Crystallization and preliminary X-ray analysis of two density populations of feline calicivirus

Two density populations of full-size feline calicivirus (FCV), the intact infectious particles (P(H)) and the empty capsids (P(L)), have been crystallized using the hanging-drop method. Exposed to high-intensity synchrotron radiation, P(H) and P(L) crystals were shown to diffract X-rays to about 3.0 and 5.5 A resolution, respectively. The P(H) crystal belongs to an orthorhombic crystal system with unit-cell dimensions a = 889.0, b = 995.0, c = 436.6 A. Based on the V(M) value (3.4 A(3) Da(-l)), it was estimated that one crystallographic asymmetric unit of P(H) crystals contains the unique content of an entire virus particle, not necessarily from the same particle. This implies the presence of 60-fold non-crystallographic redundancy. The particle orientation was obtained from a locked rotation function.