Identification and characterisation of multiple linear B cell protectopes in the respiratory syncytial virus G...

Respiratory syncytial virus (RSV) is an important respiratory pathogen in man, against which no vaccine is available. However, recent evidence suggests that antibodies to the RSV F and G proteins may play an important role in disease prevention. We previously demonstrated that BBG2Na, a subunit vaccine candidate including residues 130-230 of the Long strain G protein, protects rodents against RSV challenge. Using a panel of monoclonal antibodies (MAb) and synthetic peptides, five linear B cell epitopes were identified that mapped to residues 152-163, 165-172, 171-187 (two over-lapping epitopes) and 196-204. Antibody passive transfer and peptide immunisation studies revealed that all were protective. Pepscan analyses of anti-RSV-A and BBG2Na murine polyclonal sera suggested stronger immunogenicity of some protective epitopes (protectopes) in the context of BBG2Na compared with live virus. However, all the identified murine B cell protectopes were conserved in RSV seropositive humans. Should these protectopes correspond with protection in humans, BBG2Na may constitute a very interesting vaccine candidate against RSV.