The implications of immunopathology for parasite evolution

By definition, parasites harm their hosts, but in many infections much of the pathology is driven by the host immune response rather than through direct damage inflicted by parasites. While these immunopathological effects are often well studied and understood mechanistically in individual disease interactions, there remains relatively little understanding of their broader impact on the evolution of parasites and their hosts. Here, we theoretically investigate the implications of immunopathology, broadly defined as additional mortality associated with the host's immune response, on parasite evolution. In particular, we examine how immunopathology acting on different epidemiological traits (namely transmission, virulence and recovery) affects the evolution of disease severity. When immunopathology is costly to parasites, such that it reduces their fitness, for example by decreasing transmission, there is always selection for increased disease severity. However, we highlight a number of host–parasite interactions where the parasite may benefit from immunopathology, and highlight scenarios that may lead to the evolution of slower growing parasites and potentially reduced disease severity. Importantly, we find that conclusions on disease severity are highly dependent on how severity is measured. Finally, we discuss the effect of treatments used to combat disease symptoms caused by immunopathology.

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The possible role of the frontal and sub-parietal gland systems of the pentastomidReighardia sternae(Diesing, 1864) in the evasion of the host immune response

Parasitology ◽

10.1017/s0031182000048587 ◽

1979 ◽

Vol 78 (1) ◽

pp. 53-66 ◽

Cited By ~ 19

Author(s):

J. Riley ◽

J. L. James ◽

A. A. Banaja

Keyword(s):

Immune Response ◽

Alternative Explanation ◽

Surface Membrane ◽

Membrane System ◽

Host Immune Response ◽

Entire Surface ◽

Strong Immune Response ◽

Concomitant Immunity ◽

Host Parasite

SUMMARYThe frontal and sub-parietal glands of the pentastomidReighardia sternaeelaborate lamellate secretion which is poured on to the cuticle. The entire surface of the cuticle, including the mouth, hook pits and reproductive apertures, is coated with secretion. Electron microscope studies indicate that the glands are continuously active, which implies a turnover of surface membranes. The postulated function of these membranes is to protect certain vital areas of the host–parasite interface, notably the pores of ion-transporting cells, from the host immune response. The available evidence suggests that pentastomids do evoke a strong immune response but since most are long-lived they must circumvent it. We believe the surface membrane system to be instrumental in this. Studies on another pentastomid,Porocephalus crotaliin rats have shown that an immune response stimulated by a primary infection will kill subsequent infections and that the surface membranes are strongly immunogenic. Obvious parallels between this situation and that of schistosome infections in mammals are discussed. An alternative explanation of concomitant immunity is proposed.

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Hidden paths to endless forms most wonderful: Parasite-blind diversification of host quality

10.1101/2020.12.23.424158 ◽

2020 ◽

Author(s):

Lisa Freund ◽

Marie Vasse ◽

Gregory J. Velicer

Keyword(s):

Growth Suppression ◽

Host Population ◽

Host Quality ◽

Evolution Theory ◽

Evolutionary Diversification ◽

Adaptive Landscapes ◽

Host Parasite Interactions ◽

Parasite Evolution ◽

Host Parasite ◽

Selective Environment

Evolutionary diversification can occur in allopatry or sympatry, can be unselected or driven by selection, and can be phenotypically manifested immediately or remain phenotypically latent until later manifestation in a newly encountered environment. Diversification of host-parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host-parasite interaction phenotypes to diversify latently during parasite-blind evolution is rarely considered. Here we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of latent host quality - the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host-quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent hostquality evolution and diversification. These outcomes show that adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and that major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution (LPE) should inform host-parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.

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2210. Nasopharyngeal Detection of Streptococcus pneumoniae and Clinical Disease Severity in Children with Community-Acquired Pneumonia (CAP)

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1888 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S753-S753

Author(s):

Ki Wook Yun ◽

Alexis Juergensen ◽

Rebecca Wallihan ◽

Ankita P Desai ◽

Sherman J Alter ◽

...

