Infection of differentiated airway epithelial cells from caprine lungs by viruses of the bovine respiratory disease complex

Evaluation of the immunogenicity and protective efficacy of an inactivated vaccine candidate for sheep infected with ovine parainfluenza virus type 3

Respiratory diseases constitute a major health problem for ruminants, resulting in considerable economic losses throughout the world. Parainfluenza type 3 virus (PIV3) is one of the most important respiratory pathogens of ruminants. The pathogenicity and phylogenetic analyses of PIV3 virus have been reported in sheep and goats. However, there are no recent studies of the vaccination of sheep or goats against PIV3. Here, we developed a purified inactivated ovine parainfluenza virus type 3 (OPIV3) vaccine candidate. In addition, we immunized sheep with the inactivated OPIV3 vaccine and evaluated the immune response and pathological outcomes associated with OPIV3 TX01 infection. The vaccinated sheep demonstrated no obvious symptoms of respiratory tract infection, and there were no gross lesions or pathological changes in the lungs. The average body weight gain significantly differed between the vaccinated group and the control group (P < 0.01). The serum neutralization antibody levels rapidly increased in sheep post-vaccination and post-challenge with OPIV3. Furthermore, viral shedding in nasal swabs and viral loads in the lungs were reduced. The results of this study suggest that vaccination with this candidate vaccine induces the production of neutralizing antibodies and provides significant protection against OPIV3 infection. These results may be helpful for further studies on prevention and control strategies for OPIV3 infections.

FDA-Approved Inhibitors of RTK/Raf Signaling Potently Impair Multiple Steps of In Vitro and Ex Vivo Influenza A Virus Infections

Influenza virus (IV) infections pose a burden on global public health with significant morbidity and mortality. The limited range of currently licensed IV antiviral drugs is susceptible to the rapid rise of resistant viruses. In contrast, FDA-approved kinase inhibitors can be repurposed as fast-tracked host-targeted antivirals with a higher barrier of resistance. Extending our recent studies, we screened 21 FDA-approved small-molecule kinase inhibitors (SMKIs) and identified seven candidates as potent inhibitors of pandemic and seasonal IV infections. These SMKIs were further validated in a biologically and clinically relevant ex vivo model of human precision-cut lung slices. We identified steps of the virus infection cycle affected by these inhibitors (entry, replication, egress) and found that most SMKIs affected both entry and egress. Based on defined and overlapping targets of these inhibitors, the candidate SMKIs target receptor tyrosine kinase (RTK)-mediated activation of Raf/MEK/ERK pathways to limit influenza A virus infection. Our data and the established safety profiles of these SMKIs support further clinical investigations and repurposing of these SMKIs as host-targeted influenza therapeutics.

Use of Precision-Cut Tissue Slices as a Translational Model to Study Host-Pathogen Interaction

The recent increase in new technologies to analyze host-pathogen interaction has fostered a race to develop new methodologies to assess these not only on the cellular level, but also on the tissue level. Due to mouse-other mammal differences, there is a desperate need to develop relevant tissue models that can more closely recapitulate the host tissue during disease and repair. Whereas organoids and organs-on-a-chip technologies have their benefits, they still cannot provide the cellular and structural complexity of the host tissue. Here, precision cut tissue slices (PCTS) may provide invaluable models for complex ex-vivo generated tissues to assess host-pathogen interaction as well as potential vaccine responses in a “whole organ” manner. In this mini review, we discuss the current literature regarding PCTS in veterinary species and advocate that PCTS represent remarkable tools to further close the gap between target identification, subsequent translation of results into clinical studies, and thus opening avenues for future precision medicine approaches.

The Bacterial and Viral Agents of BRDC: Immune Evasion and Vaccine Developments

Bovine respiratory disease complex (BRDC) is a multifactorial disease of cattle which presents as bacterial and viral pneumonia. The causative agents of BRDC work in synergy to suppress the host immune response and increase the colonisation of the lower respiratory tracts by pathogenic bacteria. Environmental stress and/or viral infection predispose cattle to secondary bacterial infections via suppression of key innate and adaptive immune mechanisms. This allows bacteria to descend the respiratory tract unchallenged. BRDC is the costliest disease among feedlot cattle, and whilst vaccines exist for individual pathogens, there is still a lack of evidence for the efficacy of these vaccines and uncertainty surrounding the optimum timing of delivery. This review outlines the immunosuppressive actions of the individual pathogens involved in BRDC and highlights the key issues in the development of vaccinations against them.

Investigation of viral pathogens in cattle with bovine respiratory disease complex in Inner Mongolia, China

