Affiliation:
1. Department of Medicine, University of Washington, Seattle, Washington 98195
Abstract
ABSTRACT
We have previously shown that the TprK antigen of
T. pallidum
, Nichols strain, is predominantly expressed in treponemes obtained 10 days after infection and that the hydrophilic domain of TprK is a target of opsonic antibodies and confers significant protection against homologous challenge. The
T. pallidum
genome sequence reported the presence of a single copy of the
tprK
gene in the Nichols strain. In the present study we demonstrate size heterogeneity in the central portions of the TprK hydrophilic domains of 14 treponemal isolates. Sequence analysis of the central domains and the complete open reading frames (ORFs) of the
tprK
genes confirms this heterogeneity. Further, multiple
tprK
sequences were found in the Nichols-defined
tprK
locus in three isolates (Sea 81-4, Bal 7, and Bal 73-1). In contrast, only a single
tprK
sequence could be identified in this locus in the Nichols strain. Alignment of the DNA and deduced amino acid sequences of the whole
tprK
ORFs shows the presence of seven discrete variable domains flanked by highly conserved regions. We hypothesize that these heterogeneous regions may be involved in antigenic heterogeneity and, in particular, evasion of the immune response. The presence of different
tprK
alleles in the
tprK
locus strongly suggests the existence of genetically different subpopulations within treponemal isolates.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
93 articles.
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