An isolated nucleic acid molecule is disclosed, including a nucleotide sequence selected from the nucleotide sequence of (a) Ljungan virus 87-012, (b) Ljungan virus 145SL, (c) Ljungan virus 174F, and (d) a fragment of nucleotide sequences (a)-(c). Also disclosed are polypeptides encoded by the isolated nucleic acid, which are useful in preparing vaccines and antibodies to prevent or inhibit conditions caused by Ljungan virus, including diabetes.
