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J. Virol., Aug 1995, 4854-4862, Vol 69, No. 8
NM Clark, MC Hannibal and DM Markovitz
Human immunodeficiency virus type 2 (HIV-2), like HIV-1, causes AIDS and is
associated with AIDS cases primarily in West Africa. HIV-1 and HIV-2
display significant differences in nucleic acid sequence and in the natural
history of clinical disease. Consistent with these differences, we have
previously demonstrated that the enhancer/promoter region of HIV-2
functions quite differently from that of HIV-1. Whereas activation of the
HIV-1 enhancer following T-cell stimulation is mediated largely through
binding of the transcription factor NF-kappa B to two adjacent kappa B
sites in the HIV-1 long terminal repeat, activation of the HIV-2 enhancer
in monocytes and T cells is dependent on four cis-acting elements: a single
kappa B site, two purine-rich binding sites, PuB1 and PuB2, and a pets
site. We have now identified a novel cis-acting element within the HIV-2
enhancer, immediately upstream of the kappa B site, designated peri-kappa
B. This site is conserved among isolates of HIV-2 and the closely related
simian immunodeficiency virus, and transfection assays show this site to
mediate HIV-2 enhancer activation following stimulation of monocytic but
not T-cell lines. This is the first description of an HIV-2 enhancer
element which displays such monocyte specificity, and no comparable
enhancer element has been clearly defined for HIV-1. While a nuclear
factor(s) from both peripheral blood monocytes and T cells binds the
peri-kappa B site, electrophoretic mobility shift assays suggest that
either a different protein binds to this site in monocytes versus T cells
or that the protein recognizing this enhancer element undergoes
differential modification in monocytes and T cells, thus supporting the
transfection data. Further, while specific constitutive binding to the
peri-kappa B site is seen in monocytes, stimulation with phorbol esters
induces additional, specific binding. Understanding the monocyte-specific
function of the peri-kappa B factor may ultimately provide insight into the
different role monocytes and T cells play in HIV pathogenesis.
Copyright © 1995, American Society for Microbiology
The peri-kappa B site mediates human immunodeficiency virus type 2 enhancer activation in monocytes but not in T cells
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0642, USA.
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