Comparison of human respiratory syncytial virus A2 and 8/60 fusion glycoprotein gene sequences and mapping of sub-group specific antibody epitopes.
The fusion glycoprotein, F, of human respiratory syncytial virus is a principal target of neutralising antibodies and an important protective immunogen. Among sub-group A strains of the virus the F gene is highly conserved. A comparison of F gene sequences of two sub-group B strains, 8/60 and 18537, indicates that the gene also is conserved within this sub-group. However, both limited sequence variability and antigenic variation occurs between F genes from different virus sub-groups. Such variability may be important in the failure of natural- and vaccine-induced immunity and it is thus important to identify the variable epitopes. Three anti-F MAbs exhibiting sub-group specific neutralisation and binding to recombinant F glycoprotein were studied. Comparison of A2 and 8/60 F gene sequences revealed 64 predicted variant amino acids. In order to map the variant amino acids responsible for sub-group specific binding, three sets of chimaeric genes, in which different domains of A2 and 8/60 F were exchanged, were created and expressed. Sub-group specificity mapped to the N-terminal region of F1 for two MAbs (RS2B8 and RS348) and to the C-terminal region for the third. By using site-directed mutagenesis, sub-group specific binding of MAbs RS2B8 and RS348 was attributed to a predicted loop region between residues 200 and 216. This loop carried four residues variant between the sub-groups. Change of at least two was necessary to abrogate MAb binding.
Connor
A L
AL
The Department of Microbiology and Immunology, The Medical School, Newcastle upon Tyne, Great Britain.
Bevitt
D J
DJ
Toms
G L
GL
D000911:Antibodies, Monoclonal / Q000378:metabolism; D001666:Binding Sites, Antibody; D018604:Epitope Mapping; D005455:Fluorescent Antibody Technique; D014644:Genetic Variation; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000276:immunology; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics* / Q000276:immunology; D014760:Viral Fusion Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology
D000911:Antibodies, Monoclonal; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins