Streptococcus suis is a porcine and zoonotic pathogen in the upper respiratory tract, expressing different capsular serotypes and virulence-associated factors. Given its genomic and phenotypic diversity, the virulence potential of S. suis cannot be attributed to a single factor. Since strong inflammatory response is a hallmark of S. suis infection, the objective of this study was to investigate the differences in transcriptional host responses to two serotype 2 and one serotype 9 strains. Both serotypes are frequently found in clinical isolates. We infected porcine precision-cut lung slices (PCLSs) with two serotype 2 strains of high (strain S10) and low (strain T15) virulence, and a serotype 9 strain 8067 of moderate virulence. We observed higher expression of inflammation-related genes during early infection with strains T15 and 8067, in contrast to infection with strain 10, whose expression peaked late. In addition, bacterial gene expression from infected PCLSs revealed differences, mainly of metabolism-related and certain virulence-associated bacterial genes amongst these strains. We conclude that the strain- and time-dependent induction of genes involved in innate immune response might reflect clinical outcomes of infection in vivo, implying rapid control of infection with less virulent strains compared to the highly virulent strain S10.

Respiratory infections of livestock represent a major health issue for the animals and cause high economic losses for the farmers. Still, little is known about the intricate interactions between host cells and the many different pathogens that cause respiratory diseases, leaving a substantial knowledge gap to be filled in order to develop effective therapies. Immortalized cell lines and two-dimensional cultures of primary respiratory epithelial cells do not reflect the complex architecture and functionality of the respiratory tract tissues. Thus, it is essential to develop and apply appropriate primary cell culture systems to study respiratory diseases. In human research, the use of complex cell culture systems, such as air-liquid interface (ALI) cultures, organoids and lung-on-chip, has proceeded significantly during the last years, whereas in veterinary research, these models are only rarely used. Nevertheless, there are several three-dimensional, primary cell culture systems available to study respiratory infections of livestock. Here, we give an overview on models that are currently used in this field: nasal mucosa explants, tracheal organ cultures, ALI cultures, and precision-cut lung slices. All these models align with the 3R principle, as they can replace animal experiments to some extent and the tissue material for these culture systems can be obtained from abattoirs or veterinary research facilities. We aim to encourage other researchers to use these versatile cell culture systems to drive investigations of respiratory tract infections of livestock forward. Finally, these models are not limited to infection research, but can also be applied in other research fields and can be transferred to other animal species than livestock.

Streptococcus suis, a common member of the porcine respiratory microbiota, can cause life-threatening diseases in pigs as well as humans. A previous study identified the gene trpX as conditionally essential for in vivo survival by intrathecal infection of pigs with a transposon library of S. suis strain 10. Here, we characterized trpX, encoding a putative tryptophan/tyrosine transport system substrate-binding protein, in more detail. We compared growth capacities of the isogenic trpX-deficient mutant derivative strain 10∆trpX with its parent. Growth experiments in chemically defined media (CDM) revealed that growth of 10∆trpX depended on tryptophan concentration, suggesting TrpX involvement in tryptophan uptake. We demonstrated that trpX is part of an operon structure and co-transcribed with two additional genes encoding a putative permease and ATPase, respectively. Bioinformatics analysis identified a putative tryptophan T-box riboswitch in the 5′ untranslated region of this operon. Finally, qRT-PCR and a reporter activation assay revealed trpX mRNA induction under tryptophan-limited conditions. In conclusion, our study showed that TrpX is part of a putative tryptophan ABC transporter system regulated by a T-box riboswitch probably functioning as a substrate-binding protein. Due to the tryptophan auxotrophy of S. suis, TrpX plays a crucial role for metabolic adaptation and growth during infection.

