Nucleotide sequence of the 5'-terminus of Newcastle disease virus and assembly of the complete genomic sequence: agreement with the "rule of six".

We have determined the sequences of the 5' ends of three strains of Newcastle disease virus, permitting the assembly of the entire genomic sequence, which amounts to 15,186 nucleotides. This length is in agreement with the rule of six, which has been shown to determine replication efficiency in similar viruses. Comparison of the extreme 5' end of the trailer sequence with that of the 3'-terminal leader sequence of the virus reveals a high degree of complementarity. Variation between the 5'-terminal sequences of the different strains reveals the presence of alternative L gene polyadenylation signals, leading to correspondingly different trailer lengths.