Daily Chart: primate data hint full-length SARS-CoV-2 spike more potent vaccine antigen than spike peptides

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Full-length spike protein may make a better DNA vaccine against SARS-CoV-2 than smaller spike peptides, including the popular receptor binding domain, according to a Science paper published Thursday.

Led by Harvard’s Beth Israel Deaconess Medical Center (BIDMC), the research team compared the ability of five spike variants to induce neutralizing antibodies in non-human primates and protect the animals from viral challenge.

The full-length spike performed best at both, with the latter measured as viral load in bronchoalveolar lavage and nasal swabs.

“Optimal protection was achieved with the full-length S immunogen in both the upper and lower respiratory tracts, and reduced protection was observed with soluble constructs and smaller fragments,” the authors concluded.

None of the vaccine variants produced fully sterilizing immunity, as was seen in a recent non-human primate study of University of Oxford’s vaccine (see “Oxford Vaccine Could Reduce COVID-19 Symptoms, Won’t Provide Herd Immunity” and “Comparing Monkey Data from COVID-19 Vaccines”).

J&J, which is collaborating with BIDMC on a viral vector-based COVID-19 vaccine, told BioCentury that the data in the Science study “are not indicative of the data for the vaccine candidate in development” by J&J’s Janssen Pharmaceutical Cos.

The company said it expects to have non-human primate data from its lead vaccine candidate “in the very near future” and reiterated it anticipates starting Phase I testing by September.

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