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Serology unveils decades-long contact of the Iberian hare, Lepus granatensis, with myxoma or antigenically-related virus.
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  • Fábio A. Abade dos Santos,
  • Nuno Santos,
  • Carina Carvalho,
  • Mónica Martinez,
  • Christian Gortazar,
  • Ignacio García-Bocanegra,
  • Margarida Duarte,
  • Paulo Alves
Fábio A. Abade dos Santos
University of Lisbon Faculty of Veterinary Medicine
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Nuno Santos
CIBIO-InBIO, Research Centre in Biodiversity and Genetic Resources, Vairão, Portugal
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Carina Carvalho
INIAV
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Mónica Martinez
Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF). Centro de Investigación Agroambiental El Chaparrillo, Ciudad Real, Spain
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Christian Gortazar
SaBio Instituto de Investigación en Recursos Cinegéticos IREC (UCLM & CSIC), Ciudad Real, Spain
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Ignacio García-Bocanegra
University of Cordoba Faculty of Veterinary
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Margarida Duarte
INIAV
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Paulo Alves
CIBIO-InBIO, Research Centre in Biodiversity and Genetic Resources, Vairão, Portugal
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Abstract

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 (88 live captured, 313 hunted and 50 found dead) collected over two time periods, 1994-1999 and 2017-2019, using a rabbit commercial indirect ELISA after validation, and tested different tissues or sera by a qPCR targeting M0005L/R gene conserved in MYXV and ha-MYXV. The cut-off of ELISA Relative Index 10 = 6.1 yielded an estimated positive predictive value of 96.4% (CI95% 82.6-98.0%), by comparison with qPCR positive and negative reference hares. Overall, antibodies were detected in 12.6% (57/451) of the hares tested, of which 40.3% (23/57) were also qPCR positive. Antibodies were found in apparently healthy hares sampled in 1994-1999 (n=10, none MYXV-DNA positive), and in 2017-2019 (n=28, of which 14% were MYXV-DNA positive). For the Iberian hares hunted or live trapped, seroprevalence was significantly higher in 2017-2019 (13.0%, CI95% 9.2-18.2%) than in 1994-1999 (5.4%, CI95% 3.0-9.6%) (p=0.005), and significantly higher in 2019 (p=0.007), being lower during the winter (p<0.001). While our molecular and serological results show that Iberian hares have been in contact with MYXV or an antigenically similar virus at least since 1994, they also show an increase in seroprevalence in 2018-2019. The more remote contact of hares with MYXV may have occurred with strains that circulated in wild rabbit, or unnoticed strains circulating in Iberian hare populations. This work clearly confirms the circulation of MYXV in the Iberian hare ate least 20 years before the severe virus outbreaks observed in 2018.

Peer review status:IN REVISION

18 Aug 2020Submitted to Transboundary and Emerging Diseases
19 Aug 2020Submission Checks Completed
19 Aug 2020Assigned to Editor
20 Aug 2020Reviewer(s) Assigned
10 Sep 2020Review(s) Completed, Editorial Evaluation Pending
17 Sep 2020Editorial Decision: Revise Major
20 Oct 20201st Revision Received
20 Oct 2020Submission Checks Completed
20 Oct 2020Assigned to Editor
20 Oct 2020Reviewer(s) Assigned
01 Nov 2020Review(s) Completed, Editorial Evaluation Pending
17 Nov 2020Editorial Decision: Revise Major