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Camacho-Sillero L, Cardoso B, Beato-Benítez A, Gómez-Guillamón F, Díaz-Cao JM, Jiménez-Martín D, Caballero-Gómez J, Castro-Scholten S, Cano-Terriza D, García-Bocanegra I. Spatiotemporal monitoring of myxomatosis in European wild rabbit (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems. Transbound Emerg Dis 2022; 69:3494-3505. [PMID: 36150087 DOI: 10.1111/tbed.14709] [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: 03/24/2022] [Revised: 09/01/2022] [Accepted: 09/14/2022] [Indexed: 02/04/2023]
Abstract
A long-term active epidemiological surveillance programme was conducted to determine seroprevalence to myxoma virus (MYXV), infection prevalence and spatiotemporal patterns and factors associated with MYXV circulation in wild rabbits (Oryctolagus cuniculus) in Spanish Mediterranean ecosystems. A total of 2376 animals were sampled over four study periods: 2009-2012 (P1), 2012-2015 (P2), 2015-2018 (P3) and 2018-2021 (P4). Antibodies against MYXV were detected by a commercial indirect ELISA in 59.9% (1424/2376; 95% CI: 58.0-61.9) of wild rabbits. At least one seropositive animal was detected on 131 (96.3%) of 136 game estates sampled. MYXV infection was confirmed by PCR in 94 of 1063 (8.8%; 95% CI: 7.3-10.7) wild rabbits. Circulation of the novel recombinant MYXV (ha-MYXV) was not found in wild rabbits analysed during P4. Five statistically significant spatiotemporal clusters of high MYXV seroprevalence were identified using a Bernoulli model: one in P2 and four in P3. A generalized linear mixed model (GLMM) analysis identified sampling season (autumn), age (adult and juvenile), outbreaks of myxomatosis in the month prior to sampling, mean annual temperature, humidity and seropositivity to rabbit haemorrhagic disease virus as factors potentially linked with MYXV seropositivity. GLMM analysis identified outbreaks of myxomatosis in the month prior to sampling, MYXV seropositivity and presence of lesions compatible with myxomatosis as factors associated with MYXV infection. The results indicate high exposure, widespread but non-homogeneous distribution, and endemic circulation of MYXV in wild rabbit populations in southern Spain during the last decade. Prevalence of antibodies against MYXV showed fluctuations both within the year and over the study periods, revealing variations in the immunity of wild rabbit populations in Mediterranean ecosystems that could increase the risk of MYXV re-emergence in immunologically naïve populations. The present study highlights the importance of long-term surveillance to better understand the epidemiology of MYXV in wild lagomorphs.
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Affiliation(s)
- Leonor Camacho-Sillero
- Programa Vigilancia Epidemiológica Fauna Silvestre (PVE), Consejería de Sostenibilidad, Medio Ambiente y Economía Azul, Junta de Andalucía, Málaga, Málaga, Spain
| | - Beatriz Cardoso
- Health & Biotechnology (SaBio) Group, Instituto de Investigación en Recursos Cinegéticos (CSIC-UCLM-JCCM), Ciudad Real, Spain.,CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Porto, Portugal
| | - Adrián Beato-Benítez
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain
| | - Félix Gómez-Guillamón
- Programa Vigilancia Epidemiológica Fauna Silvestre (PVE), Consejería de Sostenibilidad, Medio Ambiente y Economía Azul, Junta de Andalucía, Málaga, Málaga, Spain
| | - José M Díaz-Cao
- Departamento de Patoloxía Animal (INVESAGA Group), Universidade de Santiago de Compostela, Lugo, Spain
| | - Débora Jiménez-Martín
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain
| | - Javier Caballero-Gómez
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain.,CIBERINFEC, ISCIII - CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain.,Unidad de Enfermedades Infecciosas, Grupo de Virología Clínica y Zoonosis, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Reina Sofía, Universidad de Córdoba (UCO), Córdoba, Spain
| | - Sabrina Castro-Scholten
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain.,CIBERINFEC, ISCIII - CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
| | - David Cano-Terriza
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain.,CIBERINFEC, ISCIII - CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
| | - Ignacio García-Bocanegra
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain.,CIBERINFEC, ISCIII - CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
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Detection of Myxoma Virus DNA in Ticks from Lagomorph Species in Spain Suggests Their Possible Role as Competent Vector in Viral Transmission. J Wildl Dis 2021; 57:423-428. [PMID: 33626569 DOI: 10.7589/jwd-d-20-00116] [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: 06/23/2020] [Accepted: 11/01/2020] [Indexed: 11/20/2022]
