Experimental Infection of Pregnant Pyrenean Chamois (Rupicapra Pyrenaica) With Border Disease Virus Subtype 4

Abstract

ABSTRACT:Border disease virus (BDV) causes high mortality in Pyrenean chamois (Rupicapra pyrenaica) on the French and Spanish sides of the Pyrenees Mountains. We investigated the pathology induced by BDV in pregnant chamois via experimental infection. Three females were inoculated during the second third of pregnancy with a BDV-4 subgroup strain isolated from a wild Pyrenean chamois during an acute epizootic. A fourth pregnant chamois and one nonpregnant ewe were kept as negative controls. Animals were monitored to assess clinical signs, hematology, viremia, and serology. Postmortem examinations included necropsy, histopathology, and quantification of viral RNA in organs. Pregnancy was unsuccessful in all inoculated animals. One died 24 days postinoculation (dpi) without showing any precursory clinical signs. The second animal had profuse diarrhea from 13 dpi to its death at 51 dpi. The third aborted at 46 dpi and was euthanized at 51 dpi. All animals were viremic from 4 dpi until death. Neutralizing antibodies against BDV-4 were detected from 12 dpi. Necropsies showed generalized lymphadenomegaly, associated in one case with disseminated petechial hemorrhages in the digestive tract. Seventyeight of 79 organs from inoculated adults and their fetuses had detectable viral RNA. The main histologic lesions in adults were mild lymphohistiocytic encephalitis associated with moderate or moderately severe lymphoid depletion. Control animals remained negative for virus (in blood and organs), antibody, and lesions upon postmortem examination. BDV infection during pregnancy in Pyrenean chamois causes severe disease leading to abortion, then death. Despite 100% fetal death following inoculation, viral RNA was recovered from all organs of infected fetuses, suggesting that persistently infected offspring could be born. Our results may help explain the reported decrease in chamois populations in several areas and suggest that great care must be taken when interpreting infection status for wildlife.

Experimental infection with high‐ and low‐virulence strains of border disease virus (BDV) in Pyrenean chamois (Rupicapra p. pyrenaica) sheds light on the epidemiological diversity of the disease

“…The present research demonstrates that, in horizontally infected chamois, high RNA loads are excreted by nasal route and to a lower extent by rectal route, for at least 18 days. This, together with the findings of previous reports demonstrating these and vaginal and oral routes as a source of virus excretion (Cabezón, Rosell, Velarde, et al, ; Cabezón et al, ; Martin et al, ), strongly suggests that horizontal transmission has been the key factor in the reported severe epidemics in the Pyrenees. Moreover, the exceptionally long viraemia of high‐virulence BDV strains in chamois may have been also of importance for the epidemiology of the disease.…”

“…In previous BDV experimental infections in chamois with high‐virulence strains, like BDV Cadí‐6, the animals developed a long‐lasting viraemia (Cabezón et al, ; Martin et al, ). The epidemiological consequences of these high‐virulence strains have been exemplified in field studies by the reports of high mortality outbreaks in free‐ranging populations.…”

“…(Cabezón et al, ) and from day 12 p.i. (Martin et al, ) onwards, highlighting the importance of horizontally infected chamois in this virus spread. In domestic ruminants, a key role in pestivirus maintenance at a population level is played by persistently infected (PI) animals.…”

“…Cabezón et al () performed an experimental infection in chamois demonstrating that a BDV‐4 strain isolated from a diseased chamois causes long‐lasting viraemia with pathological changes mainly characterized by non‐suppurative meningoencephalitis. Martin et al () infected three pregnant Pyrenean chamois with the same BDV strain. All of the animals died before parturition, and foetal death, viral presence in foetuses and adult tissues with viraemia for at least 51 days were found.…”

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Border disease

“…• Pyrenean chamois (Rupicapra pyrenaica) (Martin et al, 2013) Parameter 4 -Experimentally susceptible domestic species (or family/orders) • Sheep (Nettleton et al, 1992) • Goats (Løken et al, 1991) • Cattle (Braun et al, 2015) • Pigs (Cabez on et al, 2010a)…”