Preclinical toxicity and immunogenicity of a quadrivalent recombinant influenza hemagglutinin vaccine (SCVC101) in rhesus monkeys

SCVC101 is a novel recombinant hemagglutinin (rHA) protein-based quadrivalent seasonal influenza vaccine containing HA gene sequences of A/Wisconsin/588/2019 (H1N1) pdm09-like virus, A/Cambodia/e0826360/2020 (H3N2)-like virus, B/Washington/02/2019 (B/Victoria lineage)-like virus, and B/Phuket/3073/2013 (B/Yamagata). Significant immune responses to influenza viruses induced by SCVC101 were demonstrated in mice, rats, and rhesus monkeys. This study aimed to investigate the toxicity and immunogenicity of SCVC101 in rhesus monkeys. Under Good Laboratory Practice (GLP) conditions, rhesus monkeys received intramuscular administrations of two distinct dose levels (15 μg and 45 μg of rHA per virus strain) during weeks 0, 3, and 6 of the experimental protocol. The results showed that SCVC101 vaccination elicited a strong specific binding antibody and neutralizing antibodies in the low- and high-dose vaccine groups. No significant systemic toxicities or abnormal cardiovascular and respiratory events were observed after three doses of SCVC101 in rhesus monkeys. Therefore, our regulatory toxicology research demonstrates strong immunogenicity and a favorable safety profile of the SCVC101 vaccine.