• Top
• Background
• Materials and methods
• Results
• Conclusions

This article is part of the supplement: Fourth Dominique International Conference. Maternal chronic viral infections transmitted to infants: from mechanisms to prevention and care

Oral presentation

HIV-1 internalization in polarized human trophoblasts occurs through a peculiar endocytic pathway

Michel J Tremblay and Gaël Vidricaire

Centre de Recherche en Infectiologie, Centre Hospitalier de l'Université Laval, and Département de Biologie médicale, Université Laval, Québec (QC), Canada

corresponding author email

from Fourth Dominique Dormont International Conference. Host-Pathogen Interactions in Chronic Infections
Paris, France. 13-15 December 2007

Retrovirology 2008, 5(Suppl 1):O5doi:10.1186/1742-4690-5-S1-O5

The electronic version of this abstract is the complete one and can be found online at: http://www.retrovirology.com/content/5/S1/O5

Published:

9 April 2008

© 2008 Tremblay and Vidricaire; licensee BioMed Central Ltd.

Background

In human trophoblastic cells, a correlation between early endosomal trafficking of HIV-1 and virus infection was previously documented. However, if HIV-1 is massively internalized in these cells, the endocytic pathway(s) responsible for viral uptake is still undefined.

Materials and methods

The process through which HIV-1 is endocytosed was studied using different reagents (e.g. chlorpromazine, cholera toxin B, water-soluble cholesterol, colchicine, cytochalasin B, filipin, jasplakinolide, methyl-beta-cyclodextrin, paclitaxel, and vinblastine) and experimental strategies (e.g. transfection of JAR cells with various expression vectors, virus internalization test, infection assay, confocal laser scanning, co-localization analysis and digital image preparation).

Results

Amongst all the putative endocytic pathways present in polarized trophoblastic cells, we demonstrate that HIV-1 infection of these cells is independent of clathrin-mediated endocytosis and macropinocytosis. Importantly, treatment with the cholesterol-sequestering drug filipin severely impairs virus internalization, whereas the cholesterol-depleting compound methyl-beta-cyclodextrin has no impact on this pathway. Moreover, viral internalization is unaffected by overexpression of a mutant dynamin 2 or treatment with a kinase or tyrosine phosphatase inhibitor. Thus, HIV-1 infection in polarized trophoblastic cells occurs primarily via a clathrin-, caveolae-, and dynamin-independent pathway requiring free cholesterol. Notably, even though HIV-1 did not initially co-localize with transferrin, some virions migrate at later time points to transferrin-enriched endosomes, suggesting an unusual transit from the non-classical pathway to early endosomes. Finally, virus internalization in these cells does not involve the participation of microtubules but relies partly on actin filaments.

Conclusions

We demonstrate that HIV-1 internalization in polarized human trophoblastic cells occurs primarily via a clathrin-, caveolea-, and dynamin-independent pathway which is sensitive to a cholesterol-sequestering drug.

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