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Ruden RM, Adelman JS. Modulating disease phenotype in a songbird: A role for inflammation in disease tolerance? JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:83-91. [PMID: 36127806 DOI: 10.1002/jez.2655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 08/02/2022] [Accepted: 08/26/2022] [Indexed: 12/15/2022]
Abstract
Individual animals vary greatly in their responses to infection, either killing off the invading pathogen (resistance) or minimizing the per-pathogen costs of infection on host fitness (tolerance). Though we understand little about the physiological drivers of tolerance in wild animals, phenotypically, it manifests as milder clinical signs of disease. Here, we use a well-described disease system, finch mycoplasmosis, to evaluate the role of inflammation in disease tolerance. House finches (Haemorhous mexicanus) infected with the bacterial pathogen Mycoplasma gallisepticum (MG) develop conjunctival pathology that satisfies the cardinal signs of inflammation. We report on a captive trial performed in 2016 and replicated in 2018 that tested whether chemotherapeutics, specifically nonsteroidal anti-inflammatory drugs (NSAIDs), can reduce lesion severity, thus pushing individuals toward more tolerant phenotypes. Though birds treated with NSAIDs in the first trial developed milder pathology per unit pathogen load, we found no effect of treatment in the second trial, perhaps due to natural variation in baseline tolerance within the source population across years. Second-trial control birds developed markedly milder pathology than first-year controls, suggesting that the effect of trial swamped the effect of treatment in this study. Moving forward, using birds from a population in which the disease is absent or only recently emerged-and so tolerance has not yet been selected for-may better elucidate the role of pro-inflammatory mediators in disease tolerance.
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Affiliation(s)
- Rachel M Ruden
- Department of Natural Resource Ecology and Management, Iowa State University, Ames, Iowa, USA.,Iowa Department of Natural Resources, Ames, Iowa, USA
| | - James S Adelman
- Department of Natural Resource Ecology and Management, Iowa State University, Ames, Iowa, USA.,Department of Biological Sciences, University of Memphis, Memphis, Tennessee, USA
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The slow dynamics of mycoplasma infections in a tortoise host reveal heterogeneity pertinent to pathogen transmission and monitoring. Epidemiol Infect 2018; 147:e12. [PMID: 30251621 DOI: 10.1017/s0950268818002613] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The epidemiology of infectious diseases depends on many characteristics of disease progression, as well as the consistency of these processes across hosts. Longitudinal studies of infection can thus inform disease monitoring and management, but can be challenging in wildlife, particularly for long-lived hosts and persistent infections. Numerous tortoise species of conservation concern can be infected by pathogenic mycoplasmas that cause a chronic upper respiratory tract disease (URTD). Yet, a lack of detailed data describing tortoise responses to mycoplasma infections obscures our understanding of URTDs role in host ecology. We therefore monitored Mycoplasma agassizii infections in 14 captive desert tortoises and characterised clinical signs of disease, infection intensity, pathogen shedding and antibody production for nearly 4 years after initial exposure to donor hosts. Persistent infections established in all exposed tortoises within 10 weeks, but hosts appeared to vary in resistance, which affected the patterns of pathogen shedding and apparent disease. Delays in host immune response and changes to clinical signs and infection intensity over time resulted in inconsistencies between diagnostic tools and changes in diagnostic accuracy throughout the study. We discuss the implications these results have for URTD epidemiology and past and future research assessing disease prevalence and dynamics in tortoise populations.
