GENETIC CONSERVATION OF THE p104 GENE USED FOR PCR-BASED DIAGNOSIS AND SURVEILLANCE OF THE Theileria parva PARASITE.

Abstract

Due to cross-border domestic cow movement, the range of Theileria parva, the protozoan parasite that causes East Coast disease in cattle, has been spreading to nations where it has not been found before. Cameroon and South Sudan are two recent additions to the list. This calls into doubt the preservation of the p104 antigen gene, which is the foundation of the widely used nested PCR technique for T. parva monitoring in the blood of sick cattle. In this study, parasites circulating naturally in the field in an endemic area of Busia Kenya were sampled and analysed for p104 nucleotide polymorphisms within a 496 bp fragment. p104 sequences derived from archived T. parva isolates from distinct regions within the African continent, as well as from medium scale distances within countries were also included in the study. These included isolates originating from Tanzania, Uganda, Rwanda and South Africa. P104 sequence polymorphism was assessed in a total of 56 sequences (of which 23 were obtained from the GenBank) originating from six nations that are widely dispersed throughout the parasite's geographic distribution, which includes eastern, central, and southern Africa. Among them were parasites from the Cape Buffalo wildlife reservoir and livestock. A substantial proportion of the ten allelic variations found in these isolates were also found in the three component stocks of the Muguga cocktail, which is utilized for both the infection and treatment live immunization method to control T. parva in the field. p104 variations that were often detected were found in isolates from South Africa, Kenya, Tanzania, and Rwanda. While some isolates showed distinct alleles, the small amount of diversity found did not match the location of origin of the parasite genomes examined in this investigation. The residue-changing p104 mutations did not exhibit any signs of positive selection. The amplicons were produced using nested primer oligonucleotides, which were notably globally conserved. The results show that the p104-based PCR detection technique should be reliable over the whole T. parva range, and when paired with amplicon sequencing, it can also yield information on the genotype of the parasite.