Vaccinia virus encodes a polypeptide homologous to epidermal growth factor and transforming growth factor

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Abstract
Epidermal growth factor (EGF) and transforming growth factor type I (TGF) are polypeptides of 53 and 50 amino acid residues, respectively1,2. Both bind to EGF receptor, a 1,200-residue transmembranous glycoprotein3, leading to phosphorylation of the receptor, enhancement of its tyrosine-specific kinase activity and ultimately to stimulation of cell growth4,5. We report here that a 140-residue polypeptide encoded by one of the early genes of vaccinia virus (VV)6 is related closely to EGF and TGF. The presence of putative signal and transmembranous sequences further suggests that the viral protein might be an integral membrane protein, but that, as in the case of EGF itself7,8, the membrane-associated form may be the precursor of a soluble growth factor. Production of EGF-like growth factors by virally infected cells could account for the proliferative diseases associated with members of the poxvirus family such as Shope fibroma virus9, Yaba tumour virus10, and molluscum contagiosum virus (MCV)11.