In contrast, infection with the CXCR4-tropic SHIVmn229 resulted in a reduction in SerpinB2 mRNA levels in PBMCs; levels had fallen significantly by week 3 and remained depressed until week 11 (Fig. 1A, SHIV, p = 0.008 and 0.04, respectively). The gene discussed is CXCR4; the disease is infection.