Biological activity, binding site and affinity of monoclonal antibodies to the fusion protein of respiratory syncytial virus.

The neutralizing activity and fusion-inhibition activity per unit weight of immunoglobulin were determined for each of a panel of 20 monoclonal antibodies (MAbs) to the fusion (F) protein of respiratory syncytial (RS) virus. Neutralization did not correlate with fusion-inhibiting activity, suggesting that the F protein plays at least two independent, antibody-sensitive roles in viral infection. Antibodies with the highest biological activity against A2, a subgroup A strain of RS virus, neutralized a subgroup B strain (8/60) poorly, suggesting a degree of antigenic variation that may be important in human infection.

Binding of neutralizing monoclonal antibodies to regions of the fusion protein of respiratory syncytial virus expressed in Escherichia coli.

cDNA containing the entire coding sequence of the respiratory syncytial (RS) virus fusion (F) protein gene (574 amino acids) and two large PstI restriction fragments, encoding amino acids 18 to 212 and 214 to 574, were expressed in Escherichia coli as C-terminal chimeras with beta-galactosidase (beta-gal) in the pEX expression vector system. A further cDNA fragment, overlapping the PstI restriction site and encoding amino acids 190 to 289, was derived by PCR and expressed in a similar manner. Polyclonal rabbit serum raised against RS virus bound to all four chimeric proteins but most strongly to those containing C-terminal sequences.