Intercellular traffic of human immunodeficiency virus type 1 transactivator protein defined by monoclonal antibodies

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Abstract
Monoclonal antibodies (mAbs) directed against the amino‐terminal region (N‐terminal sequence 2–19) of transactivator protein (tat) of HIV‐1 have been shown to inhibit intercellular transactivation mediated by the extracellular tat protein. The intracellular transactivation was not significantly affected by anti‐tat mAbs. The specificity of anti‐tat mAbs in abolishing the transactivating potential of extracellular tat is documented by studies with mAbs to HIV‐1 reverse transcriptase, or to a human mammary cancer protein. None of these antibodies showed any inhibitory effect on intercellular transactivation. Specific interaction of anti‐tat IgG with tat protein expressed in Jurkat cells is further supported by experiments on immunoblotting. Extracellular tat is responsible for signals which induce a variety of biological responses in HIV‐infected cells, as well as in uninfected cells. The fact that anti‐tat mAbs can abolish the intercellular traffic of tat protein offers a unique strategy in the development of vaccines against AIDS.