Prevalence of coronavirus from diarrheic calves in the Republic of Korea

Objective: To investigate the prevalence of bovine coronavirus (BCoV), bovine rotavirus, and bovine viral diarrhea virus in the feces of normal and diarrheic Korean native calves aged 1-81 days between April and October of 2016 in the Republic of Korea. Methods: Samples were obtained from 50 normal and 93 diarrheic (56 semi-formed, 28 loose, and 9 watery feces) calves in six different regions of northern and southern Korea. These fecal samples were tested for BCoV, bovine rotavirus, and bovine viral diarrhea virus by RT-PCR. Results: Among the three pathogens examined, infection with BCoV was especially prominent in relation to diarrhea among calves aged 1-21 days [odds ratio (OR)=9.3, 95% confidence interval (CI): 1.1-78.9; P=0.02). Infection with BCoV alone (OR=2.9; 95% CI: 1.1-7.6; P=0.03) or co-infection of BCoV with bovine viral diarrhea virus (OR=3.6; 95% CI: 1.0-12.4; P=0.04) was significantly associated with the development of loose feces. Grazing and colostrum intake strongly reduced the occurrence of diarrhea as compared to housed calves (OR=0.2; 95% CI: 0.1-0.4; P=0.00) and calves that had not been fed colostrum (OR=0.2; 95% CI: 0.1-0.7; P=0.02), respectively. Conclusions: The present study suggests that BCoV is involved in calf diarrhea in the Republic of Korea. Therefore, grazing and colostrum intake is recommended for preventing and controlling calf diarrhea caused by BCoV.

Prevalence of coronavirus from diarrheic calves in the Republic of Korea

Objective:To investigate the prevalence of bovine coronavirus (BCoV),bovine rotavirus,and bovine viral diarrhea virus in the feces of normal and diarrheic Korean native calves aged 1-81 days between April and October of 2016 in the Republic of Korea.Methods:Samples were obtained from 50 normal and 93 diarrheic (56 semi-formed,28 loose,and 9 watery feces)calves in six different regions of northern and southern Korea.These fecal samples were tested for BCoV,bovine rotavirus,and bovine viral diarrhea virus by RT-PCR.Results:Among the three pathogens examined,infection with BCoV was especially prominent in relation to diarrhea among calves aged 1-21 days [odds ratio (OR)=9.3,95％ confidence interval (CI):1.1-78.9;P=0.02).Infection with BCoV alone (OR=2.9;95％ CI:1.1-7.6;P=0.03) or coinfection of BCoV with bovine viral diarrhea virus (OR=3.6;95％ CI:1.0-12.4;P=0.04) was significantly associated with the development of loose feces.Grazing and colostrum intake strongly reduced the occurrence of diarrhea as compared to housed calves (OR=0.2;95％ CI:0.1-0.4;P=0.00) and calves that had not been fed colostrum (OR=0.2;95％ CI:0.1-0.7;P=0.02),respectively.Conclusions:The present study suggests that BCoV is involved in calf diarrhea in the Republic of Korea.Therefore,grazing and colostrum intake is recommended for preventing and controlling calf diarrhea caused by BCoV.

A semi-nested RT-PCR assay targeted to hemagglutinin-esterase gene of Bovine Coronavirus / Reação de hemi-nested RT-PCR dirigida ao gene da hemaglutinina-esterase do Coronavírus Bovino

