
<ArticleTitle>Analysis of dominant-negative effects of mutant <prot>Env</prot> proteins of human immunodeficiency virus type 1.</ArticleTitle>
<AbstractText>The <prot>Env</prot> protein of human immunodeficiency virus type 1 is assembled into a stable trimer, and oligomerization is required for maintenance of viral infectivity. This property of <prot>Env</prot> suggests that <prot>Env</prot> mutants may have a dominant-negative effect on virus infectivity. To investigate this possibility, we established a packaging cell line in which both wild-type and mutant <prot>Env</prot> proteins could be expressed simultaneously in a single cell. We analyzed the effects of two types of <prot>Env</prot> mutants: cytoplasmic tail-truncated TM mutants and a mutant defective in <prot>gp120</prot>/<prot>gp41</prot> cleavage. The cytoplasmic tail-truncated proteins were found to be incorporated into virions by forming an oligomer with wild-type TM, but could not inhibit the wild-type function. In contrast, phenotypic mixing of cleavage-defective <prot>Env</prot> with the wild-type protein caused dramatic inhibition of infectivity, indicating that this mutant has a strong dominant-negative phenotype.</AbstractText>
