STRUCTURE OF COXSACKIEVIRUS B1 COMPLEXED WITH AN ANTIVIRAL AGENT. Karen N. Lentz¹, Allen D. Smith¹, Sheila C. Geisler¹, Stu Cox², Jason DeMartino², V. Girijavallabhan², John O'Connell², and Edward Arnold¹, ¹Center for Advanced Biotechnology and Medicine, and Rutgers University Department of Chemistry, 679 Hoes Lane, Piscataway, NJ 08854, ²Antiviral Chemotherapy, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033

Coxsackievirus B1 (CVB1) is a member of the picornavirus family and causes a wide variety of human diseases. These include common colds, mild febrile illness, encephalitis, and acute myocarditis. The picornaviruses are small (approximately 300 Å in diameter) RNA viruses that have an iscosahedrally systematic caspid. This caspid contains 60 copies of each of four coat proteins VP1, VP2, VP3, and VP4. Several structures of picornaviruses have been determined to date, however, no three-dimensional structure is currently available for CVB1. We report here the crystallization, X-ray diffraction analysis, and structure determination of CVB1 complexed to a potent antiviral agent.

Crystals of CVB1 complexed to an antiviral agent in the SCH 47802 series were grown in the presence of Li₂SO₄ and PEG using a modification of the vapor diffusion technique. Small triangular blocks appear in 2-5 days, the largest measuring 0.2 x 0.2 x 0.3 mm. These crystals diffract X-rays to at least 2.6 Å resolution at CHESS. Data analysis indicates that these crystals belong to space group C222₁ with cell dimensions of a=345.7, b=497.2.4, and c=485.9 Å, and [[alpha]]=[[beta]]=[[gamma]]=90deg.. A dataset was collected at the CHESS F1 station that is 50% complete to 3.0 Å resolution with a R_merge of 10.6%.

Molecular replacement was used to solve the structure using a starting model of coxsackievirus B3. Rotation and translation functions indicate that the particle is rotated 54.8deg. around the y-axis relative to a standard icosahedral orientation and that the position of the particle center is at y=0.19. After the molecular replacement solution was determined, thirty-fold non-crystallographic symmetry averaging was used to improve the electron density and the phases. Electron density consistent with bound antiviral agent is present in the drug binding pocket. Details of the interactions between the antiviral agent and the virus will be presented, as well as a comparison between CVB1 and other picornaviruses.