scholarly journals Immune defence, parasite evasion strategies and their relevance for ‘macroscopic phenomena’ such as virulence

2008 ◽  
Vol 364 (1513) ◽  
pp. 85-98 ◽  
Author(s):  
Paul Schmid-Hempel
Keyword(s):  
Immune Evasion ◽  
Life History Theory ◽  
Evolutionary Ecology ◽  
Parasite Clearance ◽  
Multiple Infections ◽  
Parasite Fitness ◽  
Host Parasite Interactions ◽  
Evolution Of Virulence ◽  
Host Parasite ◽  
Insight Into

The discussion of host–parasite interactions, and of parasite virulence more specifically, has so far, with a few exceptions, not focused much attention on the accumulating evidence that immune evasion by parasites is not only almost universal but also often linked to pathogenesis, i.e. the appearance of virulence. Now, the immune evasion hypothesis offers a deeper insight into the evolution of virulence than previous hypotheses. Sensitivity analysis for parasite fitness and life-history theory shows promise to generate a more general evolutionary theory of virulence by including a major element, immune evasion to prevent parasite clearance from the host. Also, the study of dose–response relationships and multiple infections should be particularly illuminating to understand the evolution of virulence. Taking into account immune evasion brings immunological processes to the core of understanding the evolution of parasite virulence and for a range of related issues such as dose, host specificity or immunopathology. The aim of this review is to highlight the mechanism underlying immune evasion and to discuss possible consequences for the evolutionary ecology analysis of host–parasite interactions.

scholarly journals Social hosts evade predation but have deadlier parasites

2021 ◽  
Author(s):  
Jason Walsman ◽  
Mary J. Janecka ◽  
David R. Clark ◽  
Rachael D. Kramp ◽  
Faith Rovenolt ◽  
...  
Keyword(s):  
Social Behaviour ◽  
Evolutionary Ecology ◽  
Group Living ◽  
Common Garden ◽  
Virulence Evolution ◽  
The Common ◽  
Trinidadian Guppy ◽  
Host Parasite ◽  
Predator Defence ◽  
Insight Into

AbstractParasites exploit hosts to replicate and transmit, but overexploitation kills both host and parasite1: parasite virulence evolves to balance these costs and benefits. Predators can in theory shift this balance by consuming hosts2–4. However, the non-consumptive effects of predators may be as important as their consumptive effects5. Here, we use an eco-coevolutionary model to show that predators select for host grouping, a common anti-predator, defensive social behaviour6. Host grouping simultaneously increases parasite transmission, thus within-host parasite competition, and therefore favours more exploitative, virulent, parasites7. When parametrized with data from the guppy-Gyrodactylus spp. system, including our experimentally demonstrated trade-off between virulence and transmission, our model accurately predicted the common garden-assayed virulence of 18 parasite lines collected from four Trinidadian guppy populations under different predation regimes. The quantitative match between theory and data lends credence to the model’s insight that the non-consumptive, social behaviour pathway is entirely responsible for the observed increase in virulence with predation pressure. Our results indicate that parasites play an important, underappreciated role in guppy evolutionary ecology. Moreover, group living is a common anti-predator defence6 and our general model accommodates host-parasite interactions across taxa: its insight into the interactions among predation, sociality, and virulence evolution may apply broadly. Our results additionally suggest that social distancing, by reducing host-host contact, can select for less virulent parasites and pathogens.

scholarly journals Interactions among bacterial strains and fluke genotypes shape virulence of co-infection

2015 ◽  
Vol 282 (1821) ◽  
pp. 20152097 ◽  
Author(s):  
Katja-Riikka Louhi ◽  
Lotta-Riina Sundberg ◽  
Jukka Jokela ◽  
Anssi Karvonen
Keyword(s):  
Evolutionary Dynamics ◽  
Parasite Species ◽  
Bacterial Strains ◽  
Parasite Fitness ◽  
Host Parasite Interactions ◽  
Host Health ◽  
Infection Focus ◽  
Host Mortality ◽  
Host Parasite ◽  
Virulent Parasite

