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

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.

First detection and molecular characterization of rabbit hemorrhagic disease virus (RHDV) in Algeria

“…In agreement with our findings, it has been reported that GI.2 strains induced, at least, 80% mortality ( 45 ). Moreover, in this study, RHDV positive samples were collected from rabbits at different ages and sexes, thereby contributing to confirm that GI.2 infects male and female rabbits at all ages ( 5 , 6 , 8 , 19 , 33 , 46 ).…”

“…Analysis of the VP60 ML tree revealed that all Algerian strains clustered within the strongly supported GI.2 group (bootstrap value 100), but they were further distributed into two distinct clusters. Indeed, the strain Algeria 002 grouped with the Tunisian GI.2 strains isolated from 2018 to 2020 (bootstrap value of 99) ( 33 ). The remaining six strains isolated between 2020 and 2021 (Algeria 024, 027, 052, 068, 076, and 083) appeared closely related to North American GI.2 strains (from 2020 to 2021; bootstrap value of 99.8).…”

“…Recently, outbreaks of RHD have been recorded in countries in North Africa, including Morocco ( 8 ), Tunisia ( 33 , 34 ) and Egypt ( 35 – 37 ). In addition, RHD was strongly suspected in Algeria due to the observation of high mortality rates and clinical signs in domestic rabbits, suggestive of the presence of the virus since at least 2018, but has never been confirmed.…”

Vaccination against Rabbit Hemorrhagic Disease Virus 2 (RHDV2) Using a Baculovirus Recombinant Vaccine Provides Durable Immunity in Rabbits

“…In New Zealand and Australia, where rabbits are considered an agricultural pest, the virus was released intentionally as a means of biological population control, where it reduced the population by nearly 95% [ 4 ]. In 2010, a novel strain of the virus, referred to as RHDV GI.2 or RHDV2, emerged in France and has since spread globally to nearly every continent, including Europe, Asia, Australia, Africa, and North America [ 5 , 6 , 7 , 8 , 9 ]. The original virus responsible for RHD, now called RHDV G1.1 or RHDV, has a high mortality rate in European rabbits ( Oryctolagus cuniculus ) but typically does not cause disease in other lagomorph species, while RHDV2 has a much broader host range, with documented infections in a variety of wild lagomorphs, including cottontails ( Sylvilagus spp.)…”

Epidemiological characterization and risk assessment of rabbit haemorrhagic disease virus 2 (RHDV2/b/GI.2) in the world

“…In January 2014, a strain of RHDV2 was found in dead rabbits vaccinated against RHDV in Australia, representing a transoceanic transmission of RHDV2 from Europe to Australia [ 14 ]. In February 2015, RHDV2 spread to Tunisia [ 15 ], the northernmost country in Africa, separated from Europe by the sea. In 2017, cases of RHDV2 were also reported in Morocco [ 16 ], an African country across the sea from Spain.…”