Pathog Dis. 2016 Aug;74(6). pii: ftw066. doi: 10.1093/femspd/ftw066.

Identification of a virulence determinant that is conserved in the Jawetz and Heyl biotypes of [Pasteurella] pneumotropica


Hiraku Sasaki 1*, Hiroki Ishikawa 2, Hayato Terayama 3, Ryoki Asano 4, Eiichi Kawamoto 5, Hidetoshi Ishibashi 5, Ron Boot 6

1 Department of Health Science, School of Health and Sports Science, Juntendo University, 1-1 Hiraga-gakuendai, Inzai, Chiba 270 – 1695, Japan

2 Department of Microbiology, Showa University School of Medicine, 1-5-8 Hatanodai, Tokyo 142 – 8555, Japan

3 Department of Anatomy, Division of Basic Medical Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259 – 1193, Japan

4 Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, 41 – 438 Kaidobata-Nishi, Shimoshinjo-Nakano, Akita 010 – 0195, Japan

5 Animal Research Center, Tokyo Medical University, 6-1-1 Shinjuku, Tokyo 160 – 8402, Japan

f National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9 3721 MA Bilthoven, the Netherlands



[Pasteurella] pneumotropica is a ubiquitous bacterium frequently isolated from laboratory rodents. Although this bacterium causes various diseases in immunosuppressed animals, little is known about major virulence factors and their roles in pathogenicity. To identify virulence factors, we sequenced the genome of [P.] pneumotropica biotype Heyl strain ATCC 12555, and compared the resulting non-contiguous draft genome sequence with the genome of biotype Jawetz strain ATCC 35149. Among a large number of genes encoding virulence-associated factors in both strains, four genes encoding for YadA-like proteins which are known virulence factors that function in host cell adherence and invasion in many pathogens. In this study, we assessed YadA distribution and biological activity as an example of one of virulence – associated factor shared with biotype Jawetz and Heyl. More than half of mouse isolates were found to have at least one of these genes; whereas, the majority of rat isolates did not. Autoagglutination activity, and ability to bind to mouse collagen type IV and mouse fibroblast cells, was significantly higher in YadA-positive than YadA-negative strains. To conclude, we identified a large number of candidate genes predicted to influence [P.] pneumotropica pathogenesis.

Keywords: Adherence; Pasteurella pneumotropica; YadA




[Pasteurella] pneumotropica is a Gram-negative rod-shaped bacterium and, as a latest literature, this bacterium including two biotypes is reclassified as Rodentibacter spp. (1). These bacterial species are an opportunistic pathogen in laboratory rodents; however, detailed virulence-associated genes and their products are still unavailable. Although we have finished draft genome sequence of type strain ATCC 35149T and identified putative virulence-associated genes, certain virulences that are commonly found in Rodentibacter spp. could not be clarified (2). Then, we have performed whole genome sequencing of a representative strain ATCC 12555 of R. heylii (former biotype Heyl), and report the results of evaluation of the non-contiguous finished quality sequence, by comparison with the R. pneumotropicus (former biotype Jawetz) genome, to determine major and common virulence factors.

Comparative genome analysis was performed on strain ATCC 12555 using ATCC 35149 as a reference sequence. A total of 1,855 genes were highly similar in both species, and of these, 86 were assumed to be virulence-associated genes, including those that were multiple components of the same virulence factor. Genes encoding RTX exoprotein, FHA, IbpA and type VI secretion system proteins were identified as common virulence-associated genes in both species. Among the virulence-associated gene products, multiple genes encoding trimeric autotransporter adhesin YadA domain containing proteins, which are known to promote pathogenicity and virulence in host cells through cell adhesion, were identified and characterized as similar virulence factors in YadA-positive strains. The YadA might not be certain virulences in Rodentibacter spp. since all the wild-type strains did not have the genes-encoding YadA; however, the virulence-associated genes identified in this study might be candidate of major virulences in Rodentibacter spp. (3).



Figure 1. The R. heylii strain ATCC 12555 (former P. pneumotropica biotype Heyl) by scanning electron microscope. The SEM was performed by Support Center for Medical Research and Education, Tokai University.



  1. Adhikary S, Nicklas W, Bisgaard M, Boot R, Kuhnert P, Waberschek T, Aalbæk B, Korczak B, Christensen H. Rodentibacter nov. including Rodentibacter pneumotropicus comb. nov., Rodentibacter heylii sp. nov., Rodentibacter myodis sp. nov., Rodentibacter ratti sp. nov., Rodentibacter heidelbergensis sp. nov., Rodentibacter trehalosifermentans sp. nov., Rodentibacter rarus sp. nov., Rodentibacter mrazii and two genomospecies. Int J Syst Evol Microbiol. 2017 Jun;67(6):1793-1806.
  2. Sasaki H, Ishikawa H, Asano R, Ueshiba H, Matsumoto T, Boot R, Kawamoto E. Draft genome sequence of the rodent opportunistic pathogen Pasteurella pneumotropica ATCC 35149T. Genome Announc. 2014 Aug 7;2(4). pii: e00771-14.
  3. Sasaki H, Ishikawa H, Terayama H, Asano R, Kawamoto E, Ishibashi H, Boot R. Identification of a virulence determinant that is conserved in the Jawetz and Heyl biotypes of [Pasteurella] pneumotropica. Pathog Dis. 2016 Aug;74(6). pii: ftw066.