Bovine respiratory coronavirus enhances bacterial adherence by upregulating expression of cellular receptors on bovine respiratory epithelial cells

Bovine respiratory syncytial virus enhances the attachment of Trueperella pyogenes to cells

In cattle, bovine respiratory syncytial virus (BRSV) is associated with secondary bacterial infections; however, the mechanisms of the interaction between BRSV and bacteria are unclear. Trueperella pyogenes (T. pyogenes) causes pneumonia in cattle and is involved in secondary infections following viral infections. In this study, we evaluated the effect of BRSV infection on the adhesion of T. pyogenes to BRSV-infected cells. BRSV infection significantly enhanced the adhesion of T. pyogenes to cells in a multiplicity of infection- and time-dependent manner. The BRSV-mediated change in the adhesion of T. pyogenes was widely observed in various cell types and bacterial strains. The results from the gentamicin protection assay showed that BRSV infection did not affect the intracellular invasion ability of T. pyogenes. Furthermore, adhesion assays conducted using BRSV G protein-expressing cells and anti-BRSV G antibodies revealed that the increased adhesion of T. pyogenes to cells was mediated by the G protein of BRSV. In addition, immunofluorescence assay revealed the colocalization of BRSV G protein and T. pyogenes. Thus, BRSV infection can potentially lead to bovine respiratory disease complex by promoting the adhesion of T. pyogenes to the infected cells.

Pseudorabies virus infection increases the permeability of the mammalian respiratory barrier to facilitate Pasteurella multocida infection

Interaction between viruses and bacteria during the development of infectious diseases is a complex question that requires continuous study. In this study, we explored the interactions between pseudorabies virus (PRV) and Pasteurella multocida (PM), which are recognized as the primary and secondary agents of porcine respiratory disease complex (PRDC), respectively. In vivo tests using mouse models demonstrated that intranasal inoculation with PRV at a sublethal dose induced disruption of murine respiratory barrier and promoted the invasion and damages caused by PM through respiratory infection. Inoculation with PRV also disrupted the barrier function of murine and porcine respiratory epithelial cells, and accelerated the adherence and invasion of PM to the cells. In mechanism, PRV infection resulted in decreased expression of tight junction proteins (ZO-1, occludin) and adherens junction proteins (β-catenin, E-cadherin) between neighboring respiratory epithelial cells. Additionally, PRV inoculation at an early stage downregulated multiple biological processes contributing to epithelial adhesion and barrier functions while upregulating signals beneficial for respiratory barrier disruption (e.g., the HIF-1α signaling). Furthermore, PRV infection also stimulated the upregulation of cellular receptors (CAM5, ICAM2, ACAN, and DSCAM) that promote bacterial adherence. The data presented in this study provide insights into the understanding of virus-bacteria interactions in PRDC and may also contribute to understanding the mechanisms of secondary infections caused by different respiratory viruses (e.g., influenza virus and SARS-CoV-2) in both medical and veterinary medicine.

IMPORTANCE

Co-infections caused by viral and bacterial agents are common in both medical and veterinary medicine, but the related mechanisms are not fully understood. This study investigated the interactions between the zoonotic pathogens PRV and PM during the development of respiratory infections in both cell and mouse models, and reported the possible mechanisms which included: (i) the primary infection of PRV may induce the disruption and/or damage of mammal respiratory barrier, thereby contributing to the invasion of PM; (ii) PRV infection at early stage accelerates the transcription and/or expression of several cellular receptors that are beneficial for bacterial adherence. This study may shed a light on understanding the mechanisms on the secondary infection of PM promoted by different respiratory viruses (e.g., influenza virus and SARS-CoV-2) in both medical and veterinary medicine.

