Interference with HIV-induced syncytium formation and viral infectivity by inhibitors of trimming glucosidase

Abstract

Human immunodeficiency virus (HIV), the causative agent of AIDS, infects human lymphocytes and monocytes1,2. An interaction between the viral envelope gp120 and CD4 protein is required to initiate an infectious cycle3–7. HIV infection in vitro induces syncytium formation by cell-to-cell fusion; this aspect of viral cytopathogenicity is even more dependent on gp120–CD4 interactions4. That gp120 is extremely heavily glycosylated (31–36 N-linked glycans per molecule), suggests involvement of N-linked glycans in the gp120–CD4 interaction8. We therefore investigated the effects of castanospermine, 1-deoxynojirimycin (dNM) and 1-deoxymannojirimycin (dMM), three trimming glycosidase inhibitors which perturb N-linked glycan structure9, on induction of the formation of syncytium between HIV-infected and CD4-expressing cells. The glucosidase inhibitors castanospermine and dNM, but not the mannosidase inhibitor dMM, inhibited syncytium formation and interfered with infectivity. The potential of glucosidase inhibitors as anti-HIV therapeutic agents deserves further investigation, especially because dNM and related compounds show little toxicity in vitro and in vivo 9–11.