Determination of the coding capacity of the M genome segment of nephropathia epidemica virus strain Hällnäs B1 by molecular cloning and nucleotide sequence analysis.

The M genome RNA segment of nephropathia epidemica virus (NEV) strain Hällnäs B1 was characterized by molecular cloning and DNA nucleotide sequencing of the corresponding cDNA clones. The size of the M RNA segment is 3682 nucleotides. The 3' and 5' terminal sequences are complementary for 21 bases and their predicted secondary structure is very stable. The viral complementary messenger RNA possesses a single long open reading frame with a coding capacity of 1148 amino acids (polypeptide of 126 kDa). A comparison of the NEV M segment to that of Hantaan virus strain 76-118 reveals 61% sequence homology at the nucleotide level and 53% at the deduced amino acid level. Four out of five potential asparagine-linked glycosylation sites of the encoded glycoproteins have been conserved between NEV and Hantaan M. The isoelectric points (IEP) are nearly identical. Furthermore it was found that 90% of all cysteine residues have been conserved. Putative NEV G1 and G2 are preceded by a short hydrophobic sequence as shown for G1 and G2 of Hantaan virus. Hydrophilicity profiles of the two segments are of striking similarity. These data indicate that NEV- and Hantaan virus M-encoded polypeptides seem to be very similar in structure and function despite the relatively low amino acid sequence homology.