Systematic Veterinary Virology

ANTIGENICITY & STRAINS

• BVDV is closely related to classical swine fever and ovine Border disease viruses.
• BVDV occurs in two forms
• Non-cytopathogenic and
• Cytopathogenic.
• There are two antigenically distinct genotypes (types 1 and 2), and virus isolates within these groups exhibit considerable biological and antigenic diversity.
• BVD-I (genotype 1) comprises the classic BVD virus isolates including commonly used vaccine strains.
• BVD-II (genotype 2) comprises newly described BVD viruses strains but have been isolated from as early as 1981.
• Each genotype contains cytopathic and non-cytopathic biotypes and both genotypes are capable of producing clinically similar syndromes in cattle. However, it is the non-cytopathogenic biotype that circulates in cattle populations.
• The two genotypes may be differentiated from each other, and from other pestiviruses, by monoclonal antibodies (MAbs) directed against the E2 and ERNS major glycoproteins, or by genetic analysis.