Transcriptional profile of Glaesserella parasuis in swine serosal and joint fluids

Daniel Ward Nielsen ¹ Kaitlyn Sarlo Davila ¹ Susan L. Brockmeier ² Samantha Hau ^2*

• ¹ Ruminant Diseases and Immunology Research Unit, National Animal Disease Center, Agricultural Research Service (USDA), Ames, United States
• ² Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service (USDA), Ames, United States

Glaesserella 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 serovar 5 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.