Frontiers in Microbiology (Mar 2019)

Streptococcus canis Are a Single Population Infecting Multiple Animal Hosts Despite the Diversity of the Universally Present M-Like Protein SCM

  • Marcos D. Pinho,
  • Geoffrey Foster,
  • Constança Pomba,
  • Miguel P. Machado,
  • Johanna L. Baily,
  • Thijs Kuiken,
  • José Melo-Cristino,
  • Mário Ramirez,
  • The Portuguese Group for the Study of Streptococcal Infections,
  • Teresa Vaz,
  • Marília Gião,
  • Rui Ferreira,
  • Ana Cristina Silva,
  • Hermínia Costa,
  • Maria Fátima Silva,
  • Maria Amélia Afonso,
  • Ana Domingos,
  • Gina Marrão,
  • José Grossinho,
  • Paulo Lopes,
  • Angelina Lameirão,
  • Gabriela Abreu,
  • Aurélia Selaru,
  • Hermínia Marques,
  • Margarida Tomaz,
  • Paula Mota,
  • Maria Helena Ramos,
  • Ana Paula Castro,
  • Fernando Fonseca,
  • Nuno Canhoto,
  • Teresa Afonso,
  • Teresa Pina,
  • Helena Peres,
  • Odete Chantre,
  • Joã Marques,
  • Cristina Marcelo,
  • Isabel Peres,
  • Isabel Lourenço,
  • Margarida Pinto,
  • Lurdes Monteiro,
  • Luís Marques Lito,
  • Cristina Toscano,
  • Maria Ana Pessanha,
  • Elmano Ramalheira,
  • Raquel Diaz,
  • Sónia Ferreira,
  • Inês Cravo Roxo,
  • Ana Paula Castro,
  • Graça Ribeiro,
  • Rui Tomé,
  • Celeste Pontes,
  • Luísa Boaventura,
  • Catarina Chaves,
  • Teresa Reis,
  • Ana Buschy Fonseca,
  • Manuela Ribeiro,
  • Helena Gonçalves,
  • Alberta Faustino,
  • Adelaide Alves,
  • Maria Cármen Iglesias,
  • Ilse Fontes,
  • Paulo Martinho,
  • Maria Luísa Gonçalves Olga Neto,
  • Luísa Sancho,
  • Adriana Coutinho,
  • José Diogo,
  • Ana Rodrigues,
  • Maria Antónia Read Valquíria Alves Margarida Monteiro,
  • Rosa Bento

DOI
https://doi.org/10.3389/fmicb.2019.00631
Journal volume & issue
Vol. 10

Abstract

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Streptococcus canis is an animal pathogen which occasionally causes infections in humans. The S. canis M-like protein (SCM) encoded by the scm gene, is its best characterized virulence factor but previous studies suggested it could be absent in a substantial fraction of isolates. We studied the distribution and variability of the scm gene in 188 S. canis isolates recovered from companion animals (n = 152), wild animal species (n = 20), and humans (n = 14). Multilocus sequence typing, including the first characterization of wildlife isolates, showed that the same lineages are present in all animal hosts, raising the possibility of extensive circulation between species. Whole-genome analysis revealed that emm-like genes found previously in S. canis correspond to divergent scm genes, indicating that what was previously believed to correspond to two genes is in fact the same scm locus. We designed primers allowing for the first time the successful amplification of the scm gene in all isolates. Analysis of the scm sequences identified 12 distinct types, which could be divided into two clusters: group I (76%, n = 142) and group II (24%, n = 46) sharing little sequence similarity. The predicted group I SCM showed extensive similarity with each other outside of the N-terminal hypervariable region and a conserved IgG binding domain. This domain was absent from group II SCM variants found in isolates previously thought to lack the scm gene, which also showed greater amino acid variability. Further studies are necessary to elucidate the possible host interacting partners of the group II SCM variants and their role in virulence.

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