This in invention relates to methods for the nucleic acid amplification of multiple variants (strains) of any pathogen present in a sample, and preferably in a sample from a pathogen infected individual. In preferred embodiments, the pathogen is a retrovirus, such as HIV. The amplified pathogen nucleic acid can be used to identify the pathogen variants present in a sample, to quantitate the pathogen present in a sample, and as a nucleic acid vaccine, or in the preparation of antigen presenting cell vaccines. Nucleic acids produced by the methods of the invention or the proteins encoded thereby can be used to transfect/load antigen presenting cells. The loaded antigen presenting cells can then be used as a vaccine for the treatment of pathogen infection.； In another embodiment, nucleic acids produced by the methods of the invention can be used directly as nucleic acid vaccines without prior loading into antigen presenting cells.