Keyword(s):

Immune Response ◽

Streptococcus Pneumoniae ◽

Disease Severity ◽

Host Immune Response ◽

Advisory Board ◽

Diagnostic Methods ◽

Clinical Disease ◽

Healthy Children ◽

Pneumococcal Carriage ◽

Research Grant

Abstract Background Streptococcus pneumoniae is the most common pyogenic bacteria associated with CAP in children, but the proportion of cases might be underestimated because of the low sensitivity of current standard diagnostic methods. Nasopharyngeal (NP) carriage of pneumococcus commonly precedes the development of pneumococcal pneumonia, and facilitates pneumococcus interactions with other respiratory pathogens and the host immune response. This study investigated the relationship between pneumococcal carriage and the severity of CAP in children. Methods We conducted a prospective, multicenter, observational study for CAP among previously healthy children aged 2 months through 18 years in six children’s hospitals in Ohio. Blood, pleural fluid, and NP swabs were collected for pathogen detection by culture and/or polymerase chain reaction (PCR). S. pneumoniae was quantified in NP swabs by real-time PCR. Patient management followed the standard of care in each study site. Results Among 441 children with radiologically confirmed CAP, 156 (35.4%) had no bacterial or viral pathogens identified as etiologic agents. NP pneumococcal carriage rate in this group was 34.6%. Children with CAP and pneumococcal carriage (53/156) were younger (5.9 vs. 9.6 years, P < 0.001) than those with no carriage (103/156). Median neutrophil counts and median procalcitonin concentrations were significantly higher in the pneumococcal carriage group (12,030 vs. 8,370 cells/mm3 and 1.0 vs. 0.5 mg/dl, respectively; P < 0.05 for both) than in the non-carriage group. Children with documented pneumococcal carriage received respiratory support more frequently (50.0% vs. 28.2%, p = 0.012) and had a longer duration of hospitalization (3.5 ± 3.8 vs. 2.1 ± 2.0 days, P = 0.026) than those without pneumococcal carriage. Age was not associated with any of the variables used to assess clinical disease severity. Conclusion Pneumococcal carriage was associated with higher inflammatory markers and greater clinical disease severity in children with CAP in whom no pathogens were identified by standard diagnostics. This suggests that NP carriage of pneumococcus in children with CAP may modulate the host immune response and possibly influence clinical disease severity. Disclosures Octavio Ramilo, MD, Bill & Melinda Gates Foundation: Research Grant; Janssen: Research Grant; Merck: Advisory Board; NIH: Research Grant; Ohio Children’s Hospital Association (OCHA): Research Grant; Pfizer: Advisory Board, Consultant, Lectures; Sanofi/Medimmune: Advisory Board.

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Estimating effective population size for a cestode parasite infecting three-spined sticklebacks

Parasitology ◽

10.1017/s0031182018002226 ◽

2019 ◽

Vol 146 (07) ◽

pp. 883-896

Author(s):

Hannah M. Strobel ◽

Sara J. Hays ◽

Kristine N. Moody ◽

Michael J. Blum ◽

David C. Heins

Keyword(s):

Population Size ◽

Effective Population Size ◽

Gasterosteus Aculeatus ◽

Microsatellite Data ◽

Effective Population ◽

Cestode Parasite ◽

Schistocephalus Solidus ◽

Host Parasite Interactions ◽

Parasite Evolution ◽

Host Parasite

AbstractRemarkably few attempts have been made to estimate contemporary effective population size (Ne) for parasitic species, despite the valuable perspectives it can offer on the tempo and pace of parasite evolution as well as coevolutionary dynamics of host–parasite interactions. In this study, we utilized multi-locus microsatellite data to derive single-sample and temporal estimates of contemporaryNefor a cestode parasite (Schistocephalus solidus) as well as three-spined stickleback hosts (Gasterosteus aculeatus) in lakes across Alaska. Consistent with prior studies, both approaches recovered small and highly variable estimates of parasite and hostNe. We also found that estimates of hostNeand parasiteNewere sensitive to assumptions about population genetic structure and connectivity. And, while prior work on the stickleback–cestode system indicates that physiographic factors external to stickleback hosts largely govern genetic variation inS. solidus, our findings indicate that stickleback host attributes and factors internal to the host – namely body length, genetic diversity and infection – shape contemporaryNeof cestode parasites.

