Synthetic single domain antibodies to understand and fight morbilliviral infections

Background. Several RNA viruses, belonging to the family Paramyxoviridae, continue to pose threat to hundreds of thousands of human and animal lives each year. Measles virus (MeV), canine distemper virus (CDV) and Nipah virus are among the paramyxoviruses that are of high clinical relevance, and this despite the fact that very efficient vaccines are available against MeV and CDV. No specific treatment option is available to address the global burden these viruses bring each year. Several approaches have been tried simultaneously to discover antivirals against each of these RNA viruses. However, monotherapy approaches inevitably pose the challenge of the rapid emergence of escape variants against the identified antiviral. Specific aims. To potentially tackle this hurdle, this project proposal aims at discovering broadly neutralizing multidomain synthetic single domain antibodies (sybodies) to fight morbilliviruses. To achieve this ambitious goal, a two-pronged strategy will be conducted:1.Identify, characterize and format broadly neutralizing sybodies against morbilliviruses.2.Identify, characterize and format sybodies against host protein(s) promoting morbilliviral infections.Experimental design. To successfully achieve Aim 1, state-of-the-art molecular, cellular, biochemical, functional and virological technologies, that are available in my laboratory, will be combined with a tuned selection procedure associated with a unique synthetic nanobody (sybody) platform (Laboratory of Prof. Seeger, University of Zurich, Switzerland). The strategy is designed to increase the chances to discover broadly neutralizing anti-morbilliviral binders. Upon molecular characterization of their mode of inhibition, best sybody candidates will be fused together to engineer multidomain antibodies. Aim 2 will focus on the detailed molecular characterization of 'top-ranked' host factor candidates that may be essential in promoting morbillivirus infections, which were identified in a recently conducted genome-wide CRISPR/Cas9 functional screen. Later on, the discovery of sybodies blocking the identified host factor's function will be undertaken. Furthermore, best broadly neutralizing binders will be next investigated in primary cell systems against multiple strains of CDV and MeV as well as tested in well-established in vivo models of morbillivirus-induced pathogenesis. Strikingly, both aims have the great potential to discover antivirals with (i) broad-spectrum efficacy and (ii) the opportunity to mitigate the generation of drug-escape variants.Significance. Despite available vaccines, MeV and CDV still cause significant health impacts. On the other hand, both attenuated strains hold great promise as vectors against cancers. Although very attractive in supporting both indications, no FDA-approved antivirals are available against both morbilliviruses. This proposal thus aims at discovering and rationally formatting, next-generation, broadly neutralizing, multidomain antibodies to fight those viral diseases. Key advantages of the project are: (i) the direct access to an innovative platform allowing robust and fast generation of highly potent sybodies against the morbillivirus H protein, (ii) the availability of biochemically and functionally well-characterized various H constructs, (iii) the already performed CRISPR/Cas9-based genome-wide functional screen, (iv) the long-held expertise in virology in my laboratory combined with all necessary collaborators to successfully reach the goals of this project proposal, and (v) the possibility to translate the strategy of selection of broadly neutralizing sybodies to other important viruses in a near future. In summary, rationally engineered neutralizing multidomain antibodies may not only represent a highly needed line of defense against morbilliviral epidemics, but may also improve the biosafety levels of the associated virotherapy platforms.