Detection and Molecular Epidemiology of Bovine Kobuviruses in Calves With Acute Gastroenteritis for the First Time in Iran

Calf diarrhea is an important issue in cattle farms. Although rotavirus A is the primary viral agent causing calf diarrhea, infectious causatives of diarrhea remain unknown in many cases. Bovine kobuviruses are almost newly detected enteric viruses that have not been studied extensively. There is no information about the epidemiology and prevalence of kobuvirus and its importance in calf diarrhea in Iran.

The molecular epidemiology and phylogeny of kobuviruses were investigated in one-month-old diarrheic calves, and rotavirus A was simultaneously surveyed to find the outbreak rate of the co-infection of both viruses in diarrhea.

This study investigated 200 fecal diarrheic samples obtained from one-month-old calves using reverse transcription polymerase chain reaction (RT-PCR) methods. Samples were collected from rural and industrial cattle farms located in 7 provinces of Iran. The 3D domain of the RNA-dependent RNA polymerase (RdRp) enzyme of three positive samples from Mazandaran, Fars, and Isfahan provinces was subjected to the phylogenetic study.

It was found that 27 specimens are positive for kobuvirus. Although the frequency of rotavirus A detection was 24% (48 out of 200), co-infection was observed in 5 samples. Moreover, phylogenetic analysis showed a low relationship between the sequenced samples, indicating that the circulating bovine kobuviruses originated from different ancestors.

The results showed that bovine kobuvirus with different phylogenetic origins is highly prevalent in cattle farms in Iran. Regarding the low rate of co-infection with rotavirus A, bovine kobuviruses should be considered an important enteric viral agent in calf diarrhea.