Bovine coronavirus (BCoV) is a non-segmented positive-sense single-stranded RNA virus whose envelope is constituted by a lipid bilayer with four structural proteins (HE, S, E and M) giving its characteristic crown-like virions appearance. Hemagglutinin-esterase (HE), is a polymorphic protein with a function of secondary receptor binder, and studies on the diversity of HE gene allow insights on BCoV evolution and host-parasite interactions. A semi-nested RT-PCR was developed for the amplification of a 441bp-long product of the HE gene of BCoV (nt 543 to 562). Optimal annealing temperatures were tested in a gradient thermocycler for the semi-nested assay and employed in the final protocol. The analytical sensitivity was determined by 10-fold serial dilutions of the BCoV Kakegawa strain (HA titer: 256) in a BCoV-free fecal suspension, with positive results up to 10-6 dilution, a high analytical sensitivity without PCR inhibition. The final semi-nested RT-PCR protocol was applied to 21 fecal samples of cows previously positive to BCoV and DNA sequencing of the 441bp amplicons of 14 of these resulted in highly-scored BCoV HE gene sequences after BLAST/n analysis. This semi-nested RT-PCR is a powerful tool for surveys of phylogenetic diversity in field strains of BCoV and for comparative studies among different genes of Coronavirus.

O coronavírus bovino (BCoV) é um vírus RNA simples fita, de sentido positivo, não segmentado com envelope constituído de uma camada dupla de lipídios com quatro proteínas (HE, S, E e M) que resultam no aspecto de coroa dos vírions. Como a HE (hemaglutinina-esterase) é uma proteína polimórfica com uma função de receptor aglutinante secundária, estudos sobre a diversidade do gene HE podem possibilitar maiores informações sobre a evolução e interação hospedeiro-parasita do BCoV. Uma reação de hemi-nested RT-PCR foi desenvolvida para a amplificação de um produto de 441pb do gene HE do BCoV (nt 543 ao 562). Temperaturas ótimas de hibridização foram testadas em um termociclador com gradiente para a reação de hemi-nested e utilizada no protocolo final. A sensibilidade analítica foi determinada por meio da diluição serial na base 10 do BCoV amostra Kakegawa (título HA: 256) em uma suspensão fecal negativa para BCoV, resultando positiva até a diluição de 10-6, mostrando uma alta sensibilidade analítica sem inibição na PCR. O protocolo final da hemi-nested RT-PCR foi aplicado a 21 amostras fecais de vacas previamente positivas para BCoV e o sequenciamento de DNA do produto de 441pb de 14 amostras resultaram em sequências com elevado escore do gene HE do BCoV após a análise no BLAST/n. Essa hemi-nested RT-PCR é uma ferramenta poderosa para estudos de diversidade filogenética de linhagens de campo de BCoV e para estudos comparativos entre os diferentes genes dos Coronavírus.

Differentiation of Bovine coronavirus (BCoV) genotypes by a restriction enzyme assay

This article reports the use of the GsuI restriction enzyme to differentiate genotypes of Bovine Coronavirus (BCoV), based on an 18-nucleotide deletion of S1-coding region found in one of the two genotypes. It was concluded that this assay can be used as a rapid tool for BCoV genotypes differentiation.

Cross-reactivity of Vaccine and Fields Strains of Bovine Coronaviruses in Korea

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, and is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. Although the Korean BCoV vaccine strain, BC94, was isolated in 1995, there has still been no report of a molecular characterization of the vaccine strain. To characterize the vaccine strain, relationships between BC94 and field strains were investigated, based on sequence analysis and cross-immunity. We determined the complete sequences of the HE, N, and S genes from BC94 and four NVRQS isolates (SUN5, A3, 0501, 0502). Due to its major role in antigenicity, the spike proteins of the BCoVs were analyzed. BC94 showed distinctive genetic divergence from field isolates collected from 2002 to 2005. BC94, SUN5, and A3 had no virulence-specific sequence and there was a single amino acid change, from asparagine to lysine at residue 175, in the polymorphic region. Strains 0501 and 0502 had virulence-specific sequences at all seven sites. Although the recently isolated Korean BCoVs and BC94 were genetically different, the cleavage site of spike genes at 763~768 (KRRSRR) and the antigenic domain II of the spike protein, amino acid position 528, were conserved in all NVRQS isolates. The antigenic relatedness of KCD9, representative of recent Korean BCoVs, was compared with the Korean vaccine strain BC94. KCD9 showed cross-reactivity against BC94 by virus neutralization (VN) test. These results suggest that BC94 is antigenically closely related to field isolates and is still effective as a vaccine strain.

