Detection and Characterization of Bovine Coronaviruses in Fecal Specimens of Adult Cattle with Diarrhea during the Warmer Seasons

Abstract

Bovine coronavirus (BCoV) is an etiological agent associated with winter dysentery (WD), prevalent in adult cattle during the winter. Although we previously detected, isolated, and characterized BCoV strains from adult cattle with WD (WD-BCoV strains) during the winter in South Korea, the precise epidemiology, as well as the causative agent of diarrhea in adult cattle in the warmer seasons, has not been examined. We examined 184 diarrheic fecal specimens collected from 75 herds of adult cattle from seven provinces during the spring (warm), autumn (warm), and summer (hot) seasons. Bovine coronavirus-positive reactions were detected for 107 (58.2%) diarrheic fecal samples (in 47/75 herds). Of these 107 positive samples, 90 fecal samples from 33 herds tested positive for BCoV alone and 17 fecal samples from 14 herds also tested positive for other pathogens. Biological comparisons between the 9 BCoV strains isolated in this study and the 10 previously isolated WD-BCoV strains revealed that there was no receptor-destroying enzyme (RDE) activity against mouse erythrocytes in the 9 BCoV strains but the 10 WD-BCoV strains had high RDE activity. Phylogenetic analysis of the spike (S) and hemagglutinin/esterase (HE) proteins revealed that all the Korean BCoVs clustered together regardless of season and were distinct from the other known BCoVs, suggesting a distinct evolutionary pathway for the Korean BCoVs. These and previous results revealed a high prevalence and widespread geographical distribution of BCoV, suggesting that this virus is endemic in adult cattle with diarrhea in all seasons in South Korea.

An outbreak of winter dysentery caused by bovine coronavirus in a high-production dairy cattle herd from a tropical country

“…In this case, three animals died as a consequence of the disease severity, but WD-induced mortality has previously been described, even with the addition of supportive therapy (Natsuaki et al, 2007). Genetic adaptation of the winter-circulating BCoV strains has also been reported (Park et al, 2006). The presence of strains that are more pathogenic could also be a determinant of disease morbidity and mortality.…”

“…Virus replication in the hosts during infection resulted in the excretion of high viral titers, which increased the viral load in the environment and exposed the whole herd. The presence of the receptor-destroying enzyme (RDE), which might be present in circulating strains in the cold months, enhances the virulence of BCoV by facilitating the elution of mature virions from the surfaces of infected cells and more effectively disseminating the virus (Park et al, 2006). The etiological agent responsible for the outbreak infected both the small and large intestines, as blood was present in feces of diarrheic cows; this excludes a large range of enteric pathogens, which are restricted to the duodenum and jejunum .…”

“…BCoV is an enveloped virus and its environmental viability is not favored by high intensity ultraviolet (UV) light, which is present during the warmer seasons . It has recently been demonstrated that BCoVs also circulate during the warmer seasons, but there are genetic differences between the warm-season and winterseason strains, which reflects on the ability of the virus to cause disease (Park et al, 2006). However, cattle are more efficiently infected in the winter, which increases the environmental contamination and justifies the high morbidity of WD during the cold months (Clark, 1993).…”

Brazilian strain of bovine respiratory coronavirus is derived from dual enteric and respiratory tropism

“…Worldwide, BCoV is associated with BRD in cattle of all ages, shipping fever, calf diarrhea, winter dysentery (Boileau and Kapil, 2010), and dysentery during the warmer seasons (Park et al, 2006;Decaro et al, 2008). Consequently, BCoV can simultaneously cause enteric and respiratory infections in the same animal (Park et al, 2007), although genetic markers for distinguishing between strains with both types of tropism were not identified during molecular analysis of the S glycoprotein (Kanno et al, 2007).…”

Surto de diarreia em vacas de um rebanho leiteiro na região sul de Minas Gerais: detecção de coronavírus bovino nas fezes

“…A doença tem sido denominada disenteria de inverno, embora alguns surtos possam ocorrer também em estações quentes (Park et al, 2006). Em geral, sua morbidade é alta, mas a letalidade é baixa ou nula (Saif, 1990).…”