One in 10 children has 'Aids defense'

A tenth of children have a "monkey-like" immune system that stops them developing Aids, a study suggests. The study, in Science Translational Medicine, found the children's immune systems were "keeping calm", which prevented them being wiped out. An untreated HIV infection will kill 60% of children within two and a half years, but the equivalent infection in monkeys is not fatal. The findings could lead to new immune-based therapies for HIV infection. The virus eventually wipes out the immune system, leaving the body vulnerable to other infections, what is known as acquired human immunodeficiency syndrome (Aids).

The researchers analysed the blood of 170 children from South Africa who had HIV, had never had antiretroviral therapy and yet had not developed Aids. Tests showed they had tens of thousands of human immunodeficiency viruses in every millilitre of their blood. This would normally send their immune system into overdrive, trying to fight the infection, or simply make them seriously ill, but neither had happened.

This defense against Aids is almost unique to children. Adult humans' immune systems tend to go all-out to finish off the virus in a campaign that nearly always ends in failure. Children have a relatively tolerant immune system, which becomes more aggressive in adulthood - chickenpox, for example, is far more severe in adults due to the way the immune system reacts. But this does mean that as the protected children age and their immune system matures, there is a risk of them developing Aids. Some do, some remain Aids-free.

Dr. Ann Chahroudi and Dr. Guido Silvestri, from Emory University in the US, said the study may have found the "very earliest signs of coevolution of HIV in humans". In a commentary, they added: "It is not known whether it would be clinically safe for these newly identified HIV infected paediatric non-progressors to remain off-therapy. This assessment is further complicated by the fact that prevention of HIV transmission to sexual partners becomes relevant in adolescence." Both Drs. Chahroudi and Silvestri are faculty members in the IMP program.

Click here to view the full story in the BBC News.