Isolation of Eyach virus (Reoviridae, Colorado tick fever group) from Ixodes ricinus and I. ventalloi ticks in France.

During the spring of 1981, two strains of an identical virus were isolated in Mayenne, France, from Ixodes ricinus L. and Ixodes ventalloi Gil Collado, parasiting a wild rabbit (Oryctolagus cuniculus L.). Virological and serological results indicated that these strains belong to the Colorado tick fever serogroup and are indistinguishable from Eyach virus, a tick-borne virus previously described from West Germany. Study of dsRNA PAGE profiles confirmed these conclusions. The morphology and morphogenesis of French isolates were studied in infected suckling mouse brains showing some peculiar features previously described for Colorado tick fever virus. The importance of the isolation of Eyach virus in France is discussed.