The appointment signals a renewed commitment to marketing from THT, which wants to grow its 16,000-strong regular donor base to spread the message that AIDS remains a devastating illness that threatens thousands of people in Britain because of complacent attitudes.
Target, a charity specialist whose clients include The Salvation Army and Royal British Legion, will develop a strategy to expand THT's donor base through tests of new audience profiles and creative approaches.
It is expected that much of the direct marketing work will be hard-hitting to convince people of the dangers of contracting the virus.
The THT drive follows research showing that public awareness of, and support for, research into HIV and AIDS is at an all-time low, despite more than 50,000 people in the UK suffering from the illness.
Target will aim to raise awareness of THT's campaign to reduce the spread of HIV and promote good sexual health, while encouraging public support by demonstrating the impact that donations have on THT's delivery of support services to those affected by AIDS.
THT was established in 1982, following the death of Terry Higgins, one of the first people to die in the UK of AIDS.
Iconic government advertising later in the decade underlined the AIDS awareness message, but there has been no specific advertising on the condition since.
The government does, however, run a series of adult sexual health initiatives, including marketing campaigns handled by Delaney Lund Knox Warren.
Research suggests young people have become increasingly complacent about their sexual health and that because of the development of HIV treatments, many people believe the illness is curable.