Bordetella bronchiseptica Colonization Limits Efficacy, but Not Immunogenicity, of Live-Attenuated Influenza Virus Vaccine and Enhances Pathogenesis After Influenza Challenge

Intranasally administered live-attenuated influenza virus (LAIV) vaccines provide significant protection against heterologous influenza A virus (IAV) challenge. However, LAIV administration can modify the bacterial microbiota in the upper respiratory tract, including alterations in species that cause pneumonia. We sought to evaluate the effect of Bordetella bronchiseptica colonization on LAIV immunogenicity and efficacy in swine, and the impact of LAIV and IAV challenge on B. bronchiseptica colonization and disease. LAIV immunogenicity was not significantly impacted by B. bronchiseptica colonization, but protective efficacy against heterologous IAV challenge in the upper respiratory tract was impaired. Titers of IAV in the nose and trachea of pigs that received LAIV were significantly reduced when compared to non-vaccinated, challenged controls, regardless of B. bronchiseptica infection. Pneumonia scores were higher in pigs colonized with B. bronchiseptica and challenged with IAV, but this was regardless of LAIV vaccination status. While LAIV vaccination provided significant protection against heterologous IAV challenge, the protection was not sterilizing and IAV replicated in the respiratory tract of all LAIV vaccinated pig. The interaction between IAV, B. bronchiseptica, and host led to development of acute-type B. bronchiseptica lesions in the lung. Thus, the data presented do not negate the efficacy of LAIV vaccination, but instead indicate that controlling B. bronchiseptica colonization in swine could limit the negative interaction between IAV and Bordetella on swine health

Efficacy in Pigs of Inactivated and Live Attenuated Influenza Virus Vaccines against Infection and Transmission of an Emerging H3N2 Similar to the 2011-2012 H3N2v

Vaccines provide a primary means to limit disease but may not be effective at blocking infection and pathogen transmission. The objective of the present study was to evaluate the efficacy of commercial inactivated swine influenza A virus (IAV) vaccines and experimental live attenuated influenza virus (LAIV) vaccines against infection with H3N2 virus and subsequent indirect transmission to naive pigs. The H3N2 virus evaluated was similar to the H3N2v detected in humans during 2011-2012, which was associated with swine contact at agricultural fairs. One commercial vaccine provided partial protection measured by reduced nasal shedding; however, indirect contacts became infected, indicating that the reduction in nasal shedding did not prevent aerosol transmission. One LAIV vaccine provided complete protection, and none of the indirect-contact pigs became infected. Clinical disease was not observed in any group, including nonvaccinated animals, a consistent observation in pigs infected with contemporary reassortant H3N2 swine viruses. Serum hemagglutination inhibition antibody titers against the challenge virus were not predictive of efficacy; titers following vaccination with a LAIV that provided sterilizing immunity were below the level considered protective, yet titers in a commercial vaccine group that was not protected were above that level. While vaccination with currently approved commercial inactivated products did not fully prevent transmission, certain vaccines may provide a benefit by limitating shedding, transmission, and zoonotic spillover of antigenically similar H3N2 viruses at agriculture fairs when administered appropriately and used in conjunction with additional control measures

\u3cem\u3eIn Vivo\u3c/em\u3e Validation of Predicted and Conserved T Cell Epitopes in a Swine Influenza Model

Swine influenza is a highly contagious respiratory viral infection in pigs that is responsible for significant financial losses to pig farmers annually. Current measures to protect herds from infection include: inactivated whole-virus vaccines, subunit vaccines, and alpha replicon-based vaccines. As is true for influenza vaccines for humans, these strategies do not provide broad protection against the diverse strains of influenza A virus (IAV) currently circulating in U.S. swine. Improved approaches to developing swine influenza vaccines are needed. Here, we used immunoinformatics tools to identify class I and II T cell epitopes highly conserved in seven representative strains of IAV in U.S. swine and predicted to bind to Swine Leukocyte Antigen (SLA) alleles prevalent in commercial swine. Epitope-specific interferon-gamma (IFNγ) recall responses to pooled peptides and whole virus were detected in pigs immunized with multi-epitope plasmid DNA vaccines encoding strings of class I and II putative epitopes. In a retrospective analysis of the IFNγ responses to individual peptides compared to predictions specific to the SLA alleles of cohort pigs, we evaluated the predictive performance of PigMatrix and demonstrated its ability to distinguish non-immunogenic from immunogenic peptides and to identify promiscuous class II epitopes. Overall, this study confirms the capacity of PigMatrix to predict immunogenic T cell epitopes and demonstrate its potential for use in the design of epitope-driven vaccines for swine. Additional studies that match the SLA haplotype of animals with the study epitopes will be required to evaluate the degree of immune protection conferred by epitope-driven DNA vaccines in pigs

The Streptococcos suis sortases SrtB and SrtF are essential for disease in pigs.

