SM-COLSARSPROT: Highly Immunogenic Supramutational Synthetic Peptides Covering the World's Population.

Fifty ~20-amino acid (aa)-long peptides were selected from functionally relevant SARS-CoV-2 S, M, and E proteins for trial B-21 and another 53 common ones, plus some new ones derived from the virus' main genetic variants for complementary trial C-21. Peptide selection was based on tremendous SARS-CoV-2 genetic variability for analysing them concerning vast human immunogenetic polymorphism for developing the first supramutational, Colombian SARS-protection (SM-COLSARSPROT), peptide mixture. Specific physicochemical rules were followed, i.e., aa predilection for polyproline type II left-handed (PPIIL) formation, replacing ß-branched, aromatic aa, short-chain backbone H-bond-forming residues, π-π interactions (n→π* and π-CH), aa interaction with π systems, and molecular fragments able to interact with them, disrupting PPIIL propensity formation. All these modified structures had PPIIL formation propensity to enable target peptide interaction with human leukocyte antigen-DRß1* (HLA-DRß1*) molecules to mediate antigen presentation and induce an appropriate immune response. Such modified peptides were designed for human use; however, they induced high antibody titres against S, M, and E parental mutant peptides and neutralising antibodies when suitably modified and chemically synthesised for immunising 61 major histocompatibility complex class II (MHCII) DNA genotyped Aotus monkeys (matched with their corresponding HLA-DRß1* molecules), predicted to cover 77.5% to 83.1% of the world's population. Such chemically synthesised peptide mixture represents an extremely pure, stable, reliable, and cheap vaccine for COVID-19 pandemic control, providing a new approach for a logical, rational, and soundly established methodology for other vaccine development.

The First Chemically-Synthesised, Highly Immunogenic Anti-SARS-CoV-2 Peptides in DNA Genotyped Aotus Monkeys for Human Use.

Thirty-five peptides selected from functionally-relevant SARS-CoV-2 spike (S), membrane (M), and envelope (E) proteins were suitably modified for immunising MHC class II (MHCII) DNA-genotyped Aotus monkeys and matched with HLA-DRß1* molecules for use in humans. This was aimed at producing the first minimal subunit-based, chemically-synthesised, immunogenic molecules (COLSARSPROT) covering several HLA alleles. They were predicted to cover 48.25% of the world's population for 6 weeks (short-term) and 33.65% for 15 weeks (long-lasting) as they induced very high immunofluorescent antibody (IFA) and ELISA titres against S, M and E parental native peptides, SARS-CoV-2 neutralising antibodies and host cell infection. The same immunological methods that led to identifying new peptides for inclusion in the COLSARSPROT mixture were used for antigenicity studies. Peptides were analysed with serum samples from patients suffering mild or severe SARS-CoV-2 infection, thereby increasing chemically-synthesised peptides' potential coverage for the world populations up to 62.9%. These peptides' 3D structural analysis (by 1H-NMR acquired at 600 to 900 MHz) suggested structural-functional immunological association. This first multi-protein, multi-epitope, minimal subunit-based, chemically-synthesised, highly immunogenic peptide mixture highlights such chemical synthesis methodology's potential for rapidly obtaining very pure, highly reproducible, stable, cheap, easily-modifiable peptides for inducing immune protection against COVID-19, covering a substantial percentage of the human population.