Scientists have identified a cohort of HIV-positive children in sub-Saharan Africa who are not on treatment, have replicating virus and yet maintain near-normal immune function, MedPage Today reports. Studying these children may help researchers gain insights that would help craft effective HIV cure strategies.

Publishing their findings in Science Translational Medicine, researchers identified 170 children living with HIV in sub-Saharan Africa who were considered pediatric nonprogressors, meaning they had never been on HIV treatment, contracted the virus from their mothers, were older than age 5 and had a CD4 count higher than 750. They had a median age of 8.3 years, a median viral load of 26,000 and maintained CD4 levels between 815 and 1,019.

None of the children were on antiretrovirals (ARVs) because their CD4 levels were not low enough to qualify for HIV treatment under national guidelines in the countries where they lived.

The researchers compared this cohort with 105 children considered pediatric progressors, meaning they met the same qualifications as the nonprogressors except they had a CD4 count lower than 500. This group had a median age of 10.6, a median viral load of 57,500 and a median CD4 count of 336.

Compared with the progressors, the nonprogressors had “strikingly low” immune activation, which is considered the major cause of HIV disease (rather than viral replication). In the progressors, greater levels of immune activation were linked with lower CD4 counts or percentages.

Compared with the progressors, the nonprogressors also had lower levels of the CCR5 coreceptor, a protein on the surface of CD4 cells onto which most HIV latches in order to infect the immune cell. Among the nonprogressors, CCR5 levels were much lower on the central memory cells compared with the effector memory cells.

The nonprogressors had lower CCR5 coreceptor levels on the central memory CD4s than the progressors.

A memory cell has been programmed to respond to a pathogen because of previous exposure to it. With lower levels of CCR5 coreceptors among them, the memory cells would be less likely to become infected by HIV. This could help explain how the nonprogressor children maintain normal CD4 levels while experiencing high viral loads.

Blocking infection of the long-lived memory CD4 cells could be a requirement for curing the virus, the researchers theorized.

To read the MedPage Today article, click here.

To read the study abstract, click here.