Field and experimental data indicate that the eastern cottontail (Sylvilagus floridanus) is susceptible to infection with European brown hare syndrome (EBHS) virus and not with rabbit haemorrhagic disease (RHD) virus

Abstract

The eastern cottontail (Sylvilagus floridanus) is an American lagomorph. In 1966, it was introduced to Italy, where it is currently widespread. Its ecological niche is similar to those of native rabbits and hares and increasing overlap in distribution brings these species into ever closer contact. Therefore, cottontails are at risk of infection with the two lagoviruses endemically present in Italy: Rabbit Haemorrhagic Disease virus (RHDV) and European Brown Hare Syndrome Virus (EBHSV). To verify the susceptibility of Sylvilagus to these viruses, we analyzed 471 sera and 108 individuals from cottontail populations in 9 provinces of north-central Italy from 1999 to 2012. In total, 15–20% of the cottontails tested seropositive for EBHSV; most titres were low, but some were as high as 1/1280. All the cottontails virologically tested for RHDV and EBHSV were negative with the exception of one individual found dead with hares during a natural EBHS outbreak in December 2009. The cottontail and the hares showed typical EBHS lesions, and the EBHSV strain identified was the same in both species (99.9% identity). To experimentally confirm the diagnosis, we performed two trials in which we infected cottontails with both EBHSV and RHDV. One out of four cottontails infected with EBHSV died of an EBHS-like disease, and the three surviving animals developed high EBHSV antibody titres. In contrast, neither mortality nor seroconversion was detected after infection with RHDV. Taken together, these results suggest that Sylvilagus is susceptible to EBHSV infection, which occasionally evolves to EBHS-like disease; the eastern cottontail could therefore be considered a “spill over” or “dead end” host for EBHSV unless further evidence is found to confirm that it plays an active role in the epidemiology of EBHSV.

Rabbits killing hares: an invasive mammal modifies native predator–prey dynamics

“…On the other hand, we cannot be completely sure about the lack of any role of cottontails in the transmission of other diseases, whose dynamics are less related to seasonal conditions. For example, cottontails can also be infected by EBHSV (Lavazza et al, 2015), and the same applies to foxes eating infected lagomorphs (Chiari et al, 2016). We recommend future studies exploring the potential role of cottontails in the epidemiology of EBHSV, as this virus is a serious threat for hare populations in Europe (Chiari et al, 2014).…”

“…Apparent competition is another major consequence of introduced mammals, especially on islands when both a prey and a predator are introduced causing hyperpredation processes (Courchamp et al, 2000;Zhang et al, 2006). Its interactions with the native European hare Lepus europaeus are complex, because the two species select different macro-and microhabitats (Bertolino, Cordero di Montezemolo & Perrone, 2011aVidus-Rosin et al, 2011), but cottontails carry several viruses and parasites, which can potentially affect hares (Bertolino et al, 2010;Tizzani et al, 2011Tizzani et al, , 2014Zanet et al, 2013;Lavazza et al, 2015). As the various competitive dynamics arising with the introduction of invasive mammals can produce long-standing effects on ecosystems, assessing their structure and magnitude is crucial to design effective policies aimed at reducing the impact of invasive species meanwhile minimizing collateral damage to ecosystems (Bergstrom et al, 2009). This work aims at modeling the ecological impact of an invasive mammal in northern Italy.…”

“…The eastern cottontail Sylvilagus floridanus has been introduced in north-western Italy during the 1960s and it is now widespread in northern and central Italy (Bertolino, Ingegno & Girardello, 2011b;Bertolino et al, 2011c). Its interactions with the native European hare Lepus europaeus are complex, because the two species select different macro-and microhabitats (Bertolino, Cordero di Montezemolo & Perrone, 2011aVidus-Rosin et al, 2011), but cottontails carry several viruses and parasites, which can potentially affect hares (Bertolino et al, 2010;Tizzani et al, 2011Tizzani et al, , 2014Zanet et al, 2013;Lavazza et al, 2015). Finally, the red fox Vulpes vulpes, a major predator for hares in Europe (e.g.…”

Diversity of RHD virus: epidemiological, diagnostic and immunological importance

“…Królak florydzki zajmujący te same stanowiska G 1-G5), podtyp RHDVa (genogrupa 6), RHDV2 i EBHSV ekologiczne, co króliki dzikie i zające, może w określonych warunkach ulegać zakażeniu EBHSV, lecz nie jest podatny na zakażenie RHDV. Z epizootycznego i ewolucyjnego punktu widzenia gatunek Sylvilagus spełnia tu rolę "ostatecznego gospodarza", a tę ścieżkę transmisji należy uznać za "ślepy zaułek" (38).…”

“…Dowodami potwierdzającymi skok międzygatunkowy lagowirusów i udział w tym procesie królaka florydzkiego z rodzaju Sylvilagus są serokonwersja przeciwciał RHDV i EBHSV oraz ograniczona podatność na zakażenie wirusem EBHS. Prawdopodobnie pierwotne lagowirusy mogły wywoły-wać bezobjawowe zakażenia u naturalnych gospodarzy, podobnie jak miało to miejsce w przypadku łagodnych postaci myksomatozy u gatunków Sylvilagus, które okazały się śmiertelne dla królika europejskiego w następstwie międzygatunkowego przeskoku (38). Na występowanie tego zjawiska wskazują zakażenia klasycznym RHDV stwierdzone u pokrewnych gatunków zajęcy iberyjskich (Lepus granatensis) w Portugalii (50) i RHDV2 u zajęcy płowych (Lepus capensis) na Sardynii oraz zajęcy apenińskich (Lepus corsicanus) na Korsyce (12,60).…”