[Use of a synthetic peptide of HIV-2 glycoprotein 36 in antigen mixtures for the immunodiagnosis of HIV types 1 and 2]. / Uso de un péptido sintético de la glucoproteína 36 del VIH 2 en mezclas de antígenos para el inmunodiagnóstico de la infección por VIH tipo 1 y 2.

INTRODUCTION: The HIV-2 glycoprotein 36 (gp36) is often used in ELISA. An evaluation of the diagnostic indexes of antigen mixtures with a synthetic peptide of HIV2 gp36 (5) is performed in this study. METHODS: Five mixtures of gp36 (5) and the recombinant proteins of HIV1/2 were prepared. A total of 1306 samples were evaluated with UMELISA HIV1+2 RECOMBINANT used as reference. RESULTS: The variant (V-1) showed very good agreement as regards the reference method. CONCLUSION: The V-1 variant was shown to be highly effective in the immunodiagnosis of HIV 1/2.

Cleavage strongly influences whether soluble HIV-1 envelope glycoprotein trimers adopt a native-like conformation.

We compare the antigenicity and conformation of soluble, cleaved vs. uncleaved envelope glycoprotein (Env gp)140 trimers from the subtype A HIV type 1 (HIV-1) strain BG505. The impact of gp120-gp41 cleavage on trimer structure, in the presence or absence of trimer-stabilizing modifications (i.e., a gp120-gp41 disulfide bond and an I559P gp41 change, together designated SOSIP), was assessed. Without SOSIP changes, cleaved trimers disintegrate into their gp120 and gp41-ectodomain (gp41ECTO) components; when only the disulfide bond is present, they dissociate into gp140 monomers. Uncleaved gp140s remain trimeric whether SOSIP substitutions are present or not. However, negative-stain electron microscopy reveals that only cleaved trimers form homogeneous structures resembling native Env spikes on virus particles. In contrast, uncleaved trimers are highly heterogeneous, adopting a variety of irregular shapes, many of which appear to be gp120 subunits dangling from a central core that is presumably a trimeric form of gp41ECTO. Antigenicity studies with neutralizing and nonneutralizing antibodies are consistent with the EM images; cleaved, SOSIP-stabilized trimers express quaternary structure-dependent epitopes, whereas uncleaved trimers expose nonneutralizing gp120 and gp41ECTO epitopes that are occluded on cleaved trimers. These findings have adverse implications for using soluble, uncleaved trimers for structural studies, and the rationale for testing uncleaved trimers as vaccine candidates also needs to be reevaluated.