The porcine pathogen Streptococcus suis colonizes the upper respiratory tracts of pigs, potentially causing septicaemia, meningitis and death, thus placing a severe burden on the agricultural industry worldwide. It is also a zoonotic pathogen that is known to cause systemic infections and meningitis in humans. Understanding how S. suis colonizes and interacts with its hosts is relevant for future strategies of drug and vaccine development. As with other Gram-positive bacteria, S. suis utilizes enzymes known as sortases to attach specific proteins bearing cell wall sorting signals to its surface, where they can play a role in host-pathogen interactions. The surface proteins of bacteria are often important in adhesion to and invasion of host cells. In this study, markerless in-frame deletion mutants of the housekeeping sortase srtA and the two pilus-associated sortases, srtB and srtF, were generated and their importance in S. suis infections was investigated. We found that all three of these sortases are essential to disease in pigs, concluding that their cognate-sorted proteins may also be useful in protecting pigs against infection

Update on Streptococcus suis Research and Prevention in the Era of Antimicrobial Restriction: 4th International Workshop on S. suis.

Streptococcus suis is a swine pathogen and a zoonotic agent afflicting people in close contact with infected pigs or pork meat. Sporadic cases of human infections have been reported worldwide. In addition, S. suis outbreaks emerged in Asia, making this bacterium a primary health concern in this part of the globe. In pigs, S. suis disease results in decreased performance and increased mortality, which have a significant economic impact on swine production worldwide. Facing the new regulations in preventive use of antimicrobials in livestock and lack of effective vaccines, control of S. suis infections is worrisome. Increasing and sharing of knowledge on this pathogen is of utmost importance. As such, the pathogenesis and epidemiology of the infection, antimicrobial resistance, progress on diagnosis, prevention, and control were among the topics discussed during the 4th International Workshop on Streptococcus suis (held in Montreal, Canada, June 2019). This review gathers together recent findings on this important pathogen from lectures performed by lead researchers from several countries including Australia, Canada, France, Germany, Japan, Spain, Thailand, The Netherlands, UK, and USA. Finally, policies and recommendations for the manufacture, quality control, and use of inactivated autogenous vaccines are addressed to advance this important field in veterinary medicine

Shifts in the swine nasal microbiota following Bordetella bronchiseptica challenge in a longitudinal study

Bordetella bronchiseptica is a widespread, highly infectious bacterial pathogen that causes respiratory disease in swine and increases the severity of respiratory infections caused by other viral or bacterial pathogens. However, the impact of B. bronchiseptica infection on the swine respiratory microbiota has not been thoroughly investigated. Here, we aim to assess the influence of B. bronchiseptica infection on the community structure and abundance of members of the swine nasal microbiota. To do so, the nasal microbiota of a non-infected control group and a group infected with B. bronchiseptica (BB group) were characterized prior to B. bronchiseptica strain KM22 challenge (day 0) and on selected days in the weeks following B. bronchiseptica challenge (days 1, 3, 7, 10, 14, 21, 36, and 42). Bordetella bronchiseptica was cultured from nasal samples of the BB group to assess nasal colonization. The results showed that B. bronchiseptica colonization did not persistently affect the nasal bacterial diversity of either of the treatment groups (alpha diversity). However, the bacterial community structures (beta diversity) of the two treatment groups significantly diverged on day 7 when peak colonization levels of B. bronchiseptica were detected. This divergence continued through the last sampling time point. In addition, Pasteurella, Pasteurellaceae (unclassified), Mycoplasma, Actinobacillus, Streptococcus, Escherichia-Shigella, and Prevotellaceae (unclassified) showed increased abundances in the BB group relative to the control group at various time points. This study revealed that B. bronchiseptica colonization can disturb the upper respiratory tract microbiota, and further research is warranted to assess how these disturbances can impact susceptibility to secondary infections by other respiratory pathogens

