MuV particles, called virions, are pleomorphic in shape and vary in size from 100 to 600 nanometers in diameter.

The mumps virus contains a nonsegmented, single-stranded, linear genome that is 15,384 nucleotides in length and made of ribonucleic acid (RNA).

The V protein is also involved in evading host antiviral responses by means of inhibiting production and signalling of interferons.

RNPs are surrounded by an envelope, a lipid membrane, which contains two types of spikes on its surface that correspond to the HN and F glycoproteins.

Following attachment, the F protein is triggered and begins fusing the viral envelope with the host cell's membrane.

The F protein does so by changing from a metastable state to refolding to a more stable hairpin structure, which allows the contents of the virion, including the RNP, to be released into the host cell's cytoplasm.

[2][5][6] Upon entering the host cell, the RdRp begins transcribing mRNA from the genome inside the RNP.

RdRp synthesizes a cap on the 5'-end of the mRNA and a polyadenylated tail on the 3'-end consisting of hundreds of consecutive adenines.

Once a gene has been transcribed, RdRp releases it into the cytoplasm for subsequent translation of viral proteins by host ribosomes.

[5][10][11] During this process, the neuraminidase of HN proteins aids in separation from the host membrane and prevents virion aggregation.

Infection may also involve many other tissues and organs, resulting in a variety of inflammatory reactions such as encephalitis, aseptic[17] meningitis, orchitis, myocarditis, pancreatitis, nephritis, oophoritis, and mastitis.

Mumps is usually not life-threatening and typically resolves within a few weeks after the onset of symptoms, but long-term complications such as paralysis, seizures, hydrocephalus, and deafness can occur.

They found that rhesus macaques exposed to saliva taken from humans in the early stages of the disease developed mumps.

[20] Initial vaccines contained inactivated virus particles and provided short-term protection against mumps.

In the 1960s, Maurice Hilleman developed a more effective mumps vaccine using live virus particles that were taken from his then five-year-old infected daughter, Jeryl Lynn.