Cross-reactivity of Vaccine and Fields Strains of Bovine Coronaviruses in Korea

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, and is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. Although the Korean BCoV vaccine strain, BC94, was isolated in 1995, there has still been no report of a molecular characterization of the vaccine strain. To characterize the vaccine strain, relationships between BC94 and field strains were investigated, based on sequence analysis and cross-immunity. We determined the complete sequences of the HE, N, and S genes from BC94 and four NVRQS isolates (SUN5, A3, 0501, 0502). Due to its major role in antigenicity, the spike proteins of the BCoVs were analyzed. BC94 showed distinctive genetic divergence from field isolates collected from 2002 to 2005. BC94, SUN5, and A3 had no virulence-specific sequence and there was a single amino acid change, from asparagine to lysine at residue 175, in the polymorphic region. Strains 0501 and 0502 had virulence-specific sequences at all seven sites. Although the recently isolated Korean BCoVs and BC94 were genetically different, the cleavage site of spike genes at 763~768 (KRRSRR) and the antigenic domain II of the spike protein, amino acid position 528, were conserved in all NVRQS isolates. The antigenic relatedness of KCD9, representative of recent Korean BCoVs, was compared with the Korean vaccine strain BC94. KCD9 showed cross-reactivity against BC94 by virus neutralization (VN) test. These results suggest that BC94 is antigenically closely related to field isolates and is still effective as a vaccine strain.

Prokaryotic expression of the nucleocapsid protein gene in bovine coronavirus and its preliminary application / 中国人兽共患病学报

To obtain and analyze the sequence of the nucleocapsid gene from bovine coronavirus, and to produce the fusion protein of the N gene in E.coli in order to use this recombinant protein for the study of bovine coronavirus. The N gene of BCV-DQ strain was amplified by RT-PCR, in which the primers were designed on the basis of N gene sequence of BCV-Mebus strain. The PCR products of 1 347 bp in length were cloned and sequenced, and then inserted into the prokaryotic vector pET30a. The recombinant plasmids were then transformed into Escherichia coli BL21 and identified by SDS-PAGE and Western blot assay. ELISA assay was optimized of N protein as the coating antigen to detect the viruses in the clinical samples. In comparison with 6 BCV strains in GenBank, the sequence identity was proved to be more than 98.3%. Result in SDS-PAGE showed that the fusion protein had a molecular weight of 60 ku, and could be specifically recognized by mouse serum against BCV. The indirect ELISA was used to test 256 serum samples collected from Heilongjiang province and 65.23% samples were positive. On testing field samples, an overall agreement of 95.31% was generated between the the neutralization test of viruses (VN) and indirect ELISA. It is apparent that the N gene was highly conservative and is expressed in E. coli in high level,also the prokaryotic expression products of this gene show a fine reactiongenicity in immune responses. It was also suggested that the N protein may be a useful antigen for sero-diagnosis and epidemiological investigation of BCV.

Rapid detection of bovine coronavirus by a semi-nested RT-PCR / Detecção rápida do Coronavírus Bovino (BCoV) por meio de uma semi-nested RT-PCR

Bovine coronavirus (BCoV) is a member of the group 2 of the Coronavirus (Nidovirales: Coronaviridae) and the causative agent of enteritis in both calves and adult bovine, as well as respiratory disease in calves. The present study aimed to develop a semi-nested RT-PCR for the detection of BCoV based on representative up-to-date sequences of the nucleocapsid gene, a conserved region of coronavirus genome. Three primers were designed, the first round with a 463bp and the second (semi-nested) with a 306bp predicted fragment. The analytical sensitivity was determined by 10-fold serial dilutions of the BCoV Kakegawa strain (HA titre: 256) in DEPC treated ultra-pure water, in fetal bovine serum (FBS) and in a BCoV-free fecal suspension, when positive results were found up to the 10-2, 10-3 and 10-7 dilutions, respectively, which suggests that the total amount of RNA in the sample influence the precipitation of pellets by the method of extraction used. When fecal samples was used, a large quantity of total RNA serves as carrier of BCoV RNA, demonstrating a high analytical sensitivity and lack of possible substances inhibiting the PCR. The final semi-nested RT-PCR protocol was applied to 25 fecal samples from adult cows, previously tested by a nested RT-PCR RdRp used as a reference test, resulting in 20 and 17 positives for the first and second tests, respectively, and a substantial agreement was found by kappa statistics (0.694). The high sensitivity and specificity of the new proposed method and the fact that primers were designed based on current BCoV sequences give basis to a more accurate diagnosis of BCoV-caused diseases, as well as to further insights on protocols for the detection of other Coronavirus representatives of both Animal and Public Health importance.

