The present invention relates to peptides, referred to as CBD-1, CBD-2, CBM-1/TH-1, CBM-1/TH-2, CBM-2/TH-1, CBM-2/TH-2 and C-20 peptides, which are antigenic and elicit a protective immune response against HIV infection. Compositions, pharmaceutical compositions and vaccines comprising these antigenic peptides are also encompassed by the present invention, as well as neutralizing antibodies which inhibit infection of primary CD4+ T lymphocytes by various HIV isolates. Methods for diagnosis of HIV are also disclosed.