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Genetic and biological diversity among isolates of Neospora caninum

Published online by Cambridge University Press:  23 July 2001

A. SCHOCK
Affiliation:
Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik, Edinburgh EH26 0PZ, UK
E. A. INNES
Affiliation:
Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik, Edinburgh EH26 0PZ, UK
I. YAMANE
Affiliation:
National Institute of Animal Health, Laboratory of Epidemiology,Tsukuba, Ibaraki, Japan
S. M. LATHAM
Affiliation:
Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
J. M. WASTLING
Affiliation:
Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK

Abstract

Neospora caninum is a protozoan parasite that causes bovine abortion. The epidemiology of N.caninum is poorly understood and little is known about the genetic diversity of the parasite, or whether individual isolates differ in virulence. Such diversity may, among other factors, underlie the range of pathologies seen in cattle. In this study we analysed biological and genetic variation in 6 isolates of N. caninum originating from canine and bovine hosts by measurement of growth rate in vitro, Western blotting and random amplification of polymorphic DNA (RAPD). This comparative analysis of intra-species diversity demonstrated that heterogeneity exists within the species. The relative growth rate in vitro, as assessed by 3[H]uracil uptake, showed significant variation between isolates. However, no significant differences were detected between the antigenic profiles of each isolate by Western blotting. RAPD-PCR was performed on DNA from the 6 Neospora isolates; 3 strains of Toxoplasma gondii, Sarcocystis sp. and Cryptosporidium parvum were also analysed. Twenty-six RAPD primers gave rise to 434 markers of which 222 were conserved between all the Neospora isolates and distinguished them from the other Apicomplexa. An additional 54 markers were unique for Neospora but were polymorphic within the species and able to differentiate between the individual isolates. The RAPD data were subjected to pair-wise similarity and cluster analysis and showed that the Neospora isolates clustered together as a group, with T. gondii as their nearest neighbour. N. caninum isolates showed no clustering with respect either to host or geographical origin. The genetic similarity between Neospora isolates from cattle and dogs suggests that these hosts may be epidemiologically related, although further analysis of bovine and canine field samples are required. The genetic and biological diversity observed in this study may have important implications for our understanding of the pathology and epidemiology of neosporosis.

Type
Research Article
Copyright
© 2001 Cambridge University Press

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