International AIDS Society global scientific strategy: towards an HIV cure 2016

Antiretroviral therapy is not curative. Given the challenges in providing lifelong therapy to a global population of more than 35 million people living with HIV, there is intense interest in developing a cure for HIV infection. The International AIDS Society convened a group of international experts to develop a scientific strategy for research towards an HIV cure. This Perspective summarizes the group's strategy.

Stem-cell Based Engineered Immunity Against HIV Infection in the Humanized Mouse Model

With the rapid development of stem cell-based gene therapies against HIV, there is pressing requirement for an animal model to study the hematopoietic differentiation and immune function of the genetically modified cells. The humanized Bone-marrow/Liver/Thymus (BLT) mouse model allows for full reconstitution of a human immune system in the periphery, which includes T cells, B cells, NK cells and monocytes. The human thymic implant also allows for thymic selection of T cells in autologous thymic tissue. In addition to the study of HIV infection, the model stands as a powerful tool to study differentiation, development and functionality of cells derived from hematopoietic stem cells (HSCs). Here we outline the construction of humanized non-obese diabetic (NOD)-severe combined immunodeficient (SCID)-common gamma chain knockout (cγ(-/-))-Bone-marrow/Liver/Thymus (NSG-BLT) mice with HSCs transduced with CD4 chimeric antigen receptor (CD4CAR) lentivirus vector. We show that the CD4CAR HSCs can successfully differentiate into multiple lineages and have anti-HIV activity. The goal of the study is to demonstrate the use of NSG-BLT mouse model as an in vivo model for engineered immunity against HIV. It is worth noting that, because lentivirus and human tissue is used, experiments and surgeries should be performed in a Class II biosafety cabinet in a Biosafety Level 2 (BSL2) with special precautions (BSL2+) facility.

Ligation of CD4 on human blood monocytes triggers macrophage differentiation (158.8)

Human monocytes/macrophages (M/M) have an important role in innate immune responses and in controlling adaptive immune responses. One unique aspect of human M/M is that they express the CD4 molecule. The role of the CD4 molecule in human monocyte/macrophage function and development is not known. To investigate the role of CD4 expressed on human M/M, human blood monocytes were treated with soluble HLA Class II (sHLA II), a natural CD4 ligand. We determined that sHLA II:CD4 ligation triggered the differentiation of human monocytes into functional mature macrophages. These newly developed macrophages had an increased ability to induce T cell activation, suggesting enhanced immune function following CD4 ligation of these cells. We observed a calcium flux and the modulation of gene and cytokine protein expression following CD4 ligation on peripheral monocytes. This indicates that ligation of CD4 transmits a functional signal in this cell type. We found that intracellular signaling of CD4 in primary monocytes occurs through src family kinases as well as via the MAPK pathway to trigger macrophage differentiation. We show that HLA II on IFN-γ-induced HUVECs can ligate CD4 on monocytes and trigger differentiation of these cells into functional macrophages. In all, our results have identified a new function for the CD4 molecule on human peripheral monocytes in triggering the differentiation of these cells into functional macrophages following their interaction with HLA II.

Role of Vif in human immunodeficiency virus type 1 reverse transcription

The Vif protein of human immunodeficiency virus type 1 (HIV-1) is important for virion infectivity. Previous studies have shown that vif mutant HIV-1 virions are defective in their ability to synthesize proviral DNA in vivo. Here, we examine the role of Vif in viral DNA synthesis in the endogenous reverse transcriptase (RT) reaction, an in vitro assay in which virions synthesize viral DNA by using endogenous viral RNA as a template. vif mutant virions showed a significant reduction in endogenous RT activity despite similar levels of exogenous RT activity. Analysis of the viral DNA products on agarose gels demonstrated that this reflects reduced synthesis of short minus- and plus-strand DNA products in addition to those of full genomic length. Quantitative PCR analysis of endogenous reverse transcription provided further evidence for reduced formation of both initial and completed reverse transcripts. Vif had no effect on genomic RNA dimerization or the stability of the RNA dimer linkage. These results suggest that Vif is important for an early event after virus entry but preceding or during the early stages of viral DNA synthesis. This may be due to an intrinsic effect on reverse transcription or a preceding postentry event(s), such as virion uncoating or disassembly of the virion core. Drugs targeted to Vif function may provide a new therapeutic approach to inhibiting HIV-1 reverse transcription.

