Human parainfluenza virus 2 fusion glycoprotein and hemagglutinin-neuraminidase glycoprotein (HPIV2 F protein and HPIV2 HN protein)

The **Human parainfluenza virus 2 fusion glycoprotein (F) and hemagglutinin-neuraminidase glycoprotein (HN)** are two essential envelope proteins required for the virus to enter host cells. The **HN protein** binds to cell surface sialic acid receptors, serving both as an attachment factor and a neuraminidase that cleaves sialic acid to facilitate release after replication[2][8][4]. Binding of HN to its cognate receptor triggers a conformational change in the **F protein**, allowing it to mediate fusion of the viral and host cell membranes, an obligatory step for viral RNA entry into the host cell cytoplasm[1][3][4]. These proteins are major determinants of viral infectivity, tropism, and immune recognition. Both are principal antigens in the host immune response and important vaccine targets, with conformational epitopes that can elicit neutralizing antibodies[1][7]. While no approved drugs currently target these proteins in HPIV2, they are considered high-priority antiviral and vaccine targets due to their central roles in viral pathogenesis and highly conserved nature, especially of the F protein[1][3][7]. They are not classical human receptors, enzymes, or cellular proteins but are **therapeutic targets in the context of infectious disease**.

Other names

HPIV-2 F proteinHPIV-2 HN proteinHuman parainfluenza virus type 2 F and HN proteinsFusion glycoprotein (F)Hemagglutinin-neuraminidase glycoprotein (HN)

Fusion inhibition (blocking F protein conformational change to prevent membrane fusion with host cells)[3][1]. Receptor-binding inhibition (blocking HN attachment to sialic acid containing receptors)[3][2]. Abortive triggering of fusion (prematurely activating F so the virus cannot infect cells)[3].