Mumps Virus- An Overview


Mumps virus is a member of the family Paramyxoviridae, which includes other human pathogens such as measles, respiratory syncytial virus, and parainfluenza viruses. Mumps virus causes an acute infection of the salivary glands and other organs, and can lead to complications such as meningitis, orchitis, oophoritis, and pancreatitis.

The structure of mumps virus is similar to other paramyxoviruses. It consists of an outer envelope that surrounds an inner helical nucleocapsid. The envelope is derived from the host cell membrane and contains two types of glycoproteins: hemagglutinin-neuraminidase (HN) and fusion (F) protein. The HN protein binds to sialic acid receptors on the surface of host cells and facilitates viral attachment and entry. The F protein mediates the fusion of the viral envelope with the cell membrane and allows the release of the nucleocapsid into the cytoplasm. The nucleocapsid is composed of a single-stranded RNA genome that is associated with three proteins: nucleoprotein (NP), phosphoprotein (P), and large (L) protein. The NP protein forms a helical structure around the RNA and protects it from degradation. The P protein acts as a cofactor for the L protein, which is the viral RNA polymerase that transcribes and replicates the viral genome.

The mumps virus genome is about 15.3 kilobases long and has a negative polarity, meaning that it is complementary to the mRNA that is produced from it. The genome contains six genes that encode for six structural proteins: NP, P, M (matrix), F, SH (small hydrophobic), and HN. The genes are arranged in a fixed order from 3` to 5` end: 3`-NP-P-M-F-SH-HN-L-5`. The genome also has a non-coding leader sequence at the 3` end and a trailer sequence at the 5` end that are involved in transcription and replication.

The structure of mumps virus determines its infectivity, antigenicity, and pathogenicity. The envelope glycoproteins are responsible for binding to host cells and initiating infection. They are also the main targets of neutralizing antibodies that can prevent infection or limit its spread. The nucleocapsid proteins are involved in viral replication and transcription, and also elicit cellular immune responses that can clear the infection or cause tissue damage. Understanding the structure of mumps virus can help in developing effective vaccines and antiviral drugs against this important human pathogen.