Dual enteric and respiratory tropisms of winter dysentery bovine coronavirus in calves

A comprehensive molecular analysis of bovine coronavirus strains isolated from Brazil and comparison of a wild-type and cell culture-adapted strain associated with respiratory disease

Bovine coronavirus (BCoV) has dual tropisms that can trigger enteric and respiratory diseases in cattle. Despite its global distribution, BCoV field strains from Brazil remain underexplored in studies investigating the virus's worldwide circulation. Another research gap involves the comparative analysis of S protein sequences in BCoV isolates from passages in cell lines versus direct sequencing from clinical samples. Therefore, one of the objectives of our study was to conduct a comprehensive phylogenetic analysis of BCoV strains identified from Brazil, including a respiratory strain obtained during this study, comparing them with global and ancestral BCoV strains. Additionally, we performed a comparative analysis between wild-type BCoV directly sequenced from the clinical sample (nasal secretion) and the cell culture-adapted strain, utilizing the Sanger method. The field strain and multiple cell passage in cell culture (HRT-18) adapted BCoV strain (BOV19 NS) detected in this study were characterized through molecular and phylogenetic analyses based on partial fragments of 1,448 nt covering the hypervariable region of the S gene. The analyses have demonstrated that different BCoV strains circulating in Brazil, and possibly Brazilian variants, constitute a new genotype (putative G15 genotype). Compared with the ancestral prototype (Mebus strain) of BCoV, 33 nt substitutions were identified of which 15 resulted in non-synonymous mutations (nine transitions and six transversions). Now, compared with the wild-type strain was identified only one nt substitution in nt 2,428 from the seventh passage onwards, which resulted in transversion, neutral-neutral charge, and one substitution of asparagine for tyrosine at aa residue 810 (N810Y).

Characterization and Spike Gene Analysis of a Candidate Attenuated Live Bovine Coronavirus Vaccine

The bovine coronavirus (BCoV) KBR-1 strain, obtained from calf diarrhea samples collected in 2017, belongs to group GIIa. To attenuate this strain, it was subcultured continuously (up to 79 times) in HRT-18 cells, followed by 80-120 passages in MDBK cells. The KBR-1-p120 strain harvested from MDBK cells at passage 120 harbored 13 amino acid mutations in the spike gene. Additionally, the KBR-1-p120 strain showed a high viral titer and cytopathogenic effects in MDBK cells. Seven-day-old calves (negative for BCoV antigen and antibodies) that did not consume colostrum were orally inoculated with the attenuated candidate strain (KBR-1-p120), or with KBR-1 passaged 10 times (KBR-1-p10) in HRT-18 cells. Calves inoculated with KBR-1-p10 had a low diarrhea score, and BCoV RNA was detected at 3-7 days post-inoculation (DPI). The virus was also present in the duodenum, jejunum, and ileum at autopsy; however, calves inoculated with KBR-1-p120 had low levels of BCoV RNA in feces at 4-6 DPI, and no diarrhea. In addition, an extremely small amount of BCoV RNA was present in the jejunum and ileum at autopsy. The small intestines of calves inoculated with KBR-1-p120 were emulsified and used to infect calves two more times, but pathogenicity was not recovered. Therefore, the KBR-1-p120 strain has potential as a live vaccine candidate.

Equine Coronaviruses

Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In equids, equine coronavirus has been associated with diarrhea in foals and lethargy, fever, anorexia, and occasional gastrointestinal signs in adult horses. Although horses seem to be susceptible to the human severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) based on the high homology to the ACE-2 receptor, they seem to be incidental hosts because of occasional SARS-CoV-2 spillover from humans. However, until more clinical and seroepidemiological data are available, it remains important to monitor equids for possible transmission from humans with clinical or asymptomatic COVID-19.

Bovine Enteroids as an In Vitro Model for Infection with Bovine Coronavirus

Bovine coronavirus (BCoV) is one of the major viral pathogens of cattle, responsible for economic losses and causing a substantial impact on animal welfare. Several in vitro 2D models have been used to investigate BCoV infection and its pathogenesis. However, 3D enteroids are likely to be a better model with which to investigate host–pathogen interactions. This study established bovine enteroids as an in vitro replication system for BCoV, and we compared the expression of selected genes during the BCoV infection of the enteroids with the expression previously described in HCT-8 cells. The enteroids were successfully established from bovine ileum and permissive to BCoV, as shown by a seven-fold increase in viral RNA after 72 h. Immunostaining of differentiation markers showed a mixed population of differentiated cells. Gene expression ratios at 72 h showed that pro-inflammatory responses such as IL-8 and IL-1A remained unchanged in response to BCoV infection. Expression of other immune genes, including CXCL-3, MMP13, and TNF-α, was significantly downregulated. This study shows that the bovine enteroids had a differentiated cell population and were permissive to BCoV. Further studies are necessary for a comparative analysis to determine whether enteroids are suitable in vitro models to study host responses during BCoV infection.

Evolutionary adaptation of bovine coronavirus (BCoV): Screening of natural recombinations across the complete genomes

Bovine coronavirus (BCoV) is a member of pathogenic Betacoronaviruses that has been circulating for several decades in multiple host species. Given the similarity between BCoV and human coronaviruses, the current study aimed to review the complete genomes of 107 BCoV strains available on the GenBank database, collected between 1983 and 2017 from different countries. The maximum-likelihood based phylogenetic analysis revealed three main BCoV genogroups: GI, GII, and GIII. GI is further divided into nine subgenogroups: GI-a to GI-i. The GI-a to GI-d are restricted to Japan, and GI-e to GI-i to the USA. The evolutionary relationships were also inferred using phylogenetic network analysis, revealing two major distinct networks dominated by viruses identified in the USA and Japan, respectively. The USA strains-dominated Network Cluster includes two sub-branches: France/Germany and Japan/China in addition to the United States, while Japan strains-dominated Network Cluster is limited to Japan. Twelve recombination events were determined, including 11 intragenogroup (GI) and one intergenogroup (GII vs. GI-g). The breakpoints of the recombination events were mainly located in ORF1ab and the spike glycoprotein ORF. Interestingly, 10 of 12 recombination events occurred between Japan strains, one between the USA strains, and one from intercontinental recombination (Japan vs. USA). These findings suggest that geographical characteristics, and population density with closer contact, might significantly impact the BCoV infection and co-infection and boost the emergence of more complex virus lineages.

Reduction in Mortality of Calves with Bovine Respiratory Disease in Detection with Influenza C and D Virus

Both influenza C (ICV) and influenza D (IDV) viruses were recently included as bovine respiratory disease (BRD) causes, but their role in BRD has not been evaluated. Therefore, the mortality and reproductive performances of BRD calves with different isolated viruses were determined in this study. Data on 152 BRD calves with bovine viral diarrhoea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCoV), bovine parainfluenza virus 3 (BPIV-3), ICV, or IDV from nasal swab samples using real-time rt-PCR were used. The general data and respiratory signs were recorded immediately, and thereafter, the data on dead or culling calves due to BRD and reproductive performance were collected. The percentages of the BRD calves were 71.7%, 52.6%, 40.8%, 10.5%, 68.4%, and 65.8% for BVDV, BRSV, BCoV, BPIV-3, ICV, and IDV, respectively. Mucous secretion (OR = 4.27) and age ≤ 6 months (OR =14.97) had higher risks of mortality than those with serous secretion and older age. The calves with IDV had lower risks of culling than those without IDV (OR = 0.19). This study shows that most viral infections in BRD calves are a combination of viruses with BVDV, ICV, and IDV. In addition, IDV might have a role in reducing the severity of BRD calves.

