Paramyxoviruses

Paramyxoviruses are a diverse group of enveloped, nonsegmented, negative-sense RNA viruses in the family Paramyxoviridae. They infect a wide range of hosts, including humans and domestic and wild animals, and are commonly transmitted by respiratory secretions. Many cause respiratory illness, and several can produce systemic disease or neurological complications.

Their genomes are single-stranded, negative-sense RNA and are translated in the cytoplasm by the viral RNA-dependent RNA polymerase. Genome organization typically includes genes for nucleocapsid (N), phosphoprotein (P), matrix (M), fusion (F), and an attachment glycoprotein (HN, H, or G), along with the large polymerase (L); some genera also encode nonstructural proteins such as V and C. The viruses assemble at the plasma membrane and often induce syncytia, multinucleated cells, in infected tissues.

Key human pathogens include measles virus (Morbillivirus), which causes fever and generalized rash; mumps virus (Rubulavirus), which causes parotitis and sometimes aseptic meningitis; parainfluenza viruses (Respirovirus and Rubulavirus) that cause croup and bronchiolitis; and human metapneumovirus, a common cause of lower respiratory tract infection in children. Henipaviruses, Nipah and Hendra, are zoonotic and can cause severe encephalitis and respiratory failure. Other avian or animal-infecting paramyxoviruses include Newcastle disease virus and various metapneumoviruses.

Diagnosis relies on nucleic acid amplification and serology; treatment is largely supportive. Prevention varies by virus; vaccines are available for measles, mumps, and rubella, but vaccines for many other paramyxoviruses are not widely used or available. Public health measures emphasize infection control and outbreak containment.