SARS-CoV-2 mutations among minks show reduced lethality and infectivity to humans

Abstract

SARS-CoV-2 infection in minks has become a serious problem, as the virus may mutate and reinfect humans; some countries have decided to cull minks. Here, the virus sequencing data in minks were analysed and compared to those of human-virus. Although the mink-virus maintained the characteristics of human-virus, some variants rapidly mutated, adapting to minks. Some mink-derived variants infected humans, which accounted for 40% of the total SARS-CoV-2 cases in the Netherlands. These variants appear to be less lethal and infective compared to those in humans. Variants that have mutated further among minks were not found in humans. Such mink-viruses might be suitable for vaccination for humans, such as in the case of the smallpox virus, which is less infective and toxic to humans.

Fig 1. Principal Component Analysis (PCA) for samples.

A. PC1 and PC2. These axes show the adaptation process of SARS-CoV-2 to humans [19]. Seven thousand of mink-virus are coloured in transparent blue; concentrated blue show multiple stackings. This is the same in 17,000 human-virus. The white dot indicates the position of NB-EMC-35-3, a group 2 mink-virus (S1 Table). B. PC8 and PC9. Mutations found in group 2 mink-virus in the Netherlands are presented on these axes. The presented IDs are those for mink-virus. The downward blue arrow indicates the mink-derived human-virus. C. Part of panel B enlarged. All IDs indicate human-virus, except for NB-EMC-6-13. The mink-derived human-virus are circled with a blue dotted line.

Fig 2. The SARS-CoV-2 outbreak in the Netherlands.

A. Number of confirmed cases, deaths, and PC for human-virus. Before the second wave, variants had changed (coloured points of specified axes of PCs). The mink-derived human-virus appeared at and above the level of PC8 (x) indicated by the blue arrow. B. Rates of fatality (number of deaths in the following week/cases, grey) and the mink-derived variants (red). C. Comparison of fatality rates in August and October. The thick horizontal line indicates the estimation of the rate. The whiskers show 95% confidence intervals, and the boxes show the quartiles. The situation in Denmark is presented in S1 Fig.