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Three tick species parasitizing a rock python in Sri Lanka

TAPROBANICA The Journal of Asian Biodiversity ◽

10.47605/tapro.v4i1.67 ◽

2012 ◽

Vol 4 (1) ◽

pp. 54-56

Author(s):

T.S.P. Fernando ◽

H.K.A.V.A. Kulasena Fernando

Keyword(s):

Immune Response ◽

Population Dynamics ◽

Sri Lanka ◽

Food Webs ◽

Tick Species ◽

Ecosystem Health ◽

Driving Forces ◽

Host Parasite Interactions ◽

In The Wild ◽

Host Parasite

Parasitism is a relationship where one of the parties (the parasite) either harms its host or lives at the expense of it. Host parasite interactions are important driving forces in population dynamics and even extinction. These interactions are also indicators of ecosystem health and they are important in stabilizing food webs. A parasite may cause mechanical injury, stimulate a damaging inflammatory or immune response, or simply rob the host of nutrition. However in the wild most parasites must live in harmony with their hosts. If the parasites kill the host, they themselves would ultimately die without shelter and nutrition. Reptiles become hosts to a number of parasitic organisms ranging from protozoans to arthropods. Among these, ticks (hard and soft) are the most common arthropod group that parasitizes reptiles.

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Understanding the Pathophysiology of Exosomes in Schistosomiasis: A New Direction for Disease Control and Prevention

Frontiers in Immunology ◽

10.3389/fimmu.2021.634138 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yue Yuan ◽

Jianping Zhao ◽

Min Chen ◽

Huifang Liang ◽

Xin Long ◽

...

Keyword(s):

Immune Response ◽

South America ◽

Disease Control ◽

Intercellular Communication ◽

Genetic Material ◽

Parasitic Disease ◽

Internal Organs ◽

Host Parasite Interactions ◽

Control And Prevention ◽

Host Parasite

Schistosomiasis is a parasitic disease endemic to freshwater areas of Southeast Asia, Africa, and South America that is capable of causing serious damage to the internal organs. Recent studies have linked exosomes to the progression of schistosomiasis. These structures are important mediators for intercellular communication, assist cells to exchange proteins, lipids, and genetic material and have been shown to play critical roles during host–parasite interactions. This review aims to discuss the pathophysiology of exosomes in schistosomiasis and their roles in regulating the host immune response. Understanding how exosomes are involved in the pathogenesis of schistosomiasis may provide new perspectives in diagnosing and treating this neglected disease.

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Four QTL underlie resistance to a microsporidian parasite that may drive genome evolution in its Daphnia host

10.1101/847194 ◽

2019 ◽

Author(s):

Devon Keller ◽

Devin Kirk ◽

Pepijn Luijckx

Keyword(s):

Immune Response ◽

Daphnia Magna ◽

Genetic Architecture ◽

Pivotal Role ◽

Parasite Resistance ◽

Microsporidian Parasite ◽

Ecological Processes ◽

Host Parasite Interactions ◽

Host Parasite ◽

General Immune Response

AbstractDespite its pivotal role in evolutionary and ecological processes the genetic architecture underlying host-parasite interactions remains understudied. Here we use a quantitative trait loci approach to identify regions in the Daphnia magna genome that provide resistance against its microsporidium parasite Ordospora colligata. The probability that Daphnia became infected was affected by a single locus and an interaction between two additional loci. A fourth locus influenced the number of spores that grew within the host. Comparing our findings to previously published genetic work on Daphnia magna revealed that two of these loci may be the same as detected for another microsporidium parasite, suggesting a general immune response to this group of pathogens. More importantly, this comparison revealed that two regions previously identified to be under selection coincided with parasite resistance loci, highlighting the pivotal role parasites may play in shaping the host genome.

