High frequency of Aichivirus C (porcine kobuvirus) infection in piglets from different geographic regions of Brazil

The aim of this study was to evaluate the frequency of Aichivirus C infection in the three major industrial pig-producing regions of Brazil. This retrospective study evaluated 63 faecal samples that were collected between 2004 and 2011 from suckling piglets (1 to 3 weeks old) belonging to 46 pig herds located in the South, Southeast and Central-west regions of Brazil. The presence of Aichivirus C in the samples was evaluated by reverse transcription-polymerase chain reaction assay. A 216-bp fragment of the aichivirus RNA-dependent RNA polymerase gene was amplified from 48 out of 63 (76.2 %) faecal samples. Aichivirus C was identified in all the evaluated regions, and variations in the frequency of virus detection among the different Brazilian regions were observed. Aichivirus C was detected at significantly higher rates in 2-week-old (18/20; 90.0 %) and 3-week-old (19/22; 86.4 %) piglets than in 1-week-old piglets (11/21; 52.4 %) (P < 0.05). The nucleotide sequences of three amplicons clustered together with other sequences previously isolated in Brazil, revealing that there were no phylogenetic differences in the strains of Aichivirus C by region or age. This study demonstrated that Aichivirus C has been present in Brazilian pig herds for years and has spread to the major pig-producing regions of the country.