1. Chemokine Receptors: Keys to AIDS Pathogenesis?
Dan R Littman 
Cell 
Volume 93, Issue 5, Pages (May 1998)
DOI: /S (00)

2. Figure 1 Basis of HIV-1 Cellular Tropism
Previous nomenclature for viral tropism is noted at the bottom. Macrophage-tropic viruses were also named NSI (non-syncytium-inducing in T cell lines), whereas T cell line–tropic viruses were named SI (syncytium-inducing). These viruses are now named R5 and X4, respectively.
Cell  , DOI: ( /S (00) )