HIV medicines have led to dramatic improvements in health. However, there remains a concern for potential drug toxicities, cost of drugs, and need for life-long treatment. In addition, research has found that health is not completely restored in HIV-infected patients, even if they have been taking effective HIV medicines for a long time. This may be due to direct drug-toxicity, continued replication of the virus, and/or inflammation of the body in response to the virus. Therefore, a more complete understanding of how HIV stays in the body is necessary.