Most studies of virulence of infection focus on pairwise host–parasite interactions. However, hosts are almost universally co-infected by several parasite strains and/or genotypes of the same or different species. While theory predicts that co-infection favours more virulent parasite genotypes through intensified competition for host resources, knowledge of the effects of genotype by genotype (G × G) interactions between unrelated parasite species on virulence of co-infection is limited. Here, we tested such a relationship by challenging rainbow trout with replicated bacterial strains and fluke genotypes both singly and in all possible pairwise combinations. We found that virulence (host mortality) was higher in co-infections compared with single infections. Importantly, we also found that the overall virulence was dependent on the genetic identity of the co-infecting partners so that the outcome of co-infection could not be predicted from the respective virulence of single infections. Our results imply that G × G interactions among co-infecting parasites may significantly affect host health, add to variance in parasite fitness and thus influence evolutionary dynamics and ecology of disease in unexpected ways.

Identification of avir-orthologous immune evasion gene family from primate malaria parasites

Parasitology ◽  
2014 ◽  
Vol 141 (5) ◽  
pp. 641-645 ◽  
Author(s):  
SURENDRA KUMAR PRAJAPATI ◽  
OM PRAKASH SINGH
Keyword(s):  
Gene Family ◽  
Immune Evasion ◽  
Experimental Approach ◽  
Antigenic Variation ◽  
Surface Proteins ◽  
Malaria Parasites ◽  
Sequence Identity ◽  
Plasmodium Cynomolgi ◽  
Evolution Of Virulence ◽  
Insight Into

SUMMARYThe immune evasion gene family of malaria parasites encodes variant surface proteins that are expressed at the surface of infected erythrocytes and help the parasite in evading the host immune response by means of antigenic variation. The identification ofPlasmodium vivax virorthologous immune evasion gene family from primate malaria parasites would provide new insight into the evolution of virulence and pathogenesis. Threevirsubfamilies viz.vir-B, vir-Dandvir-Gwere successfully PCR amplified from primate malaria parasites, cloned and sequenced. DNA sequence analysis confirmed orthologues ofvir-Dsubfamily inPlasmodium cynomolgi, Plasmodium simium, Plasmodium simiovaleandPlasmodium fieldi. The identifiedvir-Dorthologues are 1–9 distinct members of the immune evasion gene family which have 68–83% sequence identity withvir-Dand 71·2–98·5% sequence identity within the members identified from primate malaria parasites. The absence of othervirsubfamilies among primate malaria parasites reflects the limitations in the experimental approach. This study clearly identified the presence ofvir-Dlike sequences in four species ofPlasmodiuminfecting primates that would be useful in understanding the evolution of virulence in malaria parasites.

Do parasites matter? Assessing the fitness consequences of haemogregarine infection in snakes

2006 ◽  
Vol 84 (5) ◽  
pp. 668-676 ◽  
Author(s):  
G.P. Brown ◽  
C.M. Shilton ◽  
R. Shine
Keyword(s):  
Evolutionary Ecology ◽  
Natural Populations ◽  
Blood Parasites ◽  
Antipredator Behaviour ◽  
Host Fitness ◽  
Host Parasite Interactions ◽  
Fitness Consequences ◽  
Tropical Australia ◽  
Host Parasite ◽  
Striking Contrast

Although much research in evolutionary ecology is based upon the premise that high levels of parasitism impair the host's functioning, the assumed link between parasitism and fitness has been assessed for relatively few kinds of animals. At our study site in tropical Australia, keelback snakes ( Tropidonophis mairii (Gray, 1841), Colubridae) are heavily infected with haemogregarine blood parasites: 90% of snakes that we tested carried the parasite, with the proportion of erythrocytes containing haemogregarines averaging 15% and ranging up to a remarkable 64%. Prevalence increased with snake body size, but intensity decreased with age. Unlike lizards studied previously, the snakes did not respond to haemogregarine infection by releasing immature erythrocytes into the circulation. In striking contrast to results from a recent study on a sympatric snake species, we did not find any empirical links between parasite numbers and several measures of host fitness (body condition, growth rate, feeding rate, antipredator behaviour, locomotor performance, reproductive status, reproductive output, and recapture rate). The association between this parasite and its host thus appears to be surprisingly benign, suggesting that host–parasite interactions sometimes may have only trivial consequences for host fitness in natural populations. Plausibly, host–parasite coevolution weakens or eliminates fitness costs of parasitism.

