Envelope glycoprotein intracellular transport

E. Fenouillet, I. M. Jones, The glycosylation of human immunodeficiency virus type 1 transmembrane glycoprotein (gp41) is important for the efficient intracellular transport of the envelope precursor gp 160. J. Gen. Virol. 1995, 76, 1509-1514. 

Viruses are exclusively intracellular organisms and therefore depend on the cells to multiply. A complete viral particle, or virion, consists of one nucleic acid molecule (RNA or DNA) covered by a protein layer (nucleo-capsid). Some virions have a lipid cover with a glycoprotein envelope. The main function of the virion is to transport the viral genome to the interior of the host cell to be replicated and amplified. 

Castanospermine has been screened for efficacy against simian immunodeficiency virus (265), and has been shown to prevent syncytium formation in feline astrocyte cultures infected with the feline immimodeficiency virus by modifying the viral cell envelope (266). It suppressed syncytium formation and hemolytic activity in baby hamster kidney cells infected with Newcastle disease virus however, synthesis and cell surface expression of the hemagglutinin-neuraminidase glycoprotein in the viral envelope were not affected, which strengthens the hypothesis that poor transport of the parent alkaloid across membrane barriers may limit its therapeutic use (267). Both 239 and its 6-0-butanoyl ester had comparable relative toxicities and antiviral effects on Rauscher murine leukemia virus (268), but the ester was more potent than the parent alkaloid in inhibiting replication of Moloney murine leukemia virus (258). The ester was also active against herpes simplex viruses types 1 and 2 (269,270). In the latter case, conclusive evidence was provided for intracellular hydrolysis to 239. 

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