Initial attachment of Borrelia burgdorferi spirochetes to Vero cells

BACKGROUNDAdhesion is the initial process in the establishment of any infection and can contribute to bacterial pathogenesis. Without the ability to adhere to host cell surface, there is no invasion, dissemination, or persistence and host colonization by many bacterial pathogens, including B. burgdorferi. During the infection, B. burgdorferi cells interact with cells of various origins. We are having limited information and knowledge regarding the borrelial invasion, intracellular existence and the host cell damage and the pathological effects to the host. We have investigated by electron microscope the adherence of motile Borrelia burgdorferi s.l. to Vero cells derived from the kidney of an African green monkey by electronmicroscopy. These cells have been shown as an interesting model for study of the toxic potential of many bacterial pathogens. METHODSAdherence of the long-term in vitro passaged Borrelia burgdorferi sensu lato strains to a 24-hour monolayer of primate kidney epithelial Vero cells was studied using transmission electronmicroscopy. The reaction was read after incubation at 1-hour intervals. RESULTSA vertical contact between borreliae and Vero cells was confirmed already after one hour of in vitro incubation. A cytotoxic effect of borreliae could be observed when the time of incubation was extended to 4 hour. The extent of attachment varied between the two borrelia strains tested. CONCLUSIONThe optimal time for spirochetal adhesion in our model was 1 h postinoculation. Our results suggest that borrelia attaches to the tested cells by length and by the tip. The data showed that the extent of attachment varied between the two borrelia strains tested (Tab. 1, Fig. 4, Ref. 21).