 Self-activation of the infected cell by IL-2 also stimulates the cell to become an effector cell and initiate the machinery which HIV-1 relies upon for its own proliferation.To further evade the host immune response, Nef down-regulates the cell surface and total expression of the negative immune modulator CTLA-4 by targeting the protein for lysosomal degradation.In contrast to CD28 which activates T-cells, CTLA-4 is essentially an “off-switch” which would inhibit the viral production if it were activated.