Two strains of HIV have been discovered that attack the immune system in a new way, according to research published in the January issue of Nature Medicine. It was previously thought that HIV largely affects CD4⁺ T cells, leaving CD8⁺ cells relatively untouched. Although two HIV strains from infected CD8⁺ cells had previously been isolated, it was not known whether their structures were different from those of strains that infect CD4⁺ cells.

In the new research, Saha and colleagues show that neither the CXCR4 nor CCR5 cell-surface receptors, which are the most common co-receptors used for viral entry, are required for the new strains to infect CD8⁺ cells, suggesting an altered viral structure. It is stressed that the strains come from a single patient. Kunal Saha, of Ohio State University, said: "The vital question is, just how common is this?"