Modern antiretroviral therapy (ART) has saved millions of years of life [1], but it cannot eradicate latently infected cells [2, 3]. The replication-competent provirus that remains during ART represents the major barrier to curing HIV [4]. Most of this latent reservoir resides in solid tissues and not in circulating blood, and we have yet to fully define the sanctuary sites of HIV persistence [5]. Timothy Ray Brown (known by many as the ‘Berlin Patient’) may be the closest to an HIV cure after being treated with an allogeneic hematopoietic stem cell transplant from a donor who was homozygous for the CCR5Δ32 deletion [6]. Unfortunately, this remarkable success has not been reproduced, and robust viral replication resumes almost universally following treatment interruption [7–9]. Even if strategies currently in development succeed in purging HIV from circulating CD4+ T cells, residual virus can remain in the central nervous system (CNS), gut-associated lymphoid tissue (GALT), genital tract, adipose tissue, and others [9–12].