O Coronavírus bovino (BCoV) pertence ao grupo 2 do gênero Coronavirus (Nidovirales: Coronaviridae) e é agente causador de enterites tanto em bezerros como em bovinos adultos, bem como de doença respiratória em bezerros. O presente estudo teve por objetivo desenvolver uma semi-nested RT-PCR para a detecção do BCoV com base em seqüências representativas e recentes do gene do nucleocapsídeo, região conservada do genoma dos coronavírus. Três primers foram desenhados, a primeira amplificação com um fragmento esperado de 463pb e a segunda (semi-nested) com um fragmento esperado de 306pb. A sensibilidade analítica foi determinada pela diluição do BCoV cepa Kakegawa (título HA: 256) na base de 10 em água ultra-pura tratada com DEPC, em soro fetal bovino (SFB) e em uma suspensão fecal negativa para o BCoV, onde foram encontrados resultados positivos até a diluição de 10-2, 10-3 e 10-7, respectivamente. Este resultado sugere que a quantidade total de RNA na amostra influencia na precipitação dos pellets pelo método de extração utilizado. Quando se utiliza amostra fecal, a grande quantidade de RNA total funciona como carreadora do RNA do BCoV, demonstrando elevada sensibilidade analítica e ausência de possíveis substâncias inibidoras da PCR. O protocolo final da semi-nested RT-PCR foi aplicado a 25 amostras fecais de vacas adultas, previamente avaliadas por uma nested RT-PCR RdRp utilizada como teste de referência, resultando em 20 e 17 amostras positivas para o primeiro e segundo teste, respectivamente. Os resultados dos dois sistema de diagnóstico apresentaram concordância substancial (kappa: 0,694). A elevada sensibilidade e especificidade do novo método proposto e o fato de que os primers foram desenhados baseados em sequências atuais do BCoV, oferecem bases para o diagnóstico mais acurado de infecções causadas pelo BCoV, assim como para novas perspectivas em protocolos de detecção de outros Coronavírus de importância tanto em saninade animal ...

Isolation in HRT-18 cells and molecular analysis of a BCoV strain from diarrheic feces of naturally infected calves

Bovine coronavirus (BCoV) may cause acute diarrhea in newborn calves, leading to significant economic losses for cattle farmers. There are several diagnostic techniques used to detect BCoV in calf fecal samples, but virus isolation still has advantages for antigenic and genomic characterization. This study describes the isolation in HRT-18 cells and molecular characterization of Brazilian BCoV wild-type strains. Three fecal samples from diarrheic 30 day-old calves were inoculated in HRT-18 cell monolayers, which were then evaluated for HA titers and tested using semi-nested PCR followed by RFLP and sequencing. Two samples were successfully isolated and presented HA titers of 16 and 32 units per 25 mL. The results were confirmed using semi-nested PCR and RFLP. Molecular analyses identified a cell culture-adapted strain and a wild-type strain that were genetically similar (99 percent) to each other, but more distinct than BCoV strains circulating in other countries, even in the conserved N gene.

