Transcriptional profile of Glaesserella parasuis in swine serosal and joint fluids

Authors: Nielsen, Daniel; Sarlo Davila, Kaitlyn; Brockmeier, Susan; Hau, Samantha

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2025
Publication Date: 4/24/2025
Citation: Nielsen, D.W., Sarlo Davila, K.M., Brockmeier, S., Hau, S.J. 2025. Transcriptional profile of Glaesserella parasuis in swine serosal and joint fluids. Frontiers in Veterinary Science. 12. Article 1452973. https://doi.org/10.3389/fvets.2025.1452973.
DOI: https://doi.org/10.3389/fvets.2025.1452973

Interpretive Summary: Glaesserella parasuis (G. parasuis) causes disease in pigs. This disease (Glässer’s disease) leads to inflammation of the joints (arthritis), the brain (meningitis), and the lining of the lungs, heart, and abdomen (serositis). Previous studies showed what genes G. parasuis uses when grown in growth media or in host-like conditions such as iron limitation. However, it is still unknown how G. parasuis changes what genes are active when causing arthritis or serositis. Here, we grew G. parasuis in joint fluid to represent early joint infection (arthritis) and serosal fluid to represent early serosal infection (serositis), and the changes in gene activity (transcription) were measured at 3 and 12 hours. When G. parasuis was grown in host fluid for 3 hours, bacterial membrane genes were less activated (downregulated). However, genes associated with making proteins and nutrients were more activated (upregulated) in the host fluid. Additionally, we found 11 genes with an unknown function shared between the joint and serosal fluid at the 3-hour timepoint that had changed regulation. When comparing the host fluids from 12- to 3-hours, 16 genes were regulated in the opposite direction compared to the 3-hour host fluid comparison. An investigation into these unknown and shared genes may help us learn how G. parasuis causes disease, which may be useful in preventing Glässer’s disease.

Technical Abstract: Glaesserella parasuis (G. parasuis) is the causative agent of Glässer’s disease and contributes to significant post-weaning mortality in the swine industry. Glässer’s disease is characterized by meningitis, polyserositis, and polyarthritis. Previous work has examined transcriptomic differences of G. parasuis when inoculated into different in vitro conditions, lung explants, or the lung in vivo following intratracheal challenge. However, it is still unknown how the transcriptome of G. parasuis may change to cause polyserositis or polyarthritis. Here, we incubated G. parasuis in acellular joint or serosal fluid for 3 and 12 hours to better understand transcriptional changes in the joint or serosal compartment. When G. parasuis strain 29755 was incubated in host fluid for 3 hours, cell wall, membrane, and envelope biogenesis genes were downregulated compared to G. parasuis incubated in PBS. In contrast, translation, ribosomal structure, and biogenesis and carbohydrate transport and metabolism were upregulated in the host fluid compared to PBS. Additionally, there were eleven differentially expressed genes with an unknown function shared between the acellular joint and serosal fluid at the 3-hour timepoint compared to PBS. When comparing the differences between the host fluids from 12 to 3 hours and the host fluids at 3 hours compared to PBS, this study found sixteen genes with inverse expression patterns. An investigation into the hypothetical genes identified and the nineteen shared genes in all comparisons may provide further knowledge about the pathogenesis of G. parasuis, which may be useful in developing interventions against Glässer’s disease.