Abstract

In the studies previously reported, the tick-borne protozoan parasites Theileria lestoquardi and Theileria annulata were shown to differ in their capacity to infect sheep and cattle. In the studies presented here, these findings were further supported. In vitro infectivity of T. lestoquardi and T. annulata sporozoites for peripheral blood mononuclear cells of sheep and cattle were determined by analysis of cell cultures for cell proliferation, the detection of parasites in Giemsa-stained cytospin smears and the establishment of continuously growing schizont-infected cell lines. In the same way, the development of schizont-infected cells into continuously growing cell Lines was studied with material isolated ex vivo from the sheep and cattle undergoing primary infections described elsewhere. Comparisons were also made between development of ex vivo cell Lines from animals undergoing primary infections with those of the animals undergoing challenge infection with the other parasite species. Theileria species specific primers were used in a PCR to determine the identity of the parasites in the cell lines. These in vitro studies confirmed earlier observations that T. lestoquardi was unable to infect cattle, whereas infection of all sheep with T. annulata was proven. Moreover, earlier indications of the development of partial cross-immunity in sheep of T. annulata to T. lestoquardi and vice versa were strengthened. These findings may thus have consequences for the understanding of the epidemiology of T. lestoquardi infections of sheep. On the other hand, since piroplasms were not demonstrated in sheep infected with T. annulata, such sheep will not be infective to ticks and will consequently be unlikely to play a role in the maintenance and transmission of T. annulata to cattle. (C) 1999 Elsevier Science B.V. All rights reserved.

Keywords

Theileria annulata; Theileria hirci; Theileria lestoquardi; cattle-protozoa; sheep-protozoa; experimental infections

Published in

Veterinary Parasitology
1999, Volume: 82, number: 3, pages: 193-204
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Fossum, Caroline

  • Department of Veterinary Microbiology, Swedish University of Agricultural Sciences
    

• Uggla, Arvid

  • Sveriges lantbruksuniversitet, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Clinical Science


Publication identifier

DOI: https://doi.org/10.1016/S0304-4017(99)00014-X

Permanent link to this page (URI)

https://res.slu.se/id/publ/106596