Topologically engineered antibodies and Fc-fusion proteins: a new class of multifunctional therapeutic candidates for SARS-CoV-2, cancer, and other disease (preprint)

The ability of antibodies and Fc-fusion proteins to bind multiple targets cooperatively is limited by their topology. Here we describe our discovery that ACE2 Fc-fusion proteins spontaneously cross dimerize, forming topologically distinct 'superdimers' that demonstrate extraordinary SARS-CoV-2 intra-spike cooperative binding and potently neutralize Omicron B.1.1.529 at least 100 fold better than eight clinically authorized antibodies. We also exploited cross-dimerization to topologically engineer novel superdimeric antibodies and Fc-fusion proteins with antibody-like plasma half-lives to address cancer and infectious disease therapy. These include bispecific ACE2-antibody superdimers that potently neutralize all major SARS-CoV 2 variants, and bispecific anti-cancer and anti-viral antibody superdimers that are more potent than two-antibody cocktails. Superdimers are efficiently produced from single cells, providing a new therapeutic approach to many disease indications.

Vaccination of COVID-19 Convalescent Plasma Donors Increases Binding and Neutralizing Antibodies Against SARS-CoV-2 Variants (preprint)

BackgroundCOVID-19 convalescent plasma (CCP) was widely used as passive immunotherapy during the first waves of SARS-CoV-2 infection in the US. However, based on observational studies and randomized controlled trials, beneficial effects of CCP were limited, and its use was virtually discontinued early in 2021, in concurrence with increased vaccination rates and availability of monoclonal antibody (mAb) therapeutics. However, as new variants of the SARS-CoV-2 spread, interest in CCP derived from vaccine-boosted CCP donors is resurging. The effect of vaccination of previously infected CCP donors on antibodies against rapidly spreading variants of concern (VOC) is still under investigation. Study Design/MethodsIn this study, paired samples from 11 CCP donors collected before and after vaccination were tested to measure binding antibodies levels and neutralization activity against the ancestral and SARS-CoV-2 variants (Wuhan-Hu-1, B.1.1.7, B.1.351, P.1, D614G, B.1.617.2, B.1.427) on the Ortho Vitros Spike Total Ig and IgG assays, the MSD V-PLEX SARS-CoV-2 Panel 6 arrays for IgG binding and ACE2 inhibition, and variant-specific Spike Reporter Viral Particle Neutralization (RVPN) assays. Results/FindingsBinding and neutralizing antibodies were significantly boosted by vaccination, with several logs higher neutralization for all the variants tested post-vaccination compared to the pre-vaccination samples, with no difference found among the individual variants. DiscussionVaccination of previously infected individuals boosts antibodies including neutralizing activity against all SARS-CoV-2 VOC, including the current spreading delta (B.1.617.2) variant. Animal model and human studies to assess clinical efficacy of vaccine boosted CCP are warranted, especially since 15-20% of current donations in the US are from previously infected vaccine-boosted donors.

Mouse Antibodies with Activity Against the SARS-CoV-2 D614G and B.1.351 Variants (preprint)

With the rapid spread of SARS-CoV-2 variants, including those that are resistant to antibodies authorized for emergency use, it is apparent that new antibodies may be needed to effectively protect patients against more severe disease. Differences between the murine and human antibody repertoires may allow for the isolation of murine monoclonal antibodies that recognize a different or broader range of SARS-CoV-2 variants than the human antibodies that have been characterized so far. We describe mouse antibodies B13 and O24 that demonstrate neutralizing potency against SARS-CoV-2 Wuhan (D614G) and B.1.351 variants. Such murine antibodies may have advantages in protecting against severe symptoms when individuals are exposed to new SARS-CoV-2 variants.

SARS-CoV-2 Antibody persistence in COVID-19 convalescent plasma donors (preprint)

Background Antibody response duration following SARS-CoV-2 infection tends to be variable and depends on severity of disease and method of detection. Study design and methods COVID-19 convalescent plasma (CCP) from 18 donors was collected longitudinally for a maximum of 63 - 129 days following resolution of symptoms. All the samples were initially screened by the Ortho Total Ig test to confirm positivity and subsequently tested with 7 additional direct sandwich or indirect binding assays (Ortho, Roche, Abbott, Broad Institute) directed against a variety of antigen targets (S1, RBD, and NC), along with 2 neutralization assays (Broad Institute live virus PRNT and Vitalant Research Institute Pseudovirus RVPN). Results The direct detection assays (Ortho Total Ig total and Roche Total Ig) showed increasing levels of antibodies over the time period, in contrast to the indirect IgG assays that showed a decline. Neutralization assays also demonstrated declining responses; the VRI RVPN pseudovirus had a greater rate of decline than the Broad PRNT live virus assay. Discussion These data show that in addition to variable individual responses and associations with disease severity, the detection assay chosen contributes to the heterogeneous results in antibody stability over time. Depending on the scope of the research, one assay may be preferable over another. For serosurveillance studies, direct, double Ag-sandwich assays appear to be the best choice due to their stability; in particular, algorithms that include both S1 and NC based assays can help reduce the rate of false-positivity and discriminate between natural infection and vaccine-derived seroreactivity.