Strong interaction between human herpesvirus 6 and peripheral blood monocytes/macrophages during acute infection

Human herpesvirus 6 (HHV‐6) encodes a viral chemokine and chemokine receptors that may modify the functions of monocytes/macrophages (MO/Mϕ) during productive HHV‐6 infection. The interactions between HHV‐6 and MO/Mϕ during acute infection, however, remain poorly understood. In this study, we investigated the tropism of HHV‐6 in peripheral blood mononuclear cells (PBMCs) during acute infection. We detected 637 ± 273 copies of viral DNA in 10 4 MO/Mϕ. in contrast, in 10 4 CD4+ T cells, which have been reported to be viral carriers during the acute infection of HHV‐6, we found only 115 ± 42 copies of viral DNA. Consistent with these data, virus was isolated from MO/Mϕ an order of magnitude more frequently than from CD4+ T cells. Viral mRNA U79/80, which indicates viral replication, was detectable in the MO/Mϕ. In addition, the mRNAs that encode viral chemokine receptors U12 and U51, which may modify the function of MO/Mϕ, were expressed in the cells. Therefore, productively infected MO/Mϕ may be the dominant cell population that is responsible for HHV‐6 viremia during acute HHV‐6 infection. The strong interaction of HHV‐6 with MO/Mϕ may be partly responsible for the pathogenesis of this virus. J. Med Virol. 67:364–369, 2002. © 2002 Wiley‐Liss, Inc.