Research ArticleHIV

Virion incorporation of integrin α4β7 facilitates HIV-1 infection and intestinal homing

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Science Immunology  12 May 2017:
Vol. 2, Issue 11, eaam7341
DOI: 10.1126/sciimmunol.aam7341

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Taking HIV to the gut

Antiretroviral therapy (ART) effectively limits HIV replication, but HIV+ individuals are medicated for life because ART withdrawal results in rebound of persistent virus. Developing therapies that keep viral loads low in the long term and prevent reinfection remains an important goal—one emerging approach is an antibody against integrin α4β7. Integrin α4β7 is a receptor that facilitates homing of CD4+ T cells to the gut, a key site for HIV persistence. ART-suppressed macaques that received antibodies against integrin α4β7 controlled the virus even after ART withdrawal. Here, Guzzo et al. demonstrate that integrin α4β7 is incorporated into the HIV envelope, suggesting that antibody treatment may directly interfere with the ability of HIV to target intestinal tissues. Their results change our perception of the role of integrin α4β7, a promising therapeutic target in HIV pathogenesis.

Abstract

The intestinal mucosa is a key anatomical site for HIV-1 replication and CD4+ T cell depletion. Accordingly, in vivo treatment with an antibody to the gut-homing integrin α4β7 was shown to reduce viral transmission, delay disease progression, and induce persistent virus control in macaques challenged with simian immunodeficiency virus (SIV). We show that integrin α4β7 is efficiently incorporated into the envelope of HIV-1 virions. Incorporated α4β7 is functionally active as it binds mucosal addressin cell adhesion molecule–1 (MAdCAM-1), promoting HIV-1 capture by and infection of MAdCAM-expressing cells, which in turn mediate trans-infection of bystander cells. Functional α4β7 is present in circulating virions from HIV-infected patients and SIV-infected macaques, with peak levels during the early stages of infection. In vivo homing experiments documented selective and specific uptake of α4β7+ HIV-1 virions by high endothelial venules in the intestinal mucosa. These results extend the paradigm of tissue homing to a retrovirus and are relevant for the pathogenesis, treatment, and prevention of HIV-1 infection.

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