Meeting Abstract

55.6  Tuesday, Jan. 6  Rabies Exposure, Relative Immune Function and Life-history Traits in the Big Brown Bat, Eptesicus fuscus MOORE, M.S.*; JACKSON, F.R.; TURMELLE, A.S.; PANASUK, B.J.; MENDONCA, M.T.; RUPPRECHT, C.E.; KUNZ, T.H.; MCCRACKEN, G.F.; Boston University, Boston; Centers for Disease Control and Prevention, Atlanta; University of Tennessee, Knoxville; Centers for Disease Control and Prevention, Atlanta; Auburn University, Auburn; Centers for Disease Control and Prevention, Atlanta; Boston University, Boston; University of Tennessee, Knoxville mmoore@bu.edu

This study characterized immune responses in the big brown bat, Eptesicus fuscus, and how variation in immune function relate to population differences, life-history traits and exposure to rabies virus. We used a bactericidal assay with Escherichia coli to test innate immune responses and subcutaneous injections of phytohemagglutinin (PHA) to test cell-mediated adaptive immune responses. To assess pathogen exposure, we used the rapid fluorescent focus inhibition test (RFFIT) to measure rabies virus-neutralizing antibodies (VNA). We estimated infection status from oropharyngeal swabs using nested RT-PCR and sequencing. The proportion of bats exposed to rabies virus was 2% in 2005, 17% in 2006 and 6% in 2007. Rabies viral amplicons were generated from only three of 515 individual bats. Pregnant and lactating females were more likely to exhibit VNA compared to postlactating individuals. Bactericidal ability of bat blood was significantly related to colony-level effects, reproductive stage, and sex. Specifically, postlactating bats showed greater bacterial killing compared to lactating bats and females demonstrated an ~13% greater killing ability compared to males. PHA index was significantly related to date and year. Results suggest that sex, reproductive status, colony site, and seasonal and annual variation may influence the ability of bats to respond immunologically. Moreover, our results suggest that pregnant and lactating females, which exhibit increased gregarious behavior compared to bats in other reproductive stages, have greater pathogen exposure.