Blocking α4β7 integrin binding to SIV does not improve virologic control

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Science  06 Sep 2019:
Vol. 365, Issue 6457, pp. 1033-1036
DOI: 10.1126/science.aaw7765

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An antibody is not the antidote

An HIV therapeutic that would give long-term remission without sustained antiretroviral therapy (ART) is a long-term goal. Byrareddy et al. [Science354, 197 (2016)] reported that treating simian immunodeficiency virus (SIV)–positive macaques with an antibody against integrin α4β7 during and after ART results in sustained virologic control after stopping all treatment. Three studies in this issue question the reproducibility of that result. Di Mascio et al. sequenced the virus used in the 2016 study and found that it was a variant with a stop codon in the nef gene rather than a wild-type virus. Abbink et al. used the same antibody for α4β7 as before but tested control of a more commonly used pathogenic virus. Iwamato et al. used the same nef-stop virus as in the earlier paper but combined the antibody against the integrin with an antibody against the SIV envelope glycoprotein, which also blocks viral binding of the integrin. None of these three new studies found that treating with the antibody had any effect on virologic control after stopping ART treatment.

Science, this issue p. 1025, p. 1029, p. 1033


A study in nonhuman primates reported that infusions of an antibody against α4β7 integrin, in combination with antiretroviral therapy, showed consistent, durable control of simian immunodeficiency virus (SIV) in rhesus macaques. The antibody used has pleiotropic effects, so we set out to gain insight into the underlying mechanism by comparing this treatment to treatment with non-neutralizing monoclonal antibodies against the SIV envelope glycoprotein that only block α4β7 binding to SIV Env but have no other host-directed effects. Similar to the initial study, we used an attenuated strain of SIV containing a stop codon in nef. The study used 30 macaques that all began antiretroviral therapy and then were divided into five groups to receive different antibody treatments. Unlike the published report, we found no sustained virologic control by these treatments in vivo.

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