Tetracistronic Minigenomes Elucidate a Functional Promoter for Ghana Virus and Unveils Cedar Virus Replicase Promiscuity for all Henipaviruses
Authors: Haas Griffin D. , Schmitz Katharina S. , Azarm Kristopher D. , Johnson Kendra N. , Klain William R. , Freiberg Alexander N. , Cox Robert M. , Plemper Richard K. , Lee Benhur 
Published: April 2024

Batborne henipaviruses, such as Nipah virus and Hendra virus, represent a major threat to global health due to their propensity for spillover, severe pathogenicity, and high mortality rate in human hosts. Coupled with the absence of approved vaccines or therapeutics, work with the prototypical species and uncharacterized, emergent species is restricted to high biocontainment facilities. There is a scarcity of such specialized spaces for research, and often the scope and capacity of research which can be conducted at BSL-4 is limited. Therefore, there is a pressing need for innovative life-cycle modeling systems to enable comprehensive research within lower biocontainment settings. This work showcases tetracistronic, transcription and replication competent minigenomes for Nipah virus, Hendra virus, Cedar virus, and Ghana virus, which encode viral proteins facilitating budding, fusion, and receptor binding. We validate the functionality of all encoded viral proteins and demonstrate a variety of applications to interrogate the viral life cycle. Notably, we found that the Cedar virus replicase exhibits remarkable promiscuity, efficiently rescuing minigenomes from all tested henipaviruses. We also apply this technology to GhV, an emergent species which has so far not been isolated in culture. We demonstrate that the reported sequence of GhV is incomplete, but that this missing sequence can be substituted with analogous sequences from other henipaviruses. Use of our GhV system establishes the functionality of the GhV replicase and identifies two antivirals which are highly efficacious against the GhV polymerase.

Author Summary

Henipaviruses, such as the prototypical Nipah virus and Hendra virus, are recognized as significant global health threats due to their high mortality rates and lack of effective vaccines or therapeutics. Due to the requirement for high biocontainment facilities, the scope of research which may be conducted on henipaviruses is limited. To address this challenge, we developed innovative tetracistronic, transcription and replication competent minigenomes for Nipah virus, Hendra virus, Cedar virus, as well as for the emergent species, Ghana virus. We demonstrate that these systems replicate key aspects of the viral life cycle, such as budding, fusion, and receptor binding, and are safe for use in lower biocontainment settings. Importantly, application of this system to Ghana virus revealed that its known sequence is incomplete; however, substituting the missing sequences with those from other henipaviruses allowed us to overcome this challenge. We demonstrate that the Ghana virus replicative machinery is functional and identify two orally-efficacious antivirals effective against it. Further, we compare the compatibility of divergent henipavirus replicases with heterotypic viral genetic elements, providing valuable insights for how these species have evolved. Our research offers a versatile system for life-cycle modeling of highly pathogenic henipaviruses at low biocontainment.