Pena-Briseno, A. | Search bioRxiv

bioRxiv2022

Differential recognition of computationally optimized H3 hemagglutinin influenza vaccine candidates by human antibodies

Among circulating influenza viruses in humans, H3N2 viruses typically evolve faster than other subtypes and have caused severe illness and deaths in millions of people since emerging in 1968. Computationally optimized broadly reactive antigen (COBRA) technology is one strategy to broaden vaccine-elicited antibody responses among influenza subtypes. In this study, we determined the structural integrity of an H3N2 COBRA HA, TJ5, and, as nearly all humans have pre-existing immunity to H3N2 influenza viruses, we probed the antigenic profile of several H3N2 COBRA HAs by assessing recognition of these immunogens by human B cells and monoclonal antibodies (mAbs). Of three recently described COBRA H3 HA antigens (TJ5, NG2, and J4), we determined that TJ5 and J4 HA proteins recognize pre-existing B cells (from the 2017-2018 vaccine season) more effectively than NG2 HA and a wild type Hong Kong/4801/2014 protein. H3 HA-specific human mAbs recognize wild type and COBRA HA proteins, and have functional activity against a broad panel of H3N2 viruses. mAb TJ5-5 recognizes TJ5 and J4 HA proteins, but has poor recognition of NG2 HA, similar to the global B cell analysis. To probe these recognition differences and to verify the structural integrity of the TJ5 HA protein, we determined a 3.4 [A] structure via cryo-electron microscopy of TJ5-5 complexed with the TJ5 HA, which revealed residues important to the differential binding. Overall, these studies determined that COBRA H3 HA proteins have correct antigenic and structural features, and are recognized by B cells and mAbs isolated from seasonally vaccinated humans. ImportanceVaccine development for circulating influenza viruses, particularly for the H3N2 subtype, remains challenging due to consistent antigenic drift. Computationally optimized broadly reactive antigen (COBRA) technology has proven effective for broadening influenza hemagglutinin (HA) elicited antibody responses compared to wild type immunogens. Here we determined the structural features and antigenic profiles of H3 COBRA HA proteins. Two H3 COBRA HA proteins, TJ5 and J4, are better recognized by pre-existing B cells and monoclonal antibodies from the 2017-2018 vaccine season compared to COBRA NG2 and a wild type A/Hong Kong/2014 HA protein. We determined a cryo-EM structure of one mAb that poorly recognizes NG2, mAb TJ5-5, in complex with the TJ5 COBRA HA protein and identified residues critical to mAb recognition. As NG2 is more effective than TJ5 for a recent Hong Kong/2019 virus, these data provide insights into the diminished effectiveness of influenza vaccines across vaccine seasons.

immunology↗

bioRxiv2021

Broadly reactive human monoclonal antibodies targeting the pneumococcal histidine triad protein protect against fatal pneumococcal infection

Streptococcus pneumoniae remains a leading cause of bacterial pneumonia despite the widespread use of vaccines. While vaccines are effective at reducing the incidence of most vaccine-included serotypes, a rise in infection due to non-vaccine serotypes, and moderate efficacy against some vaccine included serotypes have contributed to high disease incidence. Additionally, numerous isolates of S. pneumoniae are antibiotic or multi-drug resistant. Several conserved pneumococcal proteins prevalent in the majority of serotypes have been examined as vaccines in preclinical and clinical trials. An additional, yet unexplored tool for disease prevention and treatment is the use of human monoclonal antibodies (mAbs) targeting conserved pneumococcal proteins. Here, we isolate the first human mAbs (PhtD3, PhtD6, PhtD7, PhtD8, PspA16) against the pneumococcal histidine triad protein (PhtD), and the pneumococcal surface protein A (PspA), two conserved and protective antigens. mAbs to PhtD target diverse epitopes on PhtD, and mAb PspA16 targets the N-terminal segment of PspA. The PhtD-specific mAbs bind to multiple serotypes, while mAb PspA16 serotype breadth is limited. mAbs PhtD3 and PhtD8 prolong the survival of mice infected with pneumococcal serotype 3. Furthermore, mAb PhtD3 prolongs the survival of mice in intranasal and intravenous infection models with pneumococcal serotype 4, and in mice infected with pneumococcal serotype 3 when administered 24 hours after pneumococcal infection. All PhtD and PspA mAbs demonstrate opsonophagocytic activity, suggesting a potential mechanism of protection. Our results provide new human mAbs for pneumococcal disease prevention and treatment, and identify epitopes on PhtD and PspA recognized by human B cells.

immunology↗