Rational Development of a Polysaccharide–Protein-Conjugated Nanoparticle Vaccine Against SARS-CoV-2 Variants and Streptococcus pneumoniae (Adv. Mater. 21/2022)

Nanoparticle Vaccines In article number 2200443, Liangzhi Xie, Chengfeng Qin, and co-workers develop a novel bivalent nanoparticle vaccine that confers protection against infection of multiple SARS-CoV-2 variants and Streptococcus pneumoniae. This universal polysaccharide?protein-conjugated vaccine platform provides a powerful tool to fight against cocirculating viral and bacterial pathogens worldwide.

Rational Development of a Polysaccharide-Protein-Conjugated Nanoparticle Vaccine Against SARS-CoV-2 Variants and Streptococcus pneumoniae.

The ongoing COVID-19 pandemic caused by SARS-CoV-2 has led to millions of deaths worldwide. Streptococcus pneumoniae (S. pneumoniae) remains a major cause of mortality in underdeveloped countries. A vaccine that prevents both SARS-CoV-2 and S. pneumoniae infection represents a long-sought "magic bullet". Herein, a nanoparticle vaccine, termed SCTV01B, is rationally developed by using the capsular polysaccharide of S. pneumoniae serotype 14 (PPS14) as the backbone to conjugate with the recombinant receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. The final formulation of conjugated nanoparticles in the network structure exhibits high thermal stability. Immunization with SCTV01B induces potent humoral and Type 1/Type 2 T helper cell (Th1/Th2) cellular immune responses in mice, rats, and rhesus macaques. In particular, SCTV01B-immunized serum not only broadly cross-neutralizes all SARS-CoV-2 variants of concern (VOCs), including the most recent Omicron variant, but also shows high opsonophagocytic activity (OPA) against S. pneumoniae serotype 14. Finally, SCTV01B vaccination confers protection against challenges with the SARS-CoV-2 mouse-adapted strain and the original strain in established murine models. Collectively, these promising preclinical results support further clinical evaluation of SCTV01B, highlighting the potency of polysaccharide-RBD-conjugated nanoparticle vaccine platforms for the development of vaccines for COVID-19 and other infectious diseases.

Fabrication of Fragment Antibody-Enzyme Complex as a Sensing Element for Immunosensing.

Antibody-enzyme complexes (AECs) are ideal molecular recognition elements for immunosensing applications. One molecule possesses both a binding ability to specific targets and catalytic activity to gain signals, particularly oxidoreductases, which can be integrated into rapid and sensitive electrochemical measurements. The development of AECs using fragment antibodies rather than intact antibodies, such as immunoglobulin G (IgG), has attracted attention for overcoming the ethical and cost issues associated with the production of intact antibodies. Conventionally, chemical conjugation has been used to fabricate AECs; however, controlling stoichiometric conjugation using this method is difficult. To prepare homogeneous AECs, methods based on direct fusion and enzymatic conjugation have been developed, and more convenient methods using Catcher/Tag systems as coupling modules have been reported. In this review, we summarize the methods for fabricating AECs using fragment antibodies developed for sensing applications and discuss the advantages and disadvantages of each method.