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Vanalli C, Mari L, Casagrandi R, Boag B, Gatto M, Cattadori IM. Modeling the contribution of antibody attack rates to single and dual helminth infections in a natural system. Math Biosci 2023; 360:109010. [PMID: 37088125 DOI: 10.1016/j.mbs.2023.109010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/25/2023]
Abstract
Within-host models of infection can provide important insights into the processes that affect parasite spread and persistence in host populations. However, modeling can be limited by the availability of empirical data, a problem commonly encountered in natural systems. Here, we used six years of immune-infection observations of two gastrointestinal helminths (Trichostrongylus retortaeformis and Graphidium strigosum) from a population of European rabbits (Oryctolagus cuniculus) to develop an age-dependent, mathematical model that explicitly included species-specific and cross-reacting antibody (IgA and IgG) responses to each helminth in hosts with single or dual infections. Different models of single infection were formally compared to test alternative mechanisms of parasite regulation. The two models that best described single infections of each helminth species were then coupled through antibody cross-immunity to examine how the presence of one species could alter the host immune response to, and the within-host dynamics of, the other species. For both single infections, model selection suggested that either IgA or IgG responses could equally explain the observed parasite intensities by host age. However, the antibody attack rate and affinity level changed between the two helminths, it was stronger against T. retortaeformis than against G. strigosum and caused contrasting age-intensity profiles. When the two helminths coinfect the same host, we found variation of the species-specific antibody response to both species together with an asymmetric cross-immune response driven by IgG. Lower attack rate and affinity of antibodies in dual than single infections contributed to the significant increase of both helminth intensities. By combining mathematical modeling with immuno-infection data, our work provides a tractable model framework for disentangling some of the complexities generated by host-parasite and parasite-parasite interactions in natural systems.
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Affiliation(s)
- Chiara Vanalli
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, 16802 PA, USA.
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Brian Boag
- The James Hutton Institute, DD2 5DA Invergowrie, UK
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Isabella M Cattadori
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, 16802 PA, USA
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2
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Dagostin F, Vanalli C, Boag B, Casagrandi R, Gatto M, Mari L, Cattadori IM. The enemy of my enemy is my friend: Immune-mediated facilitation contributes to fitness of co-infecting helminths. J Anim Ecol 2023; 92:477-491. [PMID: 36478135 DOI: 10.1111/1365-2656.13863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
The conceptual understanding of immune-mediated interactions between parasites is rooted in the theory of community ecology. One of the limitations of this approach is that most of the theory and empirical evidence has focused on resource or immune-mediated competition between parasites and yet there is ample evidence of positive interactions that could be generated by immune-mediated facilitation. We developed an immuno-epidemiological model and applied it to long-term data of two gastrointestinal helminths in two rabbit populations to investigate, through model testing, how immune-mediated mechanisms of parasite regulation could explain the higher intensities of both helminths in rabbits with dual than single infections. The model framework was selected and calibrated on rabbit population A and then validated on the nearby rabbit population B to confirm the consistency of the findings and the generality of the mechanisms. Simulations suggested that the higher intensities in rabbits with dual infections could be explained by a weakened or low species-specific IgA response and an asymmetric IgA cross-reaction. Simulations also indicated that rabbits with dual infections shed more free-living stages that survived for longer in the environment, implying greater transmission than stages from hosts with single infections. Temperature and humidity selectively affected the free-living stages of the two helminths. These patterns were comparable in the two rabbit populations and support the hypothesis that immune-mediated facilitation can contribute to greater parasite fitness and local persistence.
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Affiliation(s)
- Francesca Dagostin
- Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy.,Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Chiara Vanalli
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Brian Boag
- The James Hutton Institute, Invergowrie, UK
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Isabella M Cattadori
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
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3
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Nguyen NTD, Pathak AK, Cattadori IM. Gastrointestinal helminths increase Bordetella bronchiseptica shedding and host variation in supershedding. eLife 2022; 11:70347. [DOI: 10.7554/elife.70347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/11/2022] [Indexed: 11/09/2022] Open
Abstract
Co-infected hosts, individuals that carry more than one infectious agent at any one time, have been suggested to facilitate pathogen transmission, including the emergence of supershedding events. However, how the host immune response mediates the interactions between co-infecting pathogens and how these affect the dynamics of shedding remains largely unclear. We used laboratory experiments and a modeling approach to examine temporal changes in the shedding of the respiratory bacterium Bordetella bronchiseptica in rabbits with one or two gastrointestinal helminth species. Experimental data showed that rabbits co-infected with one or both helminths shed significantly more B. bronchiseptica, by direct contact with an agar petri dish, than rabbits with bacteria alone. Co-infected hosts generated supershedding events of higher intensity and more frequently than hosts with no helminths. To explain this variation in shedding an infection-immune model was developed and fitted to rabbits of each group. Simulations suggested that differences in the magnitude and duration of shedding could be explained by the effect of the two helminths on the relative contribution of neutrophils and specific IgA and IgG to B. bronchiseptica neutralization in the respiratory tract. However, the interactions between infection and immune response at the scale of analysis that we used could not capture the rapid variation in the intensity of shedding of every rabbit. We suggest that fast and local changes at the level of respiratory tissue probably played a more important role. This study indicates that co-infected hosts are important source of variation in shedding, and provides a quantitative explanation into the role of helminths to the dynamics of respiratory bacterial infections.
