Animals 1 Cell Line 1 Feline immunodeficiency virus 1 Glycoproteins 1 HIV-1 1 Human immunodeficiency virus 1 1 Humans 1 Immunodeficiency Virus, Feline 1 Influenza virus hemagglutinin 1 Receptors, CXCR4 1 Receptors, HIV 1 Recombination, Genetic 1 T lymphocyte 1 Viral Envelope Proteins 1 Virus Attachment 1 Western blotting 1 article 1 binding assay 1 binding protein 1 cell fusion 1 cell surface 1 chemokine receptor CXCR4 1 chimeric protein 1 controlled study 1 electrophoretic mobility 1 embryo 1 env Gene Products, Human Immunodeficiency Virus 1 enzyme linked immunosorbent assay 1 flow cytometry 1 glycoprotein E1 1