Characterisation of Oriental Theileria Infections in Crossbred Cattle Within Middle Indo Gangetic Plain of India

Recent outbreaks of Oriental theileriosis in various regions worldwide have challenged the previous belief that it was a benign condition, highlighting its emergence as an economically significant disease. Understanding the prevailing genotypes of T. orientalis is essential for comprehending its pathogenesis and the resulting differences in clinical symptoms. Thus, we collected blood samples from suspected cases in different areas of Bihar and examined them microscopically. To further investigate the suspected cases of theileriosis, we utilized PCR. The results revealed the presence of Theileria annulata, T. orientalis, and instances of mixed infections involving both Theileria annulata and T. orientalis. Subtyping of T. orientalis indicated prevalence of the chitose genotype by PCR amplification. However, we also detected mixed infections of the chitose and buffeli genotypes in one samples. Notably, the ikeda genotype of T. orientalis was not identified in our study. The PCR products were sequenced, analyzed using BLAST, and subsequently submitted to the NCBI nucleotide database with the following accession numbers: OQ241436, OQ241437, OQ207675, OQ207676, OQ207677, and OQ207678. In silico sequence analysis, multiple sequence alignment of these submission and corresponding amino acid sequences revealed several relatively conserved nucleotide stretches within the central region., particularly around positions 310-320, 330-350, 430-450, 470-490, 510-530, and 570-590. The phylogenetic analysis indicates that OQ207676 and MK874825 are the most closely related, whereas OQ241436 is the most divergent sequence. The sequences cluster into two major groups, suggesting at least two evolutionary lineages within this protein family, with varying degrees of conservation and divergence. Our findings indicate that clinical theileriosis in this region is primarily caused by Theileria annulata and the T. orientalis chitose genotype.