Novel CRISPR/Cas13-based assay for detection of bovine coronavirus associated with severe diarrhea in calves

Bovine coronavirus (BCoV) is one of the important causes of diarrhoea in cattle. The virus is responsible for the high fatality rate associated with acute diarrhoea in calves. Rapid and accurate tests need to be conducted to detect the virus and minimise economic losses associated with the disease. Nucleic acid-based detection assays including PCR is an accurate test for detecting pathogens. However, these tests need skilled personnel, time and expensive devices. In this study, we developed a novel assay for the detection of BCoV in clinical cases. This novel assay combined reverse transcription-recombinase polymerase amplification with CRISPR/Cas13 and conducted a rapid visualisation of cleavage activity using a Lateral Flow Device. A conserved sequence of the BCV M gene was used as a target gene and the assays were tested in terms of specificity, sensitivity and time consumption. The result showed the specificity of the assay as 100% with no false positives being detected. Ten copies of the input RNA were enough to detect the virus and perform the assay. It took up to forty minutes for reading the results. Conducted together, the assay should be used as a rapid test to clinically diagnose infectious pathogens including bovine coronavirus. However, the assay needed the RNA to be extracted from the clinical sample in order to detect the virus. Therefore, more studies are needed to optimise the assay to be able to detect the virus in the clinical sample without extracting the RNA.

Brain invasion of bovine coronavirus: molecular analysis of bovine coronavirus infection in calves with severe pneumonia and neurological signs

IMPORTANCE

Although the role of bovine coronavirus (BCoV) in calf diarrhea and respiratory disorders is well documented, its contribution to neurological diseases is unclear.

OBJECTIVE

This study conducted virological investigations of calves showing diarrhea and respiratory and neurological signs.

METHODS

An outbreak of diarrhea, respiratory, and neurological disorders occurred among the 12 calves in July 2022 in Istanbul, Türkiye. Two of these calves exhibited neurological signs and died a few days after the appearance of symptoms. One of these calves was necropsied and analyzed using molecular and histopathological tests.

RESULTS

BCoV RNA was detected in the brain, lung, spleen, liver, and intestine of the calf that had neurological signs by real-time reverse transcription polymerase chain reaction. Immunostaining was also observed in the intestine and brain. A 622 bp S1 gene product was noted on gel electrophoresis only in the brain. Phylogenetic analysis indicated that the BCoV detected in this study had a high proximity to the BCoV strain GIb with 99.19% nucleotide sequence homology to the strains detected in Poland, Israel, Türkiye, and France. No distinct genetic lineages were observed when the brain isolate was compared with the respiratory and enteric strains reported to GenBank. In addition, the highest identity (98,72%) was obtained with the HECV 4408 and L07748 strains of human coronaviruses.

CONCLUSIONS AND RELEVANCE

The strain detected in a calf brain belongs to the GIb-European lineage and shares high sequence homology with BCoV strains detected in Europe and Israel. In addition, the similarity between the human coronaviruses (4408 and L07748) raises questions about the zoonotic potential of the strains detected in this study.

The spatial dissimilarities and connections of the microbiota in the upper and lower respiratory tract of beef cattle

Bovine respiratory disease (BRD) causes morbidity and mortality in cattle. The critical roles of the respiratory microbiota in BRD have been widely studied. The nasopharynx was the most popular sampling niche for BRD pathogen studies. The oral cavity and other niches within the respiratory tract, such as nostrils and lung, are less assessed. In this study, oropharyngeal swabs (OS), nasal swabs (NS), nasopharyngeal swabs (NP), and bronchoalveolar lavage (BAL) were collected from calves located in four countries and analyzed for investigation of the dissimilarities and connections of the respiratory microbiota. The results showed that the microbial diversity, structure, and composition in the upper and lower respiratory tract in beef cattle from China, the USA, Canada, and Italy were significantly different. The microbial taxa for each sampling niche were specific and associated with their local physiology and geography. The signature microbiota for OS, NS, NP, and BAL were identified using the LEfSe algorithm. Although the spatial dissimilarities among the respiratory niches existed, the microbial connections were observed in beef cattle regardless of geography. Notably, the nostril and nasopharynx had more similar microbiomes compared to lung communities. The major bacterial immigration patterns in the bovine respiratory tract were estimated and some of them were associated with geography. In addition, the contribution of oral microbiota to the nasal and lung ecosystems was confirmed. Lastly, microbial interactions were characterized to reveal the correlation between the commercial microbiota and BRD-associated pathogens. In conclusion, shared airway microbiota among niches and geography provides the possibility to investigate the common knowledge for bovine respiratory health and diseases. In spite of the dissimilarities of the respiratory microbiota in cattle, the spatial connections among these sampling niches not only allow us to deeply understand the airway ecosystem but also benefit the research and development of probiotics for BRD.

