Transcriptomic differences noted in Glasserella parasuis between growth in broth and on agar

Authors: Brockmeier, Susan; HAU, SAMANTHA - Oak Ridge Institute For Science And Education (ORISE); MOU, KATHY - Oak Ridge Institute For Science And Education (ORISE); Bayles, Darrell

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2019
Publication Date: 8/6/2019
Citation: Brockmeier, S., Hau, S.J., Mou, K.T., Bayles, D.O. 2019. Transcriptomic differences noted in Glasserella parasuis between growth in broth and on agar. PLoS One. 14(8):e0220365. https://doi.org/10.1371/journal.pone.0220365.
DOI: https://doi.org/10.1371/journal.pone.0220365

Interpretive Summary: Glaesserella parasuis is a bacteria that causes severe disease in pigs. We compared the genetic activity of G. parasuis grown on solid or in liquid media to better understand how G. parasuis grows in the laboratory. There was little difference in the production of genes known to contribute to disease. There were differences in production of genes involved in protein and fat production. There was also an increase in cell growth in G. parasuis grown in liquid media. This study presents new information on which proteins are exposed to the host when G. parasuis is used as a vaccine. It may also help researchers mimic animal disease in the lab.

Technical Abstract: Glaesserella parasuis is the cause of Glasser’s disease in pigs and is a significant contributor to post-weaning mortality in the swine industry. Prevention of G. parasuis disease relies primarily on bacterin vaccines, which have shown good homologous protection and variable heterologous protection. Bacterin production involves large scale growth of the bacteria and proteins produced during the proliferation phase of production become important antigens that stimulate the immune response. In order to evaluate genes activated during G. parasuis growth on different media substrates, the transcriptome of broth and agar grown G. parasuis strain 29755 were sequenced and compared. The transcription of almost all known virulence genes were comparable between broth and agar grown G. parasuis, except for the virulence associated protein D (vapD) which had increased expression in agar grown G. parasuis. Additionally, there were metabolic shifts toward increased protein and lipid production and increased cellular division in broth grown G. parasuis. The results contribute to the understanding of how growth substrate alters gene transcription and protein expression, which may impact vaccine efficacy if immunogens important to the protective immune response are not produced under specific in vitro conditions. While the results of this work are unable to fully elucidate which growth medium presents a transcriptome more representative of in vivo samples or best suited for bacterin production, it forms a foundation that can be used for future comparisons and provides a better understanding of the metabolic differences in broth and agar grown bacteria.