To the Editor: We were duly impressed with the detailed virologic studies by Clark et al. and Daar et al. (April 4 issue)1,2 documenting high levels of cytopathic human immunodeficiency virus type 1 (HIV-1) in peripheral-blood mononuclear cells and plasma over the several weeks preceding seroconversion in eight persons who presented with severe manifestations of the so-called acute HIV syndrome. The emphasis in these reports was appropriately on the marked decline in viremia coincident with the maturation of the antiviral immune response — an observation that strongly supports a role for effective immunologic control of HIV-1 replication during early … © 1991, Massachusetts Medical Society. All rights reserved.