Human Immunodeficiency Virus (HIV) researchers have discovered a group of South African children who may have a built-in defense against Acquired Immune Deficiency Syndrome (AIDS). Known as “HIV non-progressors,” the children were identified through routine blood testing because their mothers had HIV and probably transmitted the virus while they were in the womb. Yet, surprisingly, while these children’s blood contains vast quantities of HIV, they’re healthy and scientists believe they won’t ever develop AIDS.
HIV works by coopting the body’s immune cells – it first inserts genetic material into the cells, causing replication of more virus and ultimately destruction of the immune cell. If left untreated, this vicious cycle will continue until a person’s immunity is so damaged it leaves them susceptible to AIDS. On the other hand, child non-progressors do not have destruction of their immune systems or a predisposition to AIDS.
Two immune responses help prevent HIV progression in child non-progressors – reduction in immune activation and decreased infection of long-lived CD4 T-cells, which replenish general CD4-cell stock in the body and contribute to immune activity. CD4 T-cells have receptor proteins called CCR5 on their surfaces, which allow HIV particles to enter and destroy the T-cells. Child non-progressors have lower levels of CCR5 and thus lower amounts of virus entering. A monkey species, sooty mangabeys, that has natural protection from monkey HIV uses the same process.
The defense mechanism used by child non-progressors is very rare and this patient population represents only 5% to 10% of HIV-infected children. In comparison, typical children who are infected “have a 60% death rate within two years if they are not on treatment,” according to Philip Goulder, a professor of immunology at the University of Oxford. Adults normally have an average of 10 years before the onset of AIDS and 11 years prior to death.
Only 0.3% of HIV-infected adults – known as elite controllers – are naturally immune to AIDS. They remain disease-free by attacking the virus with a very strong immune response. But child non-progressors do the opposite, by “not picking a fight with a virus that you’re going to lose,” says Gould.
While the child non-progressors have opened up a new pathway towards finding a cure, there is still a lot more research and understanding needed. As Robin Shattock, a professor of mucosal infection and immunity at Imperial College London says, “This shows that humans have found an alternative way to cope with HIV infection,” but “There’s a lot to follow up on.”