Analysis of 16S rRNA gene sequences of Ehrlichia canis, Anaplasma platys, and Wolbachia species from canine blood in Japan.

In the present study, three canine blood samples from Japan, that were suspected to be ehrlichia positive were examined. After sequencing the 16S rRNA genes, each dog was found to be infected either with Ehrlichia canis (Kagoshima 1), Anaplasma platys (Okinawa 1), or Wolbachia sp. (Okinawa 2). Phylogenic analysis was performed on these sequences. The nearly entire 16S rRNA sequence of Kagoshima 1 was found to be most similar to the sequences from Oklahoma and Venezuela E. canis strains (1 base pair difference out of 1,387, 99.9% sequence identity). The 16S rRNA gene sequence of Okinawa 1 showed the closest DNA identity to the French strain of A. platys (1 base deletion out of 1,385 bp, 99.6% sequence identity). The 16S rRNA gene sequence of Okinawa 2 illustrated the closest DNA identity to that of a Wolbachia sp. from Dirofilaria immitis (98.9% sequence similarity). These data imply a low diversity within E. canis strains and within A. platys strains, including those strains reported in this study. This is also the first demonstration of Wolbachia DNA in dog blood, suggesting the involvement of Wolbachia sp. in canine febrile illnesses.