Durability and cross-reactivity of immune responses induced by a plant-based virus-like particle vaccine for COVID-19

Abstract

As the SARS-CoV-2 pandemic evolves, vaccine evaluation needs to include consideration of both durability and cross-reactivity. This report expands on previously reported results from a Phase 1 trial of an AS03-adjuvanted, plant-based coronavirus-like particle (CoVLP) displaying the spike (S) glycoprotein of the ancestral SARS-CoV-2 virus in healthy adults (NCT04450004). Humoral and cellular responses against the ancestral strain were evaluated 6 months post-second dose (D201) as secondary outcomes. Independent of dose, all vaccinated individuals retain binding antibodies, and ~95% retain neutralizing antibodies (NAb). Interferon gamma and interleukin-4 responses remain detectable in ~94% and ~92% of vaccinees respectively. In post-hoc analyses, variant-specific (Alpha, Beta, Delta, Gamma and Omicron) NAb were assessed at D42 and D201. Using a live virus neutralization assay, broad cross-reactivity is detectable against all variants at D42. At D201, cross-reactive antibodies are detectable in almost all participants against Alpha, Gamma and Delta variants (94%) and the Beta variant (83%) and in a smaller proportion against Omicron (44%). Results are similar with the pseudovirion assay. These data suggest that two doses of 3.75 µg CoVLP+AS03 elicit a durable and cross-reactive response that persists for at least 6 months post-vaccination.

Antibody persistence and safety after heterologous boosting with orally aerosolised Ad5-nCoV in individuals primed with two-dose CoronaVac previously: 12-month analyses of a randomized controlled trial

“…However, in this study, we found that the decay patterns of the NAb responses after the peaking following the boosting with aerosolized Ad5-nCoV within 12 months were similar to that following the CoronaVac boosting. Furthermore, this decline of NAb responses was obvious within the first 6 months, and much slower after that, which is consistent with that observed in individuals after receiving other vectored based or virus-like particle COVID-19 vaccines [ 15 ].…”

A phase 3 randomized controlled trial of a COVID-19 recombinant vaccine S-268019-b versus ChAdOx1 nCoV-19 in Japanese adults

“…In the follow-up phase, the booster administration with S-268019-b elicited a durable neutralizing antibody response in both groups through the end of the study. Considering that the neutralizing antibodies tend to wane in 6–8 months following administration of the second dose for multiple vaccine types in previously published studies, booster application within that time frame could ensure maintenance of protective immunity 24 , 25 . Indeed, the fact that the neutralizing antibody titer following the booster dose was higher than that after the second dose suggests that immune system was adequately primed with two initial doses to mount the response in both treatment groups.…”

Focus on Marine Animal Safety and Marine Bioresources in Response to the SARS-CoV-2 Crisis

“…To date, there are four COVID-19 vaccines that have been authorized by the Food and Drug Administration (FDA) in the US, including Pfizer-BioNTech, Moderna, Johnson & Johnson’s Janssen, and the most recently approved Novavax, with notable effectiveness [ 81 ]. Some new vaccines are also under development, such as the plant-based virus-like particle (CoVLP) vaccine by adjuvanting the purified modified SARS-CoV-2 spike protein expressed in Nicotiana benthamiana with AS03 adjuvant, which has demonstrated notable cross-reactivity against different SARS-CoV-2 variants [ 82 ]. However, with the everchanging genomic information of SARS-CoV-2 and the waning of immunity, breakthrough infections of SARS-CoV-2 have occurred in many cases in vaccinated people [ 83 ].…”