Distribution of G (VP7) and P (VP4) genotypes in buffalo group A rotaviruses isolated in Southern Italy.

Group A rotaviruses are established agents of disease in buffalo calves. Early epidemiological studies in Italian buffalo herds revealed the predominance of strains with G8 specificity and detected strains with the rare, RRV-like, VP4 P[3] genotype. To acquire additional information on the VP4 and VP7 specificities of buffalo rotaviruses, a total of 125 fecal samples were collected from buffalo calves affected with diarrhoea, in seven dairy farms in Southern Italy. Rotaviruses were detected in 21 samples (16.8%) by an immunochromatographic assay and by reverse transcription-PCR (RT-PCR). Analysis of the VP7 gene revealed that 57% (12 of 21) of the isolates were G6, 23.8% were G8 (5 of 21) and 19% (4 of 21) were G10. Analysis of the VP4 revealed that 71.4% (15 of 21) of the isolates were P[5] and that 28.6% (6 of 21) were P[1]. The most common combination of G and P types was P[5],G6 (57%), followed by P[1],G10 (19%), P[5],G8 (14%) and P[1],G8 (9.5%). While P[5],G6 rotaviruses are very common in Italian bovine herds, the antigenic combination P[1],G10 is unusual and presumably derives from reassortment between P[1] and G10 strains, that appear to be more frequent in buffaloes and bovines, respectively. The presence of bovine-like G and P serotypes suggests that in Italy the epidemiology of buffalo rotaviruses overlaps the epidemiology of bovine rotaviruses, presumably because of the strict species affinity and/or of the intermingled distribution over the same geographical areas of the buffalo and bovine herds.