Bordetella bronchiseptica is a gram-negative bacterium contributing to respiratory diseases in many different animal species. In the swine population, it occurs frequently and plays a role in the Porcine Respiratory Disease Complex as well as in the pathogenesis of atrophic rhinitis. The dermonecrotic toxin (DNT) is involved in the destruction of the nasal conchae, a hallmark of atrophic rhinitis, and several studies have shown the effects of DNT on osteoblastic cells. Surprisingly, only little is known about the interactions of DNT and respiratory epithelial cells. Thus, we investigated the influence of DNT on porcine respiratory epithelial cells during mono- and co-infections in vitro . For this, we infected porcine precision-cut lung slices and air-liquid interface cultures with a DNT-positive B. bronchiseptica wild-type strain and its isogenic DNT-deficient mutant strain. For co-infection experiments, a Streptococcus suis serotype 2 wild-type strain was used. We evaluated cytotoxic effects and colonization of both pathogens, as well as the pro-inflammatory cytokine response of the host cells. Remarkably, DNT neither contributed to the cytotoxic effects of B. bronchiseptica nor did it affect bacterial colonization. Regarding the cytokine response, pro-inflammatory cytokines were expressed mainly upon infection with B. bronchiseptica but hardly after infection with S. suis , whereas co-infection with both pathogens had an amplifying effect on cytokine expression after prolonged infection, independently of DNT. Concluding, we found no evidence that DNT contributes to the early stages of infection with B. bronchiseptica and S. suis in in vitro models of the porcine respiratory tract.

Antimicrobial resistance (AMR) is a complex and rapidly evolving global health challenge that requires well-trained professionals within a One Health framework. However, AMR education remains fragmented, with limited interdisciplinary integration and inconsistencies across disciplines. Although AMR is included in undergraduate and postgraduate curricula in human medicine, veterinary medicine, biological sciences, and pharmacology, the educational focus differs substantially between fields. Moreover, teaching focuses on biomedical and pharmacological aspects, while social, behavioural, and policy dimensions are often underrepresented, limiting the ability to address AMR as a multifaceted societal challenge. To identify gaps in AMR teaching, associated challenges and unmet educational resource needs, we conducted a three-month international survey among professionals from diverse scientific fields involved in AMR teaching. A total of 85 professionals participated in the survey, of whom 94% were actively involved in AMR teaching. AMR was most often taught within microbiology (35%) or health-related (33%) courses and was typically presented as few lectures within a module (33%). Although the general perception was that engaging teaching approaches, such as case-based learning, better support effective learning, many participants (31%) reported relying primarily on traditional lecture-based materials. Furthermore, the survey identified limited curriculum time, behavioural barriers, and funding constraints as the principle challenges to effective education. Overall, these findings indicate a strong demand for additional teaching resources, particularly interactive and application-oriented materials that support active learning and interdisciplinary education. This knowledge will support the development of an open educational resource (OER)-based interactive online educational platform, designed to enhance AMR education within a One Health context and support the training of future health professionals.

Antimicrobial resistance (AMR) is a complex and rapidly evolving global health challenge that requires well-trained professionals within a One Health framework. However, AMR education remains fragmented, with limited interdisciplinary integration and inconsistencies across disciplines. Although AMR is included in undergraduate and postgraduate curricula in human medicine, veterinary medicine, biological sciences, and pharmacology, the educational focus differs substantially between fields. Moreover, teaching focuses on biomedical and pharmacological aspects, while social, behavioural, and policy dimensions are often underrepresented, limiting the ability to address AMR as a multifaceted societal challenge. To identify gaps in AMR teaching, associated challenges and unmet educational resource needs, we conducted a three-month international survey among professionals from diverse scientific fields involved in AMR teaching. A total of 85 professionals participated in the survey, of whom 94% were actively involved in AMR teaching. AMR was most often taught within microbiology (35%) or health-related (33%) courses and was typically presented as few lectures within a module (33%). Although the general perception was that engaging teaching approaches, such as case-based learning, better support effective learning, many participants (31%) reported relying primarily on traditional lecture-based materials. Furthermore, the survey identified limited curriculum time, behavioural barriers, and funding constraints as the principle challenges to effective education. Overall, these findings indicate a strong demand for additional teaching resources, particularly interactive and application-oriented materials that support active learning and interdisciplinary education. This knowledge will support the development of an open educational resource (OER)-based interactive online educational platform, designed to enhance AMR education within a One Health context and support the training of future health professionals.