Abstract
Myxoma virus (MYXV) causes morbidity and mortality in European wild rabbits (Oryctolagus cuniculus) worldwide, and recently in Iberian hares (Lepus granatensis) in Spain. We aimed to assess the presence of MYXV-specific DNA in ixodid ticks collected from both hosts. A total of 417 ticks harvested from 30 wild lagomorphs, including wild rabbits and Iberian hares were collected from southern Spain. Enzyme-linked immunosorbent assay and PCR-sequencing were used to detect virus exposure and presence, respectively. Antibodies to MYXV were detected in 68% (17/25) of wild rabbits and in 67% (2/3) of Iberian hares. We detected MYXV DNA in 50.7% of pools of two different tick species (nymphs and adults of Rhipicephalus pusillus, and nymphs of Hyalomma lusitanicum) parasitizing rabbits and hares. The obtained partial sequence of the viral major envelope protein gene showed a mutation (G383A) within the MYXV_gp026 locus between the rabbit strain and Iberian hare strain (recently isolated in tissues of infected hares from Spain). However, in our study, the viral DNA presence was detected for the first time using tick DNA as the PCR-template, but the possible role of ticks as vectors of MYXV still needs to be elucidated.
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Abstract
Viral diseases, whether of animals or humans, are normally considered as problems to be managed. However, in Australia, two viruses have been used as landscape-scale therapeutics to control European rabbits (Oryctolagus cuniculus), the preeminent invasive vertebrate pest species. Rabbits have caused major environmental and agricultural losses and contributed to extinction of native species. It was not until the introduction of Myxoma virus that effective control of this pest was obtained at a continental scale. Subsequent coevolution of rabbit and virus saw a gradual reduction in the effectiveness of biological control that was partially ameliorated by the introduction of the European rabbit flea to act as an additional vector for the virus. In 1995, a completely different virus, Rabbit hemorrhagic disease virus (RHDV), escaped from testing and spread through the Australian rabbit population and again significantly reduced rabbit numbers and environmental impacts. The evolutionary pressures on this virus appear to be producing quite different outcomes to those that occurred with myxoma virus and the emergence and invasion of a novel genotype of RHDV in 2014 have further augmented control. Molecular studies on myxoma virus have demonstrated multiple proteins that manipulate the host innate and adaptive immune response; however the molecular basis of virus attenuation and reversion to virulence are not yet understood.
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Gates DE, Valletta JJ, Bonneaud C, Recker M. Quantitative host resistance drives the evolution of increased virulence in an emerging pathogen. J Evol Biol 2018; 31:1704-1714. [PMID: 30107064 DOI: 10.1111/jeb.13366] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/31/2018] [Accepted: 08/09/2018] [Indexed: 12/01/2022]
Abstract
Emergent infectious diseases can have a devastating impact on host populations. The high selective pressures on both the hosts and the pathogens frequently lead to rapid adaptations not only in pathogen virulence but also host resistance following an initial outbreak. However, it is often unclear whether hosts will evolve to avoid infection-associated fitness costs by preventing the establishment of infection (here referred to as qualitative resistance) or by limiting its deleterious effects through immune functioning (here referred to as quantitative resistance). Equally, the evolutionary repercussions these different resistance mechanisms have for the pathogen are often unknown. Here, we investigate the co-evolutionary dynamics of pathogen virulence and host resistance following the epizootic outbreak of the highly pathogenic bacterium Mycoplasma gallisepticum in North American house finches (Haemorhous mexicanus). Using an evolutionary modelling approach and with a specific emphasis on the evolved resistance trait, we demonstrate that the rapid increase in the frequency of resistant birds following the outbreak is indicative of strong selection pressure to reduce infection-associated mortality. This, in turn, created the ecological conditions that selected for increased bacterial virulence. Our results thus suggest that quantitative host resistance was the key factor underlying the evolutionary interactions in this natural host-pathogen system.
