DISTRIBUTION, DIVERSITY, AND HOST-SPECIFICITY OF BARTONELLA IN RODENTS FROM THE SOUTHEASTERN UNITED-STATES

A number of Bartonella isolates were obtained from seven species of ro dents sampled from 12 geographic sites representing the major biotic c ommunities of the southeastern United States. Bartonella were isolated from the blood of 42.2% of 279 tested rodents. The highest prevalence of infection typically occurred among the most commonly captured spec ies in the rodent community. Four phylogenetic groups, uniting 14 geno typic variants of Bartonella, were identified by sequence analysis of the citrate synthase gene. The level of sequence homology between geno typic groups varied from 88.8% to 96.4%, and the degree of homology am ong variants within groups was greater than or equal to 97%. Cotton ra ts (Sigmodon hispidus) harbored up to three phylogenetic groups of Bar tonella at a single site, and Bartonella of two phylogenetic groups we re isolated from a single rodent. All the Bartonella isolated from thr ee species of Peromyscus clustered in a single distinct phylogenetic g roup, suggesting some host specificity may occur. Mouse ascitic fluids produced in BALB/c mice inoculated with Bartonella of three phylogene tic groups demonstrated high indirect fluorescent antibody (IFA) titer s to homologous antigens. However, use of eight Bartonella antigens in an IFA test with sera from 394 wild-caught rodents resulted in either little or extremely low titers of antibody.