First Description of SARS-CoV-2 Infection in Two Feral American Mink (Neovison vison) Caught in the Wild

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19, is considered a pathogen of animal origin that is mainly transmitted from human to human. Several animal species can be naturally or experimentally infected by SARS-CoV-2, with compelling evidence that mink is highly susceptible to SARS-CoV-2 infection. Human-to-mink infection cases have been reported and there are also suggestions that mink-to-human infection occurs. Mink infections have been reported to date only on fur farms, except for one infected free- ranging wild mink near a Utah (USA) fur farm, which suggests a transmission pathway from farms to wild mink. We now report the detection of SARS-CoV-2 in 2 of 13 feral dark brown American mink (Neovison vison) trapped in the Valencian Community (Eastern Spain), during an invasive species trapping campaign. They were trapped in riverbeds in sparsely inhabited rural areas known to harbor self-sustained feral mink populations. The closest fur farm is about 20 km away. SARS-CoV-2 RNA was detected by two-step RT-PCR in these animals' mesenteric lymph nodes and was confirmed by sequencing a 397-nucleotide amplified region of the S gene, yielding identical sequences in both animals. A molecular phylogenetic analysis was run on this sequence, which was found to correspond to the consensus SARS-CoV-2 sequence from Wuhan. Our findings appear to represent the first example of SARS-CoV-2 acquired in the wild by feral mink in self-sustained populations.

Keywords: American mink; COVID-19; Neovison vison; SARS-CoV-2; spike; wildlife.

Figure 1

Study area. Feral American mink reports (1987–2016 [34]), trapping sites, and the closest fur farm are shown. (*) Indicates a trapping site where two of the present SARS-CoV-2-negative specimens were captured (then sharing the same UTM coordinates). Other symbols are shown in the key to the figure inset.

Figure 2

Alignment of partial S gene sequences. Sequences included, from top to bottom: Reference variant detected in Wuhan (GenBank ID: NC_045512.2); the presently identified sequence in mink 5 and 11 (in bold; both sequences are identical; GenBank and GISAID IDs MW741755 and EPI_ISL_1490748, respectively); positive control used (GISAID ID: EPI_ISL_423656); Danish mink sequence (GenBank ID: MT919536); USA mink sequence (GenBank ID: MW562304); and the variants indicated with their trivial and canonic designations (British, GISAID ID: EPI_ISL_581117; South African, GISAID ID: EPI_ISL_660605; Brazilian, GISAID ID: EPI_ISL_792680). Identical regions are marked at the bottom by asterisks. Base deviations from the Wuhan sequence are green shadowed and squared.

Figure 3

Molecular phylogenetic analysis using the sequence of a 397-nucleotide fragment of the SARS CoV-2 S gene (consensus genome coordinates, nt 22,728–23,124). The evolutionary history was inferred by the maximum likelihood method based on the Tamura–Nei model. The tree with the highest log likelihood (−2888) is shown. The percentage of trees in which the associated taxa clustered together is shown next to branches. Initial tree(s) for the heuristic search were obtained automatically by applying the Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then selecting the topology with superior log likelihood value. The tree is drawn to scale, with branch lengths according to (see scale bar at the bottom) the number of substitutions per site. The analysis involved 28 nucleotide sequences. The sequence obtained from two feral American mink reported here is highlighted in bold.