N-butyldeoxynojirimycin-mediated inhibition of human immunodeficiency virus entry correlates with impaired gp120 shedding and gp41 exposure.
The alpha-glucosidase inhibitor N-butyldeoxynojirimycin (NB-DNJ) is an inhibitor of human immunodeficiency virus (HIV) replication and HIV-induced syncytium formation in vitro. Although an NB-DNJ-mediated change in viral envelope N-glycan composition inhibits HIV entry at the level of post-CD4 binding, the exact mechanism of inhibition remains to be established. In this study we have examined the effects of NB-DNJ on virion envelope composition and CD4-induced gp120 shedding and gp41 exposure. Virion composition analysis revealed an NB-DNJ-mediated reduction of 15% in overall virion envelope glycoprotein content and a reduction of 26% in the proteolytic maturation of virion gp160. Taken together, these two effects resulted in a reduction of approximately 40% in virion gp120 content. CD4-induced shedding of gp120 from the surfaces of envelope-transfected Cos cells was undetectable when gp120 was expressed in the presence of NB-DNJ. Similarly, the shedding of virion-associated gp120 was reduced 7.4-fold. CD4-induced exposure of cryptic gp41 epitopes on the surfaces of HIV-expressing ACH-2 cells was also greatly impaired, and the exposure of virion-associated gp41 epitopes was reduced 4.0-fold. Finally, CD4-induced increases in the binding of antibodies to the V3 loop of ACH-2-cell-expressed envelope glycoproteins were reduced 25-fold when the glycoproteins were expressed in the presence of NB-DNJ. These results suggest that the NB-DNJ-mediated retention of glycosylated N-glycans inhibits HIV entry by a combined effect of a reduction in virion gp120 content and a qualitative defect within the remaining gp120, preventing it from undergoing conformational changes after CD4 binding.
Fischer
P B
PB
Department of Biochemistry, Glycobiology Institute, University of Oxford, United Kingdom.
Karlsson
G B
GB
Dwek
R A
RA
Platt
F M
FM
D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D016466:CHO Cells; D006224:Cricetinae; D015699:HIV Envelope Protein gp120 / Q000187:drug effects / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000187:drug effects / Q000378:metabolism*; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D017485:1-Deoxynojirimycin; C059896:miglustat