Variability and Global Distribution of Subgenotypes of Bovine Viral Diarrhea Virus

Abstract

Bovine viral diarrhea virus (BVDV) is a globally-distributed agent responsible for numerous clinical syndromes that lead to major economic losses. Two species, BVDV-1 and BVDV-2, discriminated on the basis of genetic and antigenic differences, are classified in the genus Pestivirus within the Flaviviridae family and distributed on all of the continents. BVDV-1 can be segregated into at least twenty-one subgenotypes (1a-1u), while four subgenotypes have been described for BVDV-2 (2a-2d). With respect to published sequences, the number of virus isolates described for BVDV-1 (88.2%) is considerably higher than for BVDV-2 (11.8%). The most frequently-reported BVDV-1 subgenotype are 1b, followed by 1a and 1c. The highest number of various BVDV subgenotypes has been documented in European countries, indicating greater genetic diversity of the virus on this continent. Current segregation of BVDV field isolates and the designation of subgenotypes are not harmonized. While the species BVDV-1 and BVDV-2 can be clearly differentiated independently from the portion of the genome being compared, analysis of different genomic regions can result in inconsistent assignment of some BVDV isolates to defined subgenotypes. To avoid non-conformities the authors recommend the development of a harmonized system for subdivision of BVDV isolates into defined subgenotypes.

Keywords: bovine viral diarrhea virus; epidemiology; genetic diversity; global distribution; subgenotyping.

Figure 1

Phylogenetic tree based on full-length N^pro encoding sequences of BVDV-1 and BVDV-2 isolates. Phylogenetic analysis of full-length N^pro encoding sequences (504 nt) of fifty BVDV-1 and nine BVDV-2 isolates was performed using the neighbor joining method [168,169]. Genetic distances were calculated by the Kimura 2-parameter model [170]. Bootstrap values were calculated for 1000 replicates [171] and are indicated only for statistically significant values (≥70%). The vertical bars and letters indicate the subgenotypes of BVDV-1 (a–r) and BVDV-2 (a and b). GenBank accession numbers of sequence data used for phylogenetic analysis are: Gi-1:AF104030, SCP: U17149, 890:U18059, Gi-4:AF144468, Gi-5:AF144469, Gi-6:AF144470, TR15:EU163979, 17237:EU747875, Soldan:AY735495, Shitara-02-06:AB359930, So-CP75:AB359929, TR73:KF154777, TR70:KF154779, TR75:KF154778, 721:AF144463, 871:AF144462, SH9:AF144473, CH-Bohni:AY894997, Suwa:AY894998, CH-05-b1:EU180037, 26-V639:AF287281, S14-1:AY735490, 3186V6:AF287282, S10:AY735489, Carlito:KP313732, TR16:EU163964, TR1:EU163950, Osloss:M96687, 1741:AF321453, Asturias-21:AY182155, CP7:U63479, G-AU:AF287285, TR23:EU163971, HB-1:KC695812, SD0803:JN400273, GS3:KC695811, 6:KC695810, J:AF287286, W:AF287290, TR26:EU163974, 11:KC207075, ZM-95:AF526381, SD-15:KR866116, 5:KC207071, BJ0701:GU120259, IS26NCP-01:AB359932, IS25CP-01:AB359931, 9:KC207073, A-AU:AF287283, L-AU:AF287287, Deer-GB1:U80902, KS86-1:AB078950, 23-15:AF287279, Astur2-36:AY182162, 519:AF144464, Leon-34:AY182160, SD-1:M96751, NADL:M31182, PE515:EU180034.