Phylogenetic study on the 5′-untranslated region of bovine viral diarrhoea virus isolates from Iran

Bovine viral diarrhoea virus is a pathogen of bovids associated with reproduction system, causing in infected animals a range of ailments, from abortion to congenital defects. In this article, the nucleotide structure of the 5'-untranslated region (5-UTR) from 7 Iranian bovine diarrhoea virus (BVDV) isolates was characterized and subjected to comparative analysis against a panel of BVDV isolates from different sources. To this end, a 288 bp-long stretch of the internal ribosome entry site was amplified by RT-PCR. The PCR products subsequently cloned into PTZ57T vector and sequenced using T7 promoter primers. This resulted in detection of 3 new point mutations G -> A and G -> T in 2 isolates. When these findings were phylogenetically assessed, all the examined Iranian isolates were deemed to belong to the type1 of BVDV. Besides, 2 subtypes were identified among these isolates. In group A, a high level of similarity (99.2%) between Iranian isolates with a cytopathic Australian strain of BVDV-1c was detected; while in group B, the 4 Iranian isolates proved to be very similar to NADL-like BVDV-1a strains. We believe that the surprisingly high level of similarity between group A Iranian isolates and their corresponding Australian strain is likely to be an indication of a shared common ancestor. If correct, the most likely explanation of this observation is the introduction of such strains from Australia to Iran, possibly through exportation of infected live animals or animal productions (e. g. semen and meat) at some points in the past. Nevertheless, this hypothesis remains to be proved as further epidemiological work at genomic level is required to understand population of BVDV in Iran.