Coronaviruses: Troubling Crown of the Animal Kingdom

The existence of coronaviruses has been known for many years. These viruses cause significant disease that primarily seems to affect agricultural species. Human coronavirus disease due to the 2002 outbreak of Severe Acute Respiratory Syndrome and the 2012 outbreak of Middle East Respiratory Syndrome made headlines; however, these outbreaks were controlled, and public concern quickly faded. This complacency ended in late 2019 when alarms were raised about a mysterious virus responsible for numerous illnesses and deaths in China. As we now know, this novel disease called Coronavirus Disease 2019 (COVID-19) was caused by Severe acute respiratory syndrome-related-coronavirus-2 (SARS-CoV-2) and rapidly became a worldwide pandemic. Luckily, decades of research into animal coronaviruses hastened our understanding of the genetics, structure, transmission, and pathogenesis of these viruses. Coronaviruses infect a wide range of wild and domestic animals, with significant economic impact in several agricultural species. Their large genome, low dependency on host cellular proteins, and frequent recombination allow coronaviruses to successfully cross species barriers and adapt to different hosts including humans. The study of the animal diseases provides an understanding of the virus biology and pathogenesis and has assisted in the rapid development of the SARS-CoV-2 vaccines. Here, we briefly review the classification, origin, etiology, transmission mechanisms, pathogenesis, clinical signs, diagnosis, treatment, and prevention strategies, including available vaccines, for coronaviruses that affect domestic, farm, laboratory, and wild animal species. We also briefly describe the coronaviruses that affect humans. Expanding our knowledge of this complex group of viruses will better prepare us to design strategies to prevent and/or minimize the impact of future coronavirus outbreaks.

Understanding the mechanisms of viral and bacterial coinfections in bovine respiratory disease: a comprehensive literature review of experimental evidence

Bovine respiratory disease (BRD) is one of the most important diseases impacting the global cattle industry, resulting in significant economic loss. Commonly referred to as shipping fever, BRD is especially concerning for young calves during transport when they are most susceptible to developing disease. Despite years of extensive study, managing BRD remains challenging as its aetiology involves complex interactions between pathogens, environmental and host factors. While at the beginning of the twentieth century, scientists believed that BRD was only caused by bacterial infections ("bovine pasteurellosis"), we now know that viruses play a key role in BRD induction. Mixtures of pathogenic bacteria and viruses are frequently isolated from respiratory secretions of animals with respiratory illness. The increased diagnostic screening data has changed our understanding of pathogens contributing to BRD development. In this review, we aim to comprehensively examine experimental evidence from all existing studies performed to understand coinfections between respiratory pathogens in cattle. Despite the fact that pneumonia has not always been successfully reproduced by in vivo calf modelling, several studies attempted to investigate the clinical significance of interactions between different pathogens. The most studied model of pneumonia induction has been reproduced by a primary viral infection followed by a secondary bacterial superinfection, with strong evidence suggesting this could potentially be one of the most common scenarios during BRD onset. Different in vitro studies indicated that viral priming may increase bacterial adherence and colonization of the respiratory tract, suggesting a possible mechanism underpinning bronchopneumonia onset in cattle. In addition, a few in vivo studies on viral coinfections and bacterial coinfections demonstrated that a primary viral infection could also increase the pathogenicity of a secondary viral infection and, similarly, dual infections with two bacterial pathogens could increase the severity of BRD lesions. Therefore, different scenarios of pathogen dynamics could be hypothesized for BRD onset which are not limited to a primary viral infection followed by a secondary bacterial superinfection.

