Diversity in the 18S SSU rRNA V4 hyper-variable region ofTheileriaspp. in Cape buffalo (Syncerus caffer) and cattle from southern Africa

Abstract

SUMMARYSequence variation within the 18S SSU rRNA V4 hyper-variable region can affect the accuracy of real-time hybridization probe-based diagnostics for the detection ofTheileriaspp. infections. This is relevant for assays that use non-specific primers, such as the real-time hybridization assay forT. parva(Sibekoet al.2008). To assess the effect of sequence variation on this test, theTheileria18S gene from 62 buffalo and 49 cattle samples was cloned and ∼1000 clones sequenced. Twenty-six genotypes were detected which included known and novel genotypes for theT. buffeli, T. mutans, T. taurotragiandT. veliferaclades. A novel genotype related toT.sp. (sable) was also detected in 1 bovine sample.Theileriagenotypic diversity was higher in buffalo compared to cattle. Polymorphism within theT. parvahyper-variable region was confirmed by aberrant real-time melting peaks and supported by sequencing of the S5 ribosomal gene. Analysis of the S5 gene suggests that this gene can be a marker for species differentiation.T. parva, T.sp. (buffalo) andT.sp. (bougasvlei) remain the only genotypes amplified by the primer set of the hybridization assay. Therefore, the 18S sequence diversity observed does not seem to affect the current real-time hybridization assay forT. parva.