Kobuvirus (Aichivirus B) infection in Brazilian cattle herds.

There are few studies involving the detection of Aichivirus B in cattle herds worldwide, and this virus has never been diagnosed in South America. This study evaluated 222 diarrhoeic faecal samples from four Brazilian geographical regions (South, Southeast, Midwest, and North), collected between February 2010 to May 2012. To evaluate the frequency of occurrence in different types of livestock, samples from beef (n = 105) and dairy (n = 117) cattle herds were evaluated. To determine the category of animals more susceptible to infection, the sampling included samples from calves (n = 182) and adults animals (n = 40). The 216 bp fragment of the Aichivirus RdRp gene was amplified by a RT-PCR assay in 18.2 % (40/222) of the samples evaluated in both beef and dairy cattle animals. The highest (P < 0.05) detection rate (20.9 %; 38/182) of the Aichivirus B was found in calves. The nucleotide sequencing analysis showed that the Brazilian Aichivirus B strains clustered in a distinct branch in the phylogenetic tree of the European and Asiatic strains. This is the first description of Aichivirus B infection in Brazilian cattle herds.