Antigenic sites variation of fusion protein of respiratory syncytial virus isolated from children with acute respiratory tract infection in Beijing area

Objective Respiratory Syncytial Virus(RSV) fusion protein is an important transmembrane glycoprotein associated with virus infection and immunity. To clarify the genetic characteristics and antigenic sites variation in F protein, comprehensive analysis was performed with 61 RSV stains isolated in Beijing area. Methods The antigenic sites area of F protein gene of RSV was amplified by RT-PCR and sequenced. The Phylogenetic trees were constructed with MEGA program. The identity matrices and genetic sites variation were determined with Bioedit software. Results Pairwise nucleotide(amino acid) sequences identities were 95.9%-100%(98.3%-100%) among 43 subtype A, 97.5%-100%(98.7%-100%) among 18 subtype B, and 83.2%-84.9%(93.1%-95.1%) between groups A and B, respectively. Phylogenetic analyses revealed that all the strains could be divided into two groups. Further, group A could be divided into 6 clusters, and group B could be divided into 3 clusters. There were 7 and 4 amino acid changes at group A and group B, respectively. Variations at antigenic site ∅ were observed in amino residues 209 and 211. No more mutation was found on the antigenic sites area except the 276(N→S) on palivizumab binding site. Conclusions The nucleotide and amino acid have high identity in F protein of Beijing RSV isolates except a few mutations. The F protein remains the potential candidate of RSV vaccine and molecular drugs. Key words: Respiratory syncytial virus; Fusion protein; Antigenic sites; Variation; Palivizumab