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Affiliation(s)
| | - John Joseph Valletta
- Centre for Mathematics & the Environment, University of Exeter, Penryn, Cornwall, UK
| | | | - Mario Recker
- Centre for Mathematics & the Environment, University of Exeter, Penryn, Cornwall, UK
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Kerr PJ, Cattadori IM, Rogers MB, Fitch A, Geber A, Liu J, Sim DG, Boag B, Eden JS, Ghedin E, Read AF, Holmes EC. Genomic and phenotypic characterization of myxoma virus from Great Britain reveals multiple evolutionary pathways distinct from those in Australia. PLoS Pathog 2017; 13:e1006252. [PMID: 28253375 PMCID: PMC5349684 DOI: 10.1371/journal.ppat.1006252] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/14/2017] [Accepted: 02/20/2017] [Indexed: 11/19/2022] Open
Abstract
The co-evolution of myxoma virus (MYXV) and the European rabbit occurred independently in Australia and Europe from different progenitor viruses. Although this is the canonical study of the evolution of virulence, whether the genomic and phenotypic outcomes of MYXV evolution in Europe mirror those observed in Australia is unknown. We addressed this question using viruses isolated in the United Kingdom early in the MYXV epizootic (1954-1955) and between 2008-2013. The later UK viruses fell into three distinct lineages indicative of a long period of separation and independent evolution. Although rates of evolutionary change were almost identical to those previously described for MYXV in Australia and strongly clock-like, genome evolution in the UK and Australia showed little convergence. The phenotypes of eight UK viruses from three lineages were characterized in laboratory rabbits and compared to the progenitor (release) Lausanne strain. Inferred virulence ranged from highly virulent (grade 1) to highly attenuated (grade 5). Two broad disease types were seen: cutaneous nodular myxomatosis characterized by multiple raised secondary cutaneous lesions, or an amyxomatous phenotype with few or no secondary lesions. A novel clinical outcome was acute death with pulmonary oedema and haemorrhage, often associated with bacteria in many tissues but an absence of inflammatory cells. Notably, reading frame disruptions in genes defined as essential for virulence in the progenitor Lausanne strain were compatible with the acquisition of high virulence. Combined, these data support a model of ongoing host-pathogen co-evolution in which multiple genetic pathways can produce successful outcomes in the field that involve both different virulence grades and disease phenotypes, with alterations in tissue tropism and disease mechanisms.
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Affiliation(s)
- Peter J. Kerr
- Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Life and Environmental Sciences and Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
- CSIRO Health and Biosecurity, Canberra, Australian Capital Territory 2601, Australia
| | - Isabella M. Cattadori
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States of America
| | - Matthew B. Rogers
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, United States of America
| | - Adam Fitch
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, United States of America
| | - Adam Geber
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, New York 10003, United States of America
| | - June Liu
- CSIRO Health and Biosecurity, Canberra, Australian Capital Territory 2601, Australia
| | - Derek G. Sim
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States of America
| | - Brian Boag
- The James Hutton Institute, Invergowrie, DD2 5DA, United Kingdom
| | - John-Sebastian Eden
- Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Life and Environmental Sciences and Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Elodie Ghedin
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, New York 10003, United States of America
| | - Andrew F. Read
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States of America
| | - Edward C. Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Life and Environmental Sciences and Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
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Kerr PJ, Liu J, Cattadori I, Ghedin E, Read AF, Holmes EC. Myxoma virus and the Leporipoxviruses: an evolutionary paradigm. Viruses 2015; 7:1020-61. [PMID: 25757062 PMCID: PMC4379559 DOI: 10.3390/v7031020] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/20/2015] [Accepted: 02/26/2015] [Indexed: 01/31/2023] Open
