FIG. 1.

Pseudotype construction and LacZ⁺ Puro^R virus production. (A) The HEMV pseudotype was constructed by PCR amplification and cloning of a region including the env gene from M. spicilegus DNA. The amplified fragment was swapped into the ecotropic packaging-deficient vector pSV-Ψ minus-E-MLV. This construct, pSV-Ψ minus-HEMV-MLV, and the packagable marker vector pLacPuro were transfected into 293T cells. Viral particles produced by these cells were then used to infect tissue culture cells. Infection efficiency was assessed by staining for β-galactosidase. (B) A similar method was used to make other LacZ⁺ Puro^R pseudotypes. A triple transfection method using pMLVgagpol, pLacPuro, and various env gene constructs produced these viruses.