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Four RHDV2 Recombinant Lineages Circulated in European Hares in Catalonia

Wild European hare in natural habitat on the Iberian Peninsula
Research: Disease, parasites & microbiology, Genetics & genomics

A 2026 study traced the genetic turnover of rabbit haemorrhagic disease virus 2, RHDV2/GI.2, in wild lagomorphs from Catalonia in northeastern Spain. Researchers analysed viral coding sequences from 44 European rabbits, 21 European hares (Lepus europaeus) and one Iberian hare collected through wildlife disease surveillance between 2014 and 2024.

RHDV2 is a highly virulent lagovirus that causes rabbit haemorrhagic disease and has caused substantial mortality in European rabbits, while infections also occur in hares. Tracking recombinant lineages therefore helps show how a damaging wildlife virus is evolving and circulating among lagomorph hosts.

All viruses carried the GI.2 capsid — the protein shell surrounding the viral genome — but parts of the non-structural genome came from other lagovirus lineages. This is viral recombination: genetic material from different viral lineages is combined into a new genome. Four recombinant profiles were identified, and all four occurred in European hares: GI.3P–GI.2 and GI.1bP–GI.2 were each found in two hares, GI.4P–GI.2 in five, and the triple recombinant GI.4(p16)–GI.1bP–GI.2 in twelve. European rabbits carried three of them. One profile was a triple recombinant in which the p16 region came from GI.4, other non-structural regions from GI.1b and the capsid from GI.2. The same recombinant profiles were found in rabbits and hares in areas where both species had confirmed cases.

Map of RHDV2 recombinant detections in wild lagomorphs in Catalonia from 2014 to 2024
Spatial distribution of RHDV2/GI.2 recombinant lineages detected in European rabbits, European hares and one Iberian hare in Catalonia between 2014 and 2024. Figure 1 from Estruch et al. (2026), CC BY 4.0.

The dominant recombinant changed over the decade

The dominant recombinant changed over the decade. GI.3P–GI.2 appeared only in 2014, GI.1bP–GI.2 persisted from 2015 to 2018, and GI.4(p16)–GI.1bP–GI.2 became the most frequent profile from 2017 to 2019. GI.4P–GI.2 first appeared in 2020 and then became predominant through 2024.

The authors conclude that recombination and lineage replacement have been important features of RHDV2 evolution in Catalonia. The changing non-structural regions may influence viral fitness — how well a variant can reproduce and persist in circulation — and epidemiological behaviour, although the function of components such as p16 is still uncertain. The occurrence of the same lineages in several wild lagomorph species also shows that the virus has circulated across host-species boundaries in the region. Because the material came from passive surveillance of animals found dead or reported sick, sample numbers varied between years and the observed turnover should not be treated as a complete census of every lineage circulating at each point in time.

Sources and image credit

  1. Estruch, J., Almeida, T., Serrano, E., Pereira, L., Rouco, C., Lavín, S., Abrantes, J., Velarde, R., & Lopes, A. M. (2026). Temporal dynamics and turnover of rabbit hemorrhagic disease virus 2 (RHDV2/GI.2) in wild lagomorphs from northeastern Spain. Microbial Ecology, 89, 89. https://doi.org/10.1007/s00248-026-02746-xPrimary open-access research article first published 21 March 2026 under CC BY 4.0. Coding sequences from 44 European rabbits, 21 European hares and one Iberian hare in Catalonia showed four recombinant RHDV2/GI.2 profiles and temporal turnover of the dominant lineages from 2014 to 2024.

Image: Salvador Escriva / Wikimedia Commons — living European hare photographed on the Iberian Peninsula; representative species image, not one of the sampled hares. · CC BY-SA 4.0 · Source

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