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Triggering and modulation of the host-parasite interplay byEchinococcus multilocularis: a review

Parasitology ◽

10.1017/s0031182009991533 ◽

2009 ◽

Vol 137 (3) ◽

pp. 557-568 ◽

Cited By ~ 21

Author(s):

N. MEJRI ◽

A. HEMPHILL ◽

B. GOTTSTEIN

Keyword(s):

Immune Response ◽

Life Cycle ◽

Intermediate Host ◽

Host Immune Response ◽

Present Review ◽

Host Responses ◽

Surface Molecules ◽

Metabolic Products ◽

Host Parasite

SUMMARYAs more facts emerge regarding the ways in whichE. multilocularis-derived molecules trigger the host immune response and modulate the host-parasite interplay, it becomes possible to envisage how the parasite can survive and proliferate in its intermediate host, while in other hosts it dies out. Through effects on cells of both the innate and adaptive arms of the immune response,E. multiloculariscan orchestrate a range of outcomes that are beneficial not only to the parasite, in terms of facilitating its intrahepatic proliferation and maturation, and thus life cycle over all, but also to its intermediate host, in limiting pathology. The present review deals with the role of metacestode surface molecules as well as excretory/secretory (E/S) metabolic products of the parasite in the modulation of the host responses such as to optimize its own survival.

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Roles of three putative salmon louse (Lepeophtheirus salmonis) prostaglandin E2 synthases in physiology and host–parasite interactions

Parasites & Vectors ◽

10.1186/s13071-021-04690-w ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Sussie Dalvin ◽

Christiane Eichner ◽

Michael Dondrup ◽

Aina-Cathrine Øvergård

Keyword(s):

Immune Response ◽

Transcript Level ◽

Prostaglandin E ◽

Lepeophtheirus Salmonis ◽

Salmon Louse ◽

Host Parasite Interactions ◽

Expression Studies ◽

Host Parasite ◽

And Oxidative Stress ◽

Microsomal Glutathione

Abstract Background The salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish. Atlantic salmon (Salmo salar) exhibit only a limited and ineffective immune response when infested with this parasite. Prostaglandins (PGs) have many biological functions in both invertebrates and vertebrates, one of which is the regulation of immune responses. This has led to the suggestion that prostaglandin E2 (PGE2) is important in the salmon louse host–parasite interaction, although studies of a salmon louse prostaglandin E2 synthase (PGES) 2 gene have not enabled conformation of this hypothesis. The aim of the present study was, therefore, to characterize two additional PGES-like genes. Methods Lepeophtheirus salmonis microsomal glutathione S-transferase 1 like (LsMGST1L) and LsPGES3L were investigated by sequencing, phylogenetics, transcript localization and expression studies. Moreover, the function of these putative PGES genes in addition to the previously identified LsPGES2 gene was analyzed in double stranded (ds) RNA-mediated knockdown (KD) salmon louse. Results Analysis of the three putative LsPGES genes showed a rather constitutive transcript level throughout development from nauplius to the adult stages, and in a range of tissues, with the highest levels in the ovaries or gut. DsRNA-mediated KD of these transcripts did not produce any characteristic changes in phenotype, and KD animals displayed a normal reproductive output. The ability of the parasite to infect or modulate the immune response of the host fish was also not affected by KD. Conclusions Salmon louse prostaglandins may play endogenous roles in the management of reproduction and oxidative stress and may be a product of salmon louse blood digestions. Graphic Abstract

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Hidden paths to endless forms most wonderful: parasite-blind diversification of host quality

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.0456 ◽

2021 ◽

Vol 288 (1949) ◽

Author(s):

Lisa Freund ◽

Marie Vasse ◽

Gregory J. Velicer

Keyword(s):

Host Population ◽

Host Quality ◽

Evolution Theory ◽

Evolutionary Diversification ◽

Adaptive Landscapes ◽

Host Parasite Interactions ◽

Parasite Evolution ◽

Host Evolution ◽

Host Parasite ◽

Selective Environment

Evolutionary diversification can occur in allopatry or sympatry, can be driven by selection or unselected, and can be phenotypically manifested immediately or remain latent until manifested in a newly encountered environment. Diversification of host–parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host–parasite interaction phenotypes to diversify latently during parasite-blind host evolution is rarely considered. Here, we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of host quality—the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent host-quality evolution and diversification. These outcomes show that (i) adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and (ii) major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution should inform host–parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.

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