Molecular Variation in the Variable-Length PCR Target and 120-Kilodalton Antigen Genes ofEhrlichia chaffeensisfrom White-Tailed Deer (Odocoileus virginianus)

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Abstract
Genes encoding two surface-expressed antigens ofEhrlichia chaffeensis, the variable-length PCR target (VLPT) and the 120-kDa antigen, which contain variable numbers of tandem repeats, were characterized forE. chaffeensisfrom white-tailed deer (Odocoileus virginianus). Both genes from infected deer contained numbers of repeats similar to those reported in genes from humans and ticks, although a new variant of the 120-kDa antigen gene containing five repeat units and coinfection with multiple VLPT and 120-kDa antigen gene genetic types were detected. Sequence analysis of both genes revealed more nucleotide variation than previously reported forE. chaffeensisfrom infected humans or ticks. This is the most extensive study ofE. chaffeensisVLPT and 120-kDa antigen gene genetic variation to date and is the first to examine genetic variation inE. chaffeensisfrom a nonhuman vertebrate host.