Genomic organization of lettuce necrotic yellows rhabdovirus.

We have mapped the genome of lettuce necrotic yellows virus (LNYV), the type member of the genus cytorhabdovirus of the family Rhabdoviridae. We have cloned and sequenced all intergenic regions and the 3' leader and 5' trailer of the negative-sense, single-stranded RNA genome of LNYV. The LNYV genome appears to contain six genes, the five expected genes coding for the virion proteins, and a sixth gene of unknown function, as for sonchus yellow net virus (SYNV), a member of the genus nucleorhabdovirus. The proposed LNYV genomic map is 3'-N-4a-4b-M-G-L-5', where N is the nucleocapsid protein gene; 4a and 4b are two genes, one of which codes for the proposed phosphoprotein P and the other for a putative protein of unknown function; M is the proposed matrix protein gene; G is the proposed glycoprotein gene; and L is the proposed transcriptase gene. The different LNYV intergenic regions have highly conserved consensus sequences, which could be divided into three components: the sequences corresponding to the 3' end of the mRNAs, intergenic sequences of variable length, and the sequences corresponding to the 5' end of the mRNAs. A leader sequence of 84 nucleotides (nt) at the 3' end of the LNYV genomic RNA preceeded the N gene. A trailer sequence of 187 nt at the 5' end of the genomic RNA followed the L gene. A comparison between LNYV leader and trailer sequences revealed complementary 3' and 5' ends, which could give rise to a putative "panhandle" structure with a two bases overhang in the leader sequence. We have compared these sequences to the corresponding sequences of SYNV as well as to vesicular stomatitis virus (VSV) and rabies virus (RV), the type members of the vesiculovirus and lyssavirus genera, respectively, of animal rhabdoviruses. Homologies were found in the intergenic regions between LNYV, SYNV, VSV, and RV, at the 3' ends of the mRNAs. LNYV intergenic sequences were of variable lengths, as were those found in RV. The consensus sequences found at the 5' ends of LNYV mRNAs differed from the highly conserved consensus transcription start sequence UUGU/A found in SYNV, VSV, and RV. Conserved sequences were also found in the first 30 nt of the leader and the last 30 nt of the trailer, between LNYV, SYNV, VSV, and RV.