Abstract
Myxoma virus (MYXV) is the type species of the Leporipoxviruses, a genus of Chordopoxvirinae, double stranded DNA viruses, whose members infect leporids and squirrels, inducing cutaneous fibromas from which virus is mechanically transmitted by biting arthropods. However, in the European rabbit (Oryctolagus cuniculus), MYXV causes the lethal disease myxomatosis. The release of MYXV as a biological control for the wild European rabbit population in Australia, initiated one of the great experiments in evolution. The subsequent coevolution of MYXV and rabbits is a classic example of natural selection acting on virulence as a pathogen adapts to a novel host species. Slightly attenuated mutants of the progenitor virus were more readily transmitted by the mosquito vector because the infected rabbit survived longer, while highly attenuated viruses could be controlled by the rabbit immune response. As a consequence, moderately attenuated viruses came to dominate. This evolution of the virus was accompanied by selection for genetic resistance in the wild rabbit population, which may have created an ongoing co-evolutionary dynamic between resistance and virulence for efficient transmission. This natural experiment was repeated on a continental scale with the release of a separate strain of MYXV in France and its subsequent spread throughout Europe. The selection of attenuated strains of virus and resistant rabbits mirrored the experience in Australia in a very different environment, albeit with somewhat different rates. Genome sequencing of the progenitor virus and the early radiation, as well as those from the 1990s in Australia and Europe, has shown that although MYXV evolved at high rates there was no conserved route to attenuation or back to virulence. In contrast, it seems that these relatively large viral genomes have the flexibility for multiple pathways that converge on a similar phenotype.
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Affiliation(s)
- Peter J Kerr
- CSIRO Biosecurity Flagship, Black Mountain Laboratories, Clunies Ross Street, Acton, ACT 2601, Australia.
| | - June Liu
- CSIRO Biosecurity Flagship, Black Mountain Laboratories, Clunies Ross Street, Acton, ACT 2601, Australia.
| | - Isabella Cattadori
- Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Elodie Ghedin
- Center for Genomics and Systems Biology, Department of Biology and Global Institute of Public Health, New York University, New York, NY 10003, USA.
| | - Andrew F Read
- Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Biological Sciences, and Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia.
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Hodcroft E, Hadfield JD, Fearnhill E, Phillips A, Dunn D, O'Shea S, Pillay D, Leigh Brown AJ. The contribution of viral genotype to plasma viral set-point in HIV infection. PLoS Pathog 2014; 10:e1004112. [PMID: 24789308 PMCID: PMC4006911 DOI: 10.1371/journal.ppat.1004112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 03/22/2014] [Indexed: 12/24/2022] Open
Abstract
Disease progression in HIV-infected individuals varies greatly, and while the environmental and host factors influencing this variation have been widely investigated, the viral contribution to variation in set-point viral load, a predictor of disease progression, is less clear. Previous studies, using transmission-pairs and analysis of phylogenetic signal in small numbers of individuals, have produced a wide range of viral genetic effect estimates. Here we present a novel application of a population-scale method based in quantitative genetics to estimate the viral genetic effect on set-point viral load in the UK subtype B HIV-1 epidemic, based on a very large data set. Analyzing the initial viral load and associated pol sequence, both taken before anti-retroviral therapy, of 8,483 patients, we estimate the proportion of variance in viral load explained by viral genetic effects to be 5.7% (CI 2.8-8.6%). We also estimated the change in viral load over time due to selection on the virus and environmental effects to be a decline of 0.05 log10 copies/mL/year, in contrast to recent studies which suggested a reported small increase in viral load over the last 20 years might be due to evolutionary changes in the virus. Our results suggest that in the UK epidemic, subtype B has a small but significant viral genetic effect on viral load. By allowing the analysis of large sample sizes, we expect our approach to be applicable to the estimation of the genetic contribution to traits in many organisms.
