Anaplasma marginale: Detection, Characterization and Phylogenetic Analysis of Major Surface Protein 5 from Buffalo Isolates in South Coastal Region of Andhra Pradesh, India

The intracellular pathogen Anaplasma marginale is one of the main causing agents of bovine anaplasmosis, a mild to severe haemolytic illness that causes significant economic damage in both dairy and meat sectors. Although there have been several reports of anaplasmosis outbreaks in Andhra Pradesh, the molecular studies on A. marginale in the state are minimal. Therefore, we aim to detect and characterize the rickettsia organism. From 2022- 2023, we collected a total of 103 blood samples from buffalos showing clinical signs of bovine anaplasmosis across four districts in south coastal region of Andhra Pradesh, India. Upon blood smear examination bovine anaplasmosis was detected in 15.53% of cases, while the msp5 gene-based polymerase chain reaction assay detected A. marginale in 32.0% of cases. The coding region of msp5 gene from four field isolates was sequenced. The phylogenetic analysis revealed that, three of the present study isolates were in one clade and clustered with isolates from Kerala, Uttar Pradesh and Thailand while one isolate clustered separately with isolates from Tamil Nadu, Tirupati and Sohag. The PCR assay was shown to be more sensitive than standard diagnostic techniques. Therefore, it might be employed as a tool in large-scale epidemiological surveys to detect animals in the carrier and subclinical states. The current data may also be useful in vaccine development studies.