A DNA sequence encoding the SARS-CoV-2 (XEC) Spike S1+S2 (YP_009724390.1, with mutations T19I, R21T, T22N, L24S, del25/27, S50L, F59S, del69/70, V127F, G142D, del144/144, F157S, R158G, N211I, del212/212, V213G, L216F, H245N, A264D, I332V, G339H, K356T, S371F, S373P, S375F, T376A, R403K, D405N, R408S, K417N, N440K, V445H, G446S, N450D, L452W, L455S, F456L, N460K, S477N, T478K, N481K, del483/483, E484K, F486P, Q493E, Q498R, N501Y, Y505H, E554K, A570V, D614G, P621S, H655Y, N679K, P681R, R682G, R683S, R685S, N764K, D796Y, F817P, A892P, A899P, S939F, A942P, Q954H, N969K, K986P, V987P, V1104L, P1143L and furin cleavage site mutants) expressed with the bacteriophage T4 fibritin and a polyhistidine tag at the C-terminus. The mutations were identified in the SARS-CoV-2 variant (known as variant XEC).