In this paper, we use canonical bundle formulas to prove various generalizations of an old theorem Kawamata on the semiampleness nef and abundant log divisors. particular, show that for klt pairs [Formula: see text] with effective, nef, nefness abundance implies semiampleness. This essentially extends Kawamata’s setting generalized abundance.

Nef is a 27 - 34 kD myristoylated protein unique to primate lentiviruses. A functional Nef gene is important for development of high viremia and simian AIDS in SIV infected rhesus macaques (1). In a transgenic mouse model expression of Nef protein alone when expressed under a CD4-promoter is sufficient to cause an AIDS like disease (2). A critical role for Nef in development of AIDS in humans i...

Monocytes and macrophages utilize the class A and B scavenger receptors to recognize and perform phagocytosis of invading microbes before a pathogen-specific immune response is generated. HIV-1 Nef protein affects the innate immune system impairing oxidative burst response and phagocytic capacity of macrophages. Our data show that exogenous recombinant myristoylated Nef protein induces a marked...

The human immunodeficiency virus type 1 (HIV-1) Nef protein upregulates the expression of the invariant chain (Ii)/major histocompatibility complex class II (MHC-II) complex at the cell surface. This complex appears to reach the antigen-loading endosomal compartment at least in part via an indirect pathway in which it is internalized from the cell surface via the adaptor protein 2 (AP-2) comple...

The impact of HIV-1 Nef-mediated HLA-I down-regulation on CD8(+) cytotoxic T lymphocytes (CTLs) varies by epitope, but the determining factors have not been elucidated. In the present study, we investigated the impact of Nef on the antiviral efficiency of HIV-1-specific CTLs targeting 17 different epitopes to define properties that determine susceptibility to Nef. The impact of Nef was not corr...

Nef proteins of primate lentiviruses promote viral replication, virion infectivity, and evasion of antiviral immune responses by modulating signal transduction pathways and downregulating expression of receptors at the cell surface that are important for efficient antigen-specific responses, such as CD4, CD28, T-cell antigen receptor, and class I and class II major histocompatibility complex. H...

Nef, an accessory protein of human and simian immunodeficiency viruses, is a critical determinant of pathogenesis that promotes the progression from infection to AIDS. The pathogenic effects of Nef are in large part dependent on its ability to downregulate the macrophage and T-cell coreceptor, CD4. It has been proposed that Nef induces downregulation by linking the cytosolic tail of CD4 to comp...

Lipid rafts, also known as detergent-resistant membranes (DRM), are microdomains in the plasma membrane enriched in sphingolipids and cholesterol (reviewed in [1, 2]). Human immunodeficiency virus 1 (HIV) buds via lipid rafts [3, 4]. However, the targeting of viral structural components to DRM and its consequences for viral replication are not understood. Moreover, the negative factor Nef from ...

Nef alters the cell surface expression of several immunoreceptors, which may contribute to viral escape. We show that Nef modifies major histocompatibility complex class II (MHC II) intracellular trafficking and thereby its function. In the presence of Nef, mature, peptide-loaded MHC II were down-modulated at the cell surface and accumulated intracellularly, whereas immature (invariant [Ii] cha...

The viral regulatory gene, nef, is unique to the human immunodeficiency viruses (HIV) and their related primate lentiviruses. Expression of the nef gene has been shown to be essential to the maintenance of high levels of virus replication and the development of pathogenesis in the animal model of simian immunodeficiency virus (SIV) infection. In contrast to this in vivo model, the use of standa...