Human parainfluenza virus 3 (HPIV-3) (HPIV-3)

Human parainfluenza virus 3 (HPIV-3) is a single-stranded, negative-sense RNA virus in the Paramyxoviridae family and Respirovirus genus, featuring an enveloped structure 125-250 nm in diameter with key proteins including nucleoprotein (N), phosphoprotein (P), RNA polymerase (L), hemagglutinin-neuraminidase (HN), fusion glycoprotein (F), and matrix protein (M). It primarily infects respiratory epithelial cells via HN-mediated receptor binding and F-driven membrane fusion, leading to viral replication, nucleocapsid assembly, and host cell damage that manifests as upper respiratory symptoms like cough and fever or severe lower tract diseases such as bronchiolitis and pneumonia, especially in infants, the elderly, and immunocompromised individuals. HPIV-3 triggers innate immune responses including interferon production and adaptive immunity via antibodies and T cells, though it evades these through rapid replication. In disease, it causes globally prevalent, highly contagious acute respiratory infections transmitted by droplets, distinct from influenza despite similar symptoms. Therapeutically, drugs like ribavirin, DAS181 (targeting sialic acid receptors), and HN/F inhibitors (BCX2798, VIQKI) address infection, with DAS181 approved for transplant-related pneumonia; vaccines including live attenuated and mRNA candidates are in development. The N-P interaction, conserved across paramyxoviruses, represents a potential antiviral target by disrupting RNA encapsidation.

Other names

HPIV3Human parainfluenza type 3 virusPIV-3

Ribavirin: Inhibits viral RNA synthesis via nebulized inhalation, oral, or IV routes DAS181: Cleaves sialic acid receptors to prevent viral attachment; approved for HPIV-associated pneumonia in transplant patients BCX2798: Inhibits hemagglutinin-neuraminidase (HN) glycoprotein function VIQKI: Derived from F protein C-terminal domain, disrupts viral fusion