Folia Parasitologica 39[3] 265-284 (1992)
SUSCEPTIBILITY OF SOME SPECIES OF RODENTS TO RICKETTSIAE
- REHACEK, J (reprint author), SLOVAK ACAD SCI, INST VIROL, DUBRAVSKA CESTA 9, CS-84246 BRATISLAVA, CZECHOSLOVAKIA
The present study was designed to test the susceptibility of free living rodents, viz Apodemus flavicollis, Microtus arvalis, Clethrionomys glareolus, Mus musculus, and outbred white mice from Dobra Voda farm, CSFR, to Coxiella burnetii, rickettsiae of the spotted fever group (Rickettsia sibirica, R. conorii, R. slovaca and R. akari) and rickettsiae of typhus group (R. typhi and R. prowazekii) by various routes of administration. The highest levels of antibodies to C. burnetti were found in A. flavicollis and M. arvalis inoculated intraperitoneally and intracerebrally. Antibodies to C. burnetii exerted peak levels between days 13 and 16 in contrast to white mice which showed maximum levels on day 28. When 10(0.5) and 10(0.05) EID50/0.25 ml of C. burnetii was administered intraperitoneally to A. flavicollis, M arvalis and white mice, the agent was detected only in organs of wild animals. In addition to spleen, the bone marrow appeared as a predilective tissue for the detection of this agent. R. akari at a dose of 10(4.5) EID50/0.25 ml caused overt illness and death in rodents. Antibody levels to R. sibirica and R. conorii were dependent on dosage, route of inoculation and duration of infection, but were not dependent on animal species. Antibodies to R. slovaca and R. akari were dependent on dosage, infection duration and animal species but were not dependent on the route of infection. For R. conorii, R. sibirica and R. slovaca a sharp increase of antibody levels with high titres on days 4-6 and peak levels about day 11 post intraperitoneal infection was characteristic. Antibody level to R. akari increased up to day 2 1. Spotted fever group rickettsiae in rodents inoculated intraperitoneally were observed in various organs, particularly in tunica vaginalis and spleen at days 2-8 post infection. R. typhi at a dose of 10(4.3) EID50/0.25 ml inoculated intracerebrally or intraperitoneally killed white mice and inoculated intraperitoneally killed C. glareolus and M. musculus. The antibody response of white mice to intraperitoneal, subcutaneous or intranasal inoculation of this rickettsia was low and no antibody was detected following peroral administration. M. musculus did not develop antibodies after intracerebral, intranasal, subcutaneous or peroral inoculation of R. typhi. The target organs for this rickettsia were the spleen and tunica vaginalis. R. prowazekii inoculated intraperitoneally into white mice at a dose of 10(6.5) EID50/0.25 ml and at a dose of 10(4.5) EID50 into C glareolus was fatal for these rodents. Following intraperitoneal inoculation of 10(2.3) and 10(4.2) EID50, this agent was not detected in both rodent species and the difference in antibody response between them was not significant in the infection duration but was evident with various doses of inoculated rickettsiae. Titres of rickettsiae measured by antibody response of intraperitoneally inoculated rodents and by the presence of agents in yolk sacs of chicken embryos showed 1 log unit higher values in rodents inoculated with C. burnetii and about 1-3 log units higher levels in rodents inoculated with R. sibirica and R. conorii. The titres of R. slovaca were almost the same in both substrates while R. akari reached the highest titres in white mice, lower in wild rodents and the lowest in yolk sacs. No significant difference was found in the titration of R. typhi and R. prowazekii between small rodents and yolk sacs of chicken embryos with the exception of M. musculus in which the titres of R. typhi were much lower. We suggest that A. flavicollis, C. glareolus and M. arvalis could be used for the isolation of rickettsiae from diverse field samples as well as for laboratory investigations, e.g. to acquire sera with high levels of antibodies to rickettsiae. However, white mouse, outbred line of Dobra Voda, is suggested as the animal of choice for work with tested members of typhus group of rickettsiae.
Published: September 1, 1992 Show citation
