Replication of Western Equine Encephalomyelitis Virus

Abstract

The ribonucleic acid (RNA) from Western equine encephalomyelitis (WEE) virions sedimented through sucrose gradients with a sedimentation coefficient of 40 S . Another viral RNA which was always associated with infected cells possessed a sedimentation coefficient of 26 S . Both 40 S and 26 S RNA had identical base compositions and densities. The 40 S RNA displayed a hyperchromic effect when heated with a T m of 57.5 C. When 40 S RNA was heated at 90 C and cooled rapidly, it sedimented with a coefficient of 26 S . Dialysis of 40 S RNA against distilled water changed its sedimentation coefficient to 26 S . The presence of 8 m urea or 50% dimethyl sulfoxide in the gradients also altered the sedimentation rate of 40 S RNA to 26 S . In the latter case, the 26 S RNA retained 10% of the infectivity originally added as 40 S RNA. Dialysis of 26 S RNA against 0.5 m NaCl or 0.05 m acetate buffer at p H 4.0 altered it so that about 50% of the radioactivity sedimented with a coefficient of 40 S . Chromatography on methylated albumin-kieselguhr columns failed to separate 40 S RNA from 26 S RNA. Viral RNA either exists in two conformations which sediment differently in sucrose or contains an extremely labile portion near the center and is easily broken into two equal pieces.