The human T-cell leukemia virus type I Tax protein trans-activates several cellular genes implicated in T-cell replication and activation. To investigate its leukemogenic potential, Tax was targeted to the mature T-lymphocyte compartment in transgenic mice by using the human granzyme B promoter. These mice developed large granular lymphocytic leukemia, demonstrating that expression of Tax in the lymphocyte compartment is sufficient for the development of leukemia. Furthermore, these observations suggest that human T-cell leukemia virus infection may be involved in the development of large granular lymphocytic leukemia.

Genetic variants of human and simian immunodeficiency virus (HIV and SIV) that evolve during the course of infection and progression to AIDS are phenotypically and antigenically distinct from their progenitor viruses present at early stages of infection. However, it has been unclear how these late variants, which are typically T-cell tropic, cytopathic and resistant to neutralizing antibodies, influence the development of clinical AIDS. To address this, we infected macaques with cloned SIVs representing prototype variants from early-, intermediate- and late-stage infection having biological characteristics typical of viruses found at similar stages of HIV infection in humans. These studies demonstrate that sequential, phenotypic and antigenic variants represent viruses that have become increasingly fit for replication in the host, and our data support the hypothesis that emerging variants have increased pathogenicity and drive disease progression in SIV and HIV infection.

CCR5, a coreceptor for HIV-1 entry, is a major target for drug and genetic intervention against HIV-1. Genetic intervention strategies have knocked down CCR5 expression levels by shRNA or disrupted the CCR5 gene using zinc finger nucleases (ZFN) or Transcription activator-like effector nuclease (TALEN). In the present study, we silenced CCR5 via CRISPR associated protein 9 (Cas9) and single guided RNAs (sgRNAs). We constructed lentiviral vectors expressing Cas9 and CCR5 sgRNAs. We show that a single round transduction of lentiviral vectors expressing Cas9 and CCR5 sgRNAs into HIV-1 susceptible human CD4+ cells yields high frequencies of CCR5 gene disruption. CCR5 gene-disrupted cells are not only resistant to R5-tropic HIV-1, including transmitted/founder (T/F) HIV-1 isolates, but also have selective advantage over CCR5 gene-undisrupted cells during R5-tropic HIV-1 infection. Importantly, using T7 endonuclease I assay we did not detect genome mutations at potential off-target sites that are highly homologous to these CCR5 sgRNAs in stably transduced cells even at 84 days post transduction. Thus we conclude that silencing of CCR5 via Cas9 and CCR5-specific sgRNAs could be a viable alternative strategy for engineering resistance against HIV-1.

No abstract

The RNA genome of the human immunodeficiency virus (HIV) is reverse-transcribed into DNA and integrated into the host genome, resulting in latent infections that are difficult to clear. Here we show an approach to eradicate HIV infections by selective elimination of host cells harboring replication-competent HIV (SECH), which includes viral reactivation, induction of cell death, inhibition of autophagy and the blocking of new infections. Viral reactivation triggers cell death specifically in HIV-1-infected T cells, which is promoted by agents that induce apoptosis and inhibit autophagy. SECH treatments can clear HIV-1 in >50% mice reconstituted with a human immune system, as demonstrated by the lack of viral rebound after withdrawal of treatments, and by adoptive transfer of treated lymphocytes into uninfected humanized mice. Moreover, SECH clears HIV-1 in blood samples from HIV-1-infected patients. Our results suggest a strategy to eradicate HIV infections by selectively eliminating host cells capable of producing HIV.

Human immunodeficiency virus type 1 (HIV-1) typically evolves from a macrophage-tropic, noncytopathic virus at early asymptomatic stages of infection to a T-cell-tropic, cytopathic, and syncytia-inducing virus population as humans progress to AIDS. This suggests that changes in virus phenotype may influence disease. Because simian immunodeficiency virus (SIV) infection in macaques is a common model system for HIV-1 pathogenesis, we determined whether SIV infection in macaques that develop simian AIDS is associated with a similar shift in viral tropism, replication, and cytopathic properties. The virus that infected the monkeys (SIVMneCL8) and predominated at early times in infection is a macrophage-tropic virus that replicates with relatively low efficiency in human T cell lines. The variant populations that arise in macaques as they progress to AIDS are more infectious for human T cell lines, exhibiting enhanced replication in CEM x 174 cells and an expanded host range that includes Molt-4 Clone 8 cells. Infections starting with equal doses of the viruses demonstrated that the late variants are cytopathic and syncytia-inducing compared to SIVMneCL8, but the variants replicate less efficiently in primary macaque macrophages. V3 sequences were generally conserved between the early and the late variants, suggesting that changes in SIVMne tropism, replication, and cytopathicity were apparently not due to alterations in V3. This study demonstrates important similarities in the phenotypic viral changes that accompany development of AIDS in SIV and HIV-1 infections and suggest that SIV may provide a model system for determining whether the rapidly replicating, T-cell-tropic cytopathic variants present late in infection and disease are indeed important in determining progression to AIDS.

Background There are questions regarding the prevalence of xenotropic murine leukemia virus-related virus (XMRV) in PCA patients and its association with the RNASEL R462Q polymorphism. We therefore investigated whether XMRV infection could be found in PCA patients from the southern United States (U.S.), and sought to verify the association with the R462Q. Methods Prostatic tissue specimens of 144 PCA patients from the southern U.S. were genotyped for R462Q by real time PCR allelic discrimination and screened for XMRV proviral DNA by nested PCR specific for the env gene. Results The R462Q polymorphism was found at an allelic frequency of 33%. XMRV was detected in 32 (22%) of the 144 patients. Patients were significantly more likely to test positive for XMRV in both tumor and normal tissue rather than either alone (κ = 0.64). Positivity for XMRV was not significantly correlated with the R462Q polymorphism (p = 0.82) or clinical pathological parameters of PCA, including Gleason score (p = 0.29). Conclusions XMRV is detectable in normal and tumor prostatic tissue from PCA patients independent of R462Q. The presence of XMRV in normal tissue suggests that infection may precede cancer onset.

Antiretroviral therapy (ART) in human immunodeficiency virus type 1 (HIV-1)-infected patients does notclear the infection and can select for drug resistance over time. Not only is drug-resistant HIV-1 a concern for infected individuals on continual therapy, but it is an emerging problem in resource-limited settings where, in efforts to stem mother-to-child-transmission of HIV-1, transient nonnucleoside reverse transcriptase inhibitor (NNRTI) therapy given during labor can select for NNRTI resistance in both mother and child. Questions of HIV-1 persistence and drug resistance are highly amenable to exploration within animals models, where therapy manipulation is less constrained. We examined a pigtail macaque infection model responsive to anti-HIV-1 therapy to study the development of resistance. Pigtail macaques were infected with a pathogenic simian immunodeficiency virus encoding HIV-1 reverse transcriptase (RT-SHIV) to examine the impact of prior exposure to a NNRTI on subsequent ART comprised of a NNRTI and two nucleoside RT inhibitors. K103N resistance-conferring mutations in RT rapidly accumulated in 2/3 infected animals after NNRTI monotherapy and contributed to virologic failure during ART in 1/3 animals. By contrast, ART effectively suppressed RT-SHIV in 5/6 animals. These data indicate that suboptimal therapy facilitates HIV-1 drug resistance and suggest that this model can be used to investigate persisting viral reservoirs.