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Inactivation Of Genes For Antigenic Variation In The Relapsing Fever Spirochete Borrelia Hermsii Reduces Infectivity In Mice And Transmission By Ticks, Sandra J. Raffel, James M. Battisti, Robert J. Fischer, Tom G. Schwan

Biological Sciences Faculty Publications

Borrelia hermsii, a causative agent of relapsing fever of humans in western North America, is maintained in enzootic cycles that include small mammals and the tick vector Ornithodoros hermsi. In mammals, the spirochetes repeatedly evade the host’s acquired immune response by undergoing antigenic variation of the variable major proteins (Vmps) produced on their outer surface. This mechanism prolongs spirochete circulation in blood, which increases the potential for acquisition by fast-feeding ticks and therefore perpetuation of the spirochete in nature. Antigenic variation also underlies the relapsing disease observed when humans are infected. However, most spirochetes switch off the bloodstream …