Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.

Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a re...

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Autores principales:	Lauri Mikonranta, Ville-Petri Friman, Jouni Laakso
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/2ce78be1245c41db9436bd69c7f3aae4
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spelling	oai:doaj.org-article:2ce78be1245c41db9436bd69c7f3aae42021-11-18T07:07:41ZLife history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.1932-620310.1371/journal.pone.0043801https://doaj.org/article/2ce78be1245c41db9436bd69c7f3aae42012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22937098/?tool=EBIhttps://doaj.org/toc/1932-6203Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm) caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the 'predator absent' selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.Lauri MikonrantaVille-Petri FrimanJouni LaaksoPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 8, p e43801 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Lauri Mikonranta Ville-Petri Friman Jouni Laakso Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
description	Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm) caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the 'predator absent' selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.
format	article
author	Lauri Mikonranta Ville-Petri Friman Jouni Laakso
author_facet	Lauri Mikonranta Ville-Petri Friman Jouni Laakso
author_sort	Lauri Mikonranta
title	Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
title_short	Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
title_full	Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
title_fullStr	Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
title_full_unstemmed	Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
title_sort	life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/2ce78be1245c41db9436bd69c7f3aae4
work_keys_str_mv	AT laurimikonranta lifehistorytradeoffsandrelaxedselectioncandecreasebacterialvirulenceinenvironmentalreservoirs AT villepetrifriman lifehistorytradeoffsandrelaxedselectioncandecreasebacterialvirulenceinenvironmentalreservoirs AT jounilaakso lifehistorytradeoffsandrelaxedselectioncandecreasebacterialvirulenceinenvironmentalreservoirs
_version_	1718423906514108416

Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.

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