Isolation and Genetic Characterization of a Bovine Coronavirus KBR-1 Strain from Calf Feces in South Korea

Bovine coronavirus (BCoV) causes severe diarrhea in neonatal calves, winter dysentery in adult cattle, and respiratory disease in feedlot cattle, resulting in economic losses. A total of 16/140 calf diarrheic feces samples collected in South Korea between 2017 and 2018 were positive for BCoV. Phylogenetic analysis of the complete spike and hemagglutinin/esterase genes revealed that the 16 Korean BCoV strains belonged to group GIIa along with Korean strains isolated after 2000, whereas Korean BCoV strains isolated before 2000 belonged to group GI. Mice and goats inoculated with an inactivated KBR-1 strain (isolated from this study) generated higher antibody titers (96 ± 13.49 and 73 ± 13.49, respectively) when mixed with the Montanide01 adjuvant than when mixed with the Carbopol or IMS1313 adjuvants. Viral antigens were detected in the large intestine, jejunum, and ileum of calves inoculated with inactivated KBR-1 vaccine (10^4.0 TCID₅₀/mL) at 14 days of post-challenge (DPC). However, no viral antigens were detected in calves vaccinated with a higher dose of inactivated KBR-1 strain (10^6.0 TCID₅₀/mL) at 14 DPC, and they had high antibody titers and stable diarrhea scores. Currently, the group GIIa is prevalent in cows in South Korea, and although further research is needed in the future, the recently isolated KBR-1 strain has potential value as a new vaccine candidate.

Recent Emergence of Bovine Coronavirus Variants with Mutations in the Hemagglutinin-Esterase Receptor Binding Domain in U.S. Cattle

Bovine coronavirus (BCoV) has spilled over to many species, including humans, where the host range variant coronavirus OC43 is endemic. The balance of the opposing activities of the surface spike (S) and hemagglutinin-esterase (HE) glycoproteins controls BCoV avidity, which is critical for interspecies transmission and host adaptation. Here, 78 genomes were sequenced directly from clinical samples collected between 2013 and 2022 from cattle in 12 states, primarily in the Midwestern U.S. Relatively little genetic diversity was observed, with genomes having >98% nucleotide identity. Eleven isolates collected between 2020 and 2022 from four states (Nebraska, Colorado, California, and Wisconsin) contained a 12 nucleotide insertion in the receptor-binding domain (RBD) of the HE gene similar to one recently reported in China, and a single genome from Nebraska collected in 2020 contained a novel 12 nucleotide deletion in the HE gene RBD. Isogenic HE proteins containing either the insertion or deletion in the HE RBD maintained esterase activity and could bind bovine submaxillary mucin, a substrate enriched in the receptor 9-O-acetylated-sialic acid, despite modeling that predicted structural changes in the HE R3 loop critical for receptor binding. The emergence of BCoV with structural variants in the RBD raises the possibility of further interspecies transmission.

Advances in Bovine Coronavirus Epidemiology

Bovine coronavirus (BCoV) is a causative agent of enteric and respiratory disease in cattle. BCoV has also been reported to cause a variety of animal diseases and is closely related to human coronaviruses, which has attracted extensive attention from both cattle farmers and researchers. However, there are few comprehensive epidemiological reviews, and key information regarding the effect of S-gene differences on tissue tendency and potential cross-species transmission remain unclear. In this review, we summarize BCoV epidemiology, including the transmission, infection-associated factors, co-infection, pathogenicity, genetic evolution, and potential cross-species transmission. Furthermore, the potential two-receptor binding motif system for BCoV entry and the association between BCoV and SARS-CoV-2 are also discussed in this review. Our aim is to provide valuable information for the prevention and treatment of BCoV infection throughout the world.

Bovine coronavirus in the lower respiratory tract of cattle with respiratory disease

Bovine coronavirus (BCoV) is a known cause of enteric disease in cattle; however, its role in bovine respiratory disease (BRD) is poorly understood, with a dearth of evidence of the detection of the virus in respiratory tract lesions. We coupled histologic evaluation of tracheal and lower airway tissues from 104 calves with BRD in which BCoV was detected in the lungs via PCR followed by direct detection of BCoV by immunohistochemistry and an RNA in situ hybridization assay (ISH; RNAscope technology). RNAscope ISH detected BCoV in respiratory epithelium in more cases than did IHC. Using both methods of direct detection, tracheal epithelial attenuation and identification of the virus within lesions were observed commonly. Our results confirm a role of BCoV in respiratory tract infection and pathology, and show that the virus likely plays a role in the development of BRD.

Bovine Coronavirus Infects the Respiratory Tract of Cattle Challenged Intranasally

Bovine Coronavirus (BCoV) is a member of a family of viruses associated with both enteric and respiratory diseases in a wide range of hosts. BCoV has been well-established as a causative agent of diarrhea in cattle, however, its role as a respiratory pathogen is controversial. In this study, fifteen calves were challenged intranasally with virulent BCoV in order to observe the clinical manifestation of the BCoV infection for up to 8 days after initial challenge, looking specifically for indication of symptoms, pathology, and presence of viral infection in the respiratory tract, as compared to six unchallenged control calves. Throughout the study, clinical signs of disease were recorded and nasal swabs were collected daily. Additionally, bronchoalveolar lavage (BAL) was performed at 4 days Post-challenge, and blood and tissue samples were collected from calves at 4, 6, or 8 days Post-challenge to be tested for the presence of BCoV and disease pathology. The data collected support that this BCoV challenge resulted in respiratory infections as evidenced by the isolation of BCoV in BAL fluids and positive qPCR, immunohistochemistry (IHC), and histopathologic lesions in the upper and lower respiratory tissues. This study can thus be added to a growing body of data supporting that BCoV is a respiratory pathogen and contributor to respiratory disease in cattle.

Natural Bovine Coronavirus Infection in a Calf Persistently Infected with Bovine Viral Diarrhea Virus: Viral Shedding, Immunological Features and S Gene Variations

Simple Summary

The evolution of a bovine coronavirus (BCoV) natural infection in a calf persistently infected with bovine viral diarrhea virus (BVDV) was described. The infected calf developed intermittent nasal discharge, diarrhea and hyperthermia. The total number of leukocytes/mL and the absolute differential number of neutrophils and lymphocytes resulted within the normal range, but the monocytes increased at T28 (time 28 post-infection) and the CD8⁺ subpopulation increased at T7 and between T28 and T35. BCoV shedding in nasal discharges and feces was detected up to three weeks post infection (p.i.) and high antibody titers persisted for up to 8 weeks p.i. Virus shedding increased until T14, contrary to what was observed in a previous study where BCoV was detected with a lower load in the co-infected (BCoV/BVDV) calves than in the calves infected with BCoV only. We can suppose that BVDV may have exacerbated the long viral excretion, as well as favoring the onset of mutations in the genome of BCoV. An extensive study was performed to verify if the selective pressure in the S gene could be a natural mode of variation of BCoV.