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Affiliation(s)
- Emma Hodcroft
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| | - Jarrod D. Hadfield
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| | | | - Andrew Phillips
- Infection and Population Health, University College London, Royal Free Hospital, London, United Kingdom
| | - David Dunn
- MRC Clinical Trials Unit Aviation House, London, United Kingdom
| | - Siobhan O'Shea
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | - Deenan Pillay
- Research Department of Infection, University College London, London, United Kingdom
| | - Andrew J. Leigh Brown
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
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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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Kerr PJ. Myxomatosis in Australia and Europe: a model for emerging infectious diseases. Antiviral Res 2012; 93:387-415. [PMID: 22333483 DOI: 10.1016/j.antiviral.2012.01.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 01/20/2012] [Accepted: 01/26/2012] [Indexed: 11/18/2022]
Abstract
Myxoma virus is a poxvirus naturally found in two American leporid (rabbit) species (Sylvilagus brasiliensis and Sylvilagus bachmani) in which it causes an innocuous localised cutaneous fibroma. However, in European rabbits (Oryctolagus cuniculus) the same virus causes the lethal disseminated disease myxomatosis. The introduction of myxoma virus into the European rabbit population in Australia in 1950 initiated the best known example of what happens when a novel pathogen jumps into a completely naïve new mammalian host species. The short generation time of the rabbit and their vast numbers in Australia meant evolution could be studied in real time. The carefully documented emergence of attenuated strains of virus that were more effectively transmitted by the mosquito vector and the subsequent selection of rabbits with genetic resistance to myxomatosis is the paradigm for pathogen virulence and host-pathogen coevolution. This natural experiment was repeated with the release of a separate strain of myxoma virus in France in 1952. The subsequent spread of the virus throughout Europe and its coevolution with the rabbit essentially paralleled what occurred in Australia. Detailed molecular studies on myxoma virus have dissected the role of virulence genes in the pathogenesis of myxomatosis and when combined with genomic data and reverse genetics should in future enable the understanding of the molecular evolution of the virus as it adapted to its new host. This review describes the natural history and evolution of myxoma virus together with the molecular biology and experimental pathogenesis studies that are informing our understanding of evolution of emerging diseases.
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Affiliation(s)
- Peter J Kerr
- CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, ACT 2601, Australia.
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11
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Mead-Briggs A, Hughes A. Records of mites and lice from wild rabbits collected throughout Great Britain. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/00222936508651629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- A.R. Mead-Briggs
- a Ministry of Agriculture, Fisheries and Food, Infestation Control Laboratory , Field Research Station , Tangley Place, Worplesdon, Guildford , Surrey
| | - A.M. Hughes
- b Royal Free Hospital School of Medicine , University of London , 8 Hunter Street, W.C.1
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Fouchet D, Guitton JS, Marchandeau S, Pontier D. Impact of myxomatosis in relation to local persistence in wild rabbit populations: the role of waning immunity and the reproductive period. J Theor Biol 2007; 250:593-605. [PMID: 18068733 DOI: 10.1016/j.jtbi.2007.10.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 10/24/2007] [Accepted: 10/27/2007] [Indexed: 10/22/2022]
Abstract
Many diseases are less severe when they are contracted in early life. For highly lethal diseases, such as myxomatosis in rabbits, getting infected early in life can represent the best chance for an individual to survive the disease. For myxomatosis, early infections are attenuated by maternal antibodies. This may lead to the immunisation of the host, preventing the subsequent development of the lethal form of the disease. But early infection of young individuals requires specific demographic and epidemiological contexts, such as a high transmission rate of the pathogen agent. To investigate other factors involved in the impact of such diseases, we have built a stochastic model of a rabbit metapopulation infected by myxomatosis. We show that the impact of the pathogen agent can be reduced by early infections only when the agent has a long local persistence time and/or when the host subpopulations are highly connected. The length of the reproductive period and the duration of acquired immunity are also important factors influencing the persistence of the pathogen and thus, the impact of the disease. Besides confirming the role of classical factors in the persistence of a pathogen agent, such as the size of the subpopulation or the degree of connectivity, our results highlight novel factors that can modulate the impact of diseases whose severity increase with age.
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Affiliation(s)
- David Fouchet
- UMR CNRS 5558 Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon1, 43 Boul. 11 Novembre 1918, 69622 Villeurbanne cedex, France.
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Effect of odor derived from lion faeces on behavior of wild rabbits. J Chem Ecol 1994; 20:631-7. [DOI: 10.1007/bf02059603] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1993] [Accepted: 11/02/1993] [Indexed: 10/25/2022]
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Abstract
National surveys of the virulence of field strains of myxoma virus were carried out in 1975 (128 virus strains) and in 1981 (123 strains), using the virulence testing method employed in a similar survey in 1962. Results showed that the virulence of field strains had increased between 1962 and 1975, and again between 1975 and 1981. The increases in virulence are thought to be a result of the development of resistance to myxomatosis in wild rabbit populations. The effects of the changes in virulence and resistance are discussed.
