key: cord-1047255-m3gjvrpe
authors: Conzelmann, Carina; Weil, Tatjana; Olari, Lia-Raluca; Gilg, Andrea; Rauch, Lena; Albers, Dan P.J.; Groß, Rüdiger; Müller, Janis A.; Münch, Jan
title: Virucidal activity of SARS-CoV-2 rapid antigen extraction buffers
date: 2021-12-27
journal: J Clin Virol
DOI: 10.1016/j.jcv.2021.105062
sha: f163e6c64f97ea60781a9b68884ce3028f5f96da
doc_id: 1047255
cord_uid: m3gjvrpe

Since diagnostic sampling material must be considered as infectious, we evaluated whether extraction buffers of SARS-CoV-2 rapid antigen test kits may inactivate SARS-CoV-2. Of concern, seven of nine tested buffers lacked potent virucidal activity. To reduce risk of infection during assay performance, virucidal antigen extraction buffers that efficiently inactivate virus should replace the extraction buffers in these commercially available point-of-care devices.

In late 2019, SARS-CoV-2 emerged as a human pathogen resulting in a pandemic with 38 several million deaths worldwide [1] . Countermeasures taken include vaccination, social inactivating [4]. Since the sampling material, i.e. saliva and nasopharyngeal swabs, must be 51 considered as infectious, the WHO recommends the handling of sample material and its 52 testing in a biological safety cabinet [5] . However, the tests are also performed at places 53 without adequate safeguards, e.g. in the private (household) and public (school, work place, 54 restaurants) [3] . We here evaluated whether extraction buffers of commercially available 55 SARS-CoV-2 antigen tests inactivate SARS-CoV-2, which would minimize the risk of 56 infection during and after assay performance. 

Hence, we here evaluated whether antigen extraction buffers of nine commercially available 63 SARS-CoV-2 antigen test kits (buffers B1-B9, Table S1 ) inactivate SARS-CoV-2, which 64 would minimize the risk of infection during and after assay performance. As control, a newly 65 developed antigen extraction buffer with known virucidal activity (buffer B10, Table S1 ) was 66 included. To be within the range of SARS-CoV-2 concentrations detected in patient swabs 67 [6,7] we used viable SARS-CoV-2 adjusted to 3.2 × 10 10 RNA copies/ml. In order to mimic Remaining viral infectivity was then determined by 50% tissue culture infectious dose 75 (TCID 50 ) analysis. As shown in Figure 1a and 1b, most buffers did not fully inactivate SARS-

CoV-2 infectivity. The PBS control demonstrated high infectivity with 1.7 × 10 5 TCID 50 /ml 77 after 1 min incubation (Figure 1a ), and 7.1 × 10 4 TCID 50 /ml after 15 min incubation ( Figure   78 1b). After 1-minute incubation, virucidal B10 diminished infectivity below the detection 79 limit, which corresponds to a 99.92% reduction (Figure 1a ). After 15 minutes incubation, B6, 80 B7 and B10 inactivated SARS-CoV-2 below the detection limit, yielding a 96.10% (B6), Buffer B10 displayed highest virucidal activity but lowest cytotoxic effects (Figure 1a, b) . 85 Thus, we further evaluated its virucidal activity against circulating SARS-CoV-2 variants of 86 concern (VOCs). As saliva rather than nasopharyngeal swabs are proposed as novel gold 

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