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Sandmeier FC, Weitzman CL, Tracy CR. An ecoimmunological approach to disease in tortoises reveals the importance of lymphocytes. Ecosphere 2018. [DOI: 10.1002/ecs2.2427] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- Franziska C. Sandmeier
- Biology Department; Colorado State University-Pueblo; 2200 Bonforte Boulevard Pueblo Colorado 81001 USA
| | - Chava L. Weitzman
- Biology Department; Program in Ecology, Evolution, and Conservation Biology; University of Nevada-Reno; 1664 N Virginia Street Reno Nevada 89557 USA
| | - C. Richard Tracy
- Biology Department; Program in Ecology, Evolution, and Conservation Biology; University of Nevada-Reno; 1664 N Virginia Street Reno Nevada 89557 USA
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Lindberg HM, McKean KA, Caraco T, Wang IN. Within-host dynamics and random duration of pathogen infection: Implications for between-host transmission. J Theor Biol 2018; 446:137-148. [PMID: 29391172 DOI: 10.1016/j.jtbi.2018.01.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 12/27/2017] [Accepted: 01/26/2018] [Indexed: 01/15/2023]
Abstract
Taking an ecological perspective, this paper reports theoretical and empirical results concerning fatal bacterial infections of adult insects. Two models, each combining deterministic and stochastic elements, characterize how the pathogen's dynamics might govern an infected host's mortality rate. We analyze the models in detail for exponential pathogen growth, and apply them to observed insect mortality when the pathogen's growth is unregulated. We then allow bacteriophage to generate fluctuations in the within-host pathogen density; we demonstrate that only one of our models matches host mortality rates when pathogen growth is regulated by phage. We generalize our results on mortality hazard of individual hosts to analyze how random duration of the infectious period can combine with probabilistic transmission events to affect between-host transmission.
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Affiliation(s)
- Heather M Lindberg
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA; Center for Science and Health Professions, Virginia Western Community College, Roanoke, VA 24015, USA
| | - Kurt A McKean
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK
| | - T Caraco
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA
| | - Ing-Nang Wang
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA.
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Sandmeier FC, Maloney KN, Tracy CR, Hyde D, Mohammadpour H, Marlow R, DuPré S, Hunter K. Chronic disease in the Mojave desert tortoise: Host physiology and recrudescence obscure patterns of pathogen transmission. Ecol Evol 2017; 7:10616-10629. [PMID: 29299243 PMCID: PMC5743692 DOI: 10.1002/ece3.3480] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/28/2017] [Accepted: 09/01/2017] [Indexed: 01/25/2023] Open
Abstract
A seminatural, factorial‐design experiment was used to quantify dynamics of the pathogen Mycoplasma agassizii and upper respiratory tract disease in the Mojave desert tortoise (Gopherus agassizii) over 2 years. Groups of initially healthy animals were separated into serologically positive (seropositive), seronegative, and artificially infected groups and paired into 23 pens. We found no evidence of long‐term immune protection to M. agassizii or of immunological memory. Initially seronegative, healthy tortoises experienced an equal amount of disease when paired with other seronegative groups as when paired with seropositive and artificially infected groups—suggesting that recrudescence is as significant as transmission in introducing disease in individuals in this host–pathogen system. Artificially infected groups of tortoises showed reduced levels of morbidity when paired with initially seronegative animals—suggesting either a dilution effect or a strong effect of pathogen load in this system. Physiological dynamics within the host appear to be instrumental in producing morbidity, recrudescence, and infectiousness, and thus of population‐level dynamics. We suggest new avenues for studying diseases in long‐lived ectothermic vertebrates and a shift in modeling such diseases.