Survival of SARS-CoV-2 and bovine coronavirus on common surfaces of living environments

Aerosols or saliva containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can contaminate living environments, and viruses can be indirectly transmitted. To understand the survival potential of the virus, the viral titers of bovine coronavirus (BCoV), as a model virus, and SARS-CoV-2 were measured on porous and non-porous surfaces. The amount of infectious BCoV recovered remained relatively high on non-porous substrates. However, it quickly decreased on several non-porous surfaces such as nitrile rubber. The time taken to reach the limit of detection on non-woven masks, as a porous substrate, was longer than that of non-porous substrates. On porous substrates other than non-woven masks, the amount of virus recovered quickly decreased, and then remained at a low level. Representative substrates were tested with SARS-CoV-2. The decrease in the amount of infectious virus recovered was similar to that of BCoV, although that of SARS-CoV-2 was more rapid. RNA derived from SARS-CoV-2 was also detected using real-time PCR, and it remained on surfaces much longer than infectious virus, on all substrates. Therefore, it is important to measure the viral titer to avoid the overestimation of infectious virus contamination in the environments. Our results suggest that the surface structure was not directly related to viral survivability.

Bovine Coronavirus Co-infection and Molecular Characterization in Dairy Calves With or Without Clinical Respiratory Disease

Bovine respiratory disease (BRD) is considered a major cause of morbidity and mortality in young calves and is caused by a range of infectious agents, including viruses and bacteria. This study aimed to determine the frequency of viral and bacterial pathogens detected in calves with BRD from high-production dairy cattle herds and to perform the molecular characterization of N and S1 genes in identified bovine coronavirus (BCoV) strains. Nasal swabs were collected from 166 heifer calves, namely, 85 symptomatic and 81 asymptomatic calves aged between 5 and 90 days, from 10 dairy cattle herds. Nasal swabs were evaluated using molecular techniques for the identification of viruses (BCoV, bovine alphaherpesvirus 1, bovine viral diarrhea virus, bovine parainfluenza virus 3, and bovine respiratory syncytial virus) and bacteria (Pasteurella multocida, Mannheimia haemolytica, Histophilus somni, and Mycoplasma bovis). In addition, five and two BCoV-positive samples were submitted to N and S1 gene amplification and nucleotide sequencing, respectively. The frequency of diagnosis of BCoV was higher (56%, 93/166) than the frequency of P. multocida (39.8%, 66/166) and M. haemolytica (33.1%, 55/166). The three microorganisms were identified in the calves of symptomatic and asymptomatic heifer calve groups. All other pathogens included in the analyses were negative. In the phylogenetic analysis of the S1 gene, the Brazilian strains formed a new branch, suggesting a new genotype, called # 15; from the N gene, the strains identified here belonged to cluster II. This study describes high rates of BCoV, P. multocida, and M. haemolytica in heifer calves from high-production dairy cattle herds with BRD. Additionally, the molecular characterization provides evidence that the circulating BCoV strains are ancestrally different from the prototype vaccine strains and even different BCoV strains previously described in Brazil.

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 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.

A Review of UK-Registered and Candidate Vaccines for Bovine Respiratory Disease

Vaccination is widely regarded as a cornerstone in animal or herd health and infectious disease management. Nineteen vaccines against the major pathogens implicated in bovine respiratory disease are registered for use in the UK by the Veterinary Medicines Directorate (VMD). However, despite annual prophylactic vaccination, bovine respiratory disease is still conservatively estimated to cost the UK economy approximately £80 million per annum. This review examines the vaccine types available, discusses the surrounding literature and scientific rationale of the limitations and assesses the potential of novel vaccine technologies.

Comparison of gut viral communities in diarrhoea and healthy dairy calves

Calf diarrhoea has been a major cause of economic losses in the global dairy industry. Many factors, including multiple pathogen infections, can directly or indirectly cause calf diarrhoea. This study compared the faecal virome between 15 healthy calves and 15 calves with diarrhoea. Significantly lower diversity of viruses was found in samples from animals with diarrhoea than those in the healthy ones, and this feature may also be related to the age of the calves. Viruses belonging to the families Astroviridae and Caliciviridae that may cause diarrhoea in dairy calves have been characterized, which revealed that reads of caliciviruses and astroviruses in diarrhoea calves were much higher than those in healthy calves. Five complete genomic sequences closely related to Smacoviridae have been identified, which may participate in the regulation of the gut virus community ecology of healthy hosts together with bacteriophages. This research provides a theoretical basis for further understanding of known or potential enteric pathogens related to calf diarrhoea.