CRYSTALLIZATION AND PRELIMINARY X-RAY STRUCTURE INVESTIGATION OF THE PORCINE VESICULAR EXANTHEMA VIRUS (S-72 STRAIN). A.M.Mikhailov. Institute of Crystallography, Moscow, Russia; V.A.Perevozchikov, Institute of Animal Protection, Vladimir, Russia; A.N.Kornev, Institute of Cell Biophysics, Pushchino, Russia

The Sakhalin-72 (S-72) virus belongs to the viruses causing vesicular diseases comprise the Calicivirus genus of the Pi- cornaviridae family. The S-72 virus was isolated in the Sakhalin region. Stadies of the reactions of diffuse precipitation and neutralization in a tissue culture with porcine convalescent serums demonstrated that immunologically, virions of this strain are significantly different, and in some instances totally different, from the porcine vesicular disease viruses of other strains. An particle of S-72 with an outside diameter of 35+2 nm has well difined projections above the capsid surface. The molecular mass of the S-72 virion is 10x10 Da. The genome of the virus is an infections RNA plus strand of molecular mass 2x10 Da. A protein sheath of the S-72 is formed by a single structural protein with molecular mass 65+5 kDa. The icosahedral capsid with the triangulation number T=3 is formed by 180 "copies" of protein molecules. The crystals were grown in the "sitting drop" mode. The optimum precipitant is a 1 M ammonium sulfate solution in a 0.2 M Tris-HCl buffer at pH 7.8. The crystallization solu tion with a volume of 20 ml was composed of 10 ml of the 1% viral suspension, 9 ml of the precipitant solution, and 1 ml of PEG 300. The crystal growth time was 2-4 weeks at 20-22 C. These are the crystals for which the diffraction range extends to 2.7-2.9 Å resolution. The packing of the virions in the crystal can be described by the sp.gr.P23 with the parameter of the unit cell a=413 Å and Z=1. The ssymmetric unit contains fifteen protein molecules of the capsid. In most cases the angular width of the reflections was equal to 0.3 .