Detection of canine distemper virus (CDV) infection and expression of its receptors nectin-4 and SLAM in uterine samples of dogs: can CDV cause persistent uterine infection?

Canine distemper virus (CDV) causes highly contagious, systemic, and fatal infections of domestic carnivores worldwide. The high genetic and antigenic variability of the CDV H protein and the specificity of its interaction with signaling lymphocyte activation molecule (SLAM) and nectin-4 play a crucial role in determining the host specificity and tropism of the virus. It remains to be definitely established whether CDV may be localised in the urogenital tract or cause abortions in pregnant dogs. In this study, we investigated SLAM- and nectin-4-associated CDV infection of uterine tissue and adaptation of CDV to uterine tissue of dogs. For this purpose, 100 canine uterus samples were included in the study. CDV was detected by PCR in dogs without clinical signs, and molecular characterization of the virus was performed by bioinformatic analysis and comparison of partial amino acid sequences of the CDV H protein. In these uterine tissues infected with CDV, cellular SLAM and nectin-4 expression using histopathological, immunohistochemical, and immunofluorescence techniques. Sequence analysis showed that CDV strains belonging to the Asia-1 lineage are circulating in dogs in Türkiye and are responsible for uterine infections. Pathological analysis revealed increased SLAM and nectin-4 expression in CDV-infected uterine tissues compared to healthy uterine tissues. CDV was detected in 13 out of 100 uterine specimens tested, and increased expression of SLAM and nectin-4 was demonstrated for the first time in infected uterine tissues. Molecular and pathological analysis indicated that CDV may play a role in receptor-associated uterine infections. The data from this study will provide a basis for more extensive future research.