The role of the environment in the evolutionary ecology of host parasite interactions

2008 ◽  
Vol 8 (3) ◽  
pp. 302-305 ◽  
Author(s):  
Pedro F. Vale ◽  
Lucie Salvaudon ◽  
Oliver Kaltz ◽  
Simon Fellous
Keyword(s):  
Evolutionary Ecology ◽  
Host Parasite Interactions ◽  
Host Parasite

scholarly journals Coevolution of virulence and immunosuppression in multiple infections

2017 ◽  
Author(s):  
Tsukushi Kamiya ◽  
Nicole Mideo ◽  
Samuel Alizon
Keyword(s):  
Evolutionary Biology ◽  
Adaptive Dynamics ◽  
Multiple Infections ◽  
Research Attention ◽  
Background Mortality ◽  
Evolution Of Virulence ◽  
Duration Of Infection ◽  
Peer Community ◽  
The Cost ◽  
Host Parasite

AbstractThis preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100043). Many components of host-parasite interactions have been shown to affect the way virulence (i.e., parasite-induced harm to the host) evolves. However, coevolution of multiple parasite traits is often neglected. We explore how an immunosuppressive mechanism of parasites affects and coevolves with virulence through multiple infections. Applying the adaptive dynamics framework to epidemiological models with coinfection, we show that immunosuppression is a double-edged-sword for the evolution of virulence. On one hand, it amplifies the adaptive benefit of virulence by increasing the abundance of coinfections through epidemiological feedbacks. On the other hand, immunosuppression hinders host recovery, prolonging the duration of infection and elevating the cost of killing the host. The balance between the cost and benefit of immunosuppression varies across different background mortality rates of hosts. In addition, we find that immunosuppression evolution is influenced considerably by the precise trade-off shape determining the effect of immunosuppression on host recovery and susceptibility to further infection. These results demonstrate that the evolution of virulence is shaped by immunosuppression while highlighting that the evolution of immune evasion mechanisms deserves further research attention.

scholarly journals Molecular Evidence that Lysiphlebia japonica Regulates the Development and Physiological Metabolism of Aphis gossypii

2020 ◽  
Vol 21 (13) ◽  
pp. 4610
Author(s):  
Xueke Gao ◽  
Hui Xue ◽  
Junyu Luo ◽  
Jichao Ji ◽  
Lijuan Zhang ◽  
...  
Keyword(s):  
Aphis Gossypii ◽  
The Body ◽  
Molecular Evidence ◽  
Functional Categories ◽  
Host Parasite Interactions ◽  
Physiological Metabolism ◽  
Major Pest ◽  
Host Parasite ◽  
The Relationship ◽  
Insight Into

Lysiphlebia japonica Ashmead (Hymenoptera, Braconidae) is an endophagous parasitoid and Aphis gossypii Glover (Hemiptera, Aphididae) is a major pest in cotton. The relationship between insect host-parasitoids and their hosts involves complex physiological, biochemical and genetic interactions. This study examines changes in the development and physiological metabolism of A. gossypii regulated by L. japonica. Our results demonstrated that both the body length and width increased compared to non-parasitized aphids. We detected significantly increases in the developmental period as well as severe reproductive castration following parasitization by L. japonica. We then used proteomics to characterize these biological changes, and when combined with transcriptomes, this analysis demonstrated that the differential expression of mRNA (up or downregulation) captured a maximum of 48.7% of the variations of protein expression. We assigned these proteins to functional categories that included immunity, energy metabolism and transport, lipid metabolism, and reproduction. We then verified the contents of glycogen and 6-phosphate glucose, which demonstrated that these important energy sources were significantly altered following parasitization. These results uncover the effects on A. gossypii following parasitization by L. japonica, additional insight into the mechanisms behind insect-insect parasitism, and a better understanding of host-parasite interactions.

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