Abstract:
The control of Theileria parva, a protozoan parasite that threatens almost 50% of the cattle population in Africa,
is still a challenge in many affected countries. Theileria parva field parasites from eastern Africa, and parasites
comprising the current live T. parva vaccine widely deployed in the same region have been reported to be
genotypically diverse. However, similar reports on T. parva parasites from southern Africa are limited, especially
in Corridor disease designated areas. Establishing the extent of genetic exchange in T. parva populations is
necessary for effective control of the parasite infection.
Twelve polymorphic microsatellite and minisatellite loci were targeted for genotypic and population genetics
analysis of T. parva parasites from South Africa, Mozambique, Kenya and Uganda using genomic DNA prepared
from cattle and buffalo blood samples. The results revealed genotypic similarities among parasites from the two
regions of Africa, with possible distinguishing allelic profiles on three loci (MS8, MS19 and MS33) for parasites
associated with Corridor disease in South Africa, and East Coast fever in eastern Africa. Individual populations
were in linkage equilibrium (VD < L), but when considered as one combined population, linkage disequilibrium
(VD > L) was observed. Genetic divergence was observed to be more within (AMOVA = 74%) than between
(AMOVA = 26%) populations. Principal coordinate analysis showed clustering that separated buffalo-derived
from cattle-derived T. parva parasites, although parasites from cattle showed a close genetic relationship. The
results also demonstrated geographic sub-structuring of T. parva parasites based on the disease syndromes
caused in cattle in the two regions of Africa.
These findings provide additional information on the genotypic diversity of T. parva parasites from South
Africa, and reveal possible differences based on three loci (MS8, MS19 and MS33) and similarities between
buffalo-derived T. parva parasites from southern and eastern Africa.
