Rapid molecular detection and isolation of canine distemper virus in naturally infected dogs

Abstract

The Canine Distemper Virus (CDV), which infects dogs and a broad range of animal species, remains a serious concern in Turkey as well as worldwide. The current study shows that CDV can be detected and isolated rapidly and specifically in naturally infected dogs. The samples used included whole blood, nasal swab, ocular swab, rectal swab, and urine (n = 250) and were collected from 50 stray dogs, which had not received any vaccine against CDV in 2016–17. The presence of the CDV genome was confirmed in 105 (42%) samples using one-Step real-time RT-PCR. In total, 39 dogs were diagnosed with CDV infection based on the detection of characteristic cytopathic effects (CPE) in MDCK cells (Madin-Darby Canine Kidney), which was further verified by the fluorescence antibody technique (FAT). A total of 12 one-Step real-time RT-PCR negative samples, consisting of 4 rectal swabs and 8 urine samples, were found to be positive by virus isolation.In the tests for viral genome detection and virus isolation, positive correlations were found for blood samples, nasal swabs, ocular swabs (p<0.01, r = 1), rectal swabs (p<0.01, r = 0.844), and urine samples (p<0.01, r = 0.697).Out of a total of 117 (46.8%) samples showing viral growth in cell culture, 37 (31.62%) were found to have a high CPE, 26 (22.23%) had medium CPE, and 54 (46.15%) had low CPE. The highest CPE levels detected by FAT were for rectal swab and urine samples. In conclusion, the one-Step real-time RT-PCR method on rectal swab samples proved to be a highly sensitive method for the rapid and reliable detection of CDV. Besides, non-modified MDCK cell cultures are better for the isolation of CDV from naturally infected dogs.