Further complexity of the genus Crinivirus revealed by the complete genome sequence of Lettuce chlorosis virus (LCV) and the similar temporal accumulation of LCV genomic RNAs 1 and 2

The sequence of Lettuce chlorosis virus (LCV) (genus Crinivirus) was determined and found to contain unique open reading frames (ORFs) and ORFs similar to those of other criniviruses, as well as 3′ non-coding regions that shared a high degree of identity. Northern blot analysis of RNA extracted from LCV-infected plants identified subgenomic RNAs corresponding to six prominent internal ORFs and detected several novel LCV-single stranded RNA species. Virus replication in tobacco protoplasts was investigated and results indicated that LCV replication proceeded with novel crinivirus RNA accumulation kinetics, wherein viral genomic RNAs exhibited a temporally similar expression pattern early in the infection. This was noticeably distinct from the asynchronous RNA accumulation pattern previously observed for Lettuce infectious yellows virus (LIYV), the type member of the genus, suggesting that replication of the two viruses likely operate via dissimilar mechanisms.