The researchers are also exploring PD-1 measurement as a diagnostic tool, said Walker. "Currently, we just count the number of helper T cells to decide when to treat someone, but we are excited about the possibility that adding PD-1 measurement might tell us more about the likelihood of progression of the disease and need for treatment in infected people," he said.
Walker said that scientists know little about the evolutionary purpose of a pathway that would deactivate such an important component of the immune system in the face of a viral attack. "It may be that in the heat of a battle that it sees it's not winning, the body makes an adjustment to try to co-exist," he said. "But we really do not know at this point."
Walker emphasized that the study could not have been done without his group's ongoing collaboration with the University of KwaZulu Natal. "These are studies that simply could not have been done in the United States," he said. "Despite the fact that these patients in Africa are living in poverty and in rural areas, it is easier for us to obtain their cooperation in such studies than with patients in the United States.
"It was with the key support of the Doris Duke Charitable Foundation and the Nelson Mandela School of Medicine that we have been able to build a biomedical research institute and develop this rich international collaboration that enables us to study the HIV epidemic at its epicenter, to gain knowledge that we could not obtain anywhere else," he said.