LOCALIZATION OF HUMAN-IMMUNODEFICIENCY-VIRUS REV IN TRANSFECTED AND VIRUS-INFECTED CELLS

The rev gene product of human immunodeficiency virus (HIV) is obligato ry for viral replication, Rev interacts specifically with a structured RNA sequence within the viral genome termed the REV response element (RRE). Although the importance of Rev for the expression of viral prot eins is well documented, its functional mechanism remains unresolved, Previous studies identified Rev in the absence of RRE to be a nuclear protein localized primarily within the nucleoli, To extend our underst anding of the role of Rev in viral replication, inmunolocalization stu dies of Rev and other nuclear components were carried out in transfect ed cells expressing both the Rev protein and RRE-containing mRNA and i n cells infected with HIV. In both types of cells, Rev-like immunoreac tivity was distributed both in the nucleoplasm and cytoplasm, Within t he nucleus, Rev immunoreactivity was not evenly distributed but was pr esent within focal concentrations, In transfected cells that were doub le labeled for Rev and SC-35, which labels a known component of splice osomes, the foci of Rev labeling were distinct from the ''speckles'' l abeled by SC-35, although Rev foci and speckles were often juxtaposed, In addition, morphological changes in the three-dimensional network o f speckles were observed in both transfected cells expressing both the Rev protein and RRE-containing mRNA and in cells infected with HIV-1 and HIV-2 Our observations are consistent with the proposed dual role of Rev in mRNA transport and splicing.