Relationship between infectivity and OspC expression in Lyme disease Borrelia

Abstract Borrelia burgdorferi sensu stricto strain 297 and B. garinii strains HP1 and 12–92 were serially subcultured for 36–50 passages in vitro for 1 year. All low-passage strains showed abundant expression of outer surface protein C (OspC) in the 22–23-kDa range, but the high-passage strains lost or showed reduced expression of OspC in comparison with the low-passage strains. The low-passage strains efficiently infected outbred ddY mice when inoculated into the hind footpad or peritoneal cavity. In contrast, the incidence of infection with the high-passage strains was low. Isolates from the bladders of mice inoculated with the high-passage strains expressed large amounts of OspC in comparison with those originally inoculated. These results indicate that OspC expression is related to the infectivity of Lyme disease borreliae.