First Isolation of Rickettsia helvetica from Ixodes ricinus Ticks in France

Abstract

Two rickettsial isolates recovered from Ixodes ricinus ticks in Puy-de-Dôme (Central France) were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot immunoassay, restriction fragment length polymorphism analysis, and sequencing of a portion of the citrate-synthase gene. By these methods, the isolates appeared to be identical to a member of the spotted fever group rickettsiae, Rickettsia helvetica. This first isolation of Rickettsia helvetica in France has epidemiologic importance; a serosurvey on Mediterranean spotted fever conducted previously in Puy-de-Dôme, where the infection is not endemic, demonstrated a high seroprevalence of nonspecific antibodies directed against spotted fever group rickettsiae lipopolysaccharides, and thus the possibility of infection due to a rickettsia different from Rickettsia conorii was suggested. The isolation of Rickettsia helvetica in anthropophilic ticks in the same area further supports this hypothesis.

Spotted Fever Group Rickettsiae in Ticks, Morocco

“…helvetica is another species identifi ed in Morocco in this study. It is one of the few SFG species in which a commonly used ompA primer set does not amplify a PCR product (7,29). However, sequencing gltA enabled defi nitive identifi cation.…”

Tick-borne rickettiosis in Guadeloupe, the French West Indies: isolation of Rickettsia africae from Amblyomma variegatum ticks and serosurvey in humans, cattle, and goats.

“…Cells from infected shell vials were trypsinized and the isolated strains were subcultured in L929 cells by subsequent trypsinizations as previously described. 9,10 Polymerase chain reaction (PCR). The DNA of the remaining half of each tick was extracted, purified, and recovered into 80 l of sterile water as previously described.…”

“…The DNA of the remaining half of each tick was extracted, purified, and recovered into 80 l of sterile water as previously described. 9,10 The amplification of a 532-basepair fragment of the gene encoding for the 190-kD outer membrane protein A (rOmpA) was performed using the previously described oligonucleotide primer pairs Rr 190.70p and Rr 190.602n (Bioprobe Systems, Montreuil-sous-Bois, France). 10 A negative (distilled water) and a positive (R. conorii DNA) control was included in each test.…”

No serological evidence of Rickettsia helvetica infection in Scandinavian sarcoidosis patients

“…helvetica was first isolated in Switzerland from Ixodes ricinus ticks in 1979 [12] and has since been isolated from the same tick in other European countries, such as France [13] and Sweden [14]. Although I. ricinus commonly bites humans, the pathogenic potential for R. helvetica remains somewhat unclear and is restricted to a few case descriptions.…”