In addition, we included a selected subset of samples from SHIVKu1-infected macaques in order to compare the differences between the extent of CC-chemokine down-regulation caused by CCR5-tropic SHIVSF162P4 and more pathogenic CXCR4-tropic SHIVKu1 at the acute stage of infection. This evidence concerns the gene CXCR4 and infection.