GLYCOSYLATION PATTERNS OF HUMAN IMMUNODEFICIENCY VIRUS - TYPE 1 (HIV-1IIIB) IN HUMAN CELL LINES OF HEMATOPOIETIC ORIGIN (MT-2 AND U937) DIFFERING BY SURFACE RECEPTORS

The classic model of HIV-1 propagation describes cell-free virion binding to surface receptors on target cells and a consequent entry. However, HIV-1 can also spread by direct cell-to-cell transfer. For HIV-1 the relative contributions of cell-cell versus cell-free dissemination is yet unknown. DC-SIGN (Dendritic Cells Specific Intercellular Grabbing Nonintegrin) molecules promote efficient HIV infection of CD4+T cells either in cis- or in trans- by selective binding to gp120. Env differs in carbohydrate structures depending on virus producing cells so affecting binding and transmission through differential glycosylation. Studies demonstrated that trans-infection could also occur through DC-SIGN independent mechanism/s, but no molecule/s were identified so far. The purpose of this study was to obtain the glycosylation patterns of HIV-1(IIIB) infected/uninfected hematopoietic cell lines (MT-2 and U937) differing by surface receptors. Preparative isoelectrofocusing (IEF) was performed for [C-14]-glucosamine labelled cytosols of each cell line. Parallelly, virus attachment-and replication-assays were performed. MT-2 cells attached 80% of the virus and demonstrated the highest glycosylated peak in the acidic region (pH 4.73) known to be occupied by HIV-1 gp120. U937 exposed glycosylation peaks dispersed at wide pH range. U937 adsorbed 21.5% of the virus and further no replication occurred. Therefore, with their low adhesion efficiency and despite presence of CD4+ and CXCR4, in absence of DC-SIGN, U937 cells could only partially tether the virus. The partial binding of X4 virus to U937 cells could not exclude participation of still unknown U937 cell surface molecule(s) hampering X4 strains binding to other human (CD4+CXCR4+ and DC-SIGN-) cells.