Molecular study and phylogenetic analysis of hemotropic Mycoplasma in Baghdad province, Iraq

Hemotrophic Mycoplasmas (HMs) are uncultivable, pleomorphic, very small epicellular, and like other Mycoplasma species lacking a cell wall. These pathogens damage and alter the erythrocytes by invading or parasitizing their surface, which can lead to persistent infections and complications. The most common HMs species in dogs are Candidatus Mycoplasmas haematoparvum (CMhp), and Mycoplasma haemocanis (Mhc).

The study aimed to detect infectious rates of hemotrophic Mycoplasma infections in dogs by molecular assay from Baghdad province for the first time.

The study included 155 dogs consisting vary breeds, ages, and both sexes from October 2023 to March 2024. The target gene for identified HMs in dogs was the 16s rRNA gene, where used two primers to amplify a fragment of approximately 618 bp of the target gene.

The PCR results indicated a 618 bp band of positive 16s rRNA gene of HMs. Six out of 155 dogs tested were positive by PCR, producing a 4% infection rate of HMs in dogs in Baghdad/Iraq (2% of each CMhp and uncultured Mycoplasma spp.), which had 100% matching with Mhc based on the 16S rRNA sequences. The highest infection rates were reported non-significantly in January in dogs older than 1 year, males, and significantly in the Malinois dogs. The main hematological values exhibited significant changes in the mean corpuscular hemoglobin concentration, RDW, and PDWS; also, normocytic normochromic and microcytic normochromic anemia were observed in two dogs infected with hemotropic mycoplasmosis. The phylogenetic analysis revealed that sequence alignment on the NCBI-BLAST site had a high identity with M. hacmocanis recorded by NCBI uncultured Mycoplasma spp. and candidatus Mycoplasma hemtoparvum. The relationship between geographical regions and uncultured Mycoplasma spp. and CMhp of the present study in the phylogenic trees revealed that sequences were grouped in the same branch of the several countries in the phylogenic tree, especially neighboring countries (Iran and Turkey).

This study is the first molecularly and phylogenetically detected of hemotropic Mycoplasma in Baghdad/Iraq. The results of phylogenetic analysis indicated that there was no specific substitution of sequences or genetic diversity of the hemotropic Mycoplasma in dogs from Iraq with other countries.