Multiple Introductions of Rabbit Hemorrhagic Disease Virus Lagovirus europaeus/GI.2 in Africa

SIMPLE SUMMARY: For more than 35 years, lagomorphs, which include rabbits and hares, have been severely affected by hemorrhagic disease viruses, such as the rabbit hemorrhagic disease virus (RHDV). Rabbits are important host species in the ecosystem, as they are prey of many species in the wild, are reared for meat production in several countries, and are kept as pets. Molecular characterization of RHDV has been key to detecting multiple introductions of this virus into Africa. Continued monitoring and control of the rabbit trade is assuming particular importance in containing the disease and reducing the socio-economic impact of outbreaks in Africa while rabbits are being promoted for poverty reduction programs. ABSTRACT: Rabbit hemorrhagic disease (RHD) causes high mortality and morbidity in European rabbits (Oryctolagus cuniculus). In Africa, the presence of the causative agent, the rabbit hemorrhagic disease virus (RHDV), was first confirmed in 1992 (genotype Lagovirus europaeus/GI.1). In 2015, the new genotype Lagovirus europaeus/GI.2 (RHDV2/b) was detected in Tunisia. Currently, GI.2 strains are present in several North and Sub-Saharan African countries. Considerable economic losses have been observed in industrial and traditional African rabbitries due to RHDV. Like other RNA viruses, this virus presents high recombination rates, with the emergence of GI.2 being associated with a recombinant strain. Recombination events have been detected with both pathogenic (GI.1b and GII.1) and benign (GI.3 and GI.4) strains. We obtained complete genome sequences of Tunisian GI.2 strains collected between 2018 and 2020 and carried out phylogenetic analyses. The results revealed that Tunisian strains are GI.3P-GI.2 strains that were most likely introduced from Europe. In addition, the results support the occurrence of multiple introductions of GI.2 into Africa, stressing the need for characterizing complete genome sequences of the circulating lagoviruses to uncover their origin. Continued monitoring and control of rabbit trade will grant a better containment of the disease and reduce the disease-associated economic losses.