Some characteristics of ovine lymphoid cells infected in vivo by Theileria hirci

Identification of Theileria lestoquardi Antigens Recognized by CD8+ T Cells

As part of an international effort to develop vaccines for Theileria lestoquardi, we undertook a limited screen to test T. lestoquardi orthologues of antigens recognised by CD8+ T lymphocyte responses against T. annulata and T. parva in cattle. Five MHC defined sheep were immunized by live T. lestoquardi infection and their CD8+ T lymphocyte responses determined. Thirteen T. lestoquardi orthologues of T. parva and T. annulata genes, previously shown to be targets of CD8+ T lymphocyte responses of immune cattle, were expressed in autologous fibroblasts and screened for T cell recognition using an IFNγ assay. Genes encoding T. lestoquardi antigens Tl8 (putative cysteine proteinase, 349 aa) or Tl9 (hypothetical secreted protein, 293 aa) were recognise by T cells from one animal that displayed a unique MHC class I genotype. Antigenic 9-mer peptide epitopes of Tl8 and Tl9 were identified through peptide scans using CD8+ T cells from the responding animal. These experiments identify the first T. lestoquardi antigens recognised by CD8+ T cell responses linked to specific MHC class I alleles.

Identification of tick vectors of ovine theileriosis in an endemic region of Iran

This study was made to determine the population of ticks in infected sheep and attempting to identify the tick vectors of ovine theileriosis in an endemic area of Iran from 2000 to 2001. A total of 188 suspected cases of ovine theileriosis from 28 flocks were clinically examined and investigated for the presence of Theileria lestoquardi in appropriate blood smears and any tick species on body of sheep. In this study, 36.17% of sheep were infected to T. lestoquardi with a parasitemia of 0.01-15%. There was no significant differences between the rate of parasitemia in sheep and the frequency of infected ticks. We found that 61.1% of the animals harboured Hyalomma a. anatolicum, 33.42% Rhipicephalus sanguineus and 0.05% Hyalomma m. marginatum. The examination of 345 tick salivary glands showed that (15%) of salivary glands of H.a. anatolicum and (4%) of R. sanguineus contained Feulgen positive bodies. Seasonally, the prevalence of Theileria infection and H.a. anatolicum infestation in sheep reached the highest level in July (62.5%) and June (23.6%), while a decrease was observed in September (24.5%) and August (17.39%), respectively. The prevalence of Theileria infection in all age groups and between male and female sheep was statistically non-significant.

The indirect fluorescent antibody test based on schizont antigen for study of the sheep parasite Theileria lestoquardi

An indirect fluorescent antibody test (IFAT), based on schizont-infected lymphoblastoid cells, was applied to study the course of antibody production in adult sheep inoculated with attenuated, in vitro grown, Theileria lestoquardi (Theileria hirci) infected cells. Bright fluorescence of the intracellular schizonts could first be demonstrated 15 days after inoculation. A 32-64-fold rise in antibody titres was recorded 1 month after infection, and substantial titres were still observed 90 days after inoculation. Fluorescence was absent with negative control sera and background staining was minimal. No serological cross-reactions were detected with sheep sera positive for Babesia motasi, Babesia ovis or Toxoplasma gondii. Results obtained did not differ when antigens prepared from three different strains of T. lestoquardi infected lymphoid cells were compared. Testing for reactivity to non-pathogenic Theileria species of sheep revealed a low degree of cross-reaction of a Theileria ovis and a Theileria separata antiserum to T. lestoquardi antigen. Cross-reactions were also observed with bovine sera positive for Theileria annulata and Theileria parva. Moreover, T. lestoquardi positive sera reacted almost equally strongly with bovine T. annulata antigen as with their homologous antigen, whereas cross-reaction with bovine T. parva antigen was less pronounced. These results indicate a close antigenic relationship between ovine T. lestoquardi and T. annulata of cattle.