Abstract

The evolution of a bovine coronavirus (BCoV) natural infection in a calf persistently infected with bovine viral diarrhea virus (BVDV) was described. The infected calf developed intermittent nasal discharge, diarrhea and hyperthermia. The total number of leukocytes/mL and the absolute differential number of neutrophils and lymphocytes resulted within the normal range, but monocytes increased at T28 (time 28 post-infection). Flow-cytometry analysis evidenced that the CD8⁺ subpopulation increased at T7 and between T28 and T35. BCoV shedding in nasal discharges and feces was detected up to three weeks post infection and high antibody titers persisted up to T56. The RNA BCoV load increased until T14, contrary to what was observed in a previous study where the fecal excretion of BCoV was significantly lower in the co-infected (BCoV/BVDV) calves than in the calves infected with BCoV only. We can suppose that BVDV may have modulated the BCoV infection exacerbating the long viral excretion, as well as favoring the onset of mutations in the genome of BCoV detected in fecal samples at T21. An extensive study was performed to verify if the selective pressure in the S gene could be a natural mode of variation of BCoV, providing data for the identification of new epidemic strains, genotypes or recombinant betacoronaviruses.

Interactions between Cryptosporidium parvum and bovine corona virus during sequential and simultaneous infection of HCT-8 cells

Neonatal diarrhoea in calves is one of the major health problems in the cattle industry. Although co-infections are often associated with greater severity of disease, there is limited information on any impact on the pathogens themselves. Herein, we studied Cryptosporidium parvum and bovine coronavirus (BCoV) in human HCT-8 cells, inoculated either sequentially or simultaneously, to investigate any influence from the co-infections. Quantitative results from (RT)-qPCR showed that prior inoculation with either of the two pathogens had no influence on the other. However, the results from simultaneous co-inoculation showed that entry of viral particles was higher when C. parvum sporozoites were present, although elevated virus copy numbers were no longer evident after 24 h. The attachment of BCoV to the sporozoites was probably due to specific binding, as investigations with bovine norovirus or equine herpes virus-1 showed no attachment between sporozoites and these viruses. Flow cytometry results at 72 h post inoculation revealed that C. parvum and BCoV infected 1-11% and 10-20% of the HCT-8 cells, respectively, with only 0.04% of individual cells showing double infections. The results from confocal microscopy corroborated those results, showing an increase in foci of infection from 24-72 h post inoculation for both pathogens, but with few double infected cells.

Bovine coronavirus infections in Turkey: molecular analysis of the full-length spike gene sequences of viruses from digestive and respiratory infections

Bovine coronavirus (BCoV) can be spread by animal activity. Although cattle farming is widespread in Turkey, there are few studies of BCoV. The aim of this study was to evaluate the current situation regarding BCoV in Turkey. This is the first study reporting the full-length nucleotide sequences of BCoV spike (S) genes in Turkey. Samples were collected from 119 cattle with clinical signs of respiratory (n = 78) or digestive tract (n = 41) infection on different farms located across widely separated provinces in Turkey. The samples were screened for BCoV using RT-nested PCR targeting the N gene, which identified BCoV in 35 samples (9 faeces and 26 nasal discharge). RT-PCR analysis of the S gene produced partial/full-length S gene sequences from 11 samples (8 faeces and 3 nasal discharge samples). A phylogenetic tree of the S gene sequences was made to analyze the genetic relationships among BCoVs from Turkey and other countries. The results showed that the local strains present in faeces and nasal discharge samples had many different amino acid changes. Some of these changes were shown in previous studies to be critical for tropism. This study provides new data on BCoV in Turkey that will be valuable in designing effective vaccine approaches and control strategies.

Bovine Coronavirus and the Associated Diseases

Coronaviruses (CoVs) possess the largest and most complex RNA genome (up to 32 kb) that encodes for 16 non-structural proteins regulating RNA synthesis and modification. Coronaviruses are known to infect a wide range of mammalian and avian species causing remarkably diverse disease syndromes. Variable tissue tropism and the ability to easily cross interspecies barriers are the well-known characteristics of certain CoVs. The 21st century epidemics of severe acute respiratory CoV (SARS-CoV), Middle East respiratory CoV and the ongoing SARS-CoV-2 pandemic further highlight these characteristics and emphasize the relevance of CoVs to the global public health. Bovine CoVs (BCoVs) are betacoronaviruses associated with neonatal calf diarrhea, and with winter dysentery and shipping fever in older cattle. Of interest, no distinct genetic or antigenic markers have been identified in BCoVs associated with these distinct clinical syndromes. In contrast, like other CoVs, BCoVs exist as quasispecies. Besides cattle, BCoVs and bovine-like CoVs were identified in various domestic and wild ruminant species (water buffalo, sheep, goat, dromedary camel, llama, alpaca, deer, wild cattle, antelopes, giraffes, and wild goats), dogs and humans. Surprisingly, bovine-like CoVs also cannot be reliably distinguished from BCoVs using comparative genomics. Additionally, there are historical examples of zoonotic transmission of BCoVs. This article will discuss BCoV pathogenesis, epidemiology, interspecies transmission, immune responses, vaccines, and diagnostics.

Coronaviruses in farm animals: Epidemiology and public health implications

Coronaviruses (CoVs) are documented in a wide range of animal species, including terrestrial and aquatic, domestic and wild. The geographic distribution of animal CoVs is worldwide and prevalences were reported in several countries across the five continents. The viruses are known to cause mainly gastrointestinal and respiratory diseases with different severity levels. In certain cases, CoV infections are responsible of huge economic losses associated or not to highly public health impact. Despite being enveloped, CoVs are relatively resistant pathogens in the environment. Coronaviruses are characterized by a high mutation and recombination rate, which makes host jumping and cross-species transmission easy. In fact, increasing contact between different animal species fosters cross-species transmission, while agriculture intensification, animal trade and herd management are key drivers at the human-animal interface. If contacts with wild animals are still limited, humans have much more contact with farm animals, during breeding, transport, slaughter and food process, making CoVs a persistent threat to both humans and animals. A global network should be established for the surveillance and monitoring of animal CoVs.

Pathology of Coronavirus Infections: A Review of Lesions in Animals in the One-Health Perspective

Coronaviruses (CoVs) are worldwide distributed RNA-viruses affecting several species, including humans, and causing a broad spectrum of diseases. Historically, they have not been considered a severe threat to public health until two outbreaks of COVs-related atypical human pneumonia derived from animal hosts appeared in 2002 and in 2012. The concern related to CoVs infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild animals is also most likely. In light of this CoV zoonotic risk, and their ability to adapt to new species and dramatically spread, it appears pivotal to understand the pathophysiology and mechanisms of tissue injury of known CoVs within the "One-Health" concept. This review specifically describes all CoVs diseases in animals, schematically representing the tissue damage and summarizing the major lesions in an attempt to compare and put them in relation, also with human infections. Some information on pathogenesis and genetic diversity is also included. Investigating the lesions and distribution of CoVs can be crucial to understand and monitor the evolution of these viruses as well as of other pathogens and to further deepen the pathogenesis and transmission of this disease to help public health preventive measures and therapies.

