Despite these challenges, targeting just the most important cell types in sanctuary sites that contribute most significantly to persistent infection could still prove worthwhile. By significantly reducing the size of the reservoir, but not necessarily eliminating it, trafficking therapy could be used alongside other therapies or in pursuit of a functional cure (see S6 Text for comments). For instance, gut associated lymphoid tissue is an important site of persistent HIV-1  and the trafficking of immune cells to the gastrointestinal tract can be reduced by integrin inhibitors (vedolizumab and natalizumab) that are routinely used for the treatment of Crohn’s disease and ulcerative colitis . These drugs consist of monoclonal antibodies that selectively target the α4β7 integrin receptor, expressed on immune cells. When used to treat simian immunodeficiency virus-infected monkeys, vedolizumab reduced the amount of virus detected in the blood . Under the hypothesis presented here, the anti- α4β7 antibody likely helped to control simian immunodeficiency virus infection after antiretroviral drug cessation by encouraging CD4 T cells to traffic away from gut-associated lymphoid tissue, to other tissue sites that have high concentrations of antiretroviral drugs.