FIGURE 8.

Colorimetric RT-LAMP allows the detection of SARS-CoV-2 VOCs and VOIs. RT-LAMP reaction was performed at 65°C for 30 min, using the WarmStart^® colorimetric LAMP 2× master mix (NEB #M1804), using multiplex N2/E1 primer sets. The amplicons were migrated in agarose gel at 2% to confirm amplification, as indicated by the characteristic ladder highlighted by GelRed^® staining. NTC, nontemplate control; CS, clinical sample; and +C, positive control. The top panel shows a schematic representation of SARS-CoV-2 spike protein (upper) and where the main mutations are highlighted and represented in SARS-CoV-2 virions (right hand side) present in VOC gamma (B.1), delta (B.1.167.2), and VOI zeta (P.2). The VOCs alpha (B.1.1.7) and beta (B.1.3.51), first reported in the United Kingdom and South Africa, respectively, are also represented. K417N: lysine-to-asparagine substitution at position 417 of spike protein at the receptor biding domain (RBD); V445A: valine-to-alanine substitution at position 445 and so on. L, leucine; Q, glutamine; E, glutamic acid; Y, tyrosine; T, threonine; P, proline; H, histidine; D, aspartic acid; S, serine; F, phenylalanine. del, deletion. Segments of SARS-CoV-2 protein NTD, N-terminal domain; CTD2, C-terminal domain 2 or C terminus of S1 fragment after furin cleavage; FP, fusion peptide; HR1, heptad repeat region 1. SARS-CoV-2 variants were previously sequenced. Variants of interest B.1.1.371 and B.1.1.374 were first reported in Saudi Arabia and Finland, respectively, (https://cov-lineages.org/). Created with biorender.com.