Fatal Interstitial Pneumonia Associated with Bovine Coronavirus in Cows from Southern Italy

An outbreak of winter dysentery, complicated by severe respiratory syndrome, occurred in January 2020 in a high production dairy cow herd located in a hilly area of the Calabria region. Of the 52 animals belonging to the farm, 5 (9.6%) died with severe respiratory distress, death occurring 3–4 days after the appearance of the respiratory signs (caught and gasping breath). Microbiological analysis revealed absence of pathogenic bacteria whilst Real-time PCR identified the presence of RNA from Bovine Coronavirus (BCoV) in several organs: lungs, small intestine (jejunum), mediastinal lymph nodes, liver and placenta. BCoV was therefore hypothesized to play a role in the lethal pulmonary infection. Like the other CoVs, BCoV is able to cause different syndromes. Its role in calf diarrhea and in mild respiratory disease is well known: we report instead the involvement of this virus in a severe and fatal respiratory disorder, with symptoms and disease evolution resembling those of Severe Acute Respiratory Syndromes (SARS).

Molecular-based cross-species evaluation of bovine coronavirus infection in cattle, sheep and goats in Ghana

Background

Apart from the huge worldwide economic losses often occasioned by bovine coronavirus (BCoV) to the livestock industry, particularly with respect to cattle rearing, continuous surveillance of the virus in cattle and small ruminants is essential in monitoring variations in the virus that could enhance host switching. In this study, we collected rectal swabs from a total of 1,498 cattle, sheep and goats. BCoV detection was based on reverse transcriptase polymerase chain reaction. Sanger sequencing of the partial RNA-dependent RNA polymerase (RdRp) region for postive samples were done and nucleotide sequences were compared with homologous sequences from the GenBank.

Results

The study reports a BCoV prevalence of 0.3%, consisting of 4 positive cases; 3 goats and 1 cattle. Less than 10% of all the animals sampled showed clinical signs such as diarrhea and respiratory distress except for high temperature which occurred in > 1000 of the animals. However, none of the 4 BCoV positive animals manifested any clinical signs of the infection at the time of sample collection. Bayesian majority-rule cladogram comparing partial and full length BCoV RdRp genes obtained in the study to data from the GenBank revealed that the sequences obtained from this study formed one large monophyletic group with those from different species and countries. The goat sequences were similar to each other and clustered within the same clade. No major variations were thus observed between our isolates and those from elsewhere.

Conclusions

Given that Ghana predominantly practices the extensive and semi-intensive systems of animal rearing, our study highlights the potential for spillover of BCoV to small ruminants in settings with mixed husbandry and limited separation between species.

Coronaviruses in cattle

Bovine coronaviruses are spread all over the world. They cause two types of clinical manifestations in cattle either an enteric, calf diarrhoea and winter dysentery in adult cattle, or respiratory in all age groups of cattle. The role of coronaviruses in respiratory infections is still a hot topic of discussion since they have been isolated from sick as well as healthy animals and replication of disease is rarely successful. Bovine coronavirus infection is characterised by high morbidity but low mortality. The laboratory diagnosis is typically based on serological or molecular methods. There is no registered drug for the treatment of virus infections in cattle and we are limited to supportive therapy and preventative measures. The prevention of infection is based on vaccination, biosecurity, management and hygiene. This paper will cover epidemiology, taxonomy, pathogenesis, clinical signs, diagnosis, therapy, economic impact and prevention of coronavirus infections in cattle.

Microbial diversity involved in the etiology of a bovine respiratory disease outbreak in a dairy calf rearing unit

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BALF is a good biological sample for the molecular diagnosis of BRD in dairy calves.

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Mixed infections of viruses and bacteria were frequent in dairy calves with respiratory disease.

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BVDV 1d in BALF samples of dairy heifer calves in a BRD outbreak was characterized.

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The calf rearing unit without prophylactic measures for respiratory infections represent a risk factor for BRD.

The etiological agents involved in a bovine respiratory disease (BRD) outbreak were investigated in a dairy heifer calf rearing unit from southern Brazil. A battery of PCR assays was performed to detect the most common viruses and bacteria associated with BRD, such as bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine alphaherpesvirus 1 (BoHV-1), bovine coronavirus (BCoV), bovine parainfluenza virus 3 (BPIV-3), Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. Bronchoalveolar lavage fluid (BALF) samples were taken from 21 heifer calves (symptomatic n = 15; asymptomatic n = 6) that, during the occurrence of the BDR outbreak, were aged between 6 and 90 days. At least one microorganism was detected in 85.7 % (18/21) of the BALF samples. Mixed infections were more frequent (72.2 %) than single infections (27.7 %). The interactions between viruses and bacteria were the most common in coinfections (55.5 %). The frequencies of BRD agents were 38.1 % for BRSV, 28.6 % for BVDV, 33.3 % for BCoV, 42.85 % for P. multocida, 33.3 % for M. bovis, and 19 % for H. somni. BoHV-1, BPIV-3, and M. haemolytica were not identified in any of the 21 BALF samples. Considering that BALF and not nasal swabs were analyzed, these results demonstrate the etiological multiplicity that may be involved in BRD outbreaks in dairy calves.

Canine Respiratory Coronavirus: A Naturally Occurring Model of COVID-19?

Discovered in 2003 at the Royal Veterinary College, London, canine respiratory coronavirus (CRCoV) is a betacoronavirus of dogs and major cause of canine infectious respiratory disease complex. Generally causing mild clinical signs of persistent cough and nasal discharge, the virus is highly infectious and is most prevalent in rehoming shelters worldwide where dogs are often closely housed and infections endemic. As the world grapples with the current COVID-19 pandemic, the scientific community is searching for a greater understanding of a novel virus infecting humans. Similar to other betacoronaviruses, SARS-CoV-2 appears to have crossed the species barrier, most likely from bats, clearly reinforcing the One Health concept. Veterinary pathologists are familiar with coronavirus infections in animals, and now more than ever this knowledge and understanding, based on many years of veterinary research, could provide valuable answers for our medical colleagues. Here I review the early research on CRCoV where seroprevalence, early immune response, and pathogenesis are some of the same key questions being asked by scientists globally during the current SARS-CoV-2 pandemic.

Sero-prevalence, cross-species infection and serological determinants of prevalence of Bovine Coronavirus in Cattle, Sheep and Goats in Ghana

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Bovine coronavirus has considerable seroprevalence in cattle across Ghana.

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Sheep and goats are kept without strict separation from cattle and show seropositivity against bovine coronavirus.

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Bovine coronavirus seroprevalence is positively correlated with large farm size.

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Highest bovine coronavirus seroprevalence was found in Ghana´s Northern Province with prevailing arid climate.

Cattle, goats and sheep are dominant livestock species in sub-Saharan Africa, with sometimes limited information on the prevalence of major infectious diseases. Restrictions due to notifiable epizootics complicate the exchange of samples in surveillance studies and suggest that laboratory capacities should be established domestically. Bovine Coronavirus (BCoV) causes mainly enteric disease in cattle. Spillover to small ruminants is possible. Here we established BCoV serology based on a recombinant immunofluorescence assay for cattle, goats and sheep, and studied the seroprevalence of BCoV in these species in four different locations in the Greater Accra, Volta, Upper East, and Northern provinces of Ghana. The whole sampling and testing was organized and conducted by a veterinary school in Kumasi, Ashanti Region of Ghana. Among sampled sheep (n = 102), goats (n = 66), and cattle (n = 1495), the seroprevalence rates were 25.8 %, 43.1 % and 55.8 %. For cattle, seroprevalence was significantly higher on larger farms (82.2 % vs 17.8 %, comparing farms with >50 or <50 animals; p = 0.027). Highest prevalence was seen in the Northern province with dry climate, but no significant trend following the north-south gradient of sampling sites was detected. Our study identifies a considerable seroprevalence for BCoV in Ghana and provides further support for the spillover of BCoV to small ruminants in settings with mixed husbandry and limited separation between species.

