Preliminary Crystallographic Study of a Complex Between an Fab of a Monoclonal Feline Peritonitis Virus Neutralizing Antibody and Its Anti-Idiotypic Fab

Abstract A complex between an Fab fragment of an E2 specific feline infectious peritonitis virus neutralizing antibody 730.1.4 and Fab fragment from an anti-idiotypic monoclonal antibody 409.5.3, was crystallized from ammonium sulfate using vapor diffusion methods. The complex crystals diffract to about 2·9 A resolution and are of orthorhombic space group P 2 1 22 1 with a = 75·2 A, b = 80·6 A and c = 187·6 A. There are two Fab molecules, or one idiotype-anti-idiotype complex, comprising the asymmetric unit. The long 187·6 A c axis suggests that the long axis of the complex might lie along this direction. Although small and radiation-sensitive, crystals are suitable for three dimensional structural analysis.