Human monoclonal antibodies for hantaviruses

PROJECT SUMMARY - RP4 The hantaviruses represent collections of diverse virus species, and these groups of viruses are ideal for prototype pathogen immunity approaches. The goal of developing medical countermeasures is to confer protective immunity to hantaviruses, which can be provided by active immunization (as in our BP4 consortium RP3 colleagues) or by passive immunization with long-acting (90-day half-life) monoclonal antibodies (mAbs). In this RP4, we will used several different state-of-the-art antibody discovery approaches to isolate and engineer optimal mAbs for this major of viruses. Virus-immune B cells will be interrogated with several well- developed human mAb discovery platforms, including high-throughput single cell sorting and single cell RNAseq techniques, or converted to stable human hybridoma cell lines. B cell line supernatants or recombinant mAbs will be subjected to high-throughput screening to identify Abs that bind to hantavirus surface proteins and functionally inhibit virus replication. Our objectives include determining the principles governing optimal mAb combinations and synergy, developing new in vitro selection methods to enhance antibody neutralization potency and breadth, and genetically modifying mAbs for extended-half-life properties to enable the use of injections of long-lived antibodies to confer protective immunity and protection like that of vaccines. Lessons learned in the year 1 to 3 studies of the prototype viruses Sin Nombre virus (SNV) and Andes virus (ANDV) will be applied to new discovery campaigns for related viruses in the same family or genera. We will focus these efforts on Hantaan virus as a model for applying Test Cases for the prototype pathogen approach. Identifying antibodies to Hantaan virus will validate the prototype pathogens approach, preparing us for an unexpected epidemic of a previously unknown hantavirus or other bunyavirus. Also, this program will isolate promising medical countermeasures for additional potential causes of future epidemics. Further, incorporating screens for wide breadth of recognition in these studies may enable identification of pan- family or pan-genus antibodies that can but used for multiple related agents, including future related pathogens for which we have not yet specifically prepared. Identifying major sites of vulnerability on the virus surface Gn- Gc proteins for recognition by neutralizing and/or protective antibodies also will be useful for our consortium partners working on antigen design. Prioritized mAbs then will be tested for therapeutic efficacy in multiple animal models of infection. The lead mAbs will be selected, and CHO cell lines will be made by our industry partner IDBiologics for Ab production, in preparation for cGMP manufacture and IND planning. The work promises to yield best-in-class mAb combinations for broad and potent activity against hantaviruses that can be used to treat or prevent human virus infections. These studies will identify protective/neutralizing epitopes of mAbs through structural studies of antigen-Ab complexes that inform immunogen design in RP3 using rational vaccine antigen design approaches.