Cross-Neutralizing Activity Against Omicron Could Be Obtained in SARS-CoV-2 Convalescent Patients Who Received Two Doses of mRNA Vaccination

Abstract

The SARS-CoV-2 variant Omicron is now under investigation. We evaluated cross-neutralizing activity against Omicron in COVID-19 convalescent patients (n = 23) who had received two doses of an mRNA vaccination (BNT162b2 or mRNA-1273). Intriguingly, after the second vaccination, the neutralizing antibody titers of subjects against SARS-CoV-2 variants, including Omicron, all became seropositive, and significant fold-increases (21.1–52.0) were seen regardless of the disease severity of subjects. Our findings thus demonstrate that two doses of mRNA vaccination to SARS-CoV-2 convalescent patients can induce cross-neutralizing activity against Omicron.

High‐resolution analysis of individual spike peptide‐specific CD4+ T‐cell responses in vaccine recipients and COVID‐19 patients

“…Other groups could show that the T‐cell and antibody responses against SARS‐CoV‐2 spike glycoprotein remain effective against the currently dominating B.1.1.529 VoC 45,87–90 . We support these observations in this high‐resolution analysis.…”

“…Other groups could show that the T‐cell and antibody responses against SARS‐CoV‐2 spike glycoprotein remain effective against the currently dominating B.1.1.529 VoC. 45 , 87 , 88 , 89 , 90 We support these observations in this high‐resolution analysis. We found that every individual in our study still had at least seven CD4 + T‐cell specificities that were conserved in all VoCs and LUMs investigated.…”

Novel monoclonal antibodies showing broad neutralizing activity for SARS-CoV-2 variants including Omicrons BA.5 and BA.2.75

“…To isolate mAbs targeting common epitopes of SARS-CoV-2 variants, we searched for antibody genes from PBMCs of infected and subsequently vaccinated patients. We selected three PBMCs from the patients who showed high neutralizing activity against all of the D614G, Delta, and Omicron BA.1 variants previously we reported (Kurahashi et al, 2022a). In the single B cells isolated from the PBMCs, ten antibody genes were further selected based on the ELISA findings of Fabs produced by the Ecobody technology (Ojima-Kato et al, 2017), and we tested the purified recombinant IgG antibodies with the V genes.…”

“…MO1 is derived from PBMCs of individuals who were infected with a SARS-CoV-2 variant□—□presumably the wildtype with only the D614G mutation in the spike□—□and then received two doses of an mRNA vaccine encoding the spike gene of the ancestral SARS-CoV-2 (Kurahashi et al, 2022a). Our finding that MO1 can broadly neutralize the early SARS-CoV-2 variants and the Omicron BA.1, BA.1.1, BA.2 and BA.5 variants demonstrates that immunity against the spike with the ancestral SARS-CoV-2 RBD sequence can protect humans by inducing neutralizing antibodies, like MO1, that recognize conserved epitopes.…”

“…We and other research groups have shown that three doses of the mRNA vaccine can protect individuals against the BA.1 and BA.2 variants of SARS-CoV-2 (Muik et al, 2022) (Furukawa et al, 2022) (Tjan et al, 2022). We have also observed that neutralizing antibodies against Omicron variants are increased in the sera of individuals received a two-dose mRNA vaccine after they had been infected with wildtype SARS-CoV-2 (D614G) (Kurahashi et al, 2022a). We therefore screened and searched those individuals’ B cells, as we suspected that it is possible that these B cells could produce antibodies that have broad neutralizing activity against SARS-CoV-2 variants including Omicron BA.5.…”