GlaxoSmithKline (GSK) and CureVac have reported that their second-generation vaccine candidate, CV2CoV, provided robust immune responses against SARS-CoV-2 challenge in a preclinical study in non-human primates.
The vaccine candidate is a non-chemically modified messenger ribonucleic acid (mRNA) that encodes the prefusion stabilised full-length spike protein of SARS-CoV-2. It is formulated within lipid nanoparticles.
In the preclinical trial, cynomolgus macaques were inoculated with two 12µg doses of either CureVac’s first-generation vaccine candidate, CVnCoV, or CV2CoV at a gap of 28 days.
Findings showed that CV2CoV could better stimulate innate and adaptive immune responses, offering quick onset of response, increased antibody titers and robust activation of memory B and T cells versus CVnCoV.
The study also analysed the effect of variants of concern and variants of interest such as Alpha, Beta, Delta, Kappa and the Lambda variant on neutralising antibody titers.
Increased antibody neutralising ability was reported with CV2CoV across all studied variants.
Animals receiving CV2CoV were observed to be well-protected following challenge infection using the original virus, with highly efficient viral clearance in the lungs and nasal passages.
GSK noted that preclinical studies in various animal models indicate the ability of the CV2CoV vaccine to stimulate quicker and robust immune responses.
CureVac chief scientific officer Dr Igor Splawski said: “In this animal model, CV2CoV is shown to induce broad antibody and cellular immune responses very similar to the breadth of the immune responses observed after infection with SARS-CoV-2.
“The current study shows that the immune responses and resulting protection produced by our second-generation candidate, based on our mRNA technology featuring targeted optimisations, are substantially improved in non-human primates against both the original SARS-CoV-2 virus as well as the Beta and Delta Variants of Concern and the Lambda Variant of Interest.”
The first clinical trial of the CV2CoV vaccine is anticipated to commence in the fourth quarter of this year.
CureVac and GSK initially partnered in July last year to develop novel products using the former’s second-generation RNA technology for various infectious disease targets.
The collaboration was further extended in February this year to develop next-generation mRNA Covid-19 vaccines.