Tg. Schwan et Bj. Hinnebusch, BLOOD-STREAM-ASSOCIATED VERSUS TICK-ASSOCIATED VARIANTS OF A RELAPSING FEVER BACTERIUM, Science, 280(5371), 1998, pp. 1938-1940
The relapsing fever spirochete, Borrelia hermsii, alternates infection
s between a mammal and a tick vector. Whether the spirochete changes;p
henotypically in the different hosts was examined by allowing the tick
vector Ornithodoros hermsi to feed on mice infected with serotype 7 o
r serotype 8 of B. hermsii. Upon infection of ticks, the spirochetal s
erotype-specific variable major proteins (Vmps) 7 and 8 became undetec
table and were replaced by Vmp33. This switch from a bloodstream- to t
ick-associated phenotype could be induced in culture by a decrease in
temperature. After tick-bite transmission back to mice, the process wa
s reversed and the spirochetes resumed expression of the same Vmp pres
ent in the previous infectious blood meal.