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Affiliation(s)
- Nhat TD Nguyen
- Center for Infectious Disease Dynamics, The Pennsylvania State University
- Department of Biology, The Pennsylvania State University
| | - Ashutosh K Pathak
- Center for Infectious Disease Dynamics, The Pennsylvania State University
- Department of Biology, The Pennsylvania State University
- Department of Infectious Diseases, University of Georgia
| | - Isabella M Cattadori
- Center for Infectious Disease Dynamics, The Pennsylvania State University
- Department of Biology, The Pennsylvania State University
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4
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Sabey KA, Song SJ, Jolles A, Knight R, Ezenwa VO. Coinfection and infection duration shape how pathogens affect the African buffalo gut microbiota. THE ISME JOURNAL 2021; 15:1359-1371. [PMID: 33328653 PMCID: PMC8115229 DOI: 10.1038/s41396-020-00855-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/10/2020] [Accepted: 11/20/2020] [Indexed: 01/07/2023]
Abstract
Changes in the gut microbiota during pathogen infection are often predicted to influence disease outcomes. However, studies exploring whether pathogens induce microbiota shifts have yielded inconsistent results. This suggests that variation in infection, rather than the presence of infection alone, might shape pathogen-microbiota relationships. For example, most hosts are coinfected with multiple pathogens simultaneously, and hosts vary in how long they are infected, which may amplify or diminish microbial shifts expected in response to a focal pathogen. We used a longitudinal anthelmintic treatment study of free-ranging African buffalo (Syncerus caffer) to examine whether (i) coinfection with bovine tuberculosis (Mycobacterium bovis, TB) and gastrointestinal nematodes, and (ii) the duration of TB infection, modified effects of single pathogens on the gut microbiota. By accounting for the interaction between TB and nematodes, we found that coinfection affected changes in microbial abundance associated with single infections. Furthermore, the duration of TB infection predicted more microbiota variation than the presence of TB. Importantly, coinfection and infection duration had nearly as much influence on microbial patterns as demographic and environmental factors commonly examined in microbiota research. These findings demonstrate that acknowledging infection heterogeneities may be crucial to understanding relationships between pathogens and the gut microbiota.
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Affiliation(s)
- Kate A Sabey
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Se Jin Song
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Center for Microbiome Innovation, University of California San Diego, La Jolla, CA, USA
| | - Anna Jolles
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR, USA
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Rob Knight
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Center for Microbiome Innovation, University of California San Diego, La Jolla, CA, USA
- Department of Computer Science and Engineering, University of California San Diego, La Jolla, CA, USA
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Vanessa O Ezenwa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
- Odum School of Ecology, University of Georgia, Athens, GA, USA.
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5
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Vanalli C, Mari L, Righetto L, Casagrandi R, Gatto M, Cattadori IM. Within-host mechanisms of immune regulation explain the contrasting dynamics of two helminth species in both single and dual infections. PLoS Comput Biol 2020; 16:e1008438. [PMID: 33226981 PMCID: PMC7721179 DOI: 10.1371/journal.pcbi.1008438] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 12/07/2020] [Accepted: 10/12/2020] [Indexed: 11/18/2022] Open
Abstract
Variation in the intensity and duration of infections is often driven by variation in the network and strength of host immune responses. While many of the immune mechanisms and components are known for parasitic helminths, how these relationships change from single to multiple infections and impact helminth dynamics remains largely unclear. Here, we used laboratory data from a rabbit-helminth system and developed a within-host model of infection to investigate different scenarios of immune regulation in rabbits infected with one or two helminth species. Model selection suggests that the immunological pathways activated against Trichostrongylus retortaeformis and Graphidium strigosum are similar. However, differences in the strength of these immune signals lead to the contrasting dynamics of infections, where the first parasite is rapidly cleared and the latter persists with high intensities. In addition to the reactions identified in single infections, rabbits with both helminths also activate new pathways that asymmetrically affect the dynamics of the two species. These new signals alter the intensities but not the general trend of the infections. The type of interactions described can be expected in many other host-helminth systems. Our immune framework is flexible enough to capture different mechanisms and their complexity, and provides essential insights to the understanding of multi-helminth infections.
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Affiliation(s)
- Chiara Vanalli
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Lorenzo Righetto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Isabella M. Cattadori
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
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6
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Cattadori IM, Pathak AK, Ferrari MJ. External disturbances impact helminth-host interactions by affecting dynamics of infection, parasite traits, and host immune responses. Ecol Evol 2019; 9:13495-13505. [PMID: 31871660 PMCID: PMC6912924 DOI: 10.1002/ece3.5805] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 10/06/2019] [Accepted: 10/11/2019] [Indexed: 01/10/2023] Open
Abstract
External perturbations, such as multispecies infections or anthelmintic treatments, can alter host-parasite interactions with consequences on the dynamics of infection. While the overall profile of infection might appear fundamentally conserved at the host population level, perturbations can disproportionately affect components of parasite demography or host responses, and ultimately impact parasite fitness and long-term persistence.We took an immuno-epidemiological approach to this reasoning and examined a rabbit-helminth system where animals were trickle-dosed with either one or two helminth species, treated halfway through the experiment with an anthelmintic and reinfected one month later following the same initial regime. Parasite traits (body length and fecundity) and host immune responses (cytokines, transcription factors, antibodies) were quantified at fixed time points and compared before and after drug treatment, and between single and dual infections.Findings indicated a resistant host phenotype to Trichostrongylus retortaeformis where abundance, body length, and fecundity were regulated by a protective immune response. In contrast, Graphidium strigosum accumulated in the host and, while it stimulated a clear immune reaction, many genes were downregulated both following reinfection and in dual infection, suggestive of a low host resistance.External perturbations affected parasite fecundity, including body length and number of eggs in utero, more significantly than abundance; however, there was no consistency in the parasite-immune relationships.Disentangling the processes affecting parasite life history, and how they relate to host responses, can provide a better understanding of how external disturbances impact disease severity and transmission, and how parasites strategies adjust to secure persistence at the host and the population level.
