characterization of VP7 (G type) and VP4 (P type) genes of bovine group A rotaviruses from field samples using RT-PCR and RFLP analysis

Characterization of the VP7 (G type) and VP4 (P type) genes of bovine group A rotaviruses (BRV) from field samples was performed using RT-PCR and RFLP analysis. After RT-PCR amplification of the full length VP7 genes and partial length VP4 genes (nucleotides 1 to 1096), four enzymes, EcoRV, NlaIV, BamHI and HpaII were used for digestion analysis. For VP7, four RFLP profiles were observed after analysis of the digests: they were designated as G6, G6s (subtype, showed about 86% nucleotide and 90% amino acid identity to reference G6 strains), G8 and G10. For VP4, three RFLP profiles were observed: designated as P[1], P[5] and P[11]. The G typing analysis of 86 BRV fecal samples from 5 states, representing at least 11 different herds revealed that 60.5% (52/86) were G6, which included G6s (9/52); 19.8% (17/86) were G10; 7% (6/86) were G8; 10.4% (9/86) were G6 and G10 mixtures including two G6s samples; and 2.3% (2/86) were G6 and G6s mixtures. The P typing analysis of the same 86 fecal samples revealed that 64% (55/86) were P[5]; 28% (24/86) were P[11]; 1.2% (1/86) were P[1] and 6 samples (7%) were mixtures of either P[11] or P[5]. When the same samples were analyzed according to G and P type specificity, all possible combinations of G and P types existed in the field. The G6P[5] type was most prevalent and accounted for 46.7% (41/86) of the samples; 12.8% (11/86) were G10P[11]; 7% (6/86) were G10P[5] and an equal number were G6sP[11]. The G6P[11] (n = 2), G8P[1] (n= 1), G8P[5] (n = 1) and G8P[11] (n = 3) combinations were also observed. The following mixed BRV infections were observed in the field samples; G6sP[5+11] (n=1), G8P[5+11] (n=1), G6+G10P[5](n=1) G6 + G10P[5 + 11] (n = 2), G6 + G6sP[11] (n = 1), G6 + G6sP[1 + 11] (n = 1), G6s + G10P[11] (n = 1) and G6s + G10P[5 + 11] (n = 1). Information on the G and P types and G/P combinations in the field samples should be useful for understanding the epidemiology of BRV and designing vaccination strategies to control BRV in the field.