Clinical trials of vaccines against the human immunodeficiency virus are underway, but initial results do not seem promising — at least for one type of vaccine. By injecting patients with a recombinant form of a viral envelope protein, gp120, the idea was to induce an antibody response that could fight subsequent infection with the virus. But in a trial of 18 people, all became infected with HIV-1 and, at the level of the immune system, those who had received the vaccine did not seem to deal with the infection any differently than unvaccinated patients.