Venezuelan encephalitis virus infection in neotropical bats. II. Experimental infections.

Eighty-nine Neotropical bats of five species were inoculated subcutaneously with epizootic or enzootic strains of Venezuelan encephalitis (VE) virus. Viremia was detected in 92.5% of all bats, but no illness attributable to virus infection was observed. Detectable viremias averaged slightly over 4 days in Artibeus jamaicensis and A. lituratus, and 2.8 days in Phyllostomus discolor, and maximal viremia titers in these three species averaged 6.9, 6.6, and 4.6 log10 SMicLD50 per ml of blood, respectively. In general Artibeus developed and maintained detectable levels of both hemagglutination-inhibition (HI) and neutralizing antibody for as long as tested (up to 506 days), although HI antibody to enzootic VE virus strains disappeared in some A. lituratus. The detectable antibody response of P. discolor was slower and of lower magnitude and shorter duration than that of Artibeus, although individual P. discolor which had lost detectable HI and N antibody resisted challenge. Vertical passage of antibody was observed in three A. lituratus offspring. Artibeus jamaicensis were found to be only slightly less susceptible to VE virus infection than a U.S. subspecies of the cotton rat (Sigmodon hispidus). No virus was recovered by mouse inoculation of organ pools of bats killed as early as 2 days and as late as 299 days after the last day of detectable viremia.