NUCLEOTIDE-SEQUENCE ANALYSIS OF THE ENV GENE AND ITS FLANKING REGIONS OF THE HUMAN SPUMARETROVIRUS REVEALS 2 NOVEL GENES

Recombinant clones that represent the 3' part of the genome of the human spumaretrovirus (foamy virus) were established from viral DNA and from DNA complementary to viral RNA. The recombinant clones were characterized by blot hybridizations and nucleotide sequence analysis. The deduced protein sequence of the clones at their 5' ends was found to be homologous to the 3' domain of retroviral reverse transcriptases. Downstream of a small intergenic pol-env region a long open reading frame of 985 amino acid residues was identified that according to its genomic location, size, glycosylation signals, and hydrophobicity profile closely resembles the lentiviral env genes. The spumaretroviral env gene is followed by two open reading frames, termed bel-1 and bel-2 which are located between env and the long terminal repeat region. The long terminal repeat of 1259 nucleotides is preceded by a polypurine tract and contains the canonical signal sequences characteristic for transcriptional regulation of retroviruses. The provisional classification of the spumaretrovirus subfamily is discussed.