Regarding envelope proteins from Pneumovirinae subfamily viruses (Paramyxoviridae family), although human respiratory syncytial virus (RSV) is contagious, causing infection in the lungs and respiratory tract [257], a phenotypically unmixed heterologous triple-pseudotyped lentiviral vector (SH/G/F-LV) using the RSV envelope proteins SH, G, and F is considered useful in RSV virology research [220]. This evidence concerns the gene ERVW-1 and infection.