Cultivation at 37 degrees C enhances Borrelia burgdorferi sensu stricto infectivity for hamsters.
Borrelia burgdorferi sensu stricto (s.s.), the causative agent of Lyme disease in North America is transmitted to the mammalian host by ticks belonging to the genus, Ixodes. Antibodies to several spirochetal proteins, most notably outer surface protein C (OspC), have been observed in early infection in both humans and laboratory animals. Thus, the expression of these proteins have been postulated to play a role in tick transmission and spirochetal infectivity for the mammalian host. B. burgdorferi strain JMNT was induced to produce increased levels of OspC by cultivation in BSK medium at 37 degrees C. To diminish expression of OspC, spirochetes were cultivated at 31 degrees C. Spirochetes shifted down from 37 degrees C to 31 degrees C or up from 31 degrees C to 37 degrees C for 1 week contained equivalent amounts of OspC. To evaluate spirochetal infectivity, hamsters were inoculated subcutaneously with 1 x 10(4) or 1 x 10(6) spirochetes grown at the above-mentioned temperatures. Hamsters inoculated with spirochetes expressing high amounts of OspC all became infected, irrespective of the inoculum size. None of the hamsters inoculated with 1 x 10(4) spirochetes grown at 31 degrees C or in cultures shifted down from 37 degrees C to 31 degrees C were infected. All infected hamsters, confirmed by isolation of spirochetes in ear and/or bladder cultures, had an antibody response to OspC. In contrast, all non-infected hamsters lacked antibodies to OspC. We conclude that cultivation of spirochetes at 37 degrees C enhances their infectivity for hamsters. This study also suggests there is a correlation between enhancement of OspC expression and spirochetal infectivity for hamsters.
Department of Medicine, School of Medicine, University of California, San Diego, La Jolla 92093, USA. mobonyo@ucsd.edu
Marygorret
M
Obonyo
Ulrike G
UG
Munderloh
Thien N
TN
Sam
Timothy J
TJ
Kurtti
D000818:Animals; D000942:Antigens, Bacterial / Q000378:metabolism; D000954:Antigens, Surface / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D001428:Bacterial Vaccines; D025065:Borrelia burgdorferi / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005408:Flagellin / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006358:Hot Temperature; D008074:Lipoproteins; D008193:Lyme Disease / Q000382:microbiology* / Q000473:pathology
D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D008074:Lipoproteins; C072045:OspA protein; C079616:OspC protein; D005408:Flagellin; C077030:OspB protein, Borrelia burgdorferi