The Investigation of Canine Distemper Virus in Different Diagnosis Materials of Dogs using Molecular and Pathological Methods, Northeastern Turkey

Background: Canine distemper virus (CDV) is highly contagious disease that affects dogs despite several control measures. This study was aimed at investigating the presence of CDV nucleic acid in different clinical and tissue materials, from naturally infected dogs, by reverse transcriptase-polymerase chain reaction (RT-PCR) and to molecularly characterize distemper strains according to the partial Nucleoprotein (NP) gene sequence. Furthermore, tissue samples under went histopathological examination for distemper infection. Methods: A total of 202 different diagnosis materials were collected from dogs (n=60) in the Kars region in northeastern Turkey. The samples were tested for CDV using RT-PCR with primers designed for the CDV NP gene. Samples determined as positive for CDV (n=7) were sequenced. Tissue samples underwent histopathological examination. Result: Most of the cases were in animals aged 0-6 months. The most common clinical finding was severe respiratory system infection. This finding was accompanied by gastrointestinal and nervous system infections. CDV nucleic acid was detected in 112 of 202 materials by RT-PCR. According to RT-PCR results, positivity rates of 88.2% (30/34), 72.2% (13/18), 60% (3/5), 55.5% (10/18), 55.5% (10/18), 51.6% (16/31), 45.5% (5/11), 37.8% (14/37) and 36.7% (11/ 30) were detected in nasal swab, lung, footpad, kidney, spleen, rectal swab, cerebrospinal fluids (CSF), leuokocyte and cerebellum samples, respectively. Viral nucleic acids were detected at higher rates in nasal swabs. The phylogenetic assessment of the amplicon sequences revealed a 97.7%-100% similarity among the Turkish CDV strains, which are independent from vaccine strains, were found to be more closely related to the European lineage. Intranuclear and intracytoplasmic inclusion bodies were detected by histopathology. This is the first study to investigate CDV in naturally infected dogs from northeastern Turkey and to provide novel and updated epidemiological information.