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Affiliation(s)
| | - K Nichole Maloney
- Department of Pathology, Microbiology, and Immunology Vanderbilt University Nashville TN USA
| | | | - David Hyde
- Biology Department University of Nevada Reno Reno NV USA
| | - Hamid Mohammadpour
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
| | - Ron Marlow
- Biology Department University of Nevada Reno Reno NV USA
| | - Sally DuPré
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
| | - Kenneth Hunter
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
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Park M, Kim S, Adelman JS, Leon AE, Hawley DM, Dalloul RA. Identification and functional characterization of the house finch interleukin-1β. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 69:41-50. [PMID: 27998740 DOI: 10.1016/j.dci.2016.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/15/2016] [Accepted: 12/15/2016] [Indexed: 06/06/2023]
Abstract
Interleukin-1β (IL-1β), an inflammatory cytokine of the IL-1 family, is primarily produced as a precursor protein by monocytes and macrophages, then matures and becomes activated through proteolytic catalysis. Although the biological characteristics of avian IL-1β are well known, little information is available about its biological role in songbird species such as house finches that are vulnerable to naturally-occurring inflammatory diseases. In this study, house finch IL-1β (HfIL-1β) was cloned, expressed, and its biological function examined. Both precursor and mature forms of HfIL-1β consisting of 269 and 162 amino acids, respectively, were amplified from total RNA of spleen and cloned into expression vectors. HfIL-1β showed high sequential and tertiary structural similarity to chicken homologue that allowed detection of the expressed mature recombinant HfIL-1β (rHfIL-1β) with anti-ChIL-1β antibody by immunoblot analysis. For further characterization, we used primary splenocytes and hepatocytes that are predominant sources of IL-1β upon stimulation, as well as suitable targets to stimulation by IL-1β. Isolated house finch splenocytes were stimulated with rHfIL-1β in the presence and absence of concanavalin A (Con A), RNA was extracted and transcript levels of Th1/Th2 cytokines and a chemokine were measured by qRT-PCR. The addition of rHfIL-1β induced significant enhancement of IL-2 transcript, a Th1 cytokine, while transcription of IL-1β and the Th2 cytokine IL-10 was slightly enhanced by rHfIL-1β treatment. rHfIL-1β also led to elevated levels of the chemokine CXCL1 and nitric oxide production regardless of co-stimulation with Con A. In addition, the production of the acute phase protein serum amyloid A and the antimicrobial peptide LEAP2 was observed in HfIL-1β-stimulated hepatocytes. Taken together, these observations revealed the basic functions of HfIL-1β including the stimulatory effect on cell proliferation, production of Th1/Th2 cytokines and acute phase proteins by immune cells, thus providing valuable insight into how HfIL-1β is involved in regulating inflammatory response.
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Affiliation(s)
- Myeongseon Park
- Avian Immunobiology Laboratory, Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Sungwon Kim
- Avian Immunobiology Laboratory, Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA; The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - James S Adelman
- Department of Natural Resource Ecology and Management, Iowa State University, Ames, IA 50011, USA
| | - Ariel E Leon
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Dana M Hawley
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Rami A Dalloul
- Avian Immunobiology Laboratory, Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
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Adelman JS, Moore IT, Hawley DM. House finch responses to Mycoplasma gallisepticum infection do not vary with experimentally increased aggression. ACTA ACUST UNITED AC 2014; 323:39-51. [PMID: 25387693 DOI: 10.1002/jez.1894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Aggression can alter infectious disease dynamics through two, non-exclusive mechanisms: 1) increasing direct contact among hosts and 2) altering hosts' physiological response to pathogens. Here we examined the latter mechanism in a social songbird by manipulating intraspecific aggression in the absence of direct physical contact. We asked whether the extent of aggression an individual experiences alters glucocorticoid levels, androgen levels, and individual responses to infection in an ecologically relevant disease model: house finches (Haemorhous mexicanus) infected with Mycoplasma gallisepticum (MG). Wild-caught male finches were housed in one of three settings, designed to produce increasing levels of aggression: 1) alone, with no neighbor ("no neighbor"), 2) next to a sham-implanted stimulus male ("sham neighbor"), or 3) next to a testosterone-implanted stimulus male ("testosterone neighbor"). Following one week of social treatment, focal males were experimentally infected with MG, which causes severe conjunctivitis and induces sickness behaviors such as lethargy and anorexia. While social treatment increased aggression as predicted, there were no differences among groups in baseline corticosterone levels, total circulating androgens, or responses to infection. Across all focal individuals regardless of social treatment, pre-infection baseline corticosterone levels were negatively associated with the severity of conjunctivitis and sickness behaviors, suggesting that corticosterone may dampen inflammatory responses in this host-pathogen system. However, because corticosterone levels differed based upon population of origin, caution must be taken in interpreting this result. Taken together, these results suggest that in captivity, although aggression does not alter individual responses to MG, corticosterone may play a role in this disease.
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