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The role of immune-mediated apparent competition in genetically diverse malaria infections

Råberg, Lars LU ; de Roode, J C; Bell, A S; Stamou, P; Gray, D and Read, A F (2006) In American Naturalist 168(1). p.41-53
Abstract
Competitive interactions between coinfecting genotypes of the same pathogen can impose selection on virulence, but the direction of this selection depends on the mechanisms behind the interactions. Here, we investigate how host immune responses contribute to competition between clones in mixed infections of the rodent malaria parasite Plasmodium chabaudi. We studied single and mixed infections of a virulent and an avirulent clone and compared the extent of competition in immunodeficient and immunocompetent mice (nude mice and T cell-reconstituted nude mice, respectively). In immunocompetent mice, the avirulent clone suffered more from competition than did the virulent clone. The competitive suppression of the avirulent clone was alleviated... (More)
Competitive interactions between coinfecting genotypes of the same pathogen can impose selection on virulence, but the direction of this selection depends on the mechanisms behind the interactions. Here, we investigate how host immune responses contribute to competition between clones in mixed infections of the rodent malaria parasite Plasmodium chabaudi. We studied single and mixed infections of a virulent and an avirulent clone and compared the extent of competition in immunodeficient and immunocompetent mice (nude mice and T cell-reconstituted nude mice, respectively). In immunocompetent mice, the avirulent clone suffered more from competition than did the virulent clone. The competitive suppression of the avirulent clone was alleviated in immunodeficient mice. Moreover, the relative density of the avirulent clone in mixed infections was higher in immunodeficient than in immunocompetent mice. We conclude that immune-mediated interactions contributed to competitive suppression of the avirulent clone, although other mechanisms, presumably competition for resources such as red blood cells, must also be important. Because only the avirulent clone suffered from immune-mediated competition, this mechanism should contribute to selection for increased virulence in mixed infections in this host-parasite system. As far as we are aware, this is the first direct experimental evidence of immune-mediated apparent competition in any host-parasite system. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
within-host competition., quantitative PCR, indirect effects, multiple infection
in
American Naturalist
volume
168
issue
1
pages
41 - 53
publisher
University of Chicago Press
external identifiers
  • wos:000239040800004
  • scopus:33746221355
ISSN
0003-0147
language
English
LU publication?
no
id
5baebe74-5187-4634-a204-a1a012015bc8 (old id 159739)
alternative location
http://www.journals.uchicago.edu/doi/pdf/10.1086/505160
date added to LUP
2008-11-06 13:24:35
date last changed
2019-04-23 01:53:17
@article{5baebe74-5187-4634-a204-a1a012015bc8,
  abstract     = {Competitive interactions between coinfecting genotypes of the same pathogen can impose selection on virulence, but the direction of this selection depends on the mechanisms behind the interactions. Here, we investigate how host immune responses contribute to competition between clones in mixed infections of the rodent malaria parasite Plasmodium chabaudi. We studied single and mixed infections of a virulent and an avirulent clone and compared the extent of competition in immunodeficient and immunocompetent mice (nude mice and T cell-reconstituted nude mice, respectively). In immunocompetent mice, the avirulent clone suffered more from competition than did the virulent clone. The competitive suppression of the avirulent clone was alleviated in immunodeficient mice. Moreover, the relative density of the avirulent clone in mixed infections was higher in immunodeficient than in immunocompetent mice. We conclude that immune-mediated interactions contributed to competitive suppression of the avirulent clone, although other mechanisms, presumably competition for resources such as red blood cells, must also be important. Because only the avirulent clone suffered from immune-mediated competition, this mechanism should contribute to selection for increased virulence in mixed infections in this host-parasite system. As far as we are aware, this is the first direct experimental evidence of immune-mediated apparent competition in any host-parasite system.},
  author       = {Råberg, Lars and de Roode, J C and Bell, A S and Stamou, P and Gray, D and Read, A F},
  issn         = {0003-0147},
  keyword      = {within-host competition.,quantitative PCR,indirect effects,multiple infection},
  language     = {eng},
  number       = {1},
  pages        = {41--53},
  publisher    = {University of Chicago Press},
  series       = {American Naturalist},
  title        = {The role of immune-mediated apparent competition in genetically diverse malaria infections},
  volume       = {168},
  year         = {2006},
}