Establishment of Theileria parva-infected bovine tissue culture in Swiss and athymic (nude) mice

Theileria parva-infected bovine lymphoid cells, grown in culture, were inoculated by different routes into neonatal and adult Swiss mice immunosuppressed by irradiation, thymectomy or inoculation of anti-lymphocyte serum. Tumour-like masses, composed of parasitized bovine lymphoid cells, formed at the site of subcutaneous inoculation in immunosuppressed neonatal and adult mice, but consistent establishment of cells following intra-peritoneal inoculation occurred only in neonatal mice. In all cases the degree of cellular establishment was proportional to the degree of immunosuppression. The best “take” was in irradiated neonatally thymectomized mice.Cells underwent short-term multiplication in mice but, as immune competence returned, the cells were rejected. There was no evidence that cells, on passage, became more adapted to grow in mice, nor that mouse cells became parasitized.Culture-derived cells were also inoculated subcutaneously into irradiated and non-irradiated nu/nu, nu/+ and Swiss mice. Tumour-like masses, composed of parasitized bovine lymphoid cells, developed at the site of inoculation in all irradiated mice. In nu/+ and Swiss mice these masses regressed after 2–3 weeks, but in the athymic nu/nu mice there was generally no rejection or cellular degeneration and parasitized cells became widely disseminated in the host's tissues and organs, in some cases causing death.T. parva-infected cells could not be established in non-irradiated nu/nu mice, nor when irradiated nu/nu mice were inoculated by the intra-peritoneal route. “Take” in irradiated neonatal nu/nu mice was also poor.Cells were passaged three times in irradiated nu/nu mice inoculated subcutaneously and it seems probable that indefinite passage of T. parva in mice can now be achieved.     

Theileriosis: The exposure of immunised cattle in aTheileria lawrencei enzootic area

Summary Three groups of steers were exposed to field challenge in aT. lawrencei-enzootic area of Kenya. Four out of five ECF-susceptible steers and four out of five steers immunised againstT. parva (Muguga) died of theileriosis, the surviving animals experiencing severe reactions. On the other hand, all five steers immunised againstT. parva (Muguga) and a strain of theileria probably homologous with the one present in the area of exposure, survived and only experienced mild reactions. These results indicated that immunisation of cattle withT. parva (Muguga) may not necessarily protect them against field challenge with certainT. lawrencei-type strains, but that immunisation with an apparently homologous strain of theileria may well do so.

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Sumario Tres groupos de novillos fueron expuestos al desafio de campo en un area de Kenya enzootica aT. lawrencei. Cuatro de cinco novillos susceptibles a la Fiebre de la Costa del Este y cuatro de cinco novillos inmunizados contraT. parva (Muguga) murieron de Theileriosis; los animales sobrevivientes experimentaron reacciones severas. De otra manera, todos los cinco novillos inmunizados contraTheileria parva (Muguga) y una cepa de theileria probablemente homologa con la presente en el area de exposición, sobrevivieron y solo experimentaron reacciones ligeras. Estos resultados indicaron de que la inmunización del ganado conT. parva (Muguga) puede no necesariamente proteger contra el desafio de campo con ciertas capas ó tipos deT. lawrencei, pero que la inmunizacion con una cepa de theileria aparentemente homóloga puede proteger.

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Résumé Trois groupes de bouvillons ont été soumis à l'épreuve sur le terrain dans une région du Kenya où sévit une enzootie àT. lawrencei. Quatre sur cinq bouvillons neufs et quatre sur cinq bouvillons immunisés contreT. parva (Muguga) sont morts, les survivants éprouvant des réactions graves. D'autre part, cinq bouvillons immunisés contreT. parva (Muguga) et une souche deTheileria probablement identique à celle présente dans la région d'exposition, ont survécu et n'ont présenté que de faibles réactions. Ces résultats montrent que l'immunisation de bovins avecT. parva (Muguga) peut ne pas les protéger nécessairement de l'épreuve sur le terrain avec certaines souches de typeT. lawrencei, mais que l'immunisation avec une souche deTheileria apparemment identique àT. lawrencei peut le faire.

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On O.D.A. secondment from the A.R.C. Institute for Research in Animal Diseases, Compton, nr. Newbury, Berks., U.K. (Research Project R 2396).

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Supported by a grant from Pfizer Corporation, New York.

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On U.S.D.A. secondment from Plum Island Animal Disease Laboratory, Box 848, Greenport, Long Island, N.Y. 11944, U.S.A.

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Project supported by the United Nations Development Programme, with the Food and Agriculture Organization of the United Nations as the Executing Agency, in co-operation with the East African Community. The Project is also supported by the Overseas Development Administration of the United Kingdom (Research Projects 2396 and 2494), the United States Department of Agriculture, the Rockefeller Foundation, the International Atomic Energy Agency and the Pfizer Corporation.     

Impact of Probing the Reproductive Tract During Early Pregnancy on Fertility of Beef Cows

This short communication reports the impact of endometrial biopsies, uterine flushings and follicular fluid aspiration procedures at day 6 post artificial insemination (AI) on pregnancy rates. In Experiment 1, cows were timed AI (TAI) and assigned to the following treatment groups: control (n = 37), uterine flushing (n = 35) and endometrial biopsy (n = 38). On day 30 post AI, pregnancy rates were 40.5%, 33% and 28.5%, respectively (p > 0.1). Pregnancy rate on day 60 was lower (p < 0.004) in flushed cows than in the controls. In Experiment 2, oestrus was detected and cows were assigned to flushing (n = 32) or biopsy (n = 33) treatments 6 days after AI, which resulted in pregnancy rates of 31% and 36%, respectively (p > 0.1). In Experiment 3, cows were, 6 days after TAI, randomly assigned to the following treatments: control (n = 84) or aspiration of the largest follicle (n = 73). Pregnancy rates on day 30 post AI were 63.5% for the control group and 53% for the aspirated group (p > 0.1). In conclusion, uterine flushing and endometrial biopsy negatively affect pregnancy rates, but neither procedure can be considered to be incompatible with pregnancy maintenance. Follicular aspiration during pregnancy does not interact with pregnancy success. The amount and quality of samples obtained are compatible with the use of cellular and molecular analysis of uterine variables from cows that failed or succeeded on maintaining pregnancy.