Localization of immunogenic domains in the human immunodeficiency virus type 2 envelope

Abstract

Highly immunogenic domains have not yet been defined in the extracellular protein of the human immunodefiency virus type 2 (HIV-2) envelope. In this study, six contiguous segments covering the entire HIV-2ST envelope were amplified and cloned into a bacterial expression vector to localize the relative immunogenic reactivity of different regions of the molecule by Western blot (immunoblot) analysis. Our results demonstrate that the extracellular protein of the HIV-2 envelope contains highly immunogenic epitopes with potential value as type-specific markers for HIV-2 infection.

PIP: Researchers from Harvard University's School of Public Health in Boston, Massachusetts aimed to define highly immunogenic domains in the extracellular protein of the HIV-2 envelope. They used the polymerase chain reaction (PCR) method to amplify 6 contiguous segments of the entire glycoprotein envelope of the ST strain of HIV-2 (minimal cytopathicity compared with other HIV strains). Once amplified, the researcher cloned the 6 segments into the bacterial expression vector p806. They used the Western blot analysis on a panel of 48 HIV-2 positive and 22 HIV-2 negative serum samples (1:1000 dilution) from Senegal to localize the relative immunogenic reactivity of different regions of the envelope recombinant proteins. The results revealed that ST11-12 and ST15-16 were reactive with 95.8% and 97.9% of the HIV-2 positive samples respectively. They found similar results with serum from other West African countries. Therefore this research showed that ST11-12 and ST15-16 are highly immunogenic domains in the HIV-2 ST envelope. (The recombinant protein ST15-16 is located at the amino end of the transmembrane glycoprotein gp36 and ST11-12 is in the middle of the extracellular glycoprotein gp36 and ST11-12 is in the middle of the extracellular glycoprotein gp120.) In addition, the researchers used the Western blot analysis to screen a panel of HIV-1 positive sera. They learned that none of the HIV-1 positive serum samples cross reacted with ST 11-12. In conclusion, ST11-12 can be used as an additional type-specific serologic marker for HIV-2 infection.