Serological screening in wild ruminants in Germany, 2021/2022: No evidence of SARS‐CoV‐2, bluetongue virus or pestivirus spread but high seroprevalences against Schmallenberg virus

Abstract

Wildlife animals may be susceptible to multiple infectious agents of public health or veterinary relevance, thereby potentially forming a reservoir that bears the constant risk of re‐introduction into the human or livestock population. Here, we serologically investigated 493 wild ruminant samples collected in the 2021/2022 hunting season in Germany for the presence of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and four viruses pathogenic to domestic ruminants, namely, the orthobunyavirus Schmallenberg virus (SBV), the reovirus bluetongue virus (BTV) and ruminant pestiviruses like bovine viral diarrhoea virus or border disease virus. The animal species comprised fallow deer, red deer, roe deer, mouflon and wisent. For coronavirus serology, additional 307 fallow, roe and red deer samples collected between 2017 and 2020 at three military training areas were included. While antibodies against SBV could be detected in about 13.6% of the samples collected in 2021/2022, only one fallow deer of unknown age tested positive for anti‐BTV antibodies, and all samples reacted negative for antibodies against ruminant pestiviruses. In an ELISA based on the receptor‐binding domain (RBD) of SARS‐CoV‐2, 25 out of 493 (5.1%) samples collected in autumn and winter 2021/2022 scored positive. This sero‐reactivity could not be confirmed by the highly specific virus neutralisation test, occurred also in 2017, 2018 and 2019, that is, prior to the human SARS‐CoV‐2 pandemic, and was likewise observed against the RBD of the related SARS‐CoV‐1. Therefore, the SARS‐CoV‐2 sero‐reactivity was most likely induced by another hitherto unknown deer virus belonging to the subgenus Sarbecovirus of betacoronaviruses.

Wild Red Deer (Cervus elaphus) Do Not Play a Role as Vectors or Reservoirs of SARS-CoV-2 in North-Eastern Poland

“…There is no evidence that spillover of SARS-CoV-2 from human to deer populations occurred in the studied territory. Our results align with other European countries’ reports on wild deer populations [ 26 , 27 , 28 ]. Comprehensive studies from the United Kingdom [ 26 ], Austria and Germany [ 28 ] showed no sign of SARS-CoV-2 in several deer species.…”

“…Recent European efforts have sought to determine whether other deer species can also act as reservoirs for the SARS-CoV-2 virus. Serological studies conducted in Germany, Austria and the United Kingdom found no evidence of spillover of SARS-CoV-2 to cervid species in these regions [ 26 , 27 , 28 ].…”

Wild red deer (Cervus elaphus) do not play a role as vectors or reservoirs of SARS-CoV-2 in northeastern Poland

“…There is no evidence that spillover of SARS-CoV-2 from human to deer populations occurred in the studied territory. Our results align with other European countries' reports onild deer populations [24][25][26]. Comprehensive studies from the United Kingdom, Austria and Germany showed no sign of SARS-CoV-2 in several deer species.…”

“…They are considered to be timid and avoid contact with humans. This may explain our and other groups results, where red deer were found to be negative for SARS-CoV-2 screening [24][25][26]. Although routes of white-tailed deer infection are unclear, deer social behaviour might be the factor facilitating the quick spread of the pathogen.…”

“…Recent efforts in Europe have sought to determine whether other deer species can also act as reservoirs for the SARS-CoV-2 virus. Serological studies conducted in Germany, Austria and the United Kingdom found no evidence of spillover of SARS-CoV-2 to cervid species [24][25][26].…”