Immunohistochemical and molecular detection of natural cases of bovine rotavirus and coronavirus infection causing enteritis in dairy calves

Bovine rotavirus (BRoV) and bovine coronavirus (BCoV) are major enteric viral pathogens responsible for calve diarrhoea. They are widespread both in dairy and beef cattle throughout the world and causing huge economic losses. The diagnosis of these agents is very difficult due to non-specific nature of lesions and the involvement of some intrinsic and extrinsic risk factors. We performed postmortem of 45 calves, which was below three months of age. Out of 45 necropscid calves, three (6.66%) cases were positive for BRoV and four (8.88%) cases were found positive for BCoV, screened by reverse transcriptase polymerase chain reaction (RT-PCR). Further RT-PCR positive cases were confirmed by immunohistochemistry (IHC) in paraffin-embedded intestinal tissue sections. Three cases of enteritis caused by BRoV showed the hallmark lesions of the shortening and fusion of villi, denudation and infiltration of mononuclear cells in the lamina propria. The BRoV antigen distribution was prominent within the lining epithelium of the villi, peyer's patches in the ileum and strong immunoreactions in the lymphocytes and some macrophages of the mesenteric lymph nodes. Four cases in which BCoV was detected, grossly lesions characterized by colonic mucosa covered with thick, fibrinous and diphtheritic membrane. Histopathologically, jejunum showed skipping lesion of micro-abscesses in crypts. The BCoV antigen distribution was prominent within the necrotic crypts in the jejunum and cryptic micro-abscesses in the colon and ileum. It is the first report of BRoV and BCoV antigen demonstration in the jejunum, colon, ileum, Peyer's patches and mesenteric lymph nodes of naturally infected calves from India by using IHC.

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The present study was to investigation of natural cases of BRoV and BCoV infection causing enteritis in dairy calves.

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Out of 45 necropscid calves, 6.66% cases for BRoV and 8.88% cases for BCoV were found positive.

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BRoV and BCoV antigen demonstration in the jejunum, colon, ileum, Peyer's patches and mesenteric lymph nodes of infected calves by using IHC.

Acute phase response in bovine coronavirus positive post-weaned calves with diarrhea

Bovine coronavirus (BCoV) is associated with severe diarrhea in calves, winter dysentery in adult cattle, and respiratory diseases in cattle of all ages. This study aimed to investigate the relationship between white blood cell counts and haptoglobin (Hp) and serum amyloid A (SAA) levels in post-weaned calves with diarrhea caused by BCoV and those that recovered from diarrhea. Blood and fecal samples were collected twice from the same animals; 17 post-weaned calves with diarrhea (first) and 15 post-weaned calves that recovered from diarrhea (second). Real-time polymerase chain reaction revealed that all 17 fecal samples from post-weaned calves with diarrhea and one out of 15 from diarrhea-recovered calves were positive for BCoV and negative for Cryptosporidium spp., Escherichia coli K99, Salmonella spp., bovine rotavirus, and bovine viral diarrhea virus. No Eimeria oocysts were detected using the flotation method. In comparison with post-weaned calves with diarrhea, in diarrhea-recovered calves, the lymphocyte count was significantly higher (P = 0.018), and the monocyte count was significantly lower (P = 0.001); however, the number of monocytes was still high. Post-weaned calves with diarrhea had a significantly higher Hp concentration (P < 0.001) compared with diarrhea-recovered calves. The results indicated that increased Hp concentration and monocytosis but not SAA may be associated with diarrhea caused by BCoV. The present study suggests that the monitoring of Hp concentration and monocyte count is useful in the diagnosis of post-weaned calves with diarrhea caused by BCoV in this field.

What is the evidence that bovine coronavirus is a biologically significant respiratory pathogen in cattle?

Coronaviruses, including bovine coronavirus (BCoV), are etiologically associated with enteric and respiratory disease across a wide range of mammalian and avian species. The role of BCoV in calfhood diarrhea is well-established, but its role in the bovine respiratory disease complex (BRDC) has been controversial. This review re-examines the evidence that BCoV is a significant pathogen in the BRDC.

Complete Genome Sequences of Four Bovine Coronavirus Isolates from Pennsylvania

We report four full-genome sequences of bovine coronavirus (BCoV) isolates from dairy calves in Pennsylvania obtained in 2016 and 2017. BCoV is a pathogen of great importance to cattle health, and this is the first report of full-genome sequences of BCoV from PA cattle.

First Complete Genome Sequence of a French Bovine coronavirus Strain

We sequenced the first Bovine coronavirus (BCoV) complete genome sequence from France. This BCoV was directly sequenced from a fecal sample collected from a calf in Normandy in 2014.

An inactivated influenza D virus vaccine partially protects cattle from respiratory disease caused by homologous challenge

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The emerging influenza D virus (IDV) caused respiratory disease in calves.

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A homologous inactivated vaccine was immunogenic and partially protective.

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IDV titers in vaccinated calves were significantly reduced compared to controls.

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Fewer vaccinates were positive for IDV by immunohistochemistry.

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These results demonstrate an etiologic role for IDV in bovine respiratory disease.

Originally isolated from swine, the proposed influenza D virus has since been shown to be common in cattle. Inoculation of IDV to naïve calves resulted in mild respiratory disease histologically characterized by tracheitis. As several studies have associated the presence of IDV with acute bovine respiratory disease (BRD), we sought to investigate the efficacy of an inactivated IDV vaccine. Vaccinated calves seroconverted with hemagglutination inhibition titers 137–169 following two doses. Non-vaccinated calves challenged with a homologous virus exhibited signs of mild respiratory disease from days four to ten post challenge which was significantly different than negative controls at days five and nine post challenge. Peak viral shedding of approximately 5 TCID₅₀/mL was measured in nasal and tracheal swabs and bronchoalveolar lavage fluids four to six days post challenge. Viral titers were significantly (P < 0.05) decreased 1.4 TCID₅₀/mL, 3.6 TCID₅₀/mL and 5.0 TCID₅₀/mL, respectively, in the aforementioned samples collected from vaccinated animals compared to non-vaccinated controls at peak shedding. Viral antigen was detected in the respiratory epithelium of the nasal turbinates and trachea by immunohistochemistry from all unvaccinated calves but in significantly fewer vaccinates. Inflammation characterized by neutrophils was observed in the nasal turbinate and trachea but not appreciably in lungs. Together these results support an etiologic role for IDV in BRD and demonstrate that partial protection is afforded by an inactivated vaccine.