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Affiliation(s)
- Isabella M. Cattadori
- Center for Infectious Disease DynamicsThe Pennsylvania State UniversityUniversity ParkPAUSA
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - Ashutosh K. Pathak
- Department of Infectious DiseasesCollege of Veterinary MedicineThe University of GeorgiaAthensGAUSA
| | - Matthew J. Ferrari
- Center for Infectious Disease DynamicsThe Pennsylvania State UniversityUniversity ParkPAUSA
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPAUSA
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7
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Lello J, McClure SJ, Tyrrell K, Viney ME. Predicting the effects of parasite co-infection across species boundaries. Proc Biol Sci 2019. [PMID: 29540516 PMCID: PMC5879626 DOI: 10.1098/rspb.2017.2610] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
It is normal for hosts to be co-infected by parasites. Interactions among co-infecting species can have profound consequences, including changing parasite transmission dynamics, altering disease severity and confounding attempts at parasite control. Despite the importance of co-infection, there is currently no way to predict how different parasite species may interact with one another, nor the consequences of those interactions. Here, we demonstrate a method that enables such prediction by identifying two nematode parasite groups based on taxonomy and characteristics of the parasitological niche. From an understanding of the interactions between the two defined groups in one host system (wild rabbits), we predict how two different nematode species, from the same defined groups, will interact in co-infections in a different host system (sheep), and then we test this experimentally. We show that, as predicted, in co-infections, the blood-feeding nematode Haemonchus contortus suppresses aspects of the sheep immune response, thereby facilitating the establishment and/or survival of the nematode Trichostrongylus colubriformis; and that the T. colubriformis-induced immune response negatively affects H. contortus This work is, to our knowledge, the first to use empirical data from one host system to successfully predict the specific outcome of a different co-infection in a second host species. The study therefore takes the first step in defining a practical framework for predicting interspecific parasite interactions in other animal systems.
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Affiliation(s)
- Joanne Lello
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK .,Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, S. Michele all'Adige, Trentino 38010, Italy.,Division of Animal, Food and Health Sciences, CSIRO, Armidale, New South Wales 2350, Australia
| | - Susan J McClure
- Division of Animal, Food and Health Sciences, CSIRO, Armidale, New South Wales 2350, Australia
| | - Kerri Tyrrell
- Division of Animal, Food and Health Sciences, CSIRO, Armidale, New South Wales 2350, Australia
| | - Mark E Viney
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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8
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Hernandez AD, Boag B, Neilson R, Forrester NL. Variable changes in nematode infection prevalence and intensity after Rabbit Haemorrhagic Disease Virus emerged in wild rabbits in Scotland and New Zealand. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2018; 7:187-195. [PMID: 29892555 PMCID: PMC5993101 DOI: 10.1016/j.ijppaw.2018.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/14/2018] [Accepted: 05/16/2018] [Indexed: 11/15/2022]
Abstract
The myxoma virus (a microparasite) reduced wild rabbit numbers worldwide when introduced in the 1950s, and is known to interact with co-infecting helminths (macroparasites) causing both increases and decreases in macroparasite population size. In the 1990s Rabbit Haemorrhagic Disease Virus (RHDV) infected rabbits and also significantly reduced rabbit numbers in several countries. However, not much is known about RHDV interactions with macroparasites. In this study, we compare prevalence and intensity of infection for three gastrointestinal nematode species (Trichostrongylus retortaeformis, Graphidium strigosum and Passalurus ambiguus) before and after RHDV spread across host populations in Scotland and New Zealand. During one common season, autumn, prevalence of T. retortaeformis was higher after RHDV spread in both locations, whereas it was lower for G. strigosum and P. ambiguus after RHDV arrived in New Zealand, but higher in Scotland. Meanwhile, intensity of infection for all species decreased after RHDV arrived in New Zealand, but increased in Scotland. The impact of RHDV on worm infections was generally similar across seasons in Scotland, and also similarities in seasonality between locations suggested effects on infection patterns in one season are likely similar year-round. The variable response by macroparasites to the arrival of a microparasite into Scottish and New Zealand rabbits may be due to differences in the environment they inhabit, in existing parasite community structure, and to some extent, in the relative magnitude of indirect effects. Specifically, our data suggest that bottom-up processes after the introduction of a more virulent strain of RHDV to New Zealand may affect macroparasite co-infections by reducing the availability of their shared common resource, the rabbits. Clearly, interactions between co-infecting micro- and macroparasites vary in host populations with different ecologies, and significantly impact parasite community structure in wildlife. Nematode communities in Scotland and New Zealand were compared pre and post Rabbit Haemorrhagic Disease Virus introduction. Similar species occur in both rabbit populations, but prevalence and intensity changed in opposing directions after RHDV. RHDV had a major impact on rabbit populations, and our data show differing impacts on macroparasites in the two countries. Variability in rabbit environment, parasite community structure, and indirect interaction processes may explain differences. Results can help understand interactions between co-infecting parasites and their epidemiology in wild and domestic animals.
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Affiliation(s)
| | - Brian Boag
- The James Hutton Institute, Invergowrie, Dundee, Scotland, DD2 5DA, UK
| | - Roy Neilson
- The James Hutton Institute, Invergowrie, Dundee, Scotland, DD2 5DA, UK
| | - Naomi L Forrester
- School of Life Sciences, Keele University, Keele, Straffordshire, ST5 5BG, UK
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9
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Ghosh S, Ferrari MJ, Pathak AK, Cattadori IM. Changes in parasite traits, rather than intensity, affect the dynamics of infection under external perturbation. PLoS Comput Biol 2018; 14:e1006167. [PMID: 29889827 PMCID: PMC6019670 DOI: 10.1371/journal.pcbi.1006167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 06/26/2018] [Accepted: 05/01/2018] [Indexed: 12/22/2022] Open
Abstract
Understanding the mechanisms that generate complex host-parasite interactions, and how they contribute to variation between and within hosts, is important for predicting risk of infection and transmission, and for developing more effective interventions based on parasite properties. We used the T. retortaeformis (TR)-rabbit system and developed a state-space mathematical framework to capture the variation in intensity of infection and egg shedding in hosts infected weekly, then treated with an anthelminthic and subsequently re-challenged following the same infection regime. Experimental infections indicate that parasite intensity accumulates more slowly in the post-anthelminthic phase but reaches similar maximum numbers. By contrast, parasite EPG (eggs per gram of feces) shed from rabbits in the post-treatment phase is lower and less variable through time. Inference based on EPG alone suggests a decline in parasite intensity over time. Using a state-space model and incorporating all sources of cross-sectional and longitudinal data, we show that while parasite intensity remains relatively constant in both experimental phases, shedding of eggs into the environment is increasingly limited through changes in parasite growth. We suggest that host immunity directly modulates both the accumulation and the growth of the parasite, and indirectly affects transmission by limiting parasite length and thus fecundity. This study provides a better understanding of how within-host trophic interactions influence different components of a helminth population. It also suggests that heterogeneity in parasite traits should be addressed more carefully when examining and managing helminth infections in the absence of some critical data on parasite dynamics.
