Correction: Bilyy et al. Rapid Generation of Coronaviral Immunity Using Recombinant Peptide Modified Nanodiamonds. Pathogens 2021, 10, 861.

In the original publication [...].

Rapid Generation of Coronaviral Immunity Using Recombinant Peptide Modified Nanodiamonds.

Vaccination remains one of the most effective tools to prevent infectious diseases. To ensure that the best possible antigenic components are chosen to stimulate a cognitive immune response, boosting antigen presentation using adjuvants is common practice. Nanodiamond-based adjuvants are proposed here as a rapid and versatile platform for antigen conjugation, utilizing peptides common to different pathogenic strains and making this strategy a good candidate for a "ready-to-use" vaccine. Initiation of an inflammatory reaction with a resulting immune response is based on the ability of living organisms to entrap nanostructures such as nanodiamonds with neutrophil extracellular traps (NETs) formation. In this work, coronavirus peptide homological for MERS-CoV, fusion inhibitor, was conjugated to nanodiamonds and used to induce neutrophilic-driven self-limiting inflammation. The resulting adjuvant was safe and did not induce any tissue damage at the site of injection. Mice immunization resulted in IgG titers of »,000 within 28 days. Immunization of rabbits resulted in the formation of a high level of antibodies persistently present for up to 120 days after the first immunization (animal lifespan ~3 years). The peptide used for immunization proved to be reactive with sera of convalescent COVID patients, demonstrating the possibility of developing pancoronaviral vaccine candidates.

The Potential of Developing Pan-Coronaviral Antibodies to Spike Peptides in Convalescent COVID-19 Patients.

Coronaviruses share conservative spike protein (S) on their enveloped membrane surface, where S1 subunit recognizes and binds the cellular receptor, and the S2 subunit mediates membrane fusion. This similarity raises the question: does coronaviral infection by one create protection to others? Convalescent SARS-CoV-2 (COVID-19) sera were tested for cross reactivity with peptides from Middle East respiratory syndrome coronavirus (MERS-CoV) which shares 74% homology. Our results showed significant cross-reactivity with a peptide of the heptad repeat 2 (HR2) domain of the MERS-CoV spike protein. Sera samples of 47 validated seropositive convalescent COVID-19 patients and 40 sera samples of control patients, collected in pre-COVID time were used to establish cross-bind reactivity with the MERS-CoV peptide. Significantly stronger binding (p < 0.0001) was observed for IgG antibodies in convalescent COVID-19 patients compared to the control group. In ELISA, MERS-CoV peptide helps to discriminate post-COVID-19 populations and non-infected ones by the presence of antibodies in blood samples. This suggests that polyclonal antibodies established during SARS-CoV-2 infection can recognize and probably decrease severity of MERS-CoV and other coronaviral infections. The high homology of the spike protein domain also suggests that the opposite effect can be true: coronaviral infections produce cross-reactive antibodies effective against SARS-CoV-2. The collected data prove that despite the core HR2 region is hidden in the native viral conformation, its exposure during cell entry makes it highly immunogenic. Since inhibitory peptides to this region were previously described, this opens new possibilities in fighting coronaviral infections and developing vaccines effective even after possible viral mutations.