Enhanced Nasopharyngeal Infection and Shedding Associated with an Epidemic Lineage of emm3 group A Streptococcus

Abstract

Background: A group A Streptococcus (GAS) lineage of genotype emm3, sequence type 15 (ST15) was associated with a six month upsurge in invasive GAS disease in the UK. The epidemic lineage (Lineage C) had lost two typical emm3 prophages, Φ315.1 and Φ315.2 associated with the superantigen ssa, but gained a different prophage (ΦUK-M3.1) associated with a different superantigen, speC and a DNAse spd1.

Methods and Results: The presence of speC and spd1 in Lineage C ST15 strains enhanced both in vitro mitogenic and DNAse activities over non-Lineage C ST15 strains. Invasive disease models in Galleria mellonella and SPEC-sensitive transgenic mice, revealed no difference in overall invasiveness of Lineage C ST15 strains compared to non-Lineage C ST15 strains, consistent with clinical and epidemiological analysis. Lineage C strains did however markedly prolong murine nasal infection with enhanced nasal and airborne shedding compared to non-Lineage C strains. Deletion of speC or spd1 in two Lineage C strains identified a possible role for spd1 in airborne shedding from the murine nasopharynx.

Conclusions: Nasopharyngeal infection and shedding of Lineage C strains was enhanced compared to nonLineage C strains and this was, in part, mediated by the gain of the DNase spd1 through prophage acquisition.

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Authors/Creators:	Afshar, B. Turner, C.E. https://orcid.org/0000-0002-4458-9748 Lamagni, T. Smith, K. Al-Shahib, A. Underwood, A. Holden, M. Efstratiou, A. Sriskandan, S.
Copyright, Publisher and Additional Information:	© 2017 Baharak Afshar, Claire E. Turner, Theresa L. Lamgni, Ken C. Smith, Ali Al-Shahib, Anthony Underwood, Matthew T. G. Holden, Androulla Efstratiou, and Shiranee Sriskandan. Published with license by Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The moral rights of the named author(s) have been asserted.
Keywords:	Streptococcus pyogenes; group A Streptococcus; nasopharyngeal infection; genotype emm3; serotype M3; invasive group A streptococcal disease; prophage; superantigens; DNases; epidemic upsurge
Dates:	Accepted: 26 April 2017 Published (online): 19 May 2017
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield)
Depositing User:	Symplectic Sheffield
Date Deposited:	09 May 2017 10:32
Last Modified:	06 May 2020 10:19
Published Version:	https://doi.org/10.1080/21505594.2017.1325070
Status:	Published
Publisher:	Taylor & Francis
Refereed:	Yes
Identification Number:	https://doi.org/10.1080/21505594.2017.1325070

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Enhanced Nasopharyngeal Infection and Shedding Associated with an Epidemic Lineage of emm3 group A Streptococcus

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