Among those attending the papal audience on Wednesday was Dr Michel Sidibé, Executive Director of UNAIDS, the United Nations body charged with coordinating a global response to the HIV-AIDS pandemic.
Last year Dr Sidibé was a guest speaker at a Rome conference on AIDS prevention and care, sponsored by the Pontifical Council for health care workers, urging closer cooperation between faith communities and organisations like his own.
After a brief meeting with Pope Benedict at the end of the audience and talks with other top Vatican officials, Dr Sidibé spoke to Philippa Hitchen about the purpose of his visit and about a current campaign to eliminate mother-to-child transmission of the HIV virus by 2015.