2005 Volume 58 Issue 11 Pages 741-745
In 2003, five heifers and a calf that calved on three different farms, farms A, B and C, within a collective farm, were identified as being persistently infected (PI) with bovine viral diarrhea virus (BVDV). To identify the epidemiological links between these multiple occurrences, genetic analyses of the 5' non-coding region (5'NCR) and E2 gene of the isolates were performed. According to the 5'NCR sequencing, five isolates consisting of four from Farm A and one from Farm C had an identical sequence. Moreover, the 5'NCR sequence of another BVDV isolate (IS17/99) obtained from a different area in 1999 was also identical. The level of identity between the isolates from Farm B and the five isolates was 90.8%. In contrast, a sequence analysis of the E2 gene revealed that the deduced level of amino acid sequence identity of the five isolates was 99.1% to 100%, whereas the identity between IS17/99 and the five isolates was 94.9% to 95.7%. In addition, the level of identity between the isolate from Farm B and the five isolates was only 70.4%. The 5'NCR and E2 gene sequence of the isolate from Farm B were identical with those of an isolate in 1999 from a calf persistently infected with BVDV that calved in the neighborhood, suggesting that the viruswas transmitted from the neighboring farm. This data shows that analysis of the E2 gene isuseful in the epidemiological investigation of field BVDV isolates.