Rabbit Hemorrhagic Disease Virus 2 Experimental Infection in Snowshoe Hares (Lepus americanus)

Rabbit hemorrhagic disease virus 2 (RHDV2) is an emerging virus of lagomorphs, with an extremely high mortality rate. Outbreaks of RHDV2 have been reported in domestic and wild European rabbits (Oryctolagus cuniculus) and wild lagomorphs globally, with the recent emergence and establishment of RHDV2 in the USA in 2018 and 2020, respectively. Here, we describe experimental infections in snowshoe hares (Lepus americanus), a species of conservation interest in the US. In this pilot study that took place January-April 2022, six hares were orally exposed to infectious virus and monitored for clinical signs and viral shedding for 2 wk. Snowshoe hares were relatively resistant to disease, with no hares succumbing to lethal infection during the experimental time frame (14 d) and animals showing histopathologic evidence of recovery from hepatic injury. Liver samples collected postmortem and pooled fecal samples collected daily were PCR positive for RHDV2, indicating that the hares were indeed infected and shedding viral particles. The majority of hares (5/6) seroconverted by the end of the study. These findings suggest that snowshoe hares are susceptible to RHDV2 and can potentially shed virus onto the landscape, but are less likely to be affected clinically than certain other species of lagomorph.