Progressive and persistent downregulation of surface CXCR4 in CD4+ T cells infected with human herpesvirus 7

We have previously shown that infection of CD4⁺ T lymphocytes with the T-lymphotropic human herpesvirus 7 (HHV-7) downregulates surface CD4, which represents the high-affinity receptor for HHV-7. In this study, we report that HHV-7 infection also causes a progressive loss of the surface CXC- chemokine receptor 4 (CXCR4) in CD4⁺ T cells, accompanied by a reduced intracellular Ca²⁺ flux and chemotaxis in response to stromal cell-derived factor-1α (SDF-1α), the specific CXCR4 ligand. Moreover, CXCR4 is downregulated from the surface of HHV-7-infected T cells independently of CD4. Because intracellular CXCR4 antigen and mRNA levels are unaffected in productively HHV-7-infected cells, the downregulation of CXCR4 apparently does not involve a transcritional block. Since CXCR4 functions in association with CD4 to permit entry of several human immunodeficiency virus (HIV) isolates, the potential of HHV-7 to persistently downregulate the surface expression of CXCR4 may provide novel strategies for limiting HIV infection.