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

Abstract

Since 2001, Pyrenean chamois (Rupicapra pyrenaica pyrenaica) populations have been affected by border disease virus (BDV) causing mortalities of more than 80% in some areas. Field studies carried out in France, Andorra, and Spain have shown different epidemiological scenarios in chamois populations. This study was designed to confirm the presence of BDV strains of a high and low virulence in free-ranging chamois populations from Pyrenees and to understand the implications of these findings to the diverse epidemiological scenarios. An experimental infection of Pyrenean chamois with a high-virulence (Cadí-6) and low-virulence (Freser-5) BDV strains was performed. Pregnant and non-pregnant animals with and without antibodies against BDV were included in each group. Cadí-6 BDV strain was confirmed to be of high virulence for seronegative adults and their foetuses. The antibody negative chamois infected with Freser-5 BDV strain did not show symptoms, presented less viral distribution and RNA load in tissues than Cadí-6 group, and cleared the virus from the serum. However, foetuses died before the end of the experiment and RNA virus was detected in sera and tissues although with lower RNA load than the Cadí-6 group.Chamois from both groups presented lesions in brain but the ones infected with the low-virulence Freser-5 BDV strain were mild and most likely transient. In both groups, seropositive pregnant females and all but one of their foetuses did not present viraemia or viral RNA in tissues. The existence of a low-virulence strain has been confirmed experimentally and related to chamois population infection dynamics in the area where it was isolated. Such strain may persist in the chamois population through PI animals and may induce cross-protection in chamois against high-virulence strains.This study demonstrates that viral strain diversity is a significant factor in the heterogeneity of epidemiological scenarios in Pyrenean chamois populations.

Distribution of Pestivirus exposure in wild ruminants in Spain

“…The susceptibility to infection by Pestiviruses A and D has also been confirmed in several free‐ranging wild ruminant species in this country (Colom‐Cadena et al., 2018; Factor et al., 2016; Fernández‐Aguilar et al., 2016; Rodríguez‐Prieto et al., 2016), where severe outbreaks of a disease associated with infection by a Pestivirus D genotype (BDV‐4 strain) have been reported in Southern chamois ( Rupicapra pyrenaica ) (Arnal et al., 2004; Luzzago et al., 2016; Marco et al., 2007). However, to date, the dynamics of viruses of the genus Pestivirus in the remaining European wild ruminant species and the putative role that these viruses play as disease agents are unknown, mainly because of the limited evidence from experimental infections (Cabezón et al., 2011; Colom‐Cadena et al., 2019; Martin et al., 2013).…”

An integrative and multi-indicator approach for wildlife health applied to an endangered caribou herd

“…Most probably vector-borne and climate linked 40 , 41 Pestivirus antibodies Health determinant Reproductive loss, possible sporadic and rare mortality reported in other species. Variability in virulence and highly mutagenic, long-term protective immunity after exposure 42 , 43 , 44 α-Herpesvirus antibodies Health determinant Ocular disease outbreaks and respiratory disease in reindeer but survival effects not demonstrated, possible reproductive loss. Long-term latency and reactivation under other stressors 45 , 46 Brucella antibodies Health determinant Reproductive loss, severe disease in some caribou but survival effects not demonstrated.…”

“…The remaining pathogens studied by serology, including pestivirus, N. caninum and α-herpesvirus, are less likely to cause significant mortality and are mostly associated with reproductive loss or other type of syndromes (Table 4 ). However, sporadic mortalities related to increased virulence in circulating pestivirus strains have been documented in other wild ungulates 52 , 42 . It is noteworthy that the sample prevalence of pestivirus, E. rhusipathiae , N. caninum and α-herpesvirus decreased along with the herd decline (Table 1 ).…”

An integrative and multi-indicator approach for wildlife health applied to an endangered caribou herd

“…The remaining pathogens studied by serology, including pestivirus, N. caninum and α-herpesvirus, are less likely to cause significant mortality and are mostly associated with reproductive loss or other type of syndromes (Table 1). However, sporadic mortalities related to increased virulence in circulating pestivirus strains have been documented in wild ungulates (Serrano et al 2015; Colom-Cadena et al 2019). It is noteworthy the decreasing trend in sample prevalence of pestivirus, E. rhusipathiae, N. caninum and α-herpesvirus along with the herd decline (Table 2).…”