Is Italy one of the countries with the highest genetic diversity of bovine viral diarrhea virus?

Genetic typing of bovine viral diarrhea virus (BVDV) has distinguished BVDV-1 and BVDV-2 species and an emerging putative third species (HoBi-like virus), recently detected in southern Italy, representing the first report of cattle natural infection in Europe. Recognizing the need to update the data on BVDV genetic variability in Italy for mounting local and European alerts, a wide collection of 5’ UTR sequences (n=371) was selected to identify the frequency of genotypes and subtypes at the herd level between 1995 and 2013. BVDV-1 showed the highest frequency. BVDV-2 was detected sporadically and the latest identification dated back to 2004. No novel HoBi-like viruses were identified. The genetic diversity of BVDV-1 in Italy is increasing, as compared to previously published findings. The circulation of 11 out of the 17 BVDV-1 subtypes recognized worldwide was reported, with BVDV-1c, k and l detected for the first time in Italy. Four distribution patterns of BVDV-1 subtypes were observed: highly prevalent subtypes with a wide temporal-spatial distribution (1b, 1e); low prevalent subtypes with a widespread geographic distribution (1a, 1d, 1g, 1h, 1k) or a restricted geographic distribution (1f); and sporadic subtypes detected only in single herds (1c, 1j, 1l).. A unique genetic variant was detected in the majority of herds, but co-circulation of different genetic variants was also observed in both milk and beef herds, confirming that the diversity of viral strains in the Italian cattle population influences the variability also at the herd level. Northern Italy ranked first for BVDV introduction, prevalence, and dispersion. Nevertheless the identification in more restricted areas of sporadic variants suggests also the risk of introduction through different commercial livestock flow or contaminated biological products.