ABSTRACT
The human respiratory syncytial virus (hRSV) fusion (F) protein is considered a major target of the neutralizing antibody response to hRSV. This glycoprotein undergoes a major structural shift from the prefusion (pre-F) to the postfusion (post-F) state at the time of virus-host cell membrane fusion. Recent evidences suggest that the pre-F state is a superior target for neutralizing antibodies compared to the post-F state. Therefore, for vaccine purposes, we have designed and characterized a recombinant hRSV F protein, called Pre-F-GCN4t, stabilized in a pre-F conformation. To show that Pre-F-GCN4t does not switch to a post-F conformation, it was compared with a recombinant post-F molecule, called Post-F-XC. Pre-F-GCN4t was glycosylated and trimeric and displayed a conformational stability different from that of Post-F-XC, as shown by chemical denaturation. Electron microscopy analysis suggested that Pre-F-GCN4t adopts a lollipop-like structure. In contrast, Post-F-XC had a typical elongated conical shape. Hydrogen/deuterium exchange mass spectrometry demonstrated that the two molecules had common rigid folding core and dynamic regions and provided structural insight for their biophysical and biochemical properties and reactivity. Pre-F-GCN4t was shown to deplete hRSV-neutralizing antibodies from human serum more efficiently than Post-F-XC. Importantly, Pre-F-GCN4t was also shown to bind D25, a highly potent monoclonal antibody specific for the pre-F conformation. In conclusion, this construct presents several pre-F characteristics, does not switch to the post-F conformation, and presents antigenic features required for a protective neutralizing antibody response. Therefore, Pre-F-GCN4t can be considered a promising candidate vaccine antigen.IMPORTANCE Human respiratory syncytial virus (RSV) is a global leading cause of infant mortality and adult morbidity. The development of a safe and efficacious RSV vaccine remains an important goal. The RSV class I fusion (F) glycoprotein is considered one of the most promising vaccine candidates, and recent evidences suggest that the prefusion (pre-F) state is a superior target for neutralizing antibodies. Our study presents the physicochemical characterization of Pre-F-GCN4t, a molecule designed to be stabilized in the pre-F conformation. To confirm its pre-F conformation, Pre-F-GCN4t was analyzed in parallel with Post-F-XC, a molecule in the post-F conformation. Our results show that Pre-F-GCN4t presents characteristics of a stabilized pre-F conformation and support its use as an RSV vaccine antigen. Such an antigen may represent a significant advance in the development of an RSV vaccine.
Subject(s)
Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Viral Fusion Proteins/chemistry , Viral Fusion Proteins/metabolism , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Antibodies, Viral/metabolism , Humans , Macromolecular Substances/ultrastructure , Mass Spectrometry , Microscopy, Electron , Models, Molecular , Protein Binding , Protein Folding , Protein Multimerization , Protein Stability , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Viral Fusion Proteins/genetics , Viral Fusion Proteins/immunologyABSTRACT
A series of new quinazoline derivatives bearing a vinylic chloride group on the 2-position was prepared by using a consecutive S(RN)1 / E(RC)1 radical strategy.
Subject(s)
Antimalarials/chemistry , Antineoplastic Agents/chemistry , Protein Kinase Inhibitors/chemistry , Quinazolines/chemistry , Vinyl Chloride/chemistry , Antimalarials/chemical synthesis , Antineoplastic Agents/chemical synthesis , Protein Kinase Inhibitors/chemical synthesis , Quinazolines/chemical synthesisABSTRACT
The protective potential of antibodies directed against group B streptococcus (GBS) Sip surface protein was determined by using the mouse neonatal infection model. Rabbit Sip-specific antibodies administered passively to pregnant mice protected their pups against a GBS lethal challenge. In addition, active immunization with purified recombinant Sip protein of female CD-1 mice induced the production of specific antibodies that also confer protection to the newborn pups against GBS strains of serotypes Ia/c, Ib, II, III, and V. These data confirm that Sip-specific antibodies can cross the placenta and conferred protective immunity against GBS infections.
