Retroviral vector targeting through insertion of epidermal growth factor into receptor binding deficient influenza A hemagglutinin results in fusion defective particles.
Targeting retroviral entry is a central theme in the development of vectors for gene therapy. The host range of a retrovirus is dependent upon the interaction of its envelope glycoprotein (Env) with a specific cell surface receptor protein, which allows viral entry. In contrast, the pH-dependent viruses enter cells through receptor-mediated endocytosis and the subsequent acidification produces conformational changes in the viral envelope protein(s) which lead to membrane fusion. We attempted to redirect retroviral vectors to epidermal growth factor (EGF) receptor expressing cells by using the pH-dependent influenza A virus hemagglutinin (HA). Wild type receptor binding was avoided either by point mutations or by deletion of the globular head structure of HA and also inserted EGF into HA. Replacement of the whole head domain was not tolerated. Two of the EGF-HA proteins bearing point mutations could be incorporated into retroviral particles, but unfortunately their fusion activity was lost. The data indicate that care must be taken when mutating multiple sites in HA, and that targeting HA requires further analysis of appropriate sites for the insertion of foreign sequences.
Institute for Biomedical Research, Georg-Speyer Haus, Paul-Ehrlich-Str. 42-44, D-60596 Frankfurt/Main, Germany.
Catherine
C
Haynes
Barbara S
BS
Schnierle
D000818:Animals; D019556:COS Cells; D004815:Epidermal Growth Factor / Q000235:genetics*; D018390:Gene Targeting; D005822:Genetic Vectors; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D009980:Influenza A virus / Q000235:genetics; D008561:Membrane Fusion; D051379:Mice; D009154:Mutation; D041681:NIH 3T3 Cells; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae / Q000472:pathogenicity*; D014771:Virion / Q000378:metabolism*
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011991:Receptors, Virus; D004815:Epidermal Growth Factor