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Affiliation(s)
- Suma Ghosh
- Department of Mathematics, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh, India
- Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Matthew J. Ferrari
- Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Ashutosh K. Pathak
- Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania, United States of America
- Odum School of Ecology, The University of Georgia, Athens, Georgia, United States of America
| | - Isabella M. Cattadori
- Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania, United States of America
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10
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Ezenwa VO. Helminth-microparasite co-infection in wildlife: lessons from ruminants, rodents and rabbits. Parasite Immunol 2017; 38:527-34. [PMID: 27426017 DOI: 10.1111/pim.12348] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/13/2016] [Indexed: 12/26/2022]
Abstract
Co-infection is now recognized as the natural state of affairs in most hosts and co-infecting parasites interact in a variety of ways that can impact host health and parasite fitness. Interactions between helminths and microparasites have captured particular attention in this regard owing to the ubiquity of helminth infections in many host populations. The mechanistic underpinnings and health implications of co-infection are typically studied in laboratory and clinical settings, but recently studies of wild species have begun to tackle similar issues. Case studies from three wild mammal groups-ruminants, rodents and rabbits-serve to highlight how wild studies are contributing to the broader co-infection literature. This work suggests that wildlife research can generate new and unique insights about helminth-microparasite co-infection that are fostered in part by studying parasite interactions in a natural context. For this reason, increased integration of wild studies with research in human, laboratory and veterinary animal populations can help pave the way towards a more complete understanding of the issue of co-infection.
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Affiliation(s)
- V O Ezenwa
- Odum School of Ecology, University of Georgia, Athens, GA, USA. .,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
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11
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Budischak SA, O'Neal D, Jolles AE, Ezenwa VO. Differential host responses to parasitism shape divergent fitness costs of infection. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12951] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Sarah A. Budischak
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Department of Ecology and Evolutionary Biology Princeton NJ USA
| | - Dawn O'Neal
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Huyck Preserve & Biological Research Station Rensselaerville NY USA
| | - Anna E. Jolles
- Department of Biomedical Sciences and Department of Integrative BiologyOregon State University Corvallis OR USA
| | - Vanessa O. Ezenwa
- Odum School of EcologyUniversity of Georgia Athens GA USA
- Department of Infectious DiseasesUniversity of Georgia Athens GA USA
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12
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Cattadori IM, Sebastian A, Hao H, Katani R, Albert I, Eilertson KE, Kapur V, Pathak A, Mitchell S. Impact of Helminth Infections and Nutritional Constraints on the Small Intestine Microbiota. PLoS One 2016; 11:e0159770. [PMID: 27438701 PMCID: PMC4954658 DOI: 10.1371/journal.pone.0159770] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 07/06/2016] [Indexed: 01/08/2023] Open
Abstract
Helminth infections and nutrition can independently alter the composition and abundance of the gastrointestinal microbiota, however, their combined effect is poorly understood. Here, we used the T. retortaeformis-rabbit system to examine how the helminth infection and host restriction from coprophagy/ready-to-absorb nutrients affected the duodenal microbiota, and how these changes related to the acquired immune response at the site of infection. A factorial experiment was performed where the bacterial community, its functionality and the immune response were examined in four treatments (Infect, Infect+Collar, Control+Collar and Control). Helminths reduced the diversity and abundance of the microbiota while the combination of parasites and coprophagic restriction led to a more diversified and abundant microbiota than infected cases, without significantly affecting the intensity of infection. Animals restricted from coprophagy and free from parasites exhibited the richest and most abundant bacterial community. By forcing the individuals to absorb nutrients from less digested food, the coprophagic restriction appears to have facilitated the diversity and proliferation of bacteria in the duodenum. Changes in the microbiota were more clearly associated with changes in the immune response for the infected than the nutrient restricted animals. The functional and metabolic characteristics of the duodenal microbiota were not significantly different between treatments. Overall, infection and diet affect the gut microbiota but their interactions and outcome can be complex. These findings can have important implications for the development of control measures to helminth infections where poor nutrition/malnutrition can also be a concern.
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Affiliation(s)
- Isabella M. Cattadori
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16082 PA, United States of America
- Department of Biology, The Pennsylvania State University, University Park, 16082 PA, United States of America
- * E-mail:
| | - Aswathy Sebastian
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Han Hao
- Department of Statistics, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Robab Katani
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Istvan Albert
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Kirsten E. Eilertson
- Department of Statistics, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Vivek Kapur
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16082 PA, United States of America
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Ashutosh Pathak
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16082 PA, United States of America
- Department of Biology, The Pennsylvania State University, University Park, 16082 PA, United States of America
| | - Susan Mitchell
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16082 PA, United States of America
- Department of Biology, The Pennsylvania State University, University Park, 16082 PA, United States of America
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13
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Mignatti A, Boag B, Cattadori IM. Host immunity shapes the impact of climate changes on the dynamics of parasite infections. Proc Natl Acad Sci U S A 2016; 113:2970-5. [PMID: 26884194 PMCID: PMC4801268 DOI: 10.1073/pnas.1501193113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Global climate change is predicted to alter the distribution and dynamics of soil-transmitted helminth infections, and yet host immunity can also influence the impact of warming on host-parasite interactions and mitigate the long-term effects. We used time-series data from two helminth species of a natural herbivore and investigated the contribution of climate change and immunity on the long-term and seasonal dynamics of infection. We provide evidence that climate warming increases the availability of infective stages of both helminth species and the proportional increase in the intensity of infection for the helminth not regulated by immunity. In contrast, there is no significant long-term positive trend in the intensity for the immune-controlled helminth, as immunity reduces the net outcome of climate on parasite dynamics. Even so, hosts experienced higher infections of this helminth at an earlier age during critical months in the warmer years. Immunity can alleviate the expected long-term effect of climate on parasite infections but can also shift the seasonal peak of infection toward the younger individuals.
