•  Seven Ad26 vectors were designed with variations of the SARS-CoV-2 S protein.

• The most successful and the variant selected for further trials is S.PP which has the "wildtype leader sequence with full-length S with mutation of the furin cleavage site and proline stabilizing mutations." 

Bowdoin College

•  The vaccine uses adenovirus serotype 26 as a vector encoding a prefusion stabilized SARS-CoV-2-spike immunogen, a protein which mediates entry of the SARS-CoV-2 into host cells. 

•  A single immunization induced a neutralizing antibody response and complete protection against SARS-CoV-2 in 5 out of 6 rhesus macaques.

•  The phase 1/2a clinical trial is now underway in Belgium and the United States with phase 3 starting in September if results are positive.

Ad26- vectored COVID-19 vaccine by Johnson & Johnson Creation/ Animal Testing

Mercado, N.B., Zahn, R., Wegmann, F. et al. Single-shot Ad26 vaccine protects against SARS-CoV-2 in rhesus macaques. Nature (2020). 
https://doi.org/10.1038/s41586-020-2607-z

Single-shot Ad26 vaccine protects against SARS-CoV-2 in rhesus macaques

Construction of Ad26 vectors

•  Neutralizing antibody responses measured by a pseudovirus neutralization assay and a live virus neutralization assay were measured in the majority of the vaccinated animals with the highest generated by the S.PP vaccine.

•  S-specific IgG and IgA responses were also induced by the Ad26-S.PP vaccine.

•  Further analysis of antibody responses showed  A variety
of Fc effector functions, including antibody-dependent neutrophil
phagocytosis (ADNP), antibody-dependent monocyte cellular phagocytosis (ADCP), antibody-dependent complement deposition (ADCD),
and antibody-dependent NK cell activation (ADNKA), as well as multiple Ig subclasses and FcR binding. 


Ad26 Vaccine Immunogenicity 

•  Animals were infected with 1.0x10^5 TCID50 SARS-CoV-2 through the intranasal and intratracheal paths.

• Animals that were vaccinated with Ad26-S.PP showed no detectable virus in BAL and only one of the animals showed a low amount of virus in NS.

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