Induction of interleukin-1 and tumor necrosis factor alpha in brain cultures by human immunodeficiency virus type 1

Cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) are produced by leukocytes and play a role in immune responses. They also function in normal brain physiology as well as in pathological conditions within the central nervous system, where they are produced by brain macrophages (microglia) and brain astrocytes. In this study, we document the ability of human immunodeficiency virus type 1 (HIV-1) to induce TNF alpha and IL-1 in primary rat brain cultures. While productive infection did not occur in these cells, it was not required for cytokine induction. Using monocyte/macrophage-tropic (JRFL) and T-cell-tropic (IIIB) strains of HIV-1, we were able to induce cytokines in both microglia and astrocytes. In addition to whole virus, recombinant envelope proteins also induced these cytokines. The induction of IL-1 and TNF alpha could be blocked by a panel of antibodies recognizing epitopes in the gp120 and gp41 areas of the envelope. Soluble recombinant CD4 did not block TNF alpha and IL-1 production. If TNF alpha and IL-1 can be induced in brain tissue by HIV-1, they may contribute to some of the neurologic disorders associated with AIDS.

The region of the envelope gene of human immunodeficiency virus type 1 responsible for determination of cell tropism

Different isolates of human immunodeficiency virus type 1 (HIV-1) vary in the cell tropisms they display, i.e., the range of cell types in which they are able to establish a productive infection. Here, we report on the phenotypes of recombinants between two molecularly cloned strains of HIV-1. Our results prove that the envelope glycoprotein gp120 is solely responsible for the difference in cell tropism between the two parental isolates and that no other genes or sequences are involved in determining the cell tropism of these strains. The region of the envelope involved in the determination of cell tropism includes sequences which encode the V3 loop of gp120. Control of cell tropism by this region of the virus env gene is a general phenomenon which applies to many different HIV-1 isolates.

[Pneumothorax in cystic fibrosis: intrapleural instillation of Atabrine]

Intrapleural instillation of quinacrine HC1 (Atabrine) was used to treat spontaneous pneumothorax in 2 young men, aged 26 and 36 years, respectively, with advanced pulmonary disease due to cystic fibrosis. Pneumothorax did not recur until 1 year later in 1 case and 2 years later in the other. This mode of therapy for pneumothorax provides a valuable alternative to surgery for the patient with cystic fibrosis, severe lung disease and marginal pulmonary reserve. Quinacrine sclerosis should be considered for management of pneumothorax in cystic fibrosis because of the high rate of recurrence. However, caution should be exercised since heart-lung transplantation cannot be performed after pleural sclerosis.

Characterization of a leukemia-derived transforming growth factor

A novel transforming growth factor activity has been identified in the serum-free medium derived from cultures of SMS-SB cells, a human pre-B acute lymphoblastic leukemia cell line. This activity (leukemia-derived transforming growth factor) was biochemically distinct from known fibroblast mitogens such as epidermal growth factor, transforming growth factor alpha, transforming growth factor beta, platelet-derived growth factor, and the endothelial cell growth factor/fibroblast growth factor family of mitogens. Leukemia-derived transforming growth factor was heterogeneous on heparin affinity chromatography, fractionating into three peaks of activity. Although these peaks differed in dose-response characteristics in agar colony and mitogenic assays, each activity was similarly inactivated by heat, acid treatment, and sulfhydryl reduction. Each of the heparin derivatives also behaved similarly on gel filtration and diethylaminoethyl chromatography. Leukemia-derived transforming growth factor was not mitogenic for normal or leukemic lymphocytes or granulocyte/macrophage progenitors. Therefore, a direct or autocrine function for this activity seems unlikely.

Transforming gene of a human leukaemia cell is unrelated to the expressed tumour virus related gene of the cell

The virally encoded oncogenes (v-onc) of avian and mammalian retroviruses are the recombinant products of normal cellular genes (c-onc) and a retroviral genome. These cellular homologues have been highly conserved during evolution and are found in human DNA. The expression of at least one c-onc under the control of a viral promoter results in transformation of cells in a manner resembling that displayed by the v-onc counterpart; the inappropriate expression of c-onc in the absence of viral influences could likewise result in the malignant state. This proposal would be strongly supported by the presence of c-onc RNAs in a variety of human tumours were they not also demonstrable in normal tissues. The role of these RNAs in the oncogenic process remains unclear. Here we report that RNA homologous to the oncogene (v-abl) of Abelson murine leukaemia virus (A-MLV) is expressed in a unique human leukaemia in a fashion different from that of other human tissues and tumours. In addition, DNA from this tumour transforms NIH-3T3 cells at a high efficiency in a transfection assay. The transfected sequences are not related to the v-abl gene, but the NIH-3T3 transformants manufacture a transforming growth factor which behaves similarly to factors produced by A-MLV-transformed NIH-3T3 fibroblasts.