The 5'-terminal non-coding region of Murray Valley encephalitis virus RNA is highly conserved.

The 5' non-coding region of the genomes of 11 isolates of Murray Valley encephalitis virus from Australia and Papua New Guinea were examined by primer extension sequencing. Although the 5' non-coding region of all isolates was found to be highly conserved, three isolates were significantly different in that they contained extra uridine residues. Two of these isolates from Papua New Guinea contained an extra uridine residue, nominally positioned after nucleotide 54, which was absent from all but one of the Australian isolates tested. This isolate (OR 156) contained a further uridine residue at the same site. These results provide further support for earlier observations on the genetic relationships between these isolates, in particular that OR 156 is more closely related to the Papua New Guinea strains than to the Australian strains.