A method for inducing an immune response against HIV in a subject includes the step of preparing an HIV-1 gp120 envelope protein coding sequence particle having an N425K mutation, introducing the HIV-1 gp120 protein coding sequence particle having an N425K mutation into an expression construct using yeast homologous recombination, transfecting a cell with the expression construct, wherein the HIV-1 particle is secreted by the cell, and administering the secreted HIV-1 particle and a pharmaceutically acceptable carrier to the subject, wherein the secreted HIV-1 particle stimulates an immune response in the subject.