More than 25 years after the discovery of the novel immunodeficiency disease that is now known as AIDS, at least 40 million people worldwide are living with HIV. Halting the epidemic therefore remains a top global health priority. In the absence of an efficacious vaccine, infected individuals are reliant on researchers to continue to unravel the biology of this virus and finesse treatment options. However, one sticking point for therapeutics has been the pool of latently infected CD4+ T cells that is present in infected individuals. These viruses remain sequestered from the action of antiviral drugs, making virus eradication impossible, and they can be drug resistant, limiting future treatment options. In this issue, Han and co-workers from the Siciliano group (page 95) address the important issue of HIV-1 latency, and consider how latent viruses can be analysed in the laboratory and detected in patients.

As HIV-1 has now been circulating among humans for at least 60 years, there is an ongoing debate about the virulence of the virus. The incredibly high mutation rate of HIV-1 has prompted some scientists to hypothesize that the virus might co-evolve with the human host to eventually yield a less virulent form. This controversial point of view is elaborated by Ariën, Vanham and Arts on page 141 of this issue.

Three new research papers recently identified a new role for the bacterial H-NS global transcription regulator as a sentinel that regulates horizontally-acquired genes. In a short Opinion on page 157, Charles Dorman, a leader in the H-NS field, sets these findings into context against the backdrop of the extensive body of literature on this important regulator, and discusses how this might impact on our understanding of gene regulatory networks and bacterial evolution.