Identification of specific variations within the HE, S1, and ORF4 genes of bovine coronaviruses associated with enteric and respiratory diseases in dairy cattle.

Abstract

The bovine Coronavirus (BCV) is the causative agent of enteric diseases including neonatal calf diarrhea (NCD) (Dea et al., 1980; Mebus et al., 1973), winter dysentery (WD) (Benfield and Saif, 1990; Dea et al., 1995), and chronic shedding in adult cattle (AD) (Tsunemitsu et Saif, 1995). BCV can also infect the upper respiratory tract of growing calves causing pneumonia (Chouljenko et al., 1998; Reynolds et al., 1985). The respiratory BCV (RBCV) is now recognized as an important agent associated to shipping fever (Storz et al., 1996). The virion possesses a single stranded, non segmented RNA genome of positive polarity, and is made of 5 structural proteins: the nucleocapsid phosphoprotein (N: 52 kDa), the matrix glycoprotein (M: 25 kDa), the peplomer glycoprotein (S: 200 kDa), the small membrane protein (E: 9.5 kDa) and the hemagglutinin esterase glycoprotein (HE: 140 kDa) (Spaan et al., 1988). Both S and HE are able to agglutinate red blood cells and elicit production of neutralizing antibodies (Dea et Tijssen, 1989; Deregt and Babiuk, 1987; Vautherot et al, 1992). The S protein has an important role to play in tropism being responsible for binding to the host cell (Spaan et al., 1988). The regions situated between the S and M genes (ORF4 and ORF5) may also be implicated in the tropism of coronaviruses (Mounir et al., 1992).