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SUMPTION KJ, FLOWERDEW JR. The ecological effects of the decline in Rabbits (Oryctolagus cuniculus L.) due to myxomatosis. Mamm Rev 1985. [DOI: 10.1111/j.1365-2907.1985.tb00396.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ross J, Sanders MF. The development of genetic resistance to myxomatosis in wild rabbits in Britain. J Hyg (Lond) 1984; 92:255-61. [PMID: 6736637 PMCID: PMC2129323 DOI: 10.1017/s0022172400064494] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The presence of genetic resistance to myxomatosis in a sample of wild rabbits from one area in England was reported in 1977. Rabbits from three other areas in Great Britain have been tested subsequently, and all cases showed similar resistance to a moderately virulent strain of myxoma virus. Rabbits from one area also showed a significant degree of resistance to a fully virulent strain of virus. It is concluded that genetic resistance to myxomatosis is widespread in wild rabbit populations in Britain. The implications of the results are discussed in relation to the co-evolution of the disease and its host.
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Abstract
Wild rabbits (Oryctolagus cuniculus) from one study area in England have been used over a period of 11 years to investigate the possible appearance of innate resistance to myxomatosis. Rabbits of 4-6 weeks old were captured alive, retained in the laboratory until at least 4 months old, and then infected with a type of myxoma virus which kills 90-95% of laboratory rabbits. Observations were made of symptoms, mortality rate and survival times.In the first 4 years of the study (1966-9), mortality rates were not significantly different from those of laboratory rabbits, although survival times of wild rabbits were appreciably longer. In 1970, the mortality rate amongst wild rabbits was 59%, in 1974 it was 17%, and in 1976 it was 20%, thus showing that a considerable degree of inherited resistance to myxomatosis has developed.The types of myxoma virus most commonly isolated from wild rabbits in Great Britain in recent years have been those which cause 70-95% mortality in laboratory rabbits. Therefore, if the degree of innate resistance demonstrated is widespread in Great Britain, there are serious implications regarding the size of the rabbit population, because myxomatosis has been an important factor in holding rabbit numbers at a relatively low level.
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Mead-Briggs AR, Vaughan JA. The differential transmissibility of Myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale). J Hyg (Lond) 1975; 75:237-47. [PMID: 1058245 PMCID: PMC2130293 DOI: 10.1017/s0022172400047276] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Laboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L) that had been infected for fever than 10-12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10-15 days and few fleas from these hosts became infective; averaging all the samples takem. 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which covered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency. For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.
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Sobey WR, Conolly D. Myxomatosis: the introduction of the European rabbit flea Spilopsyllus cuniculi (Dale) into wild rabbit populations in Australia. J Hyg (Lond) 1971; 69:331-46. [PMID: 5285938 PMCID: PMC2130908 DOI: 10.1017/s0022172400021574] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
1. The European rabbit flea Spilopsyllus cuniculi (Dale) bred successfully in wild rabbits on three properties in New South Wales and, within two breeding seasons, almost every rabbit shot within a quarter of a mile of a release site was infested.2. It was demonstrated that the flea transmitted myxoma virus in the field.3. In areas where more than 75% of the rabbits shot at the beginning of the breeding season were flea-infested and myxoma virus was present, populations failed to show the expected summer build-up.
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Sobey WR, Conolly D, Edmonds JW. Myxomatosis. The effect of age upon survival of wild and domestic rabbits (Oryctolagus cuniculus) with a degree of genetic resistance and unselected domestic rabbits infected with myxoma virus. J Hyg (Lond) 1970; 68:137-49. [PMID: 5267123 PMCID: PMC2130786 DOI: 10.1017/s002217240002859x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The response of wild and domestic rabbits with a degree of genetic resistance to myxomatosis has been shown to be markedly affected by the age at which they were infected with a virulent strain of the virus. The response, in terms of mean survival time and percentage survival, fell with increasing age from 10 to 30 weeks with little change thereafter.
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