As a multifactor disease, the bovine respiratory disease complex (BRDC) causes high morbidity and mortality that is devastating to the cattle industry. To assess viral infections in beef cattle suffering from respiratory diseases in Inner Mongolia, 302 nasal swabs and serum samples were randomly collected from cattle with mild respiratory symptoms between March 2018 and May 2019. Our results showed that the rate of RT-PCR results positive for nucleic acids of viral pathogens in 6 cities was between 54 and 80%.The rates of bovine viral diarrhea virus (BVDV), bovine herpesvirus 1 (BHV-1), bovine parainfluenza virus type 3(BPIV3), and bovine respiratory syncytial virus(BRSV)infections were 44.70% (135/302), 24.83% (75/302), 5.63% (17/302), and 6.95% (21/302),respectively. There are also 8.94% (27/302) of samples were positive for BVDV and BHV-1, and 3.97% (12/302) of samples were positive for BPIV3 and BRSV. In addition, the RT-PCR products were sequenced, and phylogenetic analysis based on these sequences was performed. The results indicated that: a) all of the BVDV isolates were BVDV-1 and were classified as BVDV-1a (66.67%) and BVDV-1b (33.33%); b) all of the BHV-1 isolates were classified as subtype 1.1; 44.44% of the isolates were closely related to modified live viral vaccine strains, and 55.56% of the isolates were closer to epidemic strains; c) all of the BPIV3 isolates belonged to BPIV3c; d) all of the BRSV isolates were classified into subgroup III. It is suggested that an important cause of respiratory diseases for beef cattle is viral infection, and phylogenetic analysis can help us choose the proper strain to develop a vaccine.

Use of precision cut lung slices as a translational model for the study of lung biology

Animal models remain invaluable for study of respiratory diseases, however, translation of data generated in genetically homogeneous animals housed in a clean and well-controlled environment does not necessarily provide insight to the human disease situation. In vitro human systems such as air liquid interface (ALI) cultures and organ-on-a-chip models have attempted to bridge the divide between animal models and human patients. However, although 3D in nature, these models struggle to recreate the architecture and complex cellularity of the airways and parenchyma, and therefore cannot mimic the complex cell-cell interactions in the lung. To address this issue, lung slices have emerged as a useful ex vivo tool for studying the respiratory responses to inflammatory stimuli, infection, and novel drug compounds. This review covers the practicality of precision cut lung slice (PCLS) generation and benefits of this ex vivo culture system in modeling human lung biology and disease pathogenesis.

Host-Pathogen Interactions of Mycoplasma mycoides in Caprine and Bovine Precision-Cut Lung Slices (PCLS) Models

Respiratory infections caused by mycoplasma species in ruminants lead to considerable economic losses. Two important ruminant pathogens are Mycoplasma mycoides subsp. Mycoides (Mmm), the aetiological agent of contagious bovine pleuropneumonia and Mycoplasma mycoides subsp. capri (Mmc), which causes pneumonia, mastitis, arthritis, keratitis, and septicemia in goats. We established precision cut lung slices (PCLS) infection model for Mmm and Mmc to study host-pathogen interactions. We monitored infection over time using immunohistological analysis and electron microscopy. Moreover, infection burden was monitored by plating and quantitative real-time PCR. Results were compared with lungs from experimentally infected goats and cattle. Lungs from healthy goats and cattle were also included as controls. PCLS remained viable for up to two weeks. Both subspecies adhered to ciliated cells. However, the titer of Mmm in caprine PCLS decreased over time, indicating species specificity of Mmm. Mmc showed higher tropism to sub-bronchiolar tissue in caprine PCLS, which increased in a time-dependent manner. Moreover, Mmc was abundantly observed on pulmonary endothelial cells, indicating partially, how it causes systemic disease. Tissue destruction upon prolonged infection of slices was comparable to the in vivo samples. Therefore, PCLS represents a novel ex vivo model to study host-pathogen interaction in livestock mycoplasma.

Modeling tuberculosis pathogenesis through ex vivo lung tissue infection

Tuberculosis (TB) is one of the top 10 causes of death worldwide. Several in vitro and in vivo experimental models have been used to study TB pathogenesis and induction of immune response during Mycobacterium tuberculosis infection. Precision cut lung tissue slices (PCLTS) is an experimental model, in which all the usual cell types of the organ are found, the tissue architecture and the interactions amongst the different cells are maintained. PCLTS in good physiological conditions, monitored by MTT assay and histology, were infected with either virulent Mycobacterium tuberculosis strain H37Rv or the TB vaccine strain Mycobacterium bovis BCG. Histological analysis showed that bacilli infecting lung tissue slices were observed in the alveolar septa, alveolar light spaces, near to type II pneumocytes, and inside macrophages. Mycobacterial infection of PCLTS induced TNF-α production, which is consistent with previous M. tuberculosis in vitro and in vivo studies. This is the first report of using PCLTS as a system to study M. tuberculosis infection. The PCLTS model provides a useful tool to evaluate the innate immune responses and other aspects during the early stages of mycobacterial infection.

Comparison of mono- and co-infection by swine influenza A viruses and porcine respiratory coronavirus in porcine precision-cut lung slices

Coronaviruses as well as influenza A viruses are widely spread in pig fattening and can cause high economical loss. Here we infected porcine precision-cut lung slices with porcine respiratory coronavirus and two Influenza A viruses to analyze if co-infection with these viruses may enhance disease outcome in swine. Ciliary activity of the epithelial cells in the bronchus of precision-cut lung slices was measured. Co-infection of PCLS reduced virulence of both virus species compared to mono-infection. Similar results were obtained by mono- and co-infection experiments on a porcine respiratory cell line. Again lower titers in co-infection groups indicated an interference of the two RNA viruses. This is in accordance with in vivo experiments, revealing cell innate immune answers to both PRCoV and SIV that are able to restrict the virulence and pathogenicity of the viruses.

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PCLS can be used to analyze porcine respiratory coronavirus infection.

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Co-infection of PCLS with PRCoV and SIV reduces viral replication efficiency.

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SIV replication is reduced after co-infection of NPTr cells with PRCoV.

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Porcine influenza and coronaviruses interfere during infection.