HIV-1 Fusion with CD4+T cells Is Promoted by Proteins Involved in Endocytosis and Intracellular Membrane Trafficking

• Authors: Mariana Marin, Emory University; Yulia Kushnareva, La Jolla Institute for Allergy & Immunology; Caleb S. Mason, Emory University; Sumit K. Chanda, Sanford Burnham Prebys Medical Discovery Institute; Gregory Melikian, Emory University
• Journal Title: Viruses
• Volume: Volume 11, Number 2
• Publisher: MDPI | 2019-02-01
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.3390/v11020100
• Subjects: Health Sciences, Medicine and Surgery; Health Sciences, Immunology; Biology, Virology
• Keywords: Science & Technology; Life Sciences & Biomedicine; Virology; HIV; virus fusion; endocytosis; shRNA screen; cell fusion; membrane trafficking; HUMAN-IMMUNODEFICIENCY-VIRUS; CLATHRIN-MEDIATED ENDOCYTOSIS; T-CELLS; ENTRY; TYPE-1; INFECTION; DYNAMIN; EXPRESSION; INHIBITOR; LIBRARY

Abstract

Licensee MDPI, Basel, Switzerland. The HIV-1 entry pathway into permissive cells has been a subject of debate. Accumulating evidence, including our previous single virus tracking results, suggests that HIV-1 can enter different cell types via endocytosis and CD4/coreceptor-dependent fusion with endosomes. However, recent studies that employed indirect techniques to infer the sites of HIV-1 entry into CD4+ T cells have concluded that endocytosis does not contribute to infection. To assess whether HIV-1 enters these cells via endocytosis, we probed the role of intracellular trafficking in HIV-1 entry/fusion by a targeted shRNA screen in a CD4+ T cell line. We performed a screen utilizing a direct virus-cell fusion assay as readout and identified several host proteins involved in endosomal trafficking/maturation, including Rab5A and sorting nexins, as factors regulating HIV-1 fusion and infection. Knockdown of these proteins inhibited HIV-1 fusion irrespective of coreceptor tropism, without altering the CD4 or coreceptor expression, or compromising the virus’ ability to mediate fusion of two adjacent cells initiated by virus-plasma membrane fusion. Ectopic expression of Rab5A in non-permissive cells harboring Rab5A shRNAs partially restored the HIV-cell fusion. Together, these results implicate endocytic machinery in productive HIV-1 entry into CD4+ T cells.