O coronavírus bovino (BCoV) pode causar diarreia aguda em bezerros recém-nascidos, ocasionando consideráveis perdas econômicas para a pecuária bovina. Várias técnicas de diagnóstico podem ser empregadas na detecção do BCoV a partir de amostras fecais de bezerros. Porém, o isolamento do BCoV em cultivo celular apresenta a vantagem de possibilitar a caracterização antigênica e molecular da estirpe viral. O presente estudo descreve o isolamento em células HRT-18, e a caracterização molecular de estirpes brasileiras do BCoV. Três amostras de fezes diarreicas de bezerros com 30 dias de idade foram inoculadas em culturas de células HRT-18. Os isolados foram avaliados por hemaglutinação (HA) e por uma semi-nested PCR seguida de RFLP e sequenciamento. Duas amostras foram isoladas e a confirmação foi verificada na semi-nested PCR e também RFLP. Na HA os títulos foram de 16 e 32 unidades por 25 mL. Análises moleculares identificam a estirpe adaptada em cultura celular e uma estirpe selvagem, como estirpes de BCoV semelhantes (99 por cento) entre si, mas distintas das circulantes em outros países, mesmo em um gene de uma proteína conservada (gene N).

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

Bovine coronavirus (BCoV) is a known cause of winter dysentery (WD) in adult cattle. The morbidity of the disease is high, that results in a significant decrease in milk production and consequently, economic losses. In the present study, we report on a classical outbreak of WD that affected a high-production Holstein dairy herd raised in a tropical country. The lactating batch included 154 cows, and 138 (90 percent) presented diarrhea in a short (nine days) period of time. Three (2 percent) cows died. The other batches of animals did not become ill. The evolution of the disease in the herd, including the clinical signs and epidemiological features, strongly suggested a WD case. Semi-nested PCR and RFLP confirmed that BCoV was the cause of the infection. Samples tested negative for all other enteric pathogens. This case report highlights the importance of BCoV in WD even in tropical countries such as Brazil.

O coronavirus bovino (BCoV) pode causar a diarreia de inverno (WD - Winter Dysentery) ao infectar bovinos adultos, particularmente em regiões de clima temperado ou frio. A morbidade da doença é alta, resultando em queda na produção de leite e, consequentemente, perdas econômicas. No presente estudo, é descrito um surto clássico de WD acometendo um rebanho de bovinos leiteiros da raça Holandesa PB, de alta produção, proveniente do estado do Paraná. O lote afetado era composto por 154 vacas em lactação, sendo que 138 (90 por cento) apresentaram diarreia em um curto (nove dias) período de tempo e 3 (2 por cento) vacas morreram em consequência da diarreia, desidratação e desequilíbrio eletrolítico. As outras categorias de animais do rebanho (bezerras, novilhas e vacas secas) não apresentaram sinal clínico. A evolução da doença clínica, assim como a epidemiologia da infecção sugeriu um quadro clássico de WD. O diagnóstico foi realizado por meio da identificação do BCoV, pela técnica de semi-nested PCR e confirmação por RFLP, em amostra fecal de uma vaca que veio a óbito. A presença de outros patógenos entéricos também foi avaliada e apresentou resultados negativos. O surto de WD descrito na região sul do Brasil alerta para a possibilidade da ocorrência dessa virose também em países situados em regiões de clima tropical.

Achados clínico patológicos durante um surto de disenteria de inverno em bovinos no Rio Grande do Sul / Clinic pathological features during a winter dysentery outbreak in cattle in Rio Grande do Sul

