Distribution of G (VP7) and P (VP4) genotypes of group A bovine rotaviruses from Tunisian calves with diarrhoea.

Abstract

To investigate the incidence, viral load and genetic diversity of bovine rotaviruses strains in Tunisia. A total of 169 faecal specimens, collected from diarrhoeic calves from several farms located in the central eastern regions of Tunisia, between January 2006 and October 2010, were analysed by semi-nested multiplex RT-PCRs for P and G genotypes identification or were genotyped by DNA sequencing. Positive samples were tested by TaqMan real-time RT-PCR to quantify the viral load. Group A bovine rotaviruses were detected in 15·4% (26/169) of the total studied cases of diarrhoea. Overall, G10 was the predominant G type, detected in 12/26 samples (46·2%) and G6 accounted for 42·3% (11/26) while P[11] was the predominant P type, detected in 12/26 samples (46·2%). Two P[5] genotypes (7·7%) were found in the collection. Dual G or P combination and genotype G8 were not found. The most common VP7/VP4 combinations were G6P[11] (30·8%; n = 8) and G10P[11] (11·5%; n = 3). The combination G10P[14] was seen in one sample, and partial typing was assessed in 53·8% (n = 14) of the cases. The viral load determined by real-time RT-PCR showed an average of 1·68 × 10(9) genome copies/g of faeces. Knowledge of P and G types could help us understand the relatedness of animal rotaviruses to viruses causing disease in humans. This is the first time that the viral load and P types of bovine rotaviruses have been determined in Tunisia, and this study contributes to a better understanding of the epidemiology of such viruses circulating in Tunisia. Nevertheless, continuous surveillance is necessary to detect the emergence of new variants.