STRIKING SIMILARITIES BETWEEN THE NUCLEOTIDE-SEQUENCE AND GENOME ORGANIZATION OF CITRUS TATTER LEAF AND APPLE STEM GROOVING CAPILLOVIRUSES

The sequence of the 3'-terminal 2956 nucleotides. excluding the poly(A ) tail, of the citrus tatter leaf virus (CTLV) genome was determined a nd compared with that of the apple stem grooving virus (ASGV) genome. The sequence of the 3'-terminal region of CTLV contains two overlappin g open reading frames (ORFs) and a 3'-terminal non-coding region of 14 2 nucleotides. The long, incomplete ORF1 ends at UAG (position 2812) a nd encodes a protein with at least 938 amino acids (M(r) > 108703). Th is protein contains the GDD motif associated with the RNA polymerase. ORF2. in a different frame within ORF1. starts at AUG (position 1248) and stops at UGA (position 2208) encoding a protein with an M(r) of 36 179 (36K). Partial homologies were found among the 36K protein of CTL V, the 50K protein of apple chlorotic leaf spot closterovirus, the 40K protein of potato virus T and the gene 1 products of caulimoviruses. The arrangement of ORFs in the 3'-terminal region of the CTLV genome i s in perfect agreement with that of the ASGV genome. The sequence of t he 3'-terminal 2956 nucleotides. excluding the poly(A) tail, of the CT LV genome shows 86.1% identity to that of the ASGV genome. Similaritie s of amino acid sequences encoded by ORF1 and ORF2 of CTLV with the co rresponding regions of ASGV are 86.1% and 97.3%, respectively. These r esults indicate that CTLV is a capillovirus closely related to ASGV.