Rabbit IL-4 was expressed in the virulent standard laboratory strain (SLS) and the attenuated Uriarra (Ur) strain of myxoma virus with the aim of creating a Th2 cytokine environment and inhibiting the development of an antiviral cell-mediated response to myxomatosis in infected rabbits. This allowed testing of a model for genetic resistance to myxomatosis in wild rabbits that have undergone 50 years of natural selection for resistance to myxomatosis. Expression of IL-4 significantly enhanced virulence of both virulent and attenuated virus strains in susceptible (laboratory) and resistant (wild) rabbits. SLS-IL-4 completely overcame genetic resistance in wild rabbits. The pathogenesis of SLS-IL-4 was compared in susceptible and resistant rabbits. The results support a model for resistance to myxomatosis of an enhanced innate immune response controlling virus replication and allowing an effective antiviral cell-mediated immune response to develop in resistant rabbits. Expression of IL-4 did not overcome immunity to myxomatosis induced by immunization.
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http://dx.doi.org/10.1016/j.virol.2004.02.031 | DOI Listing |
Epidemiol Infect
October 2023
School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia.
Wild rabbits in Australia developed genetic resistance to the myxoma virus, which was introduced as a biological control agent. However, little is known about the rate at which this evolutionary change occurred. We collated data from challenge trials that estimated rabbit resistance to myxomatosis in Australia and expressed resistance on a continuous scale, enabling trends in its development to be assessed over 45 years up to 1995.
View Article and Find Full Text PDFTransbound Emerg Dis
November 2022
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal.
The 2018 outbreak of myxomatosis in the Iberian hare (Lepus granatensis) has been hypothesized to originate from a species jump of the rabbit-associated myxoma virus (MYXV), after natural recombination with an unknown poxvirus. Iberian hares were long considered resistant to myxomatosis as no prior outbreaks were reported. To provide insights into the emergence of this recombinant virus (ha-MYXV), we investigated serum samples from 451 Iberian hares collected over two time periods almost two decades apart, 1994-1999 and 2017-2019 for the presence of antibodies and MYXV-DNA.
View Article and Find Full Text PDFJ Virol
October 2022
Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State Universitygrid.29857.31, University Park, Pennsylvania, USA.
To characterize the ongoing evolution of myxoma virus in Australian rabbits, we used experimental infections of laboratory rabbits to determine the virulence and disease phenotypes of recent virus isolates. The viruses, collected between 2012 and 2015, fell into three lineages, one of which, lineage c, experienced a punctuated increase in evolutionary rate. All viruses were capable of causing acute death with aspects of neutropenic septicemia, characterized by minimal signs of myxomatosis, the occurrence of pulmonary edema and bacteria invasions throughout internal organs, but with no inflammatory response.
View Article and Find Full Text PDFTransbound Emerg Dis
May 2021
Área de Epidemiología, Subdirección General de Sanidad e Higiene Animal y Trazabilidad, Ministerio de Agricultura, Pesca y Alimentación, Madrid, Spain.
Myxomatosis is an infectious disease caused by the myxoma virus (MYXV), which has very high mortality rates in European wild rabbits (Oryctolagus cuniculus). While sporadic cases of myxomatosis have also been reported in some hare species, these lagomorphs are considered to have a low susceptibility to MYXV infection. In the present study, we describe the spatiotemporal evolution and main epidemiological findings of novel hare MYXV (ha-MYXV or MYXV-Tol) epidemics in Iberian hares (Lepus granatensis) in Spain.
View Article and Find Full Text PDFMed Sci (Paris)
April 2020
CIBIO, Centro de investigação em biodiversidade e recursos genéticos, InBIO laboratório associado, Universidade do Porto, 4485-661 Vairão, Portugal. - Departamento de biologia, Faculdade de ciências da Universidade do Porto, 4169-007 Porto, Portugal. - Department of zoology, Faculty of sciences, University of Johannesburg, Auckland Park 2006, Afrique du Sud.
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