Evaluation of the recombinant proteins RlpB and VacJ as a vaccine for protection against Glaesserella parasuis in pigs

Funder: U.S. Department of Agriculture; doi: http://dx.doi.org/10.13039/100000199Funder: Oak Ridge Institute for Science and Education; doi: http://dx.doi.org/10.13039/100006229Funder: Department for Environment, Food and Rural Affairs; doi: http://dx.doi.org/10.13039/501100000277Abstract: Background: Glaesserella parasuis, the causative agent of Glӓsser’s disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser’s disease in pigs has been plagued with an inability to design broadly protective vaccines, as many bacterin based platforms generate serovar or strain specific immunity. Subunit vaccines are of interest to provide protective immunity to multiple strains of G. parasuis. Selected proteins for subunit vaccination should be widespread, highly conserved, and surface exposed. Results: Two candidate proteins for subunit vaccination (RlpB and VacJ) against G. parasuis were identified using random mutagenesis and an in vitro organ culture system. Pigs were vaccinated with recombinant RlpB and VacJ, outer membrane proteins with important contributions to cellular function and viability. Though high antibody titers to the recombinant proteins and increased interferon-γ producing cells were found in subunit vaccinated animals, the pigs were not protected from developing systemic disease. Conclusions: It appears there may be insufficient RlpB and VacJ exposed on the bacterial surface for antibody to bind, preventing high RlpB and VacJ specific antibody titers from protecting animals from G. parasuis. Additionally, this work confirms the importance of utilizing the natural host species when assessing the efficacy of vaccine candidates

Evaluation of the recombinant proteins RlpB and VacJ as a vaccine for protection against Glaesserella parasuis in pigs

Funder: U.S. Department of Agriculture; doi: http://dx.doi.org/10.13039/100000199Funder: Oak Ridge Institute for Science and Education; doi: http://dx.doi.org/10.13039/100006229Funder: Department for Environment, Food and Rural Affairs; doi: http://dx.doi.org/10.13039/501100000277Abstract: Background: Glaesserella parasuis, the causative agent of Glӓsser’s disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser’s disease in pigs has been plagued with an inability to design broadly protective vaccines, as many bacterin based platforms generate serovar or strain specific immunity. Subunit vaccines are of interest to provide protective immunity to multiple strains of G. parasuis. Selected proteins for subunit vaccination should be widespread, highly conserved, and surface exposed. Results: Two candidate proteins for subunit vaccination (RlpB and VacJ) against G. parasuis were identified using random mutagenesis and an in vitro organ culture system. Pigs were vaccinated with recombinant RlpB and VacJ, outer membrane proteins with important contributions to cellular function and viability. Though high antibody titers to the recombinant proteins and increased interferon-γ producing cells were found in subunit vaccinated animals, the pigs were not protected from developing systemic disease. Conclusions: It appears there may be insufficient RlpB and VacJ exposed on the bacterial surface for antibody to bind, preventing high RlpB and VacJ specific antibody titers from protecting animals from G. parasuis. Additionally, this work confirms the importance of utilizing the natural host species when assessing the efficacy of vaccine candidates

Contribution of Bordetella bronchiseptica Filamentous Hemagglutinin and Pertactin to Respiratory Disease in Swine▿ †

Bordetella bronchiseptica is pervasive in swine populations and plays multiple roles in respiratory disease. Most studies addressing virulence factors of B. bronchiseptica are based on isolates derived from hosts other than pigs. Two well-studied virulence factors implicated in the adhesion process are filamentous hemagglutinin (FHA) and pertactin (PRN). We hypothesized that both FHA and PRN would serve critical roles in the adhesion process and be necessary for colonization of the swine respiratory tract. To investigate the role of FHA and PRN in Bordetella pathogenesis in swine, we constructed mutants containing an in-frame deletion of the FHA or the PRN structural gene in a virulent B. bronchiseptica swine isolate. Both mutants were compared to the wild-type swine isolate for their ability to colonize and cause disease in swine. Colonization of the FHA mutant was lower than that of the wild type at all respiratory tract sites and time points examined and caused limited to no disease. In contrast, the PRN mutant caused similar disease severity relative to the wild type; however, colonization of the PRN mutant was reduced relative to the wild type during early and late infection and induced higher anti-Bordetella antibody titers. Together, our results indicate that despite inducing different pathologies and antibody responses, both FHA and PRN are necessary for optimal colonization of the swine respiratory tract