Molecular characterization of Ehrlichia canis from naturally infected dogs reveals a novel Asiatic-lineage and co-circulation of multiple lineages in India

• Published in: Research in veterinary science Vol. 175; p. 105311
• Main Authors: R. Parthiban, Aravindh Babu, Palavesam, Azhahianambi, Srinivasan, Sharmila, Mohanan, Arya, Ghosh, Srikanta, Krishnaswamy Gopalan, Tirumurugaan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2024
• Subjects: Asiatic lineage; Ehrlichia canis; p43; Phylogeny; Asiatic lineage; Phylogeny; Ehrlichia canis; p43
• ISSN: 0034-5288; 1532-2661; 1532-2661
• DOI: 10.1016/j.rvsc.2024.105311

Canine monocytic ehrlichiosis caused by Ehrlichia canis is an important rickettsial pathogen of dogs transmitted by Rhipicephalus sanguineus sensu lato ticks in India. Globally, molecular characterization of E. canis is done using different E. canis gene targets. This study aimed to characterize genetic diversity of uncultured Ehrlichia species from dogs by 16S rRNA and partial gp200 gene (termed as p43 region) sequences data. Phylogeny based on 16S rRNA gene did not reveal any region-specific lineages. The phylogeny based on 5′ region of E. canis gp200 gene (termed as p43 region) revealed four major clusters (A, B, C and D) and the Indian isolates fall under clusters A and B. Cluster A is characterized by an insertion of unique 141 bp tandem repeat sequence. Similar tandem repeat sequence was found in one of the E canis isolates from east-Asia, suggesting a possible divergence within this species. The study shows evidence for divergence of a new lineage within E. canis. The location of this insertion at the ‘ankyrin repeat domains' containing region is suggestive of its possible role in modulation of host responses. •This study has shown for the first time two evolutionarily divergent lineages of E. canis in India.•A unique 141 bases (49 AA) repeat within the p43 region of gp200 gene has been reported for the first time.•The location of this repeat within the ankyrin repeat containing region of gp200 suggests a probable functional role.•We have also shown that the16S rRNA gene sequence could not be used for tracing newer evolutionary lineages.