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Abstract
Mumps virus (MuV) is a negative-sense, non-segmented, RNA virus from the genus Rubulavirus and family Paramyxoviridae. A human pathogen, MuV causes acute enlargement of the parotid glands, fever, and fatigue (1). Being highly neurotropic, it is also capable of causing mild meningitis and severe encephalitis and is still the leading cause of virally acquired adolescent deafness worldwide. While mumps infection has been decreased significantly due to the introduction of the MMR vaccine in the late 1960’s, there have been several large outbreaks in young, highly vaccinated populations in the 21st century (2-5). To better control and characterize these outbreaks, a better understanding of MuV replication and the roles its proteins in replication and infection is critical. There are three key proteins involved in MuV replication: the nucleoprotein (NP) which encapsidates the RNA genome, the large (L) protein which is essential for genome replication and transcription, and the phosphoprotein (P) which acts as a cofactor for both L and NP to allow their interactions (6). In this work, we examined the roles of NP and P structure on viral RNA synthesis. Through mutational analysis of MuV NP based on the crystal structure of PIV5’s NP, we discovered impacts on viral growth kinetics and developed a mutant virus capable of producing high levels of DI particles. Furthermore, mutational studies of MuV P determined that not only is P trans-complementary in its functions, but the N- and C-terminal domains exhibit chiral properties necessary for its structural stability and assist in its ability to form homodimers, heterodimers, and its hallmark tetramer of two homodimers oriented in antiparallel. This discovery assisted in the development of a novel method of determining dynamic sites, as well as a model for the MuV P coiled-coil polar ends. This work improves our understandings of how protein structure directly impacts MuV replication and growth and advance the development of next-generation antiviral therapies and vaccine candidates.