Yeast Surface Display Approaches for Engineering Stabilized Viral Fusion Protein Subunit Vaccines
Abstract
Paramyxoviruses are responsible for many human diseases, such as mumps and measles, as well as many other diseases for which vaccines are currently not available. Two respiratory viruses within this family, respiratory syncytial virus (RSV) and human metapneumovirus (HMPV), are responsible for widespread infections in humans, with especially significant morbidity in children and the elderly. Two other emergent viruses, Nipah virus (NiV) and Hendra virus (HeV), can infect humans with highly deadly outcomes, with over 60% fatality rates. There are no vaccines available for these four viruses, although significant industrial and academic efforts are pushing RSV vaccine development forward with promising results. RSV vaccine research, which has progressed the furthest for any of these viruses, has revealed that one of the proteins exposed on the surface of the virus is the major target of the neutralizing antibody response -- this is the fusion or F protein. The F protein shape irreversibly changes dramatically during the process of infection, and the shape of this protein is critically linked to the potency of the immune response that it can generate as a vaccine antigen. Production of the F protein in a soluble form that represents the authentic shape on the virus and that can be stored and delivered as a vaccine has been very challenging. However, after years of research, variants of the RSV F protein have been generated that exhibit improved stability and immune responses in animal studies, but the approaches employed may not have yielded the best candidate vaccine, nor are these approaches easily applied to generate similar vaccine candidates for other members of the paramyxovirus family, such as HMPV, NiV, or HeV. While we know that a stabilized F protein antigen is highly desirable as a vaccine antigen, the path to generating such a stable variant is currently a time-consuming and highly virus-specific effort. Vaccine development efforts and candidate vaccines for HMPV, NiV, and HeV lag significantly behind RSV, and all four of these viruses represent our primary initial targets for antigen engineering in this research effort. In this proposal, we seek to develop a new approach to F protein antigen design that relies on modern methods for the display of large numbers of variants, which can then be subjected to an unbiased selection process based on detectable properties. In this case, we seek to use these large libraries to select highly stabilized F proteins that retain their authentic shape present in the virus, to ensure that the antigens are as stable as possible for industrial vaccine scale-up, production, and distribution, as well as to ensure that these antigens will induce highly potent neutralizing antibodies. We will first develop and validate an approach to displaying the F protein on the surface of yeast, which has been shown to be a powerful technique that enables library selection experiments. We will next generate a large library of variants for each of our four target F proteins from RSV, HMPV, NiV, and HeV and then select from each library the most stable variant through multiple rounds of screening. Representative, stabilized F proteins from each of the four viruses will be rigorously tested for their stability and suitability for future immunization experiments in animals. Finally, we believe that these library screening approaches could be adapted to develop candidate vaccine antigens for other viruses in the paramyxovirus family and to address the emergence of new viruses more rapidly. Overall, this research addresses two major areas related to two Fiscal Year Peer Reviewed Medical Research Program topics: Vaccine design for infectious disease and emerging viruses.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 07, 2017
- Source ID
- W81XWH1710127
Entities
People
- Theodore Jardetzky
Organizations
- Stanford University
- United States Army