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MESH Headings
- Aging/immunology
- Animal Distribution
- Animals
- Global Warming
- Helminthiasis, Animal/epidemiology
- Helminthiasis, Animal/immunology
- Helminthiasis, Animal/parasitology
- Helminthiasis, Animal/transmission
- Host-Parasite Interactions/immunology
- Humidity
- Intestinal Diseases, Parasitic/epidemiology
- Intestinal Diseases, Parasitic/immunology
- Intestinal Diseases, Parasitic/parasitology
- Intestinal Diseases, Parasitic/veterinary
- Intestine, Small/immunology
- Intestine, Small/parasitology
- Larva/physiology
- Life Cycle Stages
- Ovum/physiology
- Population Dynamics
- Rabbits/immunology
- Rabbits/parasitology
- Scotland/epidemiology
- Seasons
- Soil/parasitology
- Stomach/immunology
- Stomach/parasitology
- Stomach Diseases/epidemiology
- Stomach Diseases/immunology
- Stomach Diseases/parasitology
- Stomach Diseases/veterinary
- Temperature
- Trichostrongyloidea/growth & development
- Trichostrongyloidea/physiology
- Trichostrongyloidiasis/epidemiology
- Trichostrongyloidiasis/immunology
- Trichostrongyloidiasis/parasitology
- Trichostrongyloidiasis/transmission
- Trichostrongyloidiasis/veterinary
- Trichostrongylosis/epidemiology
- Trichostrongylosis/immunology
- Trichostrongylosis/parasitology
- Trichostrongylosis/transmission
- Trichostrongylosis/veterinary
- Trichostrongylus/growth & development
- Trichostrongylus/physiology
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Affiliation(s)
- Andrea Mignatti
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy; Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16082
| | - Brian Boag
- The James Hutton Institute, DD2 5DA Invergowrie, United Kingdom
| | - Isabella M Cattadori
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16082;
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14
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Cattadori IM, Wagner BR, Wodzinski LA, Pathak AK, Poole A. Infections do not predict shedding in co-infections with two helminths from a natural system. Ecology 2014; 95:1684-92. [PMID: 25039232 DOI: 10.1890/13-1538.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Given the health and economic burden associated with the widespread occurrence of co-infections in humans and agricultural animals, understanding how coinfections contribute to host heterogeneity to infection and transmission is critical if we are to assess risk of infection based on host characteristics. Here, we examine whether host heterogeneity to infection leads to similar heterogeneity in transmission in a population of rabbits single and co-infected with two helminths and monitored monthly for eight years. Compared to single infections, co-infected rabbits carried higher Trichostrongylus retortaeformis intensities, shorter worms with fewer eggs in utero, and shed similar numbers of parasite eggs. In contrast, the same co-infected rabbits harbored fewer Graphidium strigosum with longer bodies and more eggs in utero, and shed more eggs of this helminth. A positive density-dependent relationship between fecundity and intensity was found for T. retortaeformis but not G. strigosum in co-infected rabbits. Juvenile rabbits contributed to most of the infection and shedding of T. retortaeformis, while adult hosts were more important for G. strigosum dynamics of infection and transmission, and this pattern was consistent in single and co-infected individuals. This host-parasite system suggests that we cannot predict the pattern of parasite shedding during co-infections based on intensity of infection alone. We suggest that a mismatching between susceptibility and infectiousness should be expected in helminth coinfections and should not be overlooked.
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15
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Jackson JA, Hall AJ, Friberg IM, Ralli C, Lowe A, Zawadzka M, Turner AK, Stewart A, Birtles RJ, Paterson S, Bradley JE, Begon M. An immunological marker of tolerance to infection in wild rodents. PLoS Biol 2014; 12:e1001901. [PMID: 25004450 PMCID: PMC4086718 DOI: 10.1371/journal.pbio.1001901] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 05/29/2014] [Indexed: 02/02/2023] Open
Abstract
Hosts are likely to respond to parasitic infections by a combination of resistance (expulsion of pathogens) and tolerance (active mitigation of pathology). Of these strategies, the basis of tolerance in animal hosts is relatively poorly understood, with especially little known about how tolerance is manifested in natural populations. We monitored a natural population of field voles using longitudinal and cross-sectional sampling modes and taking measurements on body condition, infection, immune gene expression, and survival. Using analyses stratified by life history stage, we demonstrate a pattern of tolerance to macroparasites in mature compared to immature males. In comparison to immature males, mature males resisted infection less and instead increased investment in body condition in response to accumulating burdens, but at the expense of reduced reproductive effort. We identified expression of the transcription factor Gata3 (a mediator of Th2 immunity) as an immunological biomarker of this tolerance response. Time series data for individual animals suggested that macroparasite infections gave rise to increased expression of Gata3, which gave rise to improved body condition and enhanced survival as hosts aged. These findings provide a clear and unexpected insight into tolerance responses (and their life history sequelae) in a natural vertebrate population. The demonstration that such responses (potentially promoting parasite transmission) can move from resistance to tolerance through the course of an individual's lifetime emphasises the need to incorporate them into our understanding of the dynamics and risk of infection in the natural environment. Moreover, the identification of Gata3 as a marker of tolerance to macroparasites raises important new questions regarding the role of Th2 immunity and the mechanistic nature of the tolerance response itself. A more manipulative, experimental approach is likely to be valuable in elaborating this further.
