Evolution of a globally unique SARS-CoV-2 Spike E484T monoclonal antibody escape mutation in a persistently infected, immunocompromised individual. (preprint)

Prolonged infections in immunocompromised individuals may be a source for novel SARS-CoV-2 variants, particularly when both the immune system and antiviral therapy fail to clear the infection, thereby promoting adaptation. Here we describe an approximately 16-month case of SARS-CoV-2 infection in an immunocompromised individual. Following monotherapy with the monoclonal antibody Bamlanivimab, the individual's virus was resistant to this antibody via a globally unique Spike amino acid variant (E484T) that evolved from E484A earlier in infection. With the emergence and spread of the Omicron Variant of Concern, which also contains Spike E484A, E484T may arise again as an antibody-resistant derivative of E484A.

Comparison of Mucosal and Intramuscular Immunization against SARS-CoV-2 with Replication-Defective and Replicating Single-cycle Adenovirus Vaccines (preprint)

SARS-CoV-2 enters the body at mucosal surfaces, such as the nose and lungs. These events involve a small number of virions at these mucosal barriers and are therefore a strategic point to stop a COVID-19 infection before it starts. Despite this, most vaccines against COVID-19 are being injected into the muscle where they will not generate the highest levels of mucosal protection. The vaccines that are approved for use in humans are all replication-defective (RD) mRNA, DNA, or adenovirus (Ad) vaccines that do not amplify antigen transgenes. We developed single cycle adenovirus (SC-Ad) vectors that replicate antigen genes up to 10,000-fold in human cells, but that are disabled from producing infectious Ad particles. We show here that SC-Ad expressing the full-length SARS-CoV-2 spike protein produces 100-fold more spike protein than a matched RD-Ad-Spike vector. When Ad-permissive hamsters were immunized with these vaccines by intranasal (IN) or intramuscular (IM) routes, SC-Ad produced significantly stronger antibody responses as compared to RD-Ad against the spike protein that rose over 14 weeks after one immunization. Single IN or IM immunizations generated significant antibody responses in serum and in bronchoalveolar lavages (BALs). IN priming, but not IM priming, generated HLA-restricted CD8 T cell responses in BALs. SC-Ad-Spike generated antibodies that retain binding to spike receptor binding domains (RBDs) with mutations from new viral variants. These data suggest empowering the genomes of gene-based vaccines with the ability to amplify antigen genes can increase potency. This may be particularly advantageous when applying mucosal vaccines to combat mucosal pathogens like SARS-CoV-2. One Sentence SummaryArming adenovirus vaccines with the ability to replicate vaccine antigen genes may increase potency for systemic, or more importantly, mucosal immunization against mucosal pathogens.