Infection dynamics of Theileria annulata over a disease season following cell line vaccination

Bilgic, H. B., Aksulu, A., Bakırcı, S., Unlu, A. H., Kose, O., Hacılarlıoglu, S., Weir, W. and Karagenc, T. (2019) Infection dynamics of Theileria annulata over a disease season following cell line vaccination. Veterinary Parasitology, 265, pp. 63-73. (doi:10.1016/j.vetpar.2018.11.012) (PMID:30638522)

Bilgic, H. B., Aksulu, A., Bakırcı, S., Unlu, A. H., Kose, O., Hacılarlıoglu, S., Weir, W. and Karagenc, T. (2019) Infection dynamics of Theileria annulata over a disease season following cell line vaccination. Veterinary Parasitology, 265, pp. 63-73. (doi:10.1016/j.vetpar.2018.11.012) (PMID:30638522)

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Abstract

Tropical theileriosis is a tick-borne haemoparasitic disease of cattle caused by the protozoan parasite Theileria annulata. Globally, the economic impact of the disease is immense and enhanced control measures would improve livestock production in endemic regions. Immunisation with a live attenuated vaccine is an effective and widely used control method, however, the repeated use of live vaccines may have an impact on the field parasite population at a genetic level. Additionally, there has been an increasing number of reports of vaccine breakthrough cases in recent years. Thus, the present study was designed to evaluate the genetic composition of a parasite population over a disease season in a locality where live cell line vaccination is practised. A diverse range of parasite genotypes was identified and every T. annulata positive cattle blood sample harboured multiple parasite genotypes. An alteration in the major genotype and an increasing multiplicity of infection in individual animals was observed over the course of the disease season. Vaccination status was found not to effect within-host multiplicity of infection, while a significantly higher number of genotypes was detected in grazed cattle compared to non-grazed ones. A degree of genetic isolation was evident between parasite populations on a micro-geographic scale, which has not been reported previously for T. annulata. Analysis of parasite genotypes in vaccinated animals suggested only a transient effect of the vaccine genotype on the genetic diversity of the T. annulata population. The vaccine genotype was not detected among clones of two vaccine ‘breakthrough’ isolates and there is no suggestion that it was responsible for disease. The obtained data indicated that in the system studied there is no apparent risk of introducing the vaccine genotype into the population with only a transient effect on the genetic diversity of the parasite population during the disease season.

Item Type:Articles
Additional Information:Financial support for this study was provided by a grant from TUBITAK (Ref. TUBITAK-111O718).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Weir, Dr William
Authors: Bilgic, H. B., Aksulu, A., Bakırcı, S., Unlu, A. H., Kose, O., Hacılarlıoglu, S., Weir, W., and Karagenc, T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Veterinary Parasitology
ISSN:0304-4017
Published Online:07 December 2018
Copyright Holders:Copyright © 2018 Elsevier
First Published:First published in Veterinary Parasitology 265:63-73
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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