Cloning of the fusion gene of rinderpest virus: Comparative sequence analysis with other morbilliviruses

We have cloned the cDNA of the fusion (F) gene of the virulent (Kabete O) strain of rinderpest virus and provided a comparative analysis of its sequence with that of the F genes of measles and distemper viruses. The gene has an open reading frame of 2241 nucleotides with two potential initiation codons in-frame. Use of the first ATG would produce a polypeptide 747 amino acids long with a calculated molecular weight of 81,068. However, we suggest that the second ATG is used to generate the F₀ protein, which is 546 amino acids long with a calculated molecular weight of 58,754. During maturation, the cleavage of F₀ gives rise to the functional F₁ and F₂ polypeptides. The F₁ polypeptide is 438 amino acids long and has a calculated molecular weight of 46,791, with a single (potential) glycosylation site in its cytoplasmic domain. The F₂ polypeptide, probably 89 amino acids long after the signal sequence is cleaved, is estimated to be 9,800 Da and has three potential glycosylation sites. There is a divergence of 18.7% in amino acid sequences between rinderpest and measles virus F₀ polypeptides; between distemper and rinderpest viruses the divergence is 31.8%. No significant homology in nucleotide sequences of rinderpest DNA to measles or distemper DNA was found in the 5′ and 3′ untranslated regions.