The baculovirus-insect cell vector system is used as a high efficiency eukaryotic cloning and expression method for the production of recombinant proteins. A major application of this system is also in the development of rDNA vaccines for a variety of important human and animal diseases. This system is used to express a variety of candidate vaccine immunogens derived from the envelope gene of Human Immunodeficiency Virus (HIV). The envelope protein of HIV is the most promising candidate in the development of vaccines. HIV antigens produced from some of these recombinants have been successfully employed in a variety of immunodiagnostic assays including ELISA, Western Blotting and radioimmunoprecipitation.