Bovine viral diarrhea virus (BVDV) is an economically
important pathogen that causes gastrointestinal,
respiratory, and reproductive disease in cattle. Two
pathogenic biotypes of BVDV, cytopathic (CP) and
noncytopathic (NCP), have been described, based on
visible cytopathic effect when susceptible cell monolayers
are infected [1]. Independent of biotype, viral
strains are differentiated into types and subtypes (e.g.,
type 1a, type 1b, and type 2) based on viral RNA
sequence [2,3]. Persistent infection (PI) with BVDV
occurs when a bovine fetus is infected with a NCP strain