Here we report the expression of HIV-1 gp160 and its mutated proteins in Saccharomyces cerevisiae. Two strong hydrophobic regions, aa 511-537 and aa 679-703, were predicted by GCG Wisconsin Package software and removed to investigate the solubility of the mutated gp160 (gp160 Delta 12). The results showed that gp160 Delta 12 assumes high solubility as to be present in supernatant of cell lysate exclusively. The mutant exists as trimeric form in solutions via some inter-molecule disulfide bonds, which can be associated to monomer with the reduced reaction of DTT. The fermentation procedure was optimized to get high cell density yield and expression level as similar to 10 mg/L After purification with electro elution, gp160 Delta 12 was checked as glycosylation form by Endo-H deglycosylating catalysis. The ELISA performed with a panel of human sera suggests that the purified gp160 Delta 12 shares some determinants with gp120 and gp41, but exposes some distinct epitopes that react with early HIV-infected antibody. Thus, we may provide a novel antigen for immunodetection assay, vaccine candidate, and other relative research purposes. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.