Descreve-se um surto de disenteria de inverno que afetou 10 vacas leiteiras de uma propriedade localizada em Viamão, Rio Grande do Sul. O quadro clínico caracterizou-se por uma diarréia inicialmente líquida esverdeada com estrias de sangue e muco, evoluindo, em alguns animais, para uma diarréia de coloração marrom escura à sanguinolenta, que persistiu, em média, cinco dias. Drástica diminuição na produção de leite e no consumo de alimentos, além de graus variados de depressão também foram observados. Apenas um dos 10 animais afetados morreu. Durante a necropsia, observaram-se mucosas pálidas, conteúdo sanguinolento com presença de grande quantidade de coágulos, principalmente no cólon espiral e petéquias na mucosa do cólon. Os principais achados histológicos foram encontradas no cólon espiral, onde havia criptas dilatadas, sem epitélio de revestimento ou revestidas por epitélio pavimentoso e/ou cuboidal, por vezes com núcleos grandes e nucléolos proeminentes. Algumas criptas eram preenchidas por debris necróticos e polimorfonucleares. Na imuno-histoquímica com anticorpo monoclonal para coronavírus bovino (8F2) em cortes do cólon espiral, havia marcações positivas no citoplasma de enterócitos das criptas, nos debris necróticos destas e em macrófagos na lâmina própria.(AU)

The report describes a winter dysentery outbreak that affected 10 dairy cows from a ranch located in the county of Viamão, Rio Grande do Sul. The most significant clinical sign was profuse and watery diarrhea, which ranged from a greenish to a brownish coloration and from occasional blood streaks with mucus to a bloody diarrhea. Most cases persisted for 5 days and also included depression, drastic decrease in milk production and in food consumption. Only one of the affected animals died. The necropsy revealed pale mucosa and sanguineous content with high quantity of blood clots, particularly within the spiral colon, and petechiae on the colonic mucosa. Histopathological lesions were predominant in the spiral colon, and consisted of a high number of dilated crypts without epithelium or with the replacement of a pavement epithelium with occasional immature cuboidal cells, which sometimes showed enlarged nucleus and proeminent nucleolus. Some crypts were filled with epithelial desquamation and polymorphnuclear cells. Bovine coronavirus (8F2) monoclonal antibody was used for immunohistochemistry on sections of the spiral colon that showed positive reactions in the cytoplasm of the infected crypt epithelium, sloughed necrotic cells, and within macrophages in the lamina propria of both.(AU)

Molecular analysis of the bovine coronavirus S1 gene by direct sequencing of diarrheic fecal specimens

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. The BCoV S protein plays a fundamental role in viral attachment and entry into the host cell, and is cleaved into two subunits termed S1 (amino terminal) and S2 (carboxy terminal). The present study describes a strategy for the sequencing of the BCoV S1 gene directly from fecal diarrheic specimens that were previously identified as BCoV positive by RT-PCR assay for N gene detection. A consensus sequence of 2681 nucleotides was obtained through direct sequencing of seven overlapping PCR fragments of the S gene. The samples did not undergo cell culture passage prior to PCR amplification and sequencing. The structural analysis was based on the genomic differences between Brazilian strains and other known BCoV from different geographical regions. The phylogenetic analysis of the entire S1 gene showed that the BCoV Brazilian strains were more distant from the Mebus strain (97.8 percent identity for nucleotides and 96.8 percent identity for amino acids) and more similar to the BCoV-ENT strain (98.7 percent for nucleotides and 98.7 percent for amino acids). Based on the phylogenetic analysis of the hypervariable region of the S1 subunit, these strains clustered with the American (BCoV-ENT, 182NS) and Canadian (BCQ20, BCQ2070, BCQ9, BCQ571, BCQ1523) calf diarrhea and the Canadian winter dysentery (BCQ7373, BCQ2590) strains, but clustered on a separate branch of the Korean and respiratory BCoV strains. The BCoV strains of the present study were not clustered in the same branch of previously published Brazilian strains (AY606193, AY606194). These data agree with the genealogical construction and suggest that at least two different BCoV strains are circulating in Brazil.

