Analysis of human parainfluenza virus 3 receptor binding variants: evidence for the use of a specific sialic acid-containing receptor.

In order for the fusion protein (F) of the human parainfluenza virus type 3 (HPF3) to promote membrane fusion and viral entry, the haemagglutinin-neuraminidase (HN) glycoprotein must interact with its receptor. Sialoglycoconjugates are known to be the receptors for the HPF3 HN, however specific attachment factors or receptors for HPF3 have not been identified. In this report we describe the analysis of variants of HPF3 with increased fusion-promoting phenotypes that were selected by treatment with viral neuraminidase. The results suggest that for HPF3, the virus is specific in its use of sialic acid receptors; the majority of sialic-acid containing molecules are not targets for HPF3.