Genetic characterization of bovine viral diarrhea viruses isolated from persistently infected calves born to dams vaccinated against bovine viral diarrhea virus before breeding.
OBJECTIVE
To collect and partially characterize strains of bovine viral diarrhea viruses(BVDVs) isolated from persistently infected (PI) calves born to vaccinated dams, determine genetic diversity of the isolated viruses, and identify regional distribution of genetically similar virus subpopulations.


METHODS
17 noncytopathic (NCP) BVDVs from PI calves from 11 herds of beef or dairy cattle.


METHODS
Viral RNA was extracted from infected cell cultures, and BVDV-specific PCR primers were used to amplify > 1,000 bases of the viral genome. Derived sequences were used for molecular phylogenetic analyses to determine the viral genotype and viral genogroup and to assess genetic similarity among BVDVs.


RESULTS
Analysis of the 17 NCP strains of BVDV failed to detect a viral genotype or viral genogroup not already reported to exist in the United States. One virus was classified as genotype 1, genogroup 1b, and 16 viruses were classified as genotype 2, genogroup 2a. Genotype 2 strains were genetically diverse, and genetic similarities were not obvious among viruses from geographic regions larger than a small locale.


CONCLUSIONS
Viruses isolated from herds where a genotype 1, genogroup 1a BVDV vaccine was administered prior to breeding were primarily genetically diverse genotype 2, genogroup 2a BVDVs. Vaccination with multiple BVDV genotypes may be needed to improve protection. Methods used in this study to obtain and analyze field strains are applicable to assessing efficacy of current BVDV vaccines. Candidates for future vaccines are viruses that appear able to elude the immune response of cattle vaccinated against BVDV with existing vaccines.
Bolin
Steven R
SR
Diagnostic Center for Population and Animal Health, College of Veterinary Medicine, Michigan State University, Lansing, MI 48910, USA.
Lim
Ailam
A
Grotelueschen
Dale M
DM
McBeth
William W
WW
Cortese
Victor S
VS
D000818:Animals; D000831:Animals, Newborn; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000517:prevention & control / Q000821:virology*; D002353:Carrier State / Q000662:veterinary* / Q000821:virology; D002417:Cattle; D001908:Diarrhea Viruses, Bovine Viral / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control / Q000662:veterinary*; D010802:Phylogeny; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D014611:Vaccination / Q000662:veterinary; D014765:Viral Vaccines / Q000008:administration & dosage*
D012367:RNA, Viral; D014765:Viral Vaccines