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Affiliation(s)
| | - Amy J. Hall
- School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom
| | - Ida M. Friberg
- School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | - Catriona Ralli
- School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom
| | - Ann Lowe
- School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom
| | - Malgorzata Zawadzka
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | - Andrew K. Turner
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | | | - Richard J. Birtles
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| | - Steve Paterson
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | - Janette E. Bradley
- School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom
| | - Mike Begon
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
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16
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Abstract
AbstractTransmission success for helminths with free-living stages depends on the ability of eggs and larvae to develop and survive once in the environment. While environmental conditions are often suggested to influence egg phenology and hatching rate, immunity against parasite eggs might also play a role. We examined this hypothesis using the gastrointestinal helminths Trichostrongylus retortaeformis and Graphidium strigosum, two common infections of the European rabbit. Changes in egg hatching rate and volume were examined in relation to specific antibodies in the serum and bound to eggshells, using eggs shed in host faeces over a 15-week period. Hatching rate was consistently higher for T. retortaeformis than G. strigosum and no changes were observed between weeks. Egg volume increased for G. strigosum but decreased for T. retortaeformis. We did find evidence of egg-specific antibody responses and fewer antibodies were bound to eggs of T. retortaeformis compared to G. strigosum. Little to no association was found between antibodies and hatchability, or volume, for both helminths. We suggest that host antibodies play a relatively minor role in the egg hatching rate of these gastrointestinal helminths.
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17
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Murphy L, Pathak AK, Cattadori IM. A co-infection with two gastrointestinal nematodes alters host immune responses and only partially parasite dynamics. Parasite Immunol 2013; 35:421-32. [DOI: 10.1111/pim.12045] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 06/14/2013] [Indexed: 12/31/2022]
Affiliation(s)
- L. Murphy
- Division of Animal Production and Public Health; The Veterinary School; University of Glasgow; Glasgow UK
| | - A. K. Pathak
- Department of Biology and Center for Infectious Disease Dynamics; The Pennsylvania State University; University Park PA USA
| | - I. M. Cattadori
- Department of Biology and Center for Infectious Disease Dynamics; The Pennsylvania State University; University Park PA USA
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18
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Abstract
Co-infection of individual hosts by multiple parasite species is a pattern that is very commonly observed in natural populations. Understanding the processes that generate these patterns poses a challenge. For example, it is difficult to discern the relative roles of exposure and susceptibility in generating the mixture and density of parasites within hosts. Yet discern them we must, if we are to design and deliver successful medical interventions for co-infected populations. Here, we synthesise an emergent understanding of how processes operate and interact to generate patterns of co-infection. We consider within-host communities (or infracommunities) generally, that is including not only classical parasites but also the microbiota that are so abundant on mucosal surfaces and which are increasingly understood to be so influential on host biology. We focus on communities that include a helminth, but we expect similar inferences to pertain to other taxa. We suggest that, thanks to recent research at both the within-host (e.g. immunological) and between-host (e.g. epidemiological) scales, researchers are poised to reveal the processes that generate the observed distribution of parasite communities among hosts. Progress will be facilitated by using new technologies as well as statistical and experimental tools to test competing hypotheses about processes that might generate patterns in co-infection data. By understanding the multiple interactions that underlie patterns of co-infection, we will be able to understand and intelligently predict how a suite of co-infections (and thus the host that bears them) will together respond to medical interventions as well as other environmental changes. The challenge for us all is to become scholars of co-infections.
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Affiliation(s)
- Mark E Viney
- School of Biological Sciences, University of Bristol, Woodland Road, UK.
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19
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Hernandez AD, Poole A, Cattadori IM. Climate changes influence free-living stages of soil-transmitted parasites of European rabbits. GLOBAL CHANGE BIOLOGY 2013; 19:1028-42. [PMID: 23504881 DOI: 10.1111/gcb.12106] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 10/20/2012] [Indexed: 05/03/2023]
Abstract
Climate warming has been suggested to augment the risk of infectious disease outbreaks by extending the seasonal window for parasite growth and by increasing the rate of transmission. Understanding how this occurs in parasite-host systems is important for appreciating long-term and seasonal changes in host exposure to infection and to reduce species extinction caused by diseases. We investigated how free-living stages of two soil-transmitted helminths of the European rabbit (Oryctolagus cuniculus) responded to experimental changes in temperature by performing laboratory experiments with environmental chambers and field manipulations using open-top-chambers. This study was motivated by our previous observations that air temperature has increased over the last 30 years in our field site and that during this period intensity of infection of Graphidium strigosum but not Trichostrongylus retortaeformis was positively associated with this temperature increase. Laboratory and field experiments showed that both parasites accelerated egg development and increased hatching rate and larval survival in response to accumulating thermal energy. Both parasites behaved similarly when exposed to diverse temperature regimes, decadal trends, and monthly fluctuations, however, T. retortaeformis was more successful than G. strigosum by showing higher rates of egg hatching and larval survival. Across the months, the first day of hatching occurred earlier in warmer conditions suggesting that climate warming can lengthen the period of parasite growth and host exposure to infective stages. Also, T. retortaeformis hatched earlier than G. strigosum. These findings showed that seasonal changes in intensity, frequency, and duration of daily temperature are important causes of variability in egg hatching and larva survival. Overall, this study emphasizes the important role of climate warming and seasonality on the dynamics of free-living stages in soil-transmitted helminths and their contribution to enhance host exposure to parasitic infections. Yet, the ability to infect might ultimately depend on how hosts interact with parasites.