On the etiology of an outbreak of winter dysentery in dairy cows in Brazil

Winter dysentery (WD) is a seasonal infectious disease described worldwide that causes a marked decrease in milk production in dairy cows. In the Northern hemisphere, where the disease is classically recognized, bovine coronavirus (BCoV) has been assigned as a major etiologic agent of the disease. Nonetheless, in the Southern hemisphere, an in-deep etiological survey on WD cases had not been carried out. This study aimed to survey for BCoV by nested-RT-PCR, rotavirus by polyacrylamide gel electrophoresis (PAGE) and ELISA, bacteria by classical bacteriological methods and PCR for virulence factors and parasites by sugar flotation test on fecal samples of 21 cows from a farm during an outbreak of WD in São Paulo state, Southeastern Brazil. BCoV was detected in all 21 samples, while rotavirus was detected in two symptomatic cows. Escherichia coli, Yersinia intermedia, Providencia rustigianii Proteus penneri, Klebsiella terrigena and Enterobacter aglomerans were detected in samples from both asymptomatic and healthy cows in different associations. The study of E. coli virulence factors revealed that the strains isolated were all apathogenic. Cysts of Eimeria sp. and eggs of Strongyloidea were detected at low numbers in four of the symptomatic cows, with one co-infestation. These results suggest BCoV as the main etiologic agent of the cases of WD in Brazil, a conclusion that, with the clinical and epidemiological patterns of the disease studied herein, match those already described elsewhere. These findings give basis to the development of preventive measures and contribute to the understanding of the etiology of WD.

Em vacas leiteiras, a disenteria de inverno (DI) é uma doença infecciosa sazonal mundialmente relatada que ocasiona uma marcada queda na produção de leite; no hemisfério Norte, onde a doença é classicamente reconhecida, o coronavirus bovino (BCoV) tem um importante papel como agente etiológico. Entretanto, no hemisfério Sul, pesquisas etiológicas aprofundadas em casos de DI nunca forma realizadas. Este estudo objetivou a pesquisa de BCoV utilizando nested-RT-PCR, rotavírus utilizando eletroforese em gel de poliacrilamida (PAGE) e ELISA, bactérias com métodos bacteriológicos clássicos e PCR para fatores de virulência e parasitas pela técnica de flutuação em açúcar em 21 amostras fecais de vacas de uma fazenda durante um surto de DI no estado de São Paulo, Sudeste do Brasil. BCoV foi encontrado em todas as 21 amostras, enquanto que rotavírus foi encontrado em duas vacas sintomáticas. Escherichia coli, Yersinia intermedia, Providencia rustigiani, Proteus penneri, Klebsiella terrigena e Enterobacter aglomerans foram encontradas tanto em amostras de vacas sintomáticas quanto assintomáticas. O estudo de fatores de virulência para E. coli revelou que as amostras isoladas eram todas apatogênicas. Cistos de Eimeria sp. e ovos de Strongyloidea foram encontrados em baixos números em quatro animais sintomáticos, com uma co-infestação. Tais resultados sugerem o BCoV como o principal agente etiológico em casos de DI no Brasil, uma conclusão que, somada aos padrões clínicos e epidemiológicos da doença aqui estudada, concordam com aqueles descritos em outras regiões. Estes achados fornecem base o desenvolvimento de medidas preventivas e também contribuem para o entendimento sobre a etiologia da DI.

Serological Survey of Bovine Coronavirus in Korea

Bovine coronavirus (BCoV) is a causative agent of entero-pathogenic diarrhea in young calves and winter dysentery (WD) in adult cattle. In this study, we conducted a nationwide sero-epidemiological survey of BCoV infection in Korea. In total, 3,029 bovine sera collected between October and December 2005 were screened for the presence of antibodies against BCoV using a hemagglutination inhibition (HI) test. Half (50.0%) of individual cattle tested were positive for BCoV. The regional distribution of the seroprevalence of positive HI antibodies was 55.7% (234/420) in Gyeonggi, 53.0% (316/596) in Jeonra, 51.9% (374/720) in Chungcheong, 48.5% (401/827) in Gyeongsang, 43.9% (79/180) in Jeju, and 38.1% (109/286) in Gangwon Province. Analyzing the distribution of HI titer according to the age of the cattle showed the highest BCoV seropositive rate in 5-year-old cattle, and the incidence of cattle with an HI antibody titer of 1:160 or above was 12.1%.