Evolving views on bovine respiratory disease: An appraisal of selected key pathogens - Part 1

Bovine respiratory disease (BRD) is one of the most commonly diagnosed causes of morbidity and mortality in cattle and interactions of factors associated with the animal, the pathogen and the environment are central to its pathogenesis. Emerging knowledge of a role for pathogens traditionally assumed to be minor players in the pathogenesis of BRD reflects an increasingly complex situation that will necessitate regular reappraisal of BRD pathogenesis and control. This review appraises the role of selected key pathogens implicated in BRD pathogenesis to assess how our understanding of their role has evolved in recent years.

Pathogenesis of Korean SapelovirusA in piglets and chicks

Sapelovirus A (SV-A), formerly known as porcine sapelovirus as a member of a new genus Sapelovirus, is known to cause enteritis, pneumonia, polioencephalomyelitis and reproductive disorders in pigs. We have recently identified α2,3-linked sialic acid on GD1a ganglioside as a functional SV-A receptor rich in the cells of pigs and chickens. However, the role of GD1a in viral pathogenesis remains elusive. Here, we demonstrated that a Korean SV-A strain could induce diarrhoea and intestinal pathology in piglets but not in chicks. Moreover, this Korean SV-A strain had mild extra-intestinal tropisms appearing as mild, non-suppurative myelitis, encephalitis and pneumonia in piglets, but not in chicks. By real-time reverse transcription (RT) PCR, higher viral RNA levels were detected in faecal samples than in sera or extra-intestinal organs from virus-inoculated piglets. Immunohistochemistry confirmed that high viral antigens were detected in the epithelial cells of intestines from virus-inoculated piglets but not from chicks. This Korean SV-A strain could bind the cultured cell lines originated from various species, but replication occurred only in cells of porcine origin. These data indicated that this Korean SV-A strain could replicate and induce pathology in piglets but not in chicks, suggesting that additional porcine-specific factors are required for virus entry and replication. In addition, this Korean SV-A strain is enteropathogenic, but could spread to the bloodstream from the gut and disseminate to extra-intestinal organs and tissues. These results will contribute to our understanding of SV-A pathogenesis so that efficient anti-sapelovirus drugs and vaccines could be developed in the future.

Bovine coronavirus in naturally and experimentally exposed calves; viral shedding and the potential for transmission

Background

Bovine coronavirus (BCoV) is a widely distributed pathogen, causing disease and economic losses in the cattle industry worldwide. Prevention of virus spread is impeded by a lack of basic knowledge concerning viral shedding and transmission potential in individual animals. The aims of the study were to investigate the duration and quantity of BCoV shedding in feces and nasal secretions related to clinical signs, the presence of virus in blood and tissues and to test the hypothesis that seropositive calves are not infectious to naïve in-contact calves three weeks after BCoV infection.

Methods

A live animal experiment was conducted, with direct contact between animal groups for 24 h as challenge procedure. Four naïve calves were commingled with a group of six naturally infected calves and sequentially euthanized. Two naïve sentinel calves were commingled with the experimentally exposed group three weeks after exposure. Nasal swabs, feces, blood and tissue samples were analyzed for viral RNA by RT-qPCR, and virus isolation was performed on nasal swabs. Serum was analyzed for BCoV antibodies.

Results

The calves showed mild general signs, and the most prominent signs were from the respiratory system. The overall clinical score corresponded well with the shedding of viral RNA the first three weeks after challenge. General depression and cough were the signs that correlated best with shedding of BCoV RNA, while peak respiratory rate and peak rectal temperature appeared more than a week later than the peak shedding. Nasal shedding preceded fecal shedding, and the calves had detectable amounts of viral RNA intermittently in feces through day 35 and in nasal secretions through day 28, however virus isolation was unsuccessful from day six and day 18 from the two calves investigated. Viral RNA was not detected in blood, but was found in lymphatic tissue through day 42 after challenge. Although the calves were shedding BCoV RNA 21 days after infection the sentinel animals were not infected.

Conclusions

Prolonged shedding of BCoV RNA can occur, but detection of viral RNA does not necessarily indicate a transmission potential. The study provides valuable information with regard to producing scientifically based biosecurity advices.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0555-x) contains supplementary material, which is available to authorized users.

Middle East respiratory syndrome coronavirus: another zoonotic betacoronavirus causing SARS-like disease

The source of the severe acute respiratory syndrome (SARS) epidemic was traced to wildlife market civets and ultimately to bats. Subsequent hunting for novel coronaviruses (CoVs) led to the discovery of two additional human and over 40 animal CoVs, including the prototype lineage C betacoronaviruses, Tylonycteris bat CoV HKU4 and Pipistrellus bat CoV HKU5; these are phylogenetically closely related to the Middle East respiratory syndrome (MERS) CoV, which has affected more than 1,000 patients with over 35% fatality since its emergence in 2012. All primary cases of MERS are epidemiologically linked to the Middle East. Some of these patients had contacted camels which shed virus and/or had positive serology. Most secondary cases are related to health care-associated clusters. The disease is especially severe in elderly men with comorbidities. Clinical severity may be related to MERS-CoV's ability to infect a broad range of cells with DPP4 expression, evade the host innate immune response, and induce cytokine dysregulation. Reverse transcription-PCR on respiratory and/or extrapulmonary specimens rapidly establishes diagnosis. Supportive treatment with extracorporeal membrane oxygenation and dialysis is often required in patients with organ failure. Antivirals with potent in vitro activities include neutralizing monoclonal antibodies, antiviral peptides, interferons, mycophenolic acid, and lopinavir. They should be evaluated in suitable animal models before clinical trials. Developing an effective camel MERS-CoV vaccine and implementing appropriate infection control measures may control the continuing epidemic.

Necrotizing Enteritis and Hyperammonemic Encephalopathy Associated With Equine Coronavirus Infection in Equids

Equine coronavirus (ECoV) is a Betacoronavirus recently associated clinically and epidemiologically with emerging outbreaks of pyrogenic, enteric, and/or neurologic disease in horses in the United States, Japan, and Europe. We describe the pathologic, immunohistochemical, ultrastructural, and molecular findings in 2 horses and 1 donkey that succumbed to natural infection with ECoV. One horse and the donkey (case Nos. 1, 3) had severe diffuse necrotizing enteritis with marked villous attenuation, epithelial cell necrosis at the tips of the villi, neutrophilic and fibrinous extravasation into the small intestinal lumen (pseudomembrane formation), as well as crypt necrosis, microthrombosis, and hemorrhage. The other horse (case No. 2) had hyperammonemic encephalopathy with Alzheimer type II astrocytosis throughout the cerebral cortex. ECoV was detected by quantitative polymerase chain reaction in small intestinal tissue, contents, and/or feces, and coronavirus antigen was detected by immunohistochemistry in the small intestine in all cases. Coronavirus-like particles characterized by spherical, moderately electron lucent, enveloped virions with distinct peplomer-like structures projecting from the surface were detected by negatively stained transmission electron microscopy in small intestine in case No. 1, and transmission electron microscopy of fixed small intestinal tissue from the same case revealed similar 85- to 100-nm intracytoplasmic particles located in vacuoles and free in the cytoplasm of unidentified (presumably epithelial) cells. Sequence comparison showed 97.9% to 99.0% sequence identity with the ECoV-NC99 and Tokachi09 strains. All together, these results indicate that ECoV is associated with necrotizing enteritis and hyperammonemic encephalopathy in equids.

