CRYSTALLIZATION AND PRELIMINARY STRUCTURE-ANALYSIS OF AN INSECT VIRUS WITH T = 4 QUASI-SYMMETRY - NUDAURELIA-CAPENSIS OMEGA-VIRUS

We report the crystallization of Nudaurelia capensis omega-virus, a pathogen of the pine emperor moth. The icosahedral particle has T = 4 quasi-equivalent symmetry and is approximately 410 angstrom in diameter. Triclinic crystals (a = 414.0, b = 410.7, c = 420.1 angstrom, alpha = 59.1, beta = 58.9, gamma = 64.0-degrees) diffracting X-rays to 2.7 angstrom resolution have been analyzed using a partial data set collected at high resolution (2.7 angstrom) using conventional oscillation photography and a more complete data set collected at low resolution (50-9 angstrom) using a Siemens area detector. The pseudo-rhombohedral symmetry of the crystals created significant problems in processing the unaligned oscillation photographs. Successful processing of the films depended on the use of an auto-indexing procedure followed by systematic scaling tests of four, nearly equivalent, reduced cells. The unique cell from the area-detector data collection was identified by scaling the four possible choices with the film data. The particle orientation was determined using the rotation function.