ORIGINAL (replaced): A gp160 vaccine derived from the MN strain, the most prevalent strain of HIV-1 in the United States, has been developed. A previous study showed that a combination vaccine strategy, consisting of priming with HIVAC-1e followed by boosting with a gp160 subunit vaccine, resulted in humoral and cellular immune responses of greater and longer duration than either vaccine alone. Thus, a live vector/subunit boost approach using the MN rgp160 vaccine merits investigation.