Anti-rotavirus effects by combination therapy of stevioside and Sophora flavescens extract

Anti-rotaviral activities of Sophora flavescens extract (SFE) and stevioside (SV) from Stevia rebaudiana Bertoni either singly or in various combinations were examined in vitro and in vivo using a porcine rotavirus G5[P7] strain. Combination of SFE and SV inhibited in vitro virus replication more efficiently than each single treatment. In the piglet model, SV had no effect on rotavirus enteritis, whereas SFE improved but did not completely cure rotaviral enteritis. Interestingly, combination therapy of SFE and SV alleviated diarrhea, and markedly improved small intestinal lesion score and fecal virus shedding. Acute toxicity tests including the piglet lethal dose 50, and body weight, organ weight and pathological changes for the combination therapy did not show any adverse effect on the piglets. These preliminary data suggest that the combination therapy of SV and SFE is a potential curative medication for rotaviral diarrhea in pigs. Determination of the efficacy of this combination therapy in other species including humans needs to be addressed in the future.

A multigene approach for comparing genealogy of Betacoronavirus from cattle and horses

Gastroenteritis is one of the leading causes of morbidity and mortality among young and newborn animals and is often caused by multiple intestinal infections, with rotavirus and bovine coronavirus (BCoV) being the main viral causes in cattle. Given that BCoV is better studied than equine coronaviruses and given the possibility of interspecies transmission of these viruses, this research was designed to compare the partial sequences of the spike glycoprotein (S), hemagglutinin-esterase protein (HE), and nucleoprotein (N) genes from coronaviruses from adult cattle with winter dysentery, calves with neonatal diarrhea, and horses. To achieve this, eleven fecal samples from dairy cows with winter dysentery, three from calves, and two from horses, all from Brazil, were analysed. It could be concluded that the enteric BCoV genealogy from newborn and adult cattle is directly associated with geographic distribution patterns, when S and HE genes are taken into account. A less-resolved genealogy exists for the HE and N genes in cattle, with a trend for an age-related segregation pattern. The coronavirus strains from horses revealed Betacoronavirus sequences indistinguishable from those found in cattle, a fact previously unknown.

New and Emerging Pathogens in Canine Infectious Respiratory Disease

Canine infectious respiratory disease is a common, worldwide disease syndrome of multifactorial etiology. This review presents a summary of 6 viruses (canine respiratory coronavirus, canine pneumovirus, canine influenza virus, pantropic canine coronavirus, canine bocavirus, and canine hepacivirus) and 2 bacteria ( Streptococcus zooepidemicus and Mycoplasma cynos) that have been associated with respiratory disease in dogs. For some pathogens a causal role is clear, whereas for others, ongoing research aims to uncover their pathogenesis and contribution to this complex syndrome. Etiology, clinical disease, pathogenesis, and epidemiology are described for each pathogen, with an emphasis on recent discoveries or novel findings.

Different virulence of porcine and porcine-like bovine rotavirus strains with genetically nearly identical genomes in piglets and calves

Direct interspecies transmissions of group A rotaviruses (RVA) have been reported under natural conditions. However, the pathogenicity of RVA has never been directly compared in homologous and heterologous hosts. The bovine RVA/Cow-tc/KOR/K5/2004/G5P[7] strain, which was shown to possess a typical porcine-like genotype constellation similar to that of the G5P[7] prototype RVA/Pig-tc/USA/OSU/1977/G5P9[7] strain, was examined for its pathogenicity and compared with the porcine G5P[7] RVA/Pig-tc/KOR/K71/2006/G5P[7] strain possessing the same genotype constellation. The bovine K5 strain induced diarrhea and histopathological changes in the small intestine of piglets and calves, whereas the porcine K71 strain caused diarrhea and histopathological changes in the small intestine of piglets, but not in calves. Furthermore, the bovine K5 strain showed extra-intestinal tropisms in both piglets and calves, whereas the porcine K71 strain had extra-intestinal tropisms in piglets, but not in calves. Therefore, we performed comparative genomic analysis of the K71 and K5 RVA strains to determine whether specific mutations could be associated with these distinct clinical and pathological phenotypes. Full-length sequencing analyses for the 11 genomic segments for K71 and K5 revealed that these strains were genetically nearly identical to each other. Two nucleotide mutations were found in the 5′ untranslated region (UTR) of NSP5 and the 3′ UTR of NSP3, and eight amino acid mutations in VP1-VP4 and NSP2. Some of these mutations may be critical molecular determinants for RVA virulence and/or pathogenicity.

Pathogenicity of porcine G9P[23] and G9P[7] rotaviruses in piglets

G9 group A rotaviruses (RVAs) are considered important pathogens in pigs and humans, and pigs are hypothesized to be a potential host reservoir for human. However, intestinal and extra-intestinal pathogenicity and viremia of porcine G9 RVAs has remained largely unreported. In this study, colostrum-deprived piglets were orally infected with a porcine G9P[23] or G9P[7] strain. Histopathologically, both strains induced characteristic small intestinal lesions. Degeneration and necrosis of parenchymal cells were observed in the extra-intestinal tissues, but most predominantly in the mesenteric lymph nodes (MLNs). RVA antigen was continuously detected in the small intestinal mucosa and MLNs, but only transiently in cells of the liver, lung, and choroid plexus. Viral RNA levels were much higher in the feces and the MLNs compared to other tissues. The onset of viremia occurred at day post infection (DPI) 1 with the amount of viral RNA reaching its peak at DPI 3 or 5, before decreasing significantly at DPI 7 and remaining detectable until DPI 14. Our data suggest that porcine G9 RVAs have a strong small intestinal tropism, are highly virulent for piglets, have the ability to escape the small intestine, spread systemically via viremia, and replicate in extra-intestinal tissues. In addition, MLNs might act as a secondary site for viral amplification and the portal of systemic entry. These results add to our understanding of the pathogenesis of human G9 RVAs, and the validity of the pig model for use with both human and pig G9 RVAs in further studies.

Detection of human coronaviruses in simultaneously collected stool samples and nasopharyngeal swabs from hospitalized children with acute gastroenteritis

Background

Human coronaviruses (HCoVs) are a well-known cause of respiratory infections but their role in gastrointestinal infections is unclear. The objective of our study was to assess the significance of HCoVs in the etiology of acute gastroenteritis (AGE) in children <6 years of age.

Methods

Stool samples and nasopharyngeal (NP) swabs collected from 260 children hospitalized for AGE (160 also had respiratory symptoms) and 157 otherwise healthy control children admitted for elective surgery were tested for the presence of four HCoVs using real time RT-PCR. Registered at ClinicalTrials.gov (reg. NCT00987519).

Results

HCoVs were more frequent in patients with AGE than in controls (23/260, 8.8% versus 4/151, 2.6%; odds ratio, OR 3.3; 95% confidence interval, CI 1.3–10.0; P = 0.01). Three of four HCoV-positive members in the control group, asymptomatic when sampled, recalled gastrointestinal or respiratory symptoms within the previous 14 days. In patients with AGE, HCoVs were present in NP samples more often than in stools (22/256, 8.6%, versus 6/260, 2.3%; P = 0.0004). In 5/6 children with HCoVs detected in stools, the viruses were also detected in NP swabs. Patients had a significantly higher probability of HCoV detection in stool (OR 4; 95% CI 1.4–15.3; P = 0.006) and also in stool and/or NP (OR 3.3, 95% CI 1.3–10.0; P = 0.01) than healthy controls. All four HCoVs species were detected in stool and NP samples.

