Background information
SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) was first detected in December 2019 in Wuhan, China. Since that time the virus kept mutating, leading to new virus variants. The B.1.617.2 lineage, also known Delta variant, as G/452R.V3, “double mutant” (T478K+L452R) or VUI-21APR-02, is a SARS-CoV-2 subvariant that was first discovered in India in December 2020. The mutations of this variant affect also immune-relevant parts of structural SARS-CoV-2 proteins and the respective sequences are available in GISAID, a genome data base. The mutations listed below are taken from sequence EPI_ISL_1718882. The B.1.617.2 lineage (Delta variant) has been found to evade a pre-existing antibody response and appears to be more infectious than other variants.
In total there are 10 mutations in the surface or spike glycoprotein (“S”) of the B.1.617.2 lineage (Delta variant) compared to the Wuhan variant (reference genome GenBank MN908947.3): T19R, G142D, E156G, deletion 157, deletion 158, L452R, T478K, D614G, P681R, and D950N. This subvariant lacks the E484Q mutation.
The PepTivator SARS-CoV-2 Prot_S B.1.617.2 Mutation Pool covers selectively the mutated regions. It consists of 32 peptides of 15 aa length. The PepTivator SARS-CoV-2 Prot_S B.1.617.2 Mutation Pool can be used to supplement PepTivators covering the sequence of the wild-type spike glycoprotein (“S”) in order to detect immune responses towards both variants, Wuhan (wild type) variant and B.1.617.2 lineage (Delta variant). PepTivator Peptide pools spanning the sequence of the spike glycoprotein (“S”) of the Wuhan (wild-type) variant are PepTivator SARS-CoV-2 Prot_S (predicted immunodominant sequence domains), Prot_S1 (N-terminal S1 domain), Prot_S+ (part of the C-terminal S2 domain) and Prot_S Complete (all functional domains).
The PepTivator SARS-CoV-2 Prot_S B.1.617.2 WT Reference Pool consists of the 32 homologous peptides of the Wuhan sequence and covers T19, G142, E156, F157, R158, L452, T478, D614, P681,
and D950 of the Wuhan variant (reference genome GenBank MN908947.3). PepTivator SARS-CoV-2 Prot_S B.1.617.2 WT Reference Pool serves as a control for the SARS-CoV-2 Prot_S B.1.617.2 Mutation Pool. Comparison of the T cell immune response upon stimulation with mutation and reference pool can be used to analyze mutation specific T cell responses.
