certain arbovirus infections throughout long periods in the cold and thereby contribute to overwintering these agents. Although the presence of antibodies to JBE virus cannot be measured by routine HI or CF techniques, neutralizing antibody can be detected in varying degrees, depending on environmental temperature and incubation time. Cooperative field studies in the Far East and Mexico have yielded several as yet uncharac-terized viral isolates from various species of Chiroptera. In field studies concerned with the recent SLE outbreak in Houston, SLE virus was recovered from the blood of a bat collected in the vicinity of the epidemic. The isolation of arboviruses from naturally infected bats serves to emphasize the potential importance of this animal in providing a means of reservoiring these agents.