Conclusions

Although HCoVs were more frequently detected in patients with AGE than in the control group, high prevalence of HCoVs in NP swabs compounded by their low occurrence in stool samples and detection of other viruses in stool samples, indicate that HCoVs probably play only a minor role in causing gastrointestinal illness in children <6 years old.

Bovine coronaviruses from the respiratory tract: antigenic and genetic diversity

BoCV isolated from respiratory tract, nasal swab and broncho alveolar washing fluid samples were evaluated for genetic and antigenic differences. These BoCV from the respiratory tract of healthy and clinically ill cattle with BRD signs were compared to reference and vaccine strains based on Spike protein coding sequences and VNT using convalescent antisera. Based on this study, the BoCV isolates belong to one of two genomic clades (clade 1 and 2) which can be differentiated antigenically. The respiratory isolates from Oklahoma in this study were further divided by genetic differences into three subclades, 2a, 2b, and 2c. Reference enteric BoCV strains and a vaccine strain were in clade 1. Currently available vaccines designed to control enteric disease are based on viruses from one clade while viruses isolated from respiratory tracts, in this study, belong to the other clade.

Tropism and pathological findings associated with canine respiratory coronavirus (CRCoV)

Canine infectious respiratory disease (CIRD) occurs frequently in densely housed dog populations. One of the common pathogens involved is canine respiratory coronavirus (CRCoV), however little is known regarding its pathogenesis and the role it plays in the development of CIRD. The pathogenesis of five geographically unrelated canine respiratory coronavirus (CRCoV) isolates was investigated. Following experimental infection in dogs, all five CRCoV isolates gave rise to clinical signs of respiratory disease consistent with that observed during natural infection. The presence of CRCoV was associated with marked histopathological changes in the nares and trachea, with loss and damage to tracheal cilia, accompanied by inflammation. Viral shedding was readily detected from the oropharynx up to 10 days post infection, but there was little or no evidence of rectal shedding. The successful re-isolation of CRCoV from a wide range of respiratory and mucosal associated lymphoid tissues, and lung lavage fluids demonstrates a clear tropism of CRCoV for respiratory tissues and fulfils the final requirement for Koch's postulates. By study day 14 dogs had seroconverted to CRCoV and the antibodies raised were neutralising against both homologous and heterologous strains of CRCoV in vitro, thus demonstrating antigenic homogeneity among CRCoV strains from the two continents. Defining the role that CRCoV and other agents play in CIRD is a considerable, but important, challenge if the disease is to be managed, treated and prevented more successfully. Here we have successfully developed a model for studying the pathogenicity and the role of CRCoV in CIRD.

Coronavirus infection in intensively managed cattle with respiratory disease

Background

A detailed laboratory investigation identified bovine coronavirus (BCoV) as the aetiological agent in an outbreak of respiratory disease at a semi‐intensive beef cattle feedlot in south‐east Australia. The outbreak caused 30% morbidity in the resident population and also affected two cohorts of cattle that were newly introduced to the property.

Methods

At slaughter, pulmonary consolidation and inflammatory lesions in the trachea were identified in 15 of 49 animals. Pasteurella multocida or Histophilus somni was cultured from 3 of 7 animals with lesions. Histopathological examination revealed multifocal non‐suppurative bronchointerstitial pneumonia with formation of epithelial syncytial cells, sometimes associated with suppurative bronchopneumonia.

Results

BCoV was detected in nasal swabs and pulmonary lesions using real‐time reverse transcriptase–polymerase chain reaction (qRT‐PCR) assay and virus isolation. There was serological evidence of previous exposure to bovine viral diarrhoea virus, bovine respiratory syncytial virus and bovine parainfluenza virus type 3, but not to bovine herpesvirus type 1. None of these viral pathogens or Mycoplasma bovis was identified by qRT‐PCR.

Conclusion

This is believed to be the first report of BCoV in association with bovine respiratory disease complex in Australia.

Pathogenicity characterization of a bovine triple reassortant rotavirus in calves and piglets

Rotaviruses are important human and animal pathogens with high impact on public health and livestock industry. There is little evidence about the cross-species pathogenicity and extra-intestinal infections of animal and human reassortant rotaviruses, particularly based on all 11 genotyping data. In this study, the bovine triple reassortant KJ56-1 strain harboring two bovine-like genome segments, eight porcine-like genome segments, and one human-like genome segment was used to evaluate the cross-species pathogenicity in its parent species, calves and piglets, and to determine its abilities of causing viremia and extra-intestinal tropisms in piglets. The KJ56-1 strain isolated from a calf diarrhea fecal sample replicated without causing diarrhea and severe intestinal pathology in calves. However, piglets inoculated with this strain showed persistent severe diarrhea and marked intestinal pathology. By SYBR Green real-time RT-PCR, viral RNA was detected in the sera, mesenteric lymph node, lung, liver, choroid plexus, and cerebrospinal fluid in the experimental piglets. An immunofluorescence assay confirmed viral replication in these extra-intestinal organs and tissues. These results indicated that the bovine triple reassortant KJ56-1 strain was virulent to piglets but not to calves. Our data also demonstrated that the reassortant rotaviruses had the ability to spread to the bloodstream from the gut, enter and amplify in the mesenteric lymph node, and disseminate to the extra-intestinal organs and tissues.

Bovine coronavirus (BCV) infections in transported commingled beef cattle and sole-source ranch calves

This study investigated bovine coronavirus (BCV) in both beef calves direct from the ranch and commingled, mixed-source calves obtained from an auction market. The level of BCV-neutralizing antibodies found in the calves varied among ranches in 2 different studies in a retained-ownership program (ROP), from the ranch to the feedlot. Calves with low levels of BCV-neutralizing antibodies (16 or less) were more likely to be treated for bovine respiratory disease (BRD) than those with higher titers. In 3 studies of commingled, mixed-source calves, BCV was recovered from calves at entry to the feedlot and the infections were cleared by day 8. The BCV was identified in lung samples [bronchoalveolar lavage (BAL) collection] as well as in nasal swabs. Calves with low levels of BCV-neutralizing antibodies at entry were most likely to be shedding BCV. Bovine coronavirus was isolated from both healthy and sick calves, but not from sick calves after 4 d arrival at the feedlot. Bovine coronavirus (BCV) should be considered along with other bovine respiratory viruses in the diagnosis of etiologies in bovine respiratory disease, especially for animals that become sick shortly after arrival. If approved vaccines are developed, it would be best to carry out vaccination programs before calves are weaned, giving them sufficient time to gain active immunity before commingling with other cattle.

Bovine coronavirus associated syndromes

Bovine coronaviruses, like other animal coronaviruses, have a predilection for intestinal and respiratory tracts. The viruses responsible for enteric and respiratory symptoms are closely related antigenically and genetically. Only 4 bovine coronavirus isolates have been completely sequenced and thus, the information about the genetics of the virus is still limited. This article reviews the clinical syndromes associated with bovine coronavirus, including pneumonia in calves and adult cattle, calf diarrhea, and winter dysentery; diagnostic methods; prevention using vaccination; and treatment, with adjunctive immunotherapy.