 Superinfection case reports have shown that superinfecting strains generally had different viral epitopes from the initial infecting cell.An immune response to the initial infection would, therefore, be ineffective against the super-infecting strain, leading to the proliferation of the superinfecting strain.An HIV-1 vaccine designed to recognize specific viral epitopes would be ineffective as it would not provide protection against HIV-1 viruses that do not share the same epitope.