Genotyping of Ehrlichia canis TRP36 isolated from ticks and dogs in Iran.

Ehrlichia canis is the primary causative agent of Canine Monocytic Ehrlichiosis, a tick-borne zoonosis transmitted by Rhipicephalus sanguineus tick that significantly impacts canine health worldwide. This study investigated the prevalence rate, genetic diversity, and molecular characterization of E. canis isolated from dogs collected from northern areas of Iran and Tehran city, focusing on the tandem repeat protein 36 (TRP36) gene. A total of 355 blood samples and 199 ticks were collected from stray, sheltered, and household dogs. We identified E. canis in 21.4 % of blood and 39.19 % of tick samples, with TRP36 detected in 31 samples. Phylogenetic analysis of the TRP36 gene revealed 15 sequence types (STs), with molecular signatures and two highly conserved regions across all isolates. Notably, 60 % of isolates clustered within the Taiwan genotypic group, exhibiting specific amino acid signatures. Our findings highlight the genetic diversity and epidemiological characteristics of E. canis in Iran, providing valuable insights into the pathogen's molecular evolution and regional distribution. These results contribute to a better understanding of E. canis genotypes and their implications for ehrlichiosis diagnostics, treatment, and epidemiological control strategies.