Molecular Viral Pathogenesis - INSERM U819  

CHOW Ken / FERNANDEZ Maria Dolores / Dr HARRIAGUE Julie / Dr LAGANE Bernard / Dr LEVOYE Angélique
Dr LOZACH Pierre-Yves / Dr PLANCHENAULT Thierry / RUEDA Patricia / STAROPOLI Isabelle

  Annual Report

We investigate the entry in host cells of the viral pathogens HIV and Flaviviruses (Dengue, DV; West Nile, WN) and in particular, the mechanisms related to the interaction of their envelope glycoproteins with receptors and attachment molecules. This work relies in the identification of new viral receptors (DV) and the study, both in vitro and in vivo, of the biological and pharmacological characteristics of identified viral receptors (CXCR4 & CCR5 HIV co-receptors, lectin DC-SIGN) regarding of physiologic and viral ligands. The accumulated expertise is applied to the investigation of the pathogenesis of the WHIM syndrome (WS), a genetic leukotaxis disorder associated to exacerbated CXCR4 activation and recalcitrant, severe infections by low-risk Human Papilloma Virus (HPV).

The ongoing research on HIV entry has characterized the distribution of CD4 and CCR5 at the cell membrane of living cells and we conclude that both receptors interact constitutively. This finding sheds light on the preferential transmission and propagation in vivo of CCR5-tropic HIV isolates. Our work has contributed to the seminal observation that CXCR4, the other major HIV co-receptor, is not the sole receptor for the chemokine SDF-1, for which we have described novel biological properties displayed by the SDF-1γ isoform. We proved that RDC-1/CXCR7 binds SDF-1 and interacts with CXCR4, two characteristics that foster us to assess the role of CXCR7 in the functioning of CXCR4 under both normal and pathologic situations. We are characterizing the molecular cues accounting for the pathological gain of function of CXCR4 and the severe HPV infections in WS.

A mouse model has been developed and validated to demonstrate the etiologic role of the exacerbated CXCR4 activation in the WS pathogenesis. Regarding the role of attachment factors in HIV entry in dendritic cells (DC), we elucidated the role played by the lectin DC-SIGN regarding both the infection and the unsurpassed capacity of this DC-expressed lectin, to transmit HIV to CD4 T lymphocytes. We concluded that efficient and delayed HIV transmission from DC to T cells excludes cell capture of infectious viruses and relies in the productive infection mediated by the in cis collaboration of DC-SIGN with canonical receptors CD4/CCR5.

Concerning flavivirus entry and dissemination within the organism, our data indicate that immature DC, which are normal residents in the skin, are the first target of flavivirus. We show that DC support DV-entry and -infection by a DC-SIGN- mediated mechanism which relies in the enhanced capture of DV and does not require DC-SIGN internalization. We have identified the critical sugar residues in DV-envelope glycoprotein involved in DC-SIGN-mediated DV entry. We investigate in a human-DC-SIGN transgenic mouse, the role played by DC-SIGN in the dissemination of infection either by DV or WN. Using genetic approaches and high-throughput screenings (siRNA, cDNA) we identify flavivirus receptors and host cell factors regulating virus entry.


DC-SIGN-dependent, DV-infection (DV E) analyzed in a cDNA cell-microrray. Collaboration with Dr. X. Gidrol (CEA, France).


Publications 2006 of the unit on Pasteur's references database

Activity Reports 2006 - Institut Pasteur
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