What is the fine-grained topic of the following text: A London man has no remaining detectable HIV a year and a half after undergoing a bone marrow stem cell transplant to treat lymphoma, according to a presentation at the Conference on Retroviruses and Opportunistic Infections (CROI 2019), taking place this week in Seattle. Only return the topic.
HIV eradication following a bone marrow stem cell transplant in a London man.