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Lambrechts, Louis; Halbert, Jean; Durand, Patrick; Gouagna, Louis‐Clément; Koella, Jacob C.

doi:10.1186/1475-2875-4-3

Cited by 148 publications

(63 citation statements)

References 35 publications

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“…In Schistosoma mansoni, high virulence was associated with high replication rates in definitive hosts but not intermediate hosts, although replication rates did vary across substrains in both intermediate and definitive hosts (Davies et al 2001). Measurements of parasite virulence in vivo can be confounded with genotypic interactions between host and parasite influencing observed virulence, this has been shown most clearly in plant-pathogen systems (Salvaudon et al 2005) and also in animal models (Carius et al 2001;Lambrechts et al 2005) and may be a factor for future consideration. However, it is clear that the potential for variation in virulence exists within parasite species.…”

Section: Discussionmentioning

confidence: 99%

Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses

2008

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Parasites represent a major threat to all organisms which has led to the evolution of an array of complex and effective defence mechanisms. Common to both vertebrates and invertebrates are innate immune mechanisms that can be either constitutively expressed or induced on exposure to infection. In nature, we find that a combination of both induced and constitutive responses are employed by vertebrates, invertebrates and, to an extent, plants when they are exposed to a parasite. Here we use a simple withinhost model motivated by the insect immune system, consisting of both constitutive and induced responses, to address the question of why both types of response are maintained so ubiquitously. Generally, induced responses are thought to be advantageous because they are only used when required but are too costly to maintain constantly, while constitutive responses are advantageous because they are always ready to act. However, using a simple cost function but with no a priori assumptions about relative costs, we show that variability in parasite growth rates selects for a strategy that combines both constitutive and induced defences. Differential costs are therefore not necessary to explain the adoption of both forms of defence. Clearly, hosts are likely to be challenged by variable parasites in nature and this is sufficient to explain why it is optimal to deploy both arms of the innate immune system.

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Section: Discussionmentioning

confidence: 99%

Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses

2008

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“…Examples span a range of taxonomic groupings, including (on the host side) crustaceans, insects and nematodes, and their interaction with infecting bacteria, protozoa or parasitoids (Carius et al 2001;Decaestecker et al 2003;Schulenburg & Ewbank 2004;Lambrechts et al 2005;Dubuffet et al 2007). Plant-pathogen systems (e.g.…”

Section: Host Genotype By Pathogen Genotype Interactionsmentioning

confidence: 99%

Immunity in a variable world

Lazzaro

Little

2008

Phil. Trans. R. Soc. B

329

332

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Immune function is likely to be a critical determinant of an organism's fitness, yet most natural animal and plant populations exhibit tremendous genetic variation for immune traits. Accumulating evidence suggests that environmental heterogeneity may retard the long-term efficiency of natural selection and even maintain polymorphism, provided alternative host genotypes are favoured under different environmental conditions. 'Environment' in this context refers to abiotic factors such as ambient temperature or availability of nutrient resources, genetic diversity of pathogens or competing physiological demands on the host. These factors are generally controlled in laboratory experiments measuring immune performance, but variation in them is likely to be very important in the evolution of resistance to infection. Here, we review some of the literature emphasizing the complexity of natural selection on immunity. Our aim is to describe how environmental and genetic heterogeneities, often excluded from experimentation as 'noise', may determine the evolutionary potential of populations or the potential for interacting species to coevolve.

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“…Because these studies often focus on the total allocation of resources towards an immune response, however, they tend to under-emphasize other important aspects, such as an immune response's specificity, inducibility and timing (Harvell 1990;Schmid-Hempel & Ebert 2003;Schmid-Hempel 2005). Immune function is not a simple, static process, but rather a dynamic and complex system of interrelated mechanisms that are differentially effective against specific pathogens or pathogen types (Lambrechts et al 2005), and whose expression may vary considerably during an immune response . Thus, potential hosts may differ not only in their overall allocation to the immune system, but also in how and when that allocation is used.…”

Section: Introductionmentioning

confidence: 99%

Sex-specific variation in the emphasis, inducibility and timing of the post-mating immune response in Drosophila melanogaster

Winterhalter

Fedorka

2008

Proc. R. Soc. B.

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Ecological immunology attempts to explain variation in immune function. Much of this work makes predictions about how potential hosts should invest in overall immunity. However, this 'overall' perspective under-emphasizes other critical aspects, such as the specificity, inducibility and timing of an immune response. Here, we investigate these aspects by examining gene regulation across several immune system components in both male and female Drosophila melanogaster prior to and after mating. To elucidate potentially important temporal dynamics, we also assayed several genes over time. We found that males and females emphasized different components of their immune system, however overall investment was similar. Specifically, the sexes emphasized different gene paralogues within major gene families, and males tended to invest more in gram-negative defence. By contrast, the inducibility of the immune response was both transient (lasting approx. 24 hours) and equal between the sexes. Furthermore, mating tended to induce humoral gene upregulation, while cell-mediated genes were unaffected. Within the humoral system, gram-negative bacterial defence genes exhibited a greater inducibility than those associated with fungal or gram-positive bacterial defence. Our results suggest that variation in the effectiveness of the immune response between the sexes may be driven by differences in emphasis rather than overall investment.

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Cited by 148 publications

References 35 publications

Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses

Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses

Immunity in a variable world

Sex-specific variation in the emphasis, inducibility and timing of the post-mating immune response in Drosophila melanogaster

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