The cleavage activation and sites of glycosylation in the fusion protein of Hendra virus

Hendra virus (HeV) is an unclassified member of the Paramyxoviridae family that causes systemic infections in humans, horses, cats, guinea pigs and flying foxes. The fusion protein (F0) of members of the Paramyxoviridae family that cause systemic infections in vivo contains a basic amino acid-rich region at which the protein is activated by cleavage into two subunits (F1 and F2). HeV F0 lacks such a domain. We have determined the cleavage site in HeV F0 by sequencing the amino terminus of the F1 subunit and in view of the potential effect of glycosylation on the cleavage process have ascertained the sites at which F0 is glycosylated. The results indicate that unlike other members of the family that replicate in cultured cells and cause systemic infections in vivo, cleavage of HeV F0 occurs at a single lysine (reside 109) in the sequence Asp–Val–Lys–↓–Leu. Although HeVgenotypically resembles members of the Respirovirus and Rubulavirus genera in having potential N–linked glycosylation sites in both the F1 and F2 subunits, we show that phenotypically HeV may more closely resemble members of the Morbillivirus genus that contain N–linked glycans only in the F2 subunit.