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Affiliation(s)
- Alexander D Hernandez
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
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20
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Boag B, Hernandez AD, Cattadori IM. Observations on the epidemiology and interactions between myxomatosis, coccidiosis and helminth parasites in a wild rabbit population in Scotland. EUR J WILDLIFE RES 2013. [DOI: 10.1007/s10344-013-0704-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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21
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Variability in the intensity of nematode larvae from gastrointestinal tissues of a natural herbivore. Parasitology 2013; 140:632-40. [PMID: 23351661 DOI: 10.1017/s0031182012001898] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The migration of infective nematode larvae into the tissues of their hosts has been proposed as a mechanism of reducing larval mortality and increase parasite lifetime reproductive success. Given that individual hosts differ in the level of exposure, strength of immune response and physiological conditions we may expect the number of larvae in tissue to vary both between and within hosts. We used 2 gastrointestinal nematode species common in the European rabbit (Oryctolagus cuniculus) and examined how the number of larvae in the tissue changed with the immune response, parasite intensity-dependent constraints in the lumen and seasonal weather factors, in rabbits of different age, sex and breeding status. For both nematode species, larvae from the gastrointestinal tissue exhibited strong seasonal and host age-related patterns with fewer larvae recovered in summer compared to winter and more in adults than in juveniles. The number of larvae of the 2 nematodes was positively associated with intensity of parasite infection in the lumen and antibody responses while it was negatively related with air temperature and rainfall. Host sex, reproductive status and co-infection with the second parasite species contributed to increase variability between hosts. We concluded that heterogeneities in host conditions are a significant cause of variability of larval abundance in the gastrointestinal tissues. These findings can have important consequences for the dynamics of nematode infections and how parasite's life-history strategies adjust to host changes.
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22
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Abate E, Belayneh M, Gelaw A, Idh J, Getachew A, Alemu S, Diro E, Fikre N, Britton S, Elias D, Aseffa A, Stendahl O, Schön T. The impact of asymptomatic helminth co-infection in patients with newly diagnosed tuberculosis in north-west Ethiopia. PLoS One 2012; 7:e42901. [PMID: 22952620 PMCID: PMC3430660 DOI: 10.1371/journal.pone.0042901] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 07/12/2012] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Areas endemic of helminth infection, tuberculosis (TB) and HIV are to a large extent overlapping. The aim of this study was to assess the impact of asymptomatic helminth infection on the immunological response among TB patients with and without HIV, their house hold contacts and community controls. METHODOLOGY Consecutive smear positive TB patients (n = 112), their household contacts (n = 71) and community controls (n = 112) were recruited in Gondar town, Ethiopia. Stool microscopy, HIV serology, serum IgE level, eosinophil and CD4 counts were performed and tuberculosis patients were followed up for 3 months after initiation of anti-TB treatment. RESULTS Helminth co-infection rate was 29% in TB patients and 21% in both community control and household contacts (p = 0.3) where Ascaris lumbricoides was the most prevalent parasite. In TB patients the seroprevalence of HIV was 47% (53/112). Eosinophilia and elevated IgE level were significantly associated with asymptomatic helminth infection. During TB treatment, the worm infection rate of HIV+/TB patients declined from 31% (10/32) at week 0 to 9% (3/32) at week 2 of TB treatment, whereas HIV-/TB patients showed no change from baseline to week 2, 29% (13/45) vs. 22.2% (10/45). This trend was stable at week 8 and 12 as well. CONCLUSION One third of smear positive TB patients were infected with helminths. Eosinophilia and elevated IgE level correlated with asymptomatic worm infection, indicating an effect on host immunity. The rate of worm infection declined during TB treatment in HIV+/TB co-infected patients whereas no decline was seen in HIV-/TB group.
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Affiliation(s)
- Ebba Abate
- Department of Immunology and Molecular Biology, University of Gondar, Gondar, Ethiopia.
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23
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Pathak AK, Pelensky C, Boag B, Cattadori IM. Immuno-epidemiology of chronic bacterial and helminth co-infections: observations from the field and evidence from the laboratory. Int J Parasitol 2012; 42:647-55. [PMID: 22584129 DOI: 10.1016/j.ijpara.2012.04.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/21/2012] [Accepted: 04/12/2012] [Indexed: 12/12/2022]
Abstract
Co-infections can alter the host immune responses and modify the intensity and dynamics of concurrent parasitic species. The extent of this effect depends on the properties of the system and the mechanisms of host-parasite and parasite-parasite interactions. We examined the immuno-epidemiology of a chronic co-infection to reveal the immune mediated relationships between two parasites colonising independent organs, and the within-host molecular processes influencing the dynamics of infection at the host population level. The respiratory bacterium, Bordetella bronchiseptica, and the gastrointestinal helminth, Graphidium strigosum, were studied in the European rabbit (Oryctolagus cuniculus), using long-term field data and a laboratory experiment. We found that 65% of the rabbit population was co-infected with the two parasites; prevalence and intensity of co-infection increased with rabbit age and exhibited a strong seasonal pattern with the lowest values recorded during host breeding (from April to July) and the highest in the winter months. Laboratory infections showed no significant immune-mediated effects of the helminth on bacterial intensity in the lower respiratory tract but a higher abundance was observed in the nasal cavity during the chronic phase of the infection, compared with single bacterial infections. In contrast, B. bronchiseptica enhanced helminth intensity and this was consistent throughout the 4-month trial. These patterns were associated with changes in the immune profiles between singly and co-infected individuals for both parasites. This study confirmed the general observation that co-infections alter the host immune responses but also highlighted the often ignored role of bacterial infection in helminth dynamics. Additionally, we showed that G. strigosum had contrasting effects on B. bronchiseptica colonising different parts of the respiratory tract. At the host population level our findings suggest that B. bronchiseptica facilitates G. strigosum infection, and re-infection with G. strigosum assists in maintaining bacterial infection in the upper respiratory tract and thus long-term persistence.
