Outer surface protein C (
OspC) of the
Lyme disease spirochetes is an important
virulence factor that has potential utility for
vaccine development. Of the 21
OspC types that have been identified, it has been postulated that types A, B, I, and K are specifically associated with invasive
infections. Through an analysis of isolates collected from patients in Maryland we found that
OspC types C, D, and N are also associated with invasive
infections. This observation suggests that there is greater diversity in the group of
OspC types associated with invasive
infection than has been previously suggested. Detailed knowledge of the antigenic structure of
OspC is essential for
vaccine development. To determine if the antibody response to
OspC is type specific,
recombinant proteins of several different
OspC types were immunoblotted and screened with sera from mice infected with isolates having known
OspC types. These analyses revealed a high degree of specificity in the antibody response and suggested that the
immunodominant epitopes of
OspC reside in the variable domains of the
protein. To localize these
epitopes,
OspC fragments were generated and screened with serum collected from infected mice. These analyses led to identification of previously uncharacterized
epitopes that define the type specificity of the
OspC antibody response. These analyses provide important insight into the antigenic structure of
OspC and also provide a basis for understanding the variable nature of the antibody response to this important
virulence factor of the
Lyme disease spirochetes.