Degradation of Cowpea Chlorotic Mottle Virus Ribonucleic Acid in situ

Department of Virology, Agricultural University, Binnenhaven 11, Wageningen, The Netherlands Immediately after purification of cowpea chlorotic mottle virus (CCMV) in situ degradation of RNA-2 into two distinct RNA fragments begins. Upon storage of purified virus, even at 4 °C, all four virus RNAs degraded into small heterogeneous pieces. Addition of thiols accelerated degradation, as did higher temperatures. Addition of chelating agents in low concentrations prevented the in situ RNA degradation. Isolated CCMV-RNA was not degraded in the presence of thiol compounds. If the RNA was, however, reassembled with isolated coat protein into virus-like particles, degradation of the RNA occurred. A mixture of empty protein capsids and RNA also caused degradation of RNA. In a mixture of isolated RNA and purified virus, both degradation of added and in situ RNA occurred, but not to the extent of the degradation of the same amount of RNA within virions. Addition of radical scavengers to purified virus partially prevented the in situ degradation of CCMV-RNA, suggesting a radical mediated mechanism for the nucleic acid degradation. Received 24 August 1977; accepted 4 November 1977.