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Affiliation(s)
- Ashutosh K Pathak
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
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24
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Thakar J, Pathak AK, Murphy L, Albert R, Cattadori IM. Network model of immune responses reveals key effectors to single and co-infection dynamics by a respiratory bacterium and a gastrointestinal helminth. PLoS Comput Biol 2012; 8:e1002345. [PMID: 22253585 PMCID: PMC3257297 DOI: 10.1371/journal.pcbi.1002345] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 11/25/2011] [Indexed: 12/22/2022] Open
Abstract
Co-infections alter the host immune response but how the systemic and local processes at the site of infection interact is still unclear. The majority of studies on co-infections concentrate on one of the infecting species, an immune function or group of cells and often focus on the initial phase of the infection. Here, we used a combination of experiments and mathematical modelling to investigate the network of immune responses against single and co-infections with the respiratory bacterium Bordetella bronchiseptica and the gastrointestinal helminth Trichostrongylus retortaeformis. Our goal was to identify representative mediators and functions that could capture the essence of the host immune response as a whole, and to assess how their relative contribution dynamically changed over time and between single and co-infected individuals. Network-based discrete dynamic models of single infections were built using current knowledge of bacterial and helminth immunology; the two single infection models were combined into a co-infection model that was then verified by our empirical findings. Simulations showed that a T helper cell mediated antibody and neutrophil response led to phagocytosis and clearance of B. bronchiseptica from the lungs. This was consistent in single and co-infection with no significant delay induced by the helminth. In contrast, T. retortaeformis intensity decreased faster when co-infected with the bacterium. Simulations suggested that the robust recruitment of neutrophils in the co-infection, added to the activation of IgG and eosinophil driven reduction of larvae, which also played an important role in single infection, contributed to this fast clearance. Perturbation analysis of the models, through the knockout of individual nodes (immune cells), identified the cells critical to parasite persistence and clearance both in single and co-infections. Our integrated approach captured the within-host immuno-dynamics of bacteria-helminth infection and identified key components that can be crucial for explaining individual variability between single and co-infections in natural populations. Infections with different infecting agents can alter the immune response against any one parasite and the relative abundance and persistence of the infections within the host. This is because the immune system is not compartmentalized but acts as a whole to allow the host to maintain control of the infections as well as repair damaged tissues and avoid immuno-pathology. There is no comprehensive understanding of the immune responses during co-infections and of how systemic and local mechanisms interact. Here we integrated experimental data with mathematical modelling to describe the network of immune responses of single and co-infection by a respiratory bacterium and a gastrointestinal helminth. We were able to identify key cells and functions responsible for clearing or reducing both parasites and showed that some mechanisms differed between type of infection as a result of different signal outputs and cells contributing to the immune processes. This study highlights the importance of understanding the immuno-dynamics of co-infection as a host response, how immune mechanisms differ from single infections and how they may alter parasite persistence, impact and abundance.
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Affiliation(s)
- Juilee Thakar
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ashutosh K. Pathak
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Lisa Murphy
- Division of Animal Production and Public Health, Veterinary School, University of Glasgow, Glasgow, United Kingdom
| | - Réka Albert
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Isabella M. Cattadori
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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25
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Pathak AK, Biarnes MC, Murphy L, Cattadori IM. Snapshot of spatio-temporal cytokine responses to single and co-infections with helminths and bacteria. RESULTS IN IMMUNOLOGY 2011; 1:95-102. [PMID: 24371558 DOI: 10.1016/j.rinim.2011.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 10/21/2011] [Accepted: 10/31/2011] [Indexed: 12/24/2022]
Abstract
Cytokines play a key role in maintaining communication between organs and in so doing modulate the interaction between concurrent infections. The extent of these effects depends on the properties of the organ infected and the intensity and type of infections. To determine systemic bystander effects among organs, IFN-γ, IL-4 and IL-10 gene expression was quantified at 7 days post-challenge in directly infected and uninfected organs during single and co-infections with the respiratory bacterium Bordetella bronchiseptica and the gastrointestinal helminths Graphidium strigosum and Trichostrongylus retortaeformis. Results showed that cytokine expression in a specific organ was influenced by the type of infection occurring in another organ, and this bystander effect was more apparent in some organs than others. Within the same organ the relative cytokine expression was consistent across infections, although some cytokines were more affected by bystander effects than others. For the infected gastrointestinal tract, a stronger cytokine response was observed in the tissue that harbored the majority of helminths (i.e. duodenum and fundus). Overall, co-infections altered the intensity but to a lesser extent the relative cytokine profile against the focal infection, indicating clear bystander effects and low organ compartmentalization. However, organs appear to actively modulate cytokine expression to avoid potential immuno-pathological consequences.
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Key Words
- AR-1, autoregressive function of order 1
- B, B. bronchiseptica single infection
- BG, B. bronchiseptica+G. strigosum dual-infection
- BT, B. bronchiseptica+T. retortaeformis dual-infection
- BTG, B. bronchiseptica+T. retortaeformis+G. strigosum triple infection
- Bordetella bronchiseptica
- Bystander effects
- Co-infections
- Cytokine gene expression
- DPI, days post-infection
- GLM, generalized linear models
- Graphidium strigosum
- IFN-γ, Interferon-gamma
- IL-10, Interleukin-10
- IL-4, Interleukin-4
- LME-REML, linear mixed effect models with restricted maximum likelihood
- SI, small intestine
- T, T. retortaeformis single infection
- TG, T. retortaeformis+G. strigosum dual helminth co-infection
- Trichostrongylus retortaeformis
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Affiliation(s)
- Ashutosh K Pathak
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA ; Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Michael C Biarnes
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Lisa Murphy
- Division of Animal Production and Public Health, Veterinary School, University of Glasgow, Glasgow G61 1QH, UK
| | - Isabella M Cattadori
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA ; Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
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