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. 2017 Nov 15;13(1):336.
doi: 10.1186/s12917-017-1257-3.

Detection of rabbit Haemorrhagic disease virus 2 during the wild rabbit (Oryctolagus cuniculus) eradication from the Berlengas archipelago, Portugal

F A Abade Dos Santos  1   2 , C Carvalho  3 , Oliveira Nuno  4 , J J Correia  5 , M Henriques  6 , M C Peleteiro  5 , M Fevereiro  6 , M D Duarte  6
Affiliations

Detection of rabbit Haemorrhagic disease virus 2 during the wild rabbit (Oryctolagus cuniculus) eradication from the Berlengas archipelago, Portugal

F A Abade Dos Santos et al. BMC Vet Res. .

Abstract

Background: In the regular wildlife monitoring action carried out in the summer of the past few years at the Berlenga Island, wild rabbits (Oryctolagus cuniculus) have been repeatedly found dead. However, the origin of those deaths was never investigated. Our aim was to investigate the cause of death of 11 rabbits collected between April and May 2016.

Results: While screening samples from rabbit carcasses for the major viral rabbit pathogens, five tested positive to RHDV2 but all were negative for RHDV and myxoma virus (MYXV). For six RHDV2-negative specimens, emaciation and parasitism were considered the most probable cause of death. Lesions identified in the RHDV2-positive rabbits included non-suppurative diffuse hepatic necrosis and pulmonary lesions varying from congestion and oedema of the lungs to interstitial pneumonia. Sequencing analysis of the vp60 gene obtained from two specimens showed identical vp60 sequences. Comparison with other known RHDV2 strains from public databases through BLAST analysis revealed a closer similarity with strains from Alentejo collected during 2013. Maximum Likelihood and Bayesian phylogenetic analysis showed that the 2016 strains from the archipelago have a higher resemblance with a group of strains mostly collected in the South of Portugal between 2013 and 2014.

Conclusion: The results suggest that RHDV2 may have been introduced on the Berlenga Island a few years ago, having evolved separately from mainland strains due to insularity.

Keywords: Berlenga Island; Berlengas; Oryctolagus cuniculus; RHDV2; Rabbit haemorrhagic disease virus; UNESCO; Wild rabbit.

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Conflict of interest statement

Ethics approval and consent to participate

This article does not contain any studies with human or animal subjects. All biological samples were collected from animals found dead in the Berlenga Island, Portugal. The carcasses were collected within the scope of the LIFE Berlengas project (Conserving threatened habitats and species in Berlengas SPA through sustainable management, LIFE13 NAT/PT/000458).

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests. All permissions to handling animals and collect rabbit samples were obtained from the national authorities.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Berlengas Island, the major island of the Berlengas’ archipelago, located in the Portuguese maritime coast, and Peniche municipality (Portugal mainland) are marked on the map
Fig. 2
Fig. 2
Density of the wild rabbit population in the Berlengas Natural Reserve calculated through several transects performed over 2015 and 2016
Fig. 3
Fig. 3
Maximum Likelihood (ML) phylogenetic tree of the RHDV2 vp60 complete nucleotide sequences from the Berlenga island (2016) and others originated in Portugal mainland, Azores, Spain, France, Italy and Malta, available in Genbank. Bootstrap values (BS) are shown next to the nodes if equal or greater than 70. Sequence KC345614 (not displayed) was chosen as outgroup to root the tree. In the left side tree, the major groups are collapsed to facilitate visualization. a-HE800531, HE819400; b-JX106023, KC345611–12; c-HE800529, HE800530, HE800532 and FR819781; d-JQ929052, KC907712 and JX106022; e-KM87868; f-KP129395; g-KM979445; h-KM115675–76; i-KM115712–13; j-KT000295, KT000303, KT000308, KT000311, KT000316–319, KT000322–325 KT000327, KT000329–330, KT000332–333, KT000336, KT000339 and KT000341–343; k-KX132812 and KX132813; l-KM115684–5; m-KP129396; n-KJ957809 and KJ957810; o-KC741409; p-KP129397 and KP129399. “M-o-Novo” refers to the municipality of Montemor-o-Novo. A close-up of the RHDV2 strains more closely related with the strains from the Berlenga Island is shown in the right side of the figure
Fig. 4
Fig. 4
Liver of rabbit positive to RHDV2. a - Diffuse hepatocyte coagulation necrosis with no pattern distribution. Most hepatocytes are karyolytic and only very few display karyorrhexis or pyknosis. b – Detail of A showing necrotic hepatic cells dysplaing karyorrhexis and pyknosis (H&E)
Fig. 5
Fig. 5
Lung of rabbits positive to RHDV2. a – Alveolar congestion and oedema. b-Interstitial pneumonia with inflammatory infiltrates in the alveolar septa by mononuclear cells, which are also present in the alveolar lumen (H&E)
See this image and copyright information in PMC

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