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

We identified novel neutralizing monoclonal antibodies against SARS-CoV-2 variants (including Omicron) from individuals received two doses of mRNA vaccination after they had been infected with wildtype. We named them MO1, MO2 and MO3. MO1 shows high neutralizing activity against authentic variants: D614G, Delta, BA.1, BA.1.1, BA.2, and BA.2.75 and BA.5. Our findings confirm that the wildtype-derived vaccination can induce neutralizing antibodies that recognize the epitopes conserved among the SARS-CoV-2 variants (including BA.5 and BA.2.75). The monoclonal antibodies obtained herein could serve as novel prophylaxis and therapeutics against not only current SARS-CoV-2 viruses but also future variants that may arise.

Cross-neutralizing activity against Omicron could be obtained in SARS-CoV-2 convalescent patients who received two doses of mRNA vaccination (preprint)

The SARS-CoV-2 variant Omicron is now under investigation. We evaluated cross-neutralizing activity against Omicron in COVID-19 convalescent patients who had received two doses of an mRNA vaccination. Surprisingly and interestingly, after the second vaccination, the subject neutralizing antibody titers including that against Omicron all became seropositive, and significant fold-increases were seen regardless of the subject disease severity. Our findings thus demonstrate that at least two doses of mRNA vaccination to SARS-CoV-2 convalescent patients can induce cross-neutralizing activity against Omicron.

Cross-neutralizing activity against SARS-CoV-2 variants in COVID-19 patients: Comparison of four waves of the pandemic in Japan (preprint)

ABSTRACT In March 2021, Japan is facing a 4th wave of SARS-CoV-2 infection. To prevent further spread of infection, sera cross-neutralizing activity of patients previously infected with conventional SARS-CoV-2 against novel variants is important but is not firmly established. We investigated the neutralizing potency of 81 COVID-19 patients’ sera from 4 waves of pandemic against SARS-CoV-2 variants using their authentic viruses. Most sera had neutralizing activity against all variants, showing similar activity against B.1.1.7 and D614G, but lower activity especially against B.1.351. In the 4th wave, sera-neutralizing activity against B.1.1.7 was significantly higher than that against any other variants, including D614G. The cross-neutralizing activity of convalescent sera was effective against all variants but was potentially weaker for B.1.351.