Myxoma virus (MV) is a rabbit-specific poxvirus, whose unexpected tropism to human cancer cells has led to studies exploring its potential use in oncolytic therapy. MV infects a wide range of human cancer cells in vitro, in a manner intricately linked to the cellular activation of Akt kinase. MV has also been successfully used for treating human glioma xenografts in immunodeficient mice. This study examines the effectiveness of MV in treating primary and metastatic mouse tumors in immunocompetent C57BL6 mice. We have found that several mouse tumor cell lines, including B16 melanomas, are permissive to MV infection. B16F10 cells were used for assessing MV replication and efficacy in syngeneic primary tumor and metastatic models in vivo. Multiple intratumoral injections of MV resulted in dramatic inhibition of tumor growth. Systemic administration of MV in a lung metastasis model with B16F10LacZ cells was dramatically effective in reducing lung tumor burden. Combination therapy of MV with rapamycin reduced both size and number of lung metastases, and also reduced the induced antiviral neutralizing antibody titres, but did not affect tumor tropism. These results show MV to be a promising virotherapeutic agent in immunocompetent animal tumor models, with good efficacy in combination with rapamycin.

The authors have recently demonstrated that wild-type myxoma virus (MV) tagged with gfp (vMyxgfp) can generate a tumor-specific infection that productively infects and clears human tumor-derived xenografts when injected intratumorally into human gliomas transplanted into immunodeficient mice (Lun et al, 2005). To expand the understanding of MV tropism in cancer cells from a specific tissue lineage, the authors have screened a series of human glioma cells (U87, U118, U251, U343, U373) for myxoma virus replication and oncolysis. To assess the viral tropism determinants for these infections, the authors have screened myxoma virus knockout constructs that have been deleted for specific host range genes (M-T2, M-T4, M-T5, M11L, and M063), as well as a control MV gene knockout construct with no known host range function (vMyx135KO) but is highly attenuated in rabbits. The authors report wide variation in the ability of various vMyx-hrKOs to replicate and spread in the human glioma cells as measured by early and late viral gene expression. This differential ability to support vMyx-hrKO productive viral replication is consistent with levels of endogenous activated Akt in the various gliomas. The authors have identified one vMyx-hrKO virus (vMyx63KO) and one nonhost range knockout construct (vMyx135KO) that appear to replicate in the gliomas even more efficiently than the wild-type virus and that reduce the viability of the infected gliomas. These knockout viruses also inhibit the proliferation of gliomas in a manner similar to the wild-type virus. Together these data, as well as the fact that these knockout viruses are attenuated in their natural hosts, may represent environmentally safer candidate oncolytic viruses for usage in human trials.

We previously reported that interleukin (IL)-4 treatment of nonobese diabetic (NOD) mice elevates intrapancreatic CCL4 expression and protects from type 1 diabetes. Here, we show that antibody neutralization of CCL4 abrogates the ability of T-cells from IL-4 -treated NOD mice to transfer protection against type 1 diabetes. Intradermal delivery of CCL4 via a plasmid vector stabilized by incorporation of the Epstein-Barr virus EBNA1/oriP episomal maintenance replicon (pHERO8100-CCL4) to NOD mice beginning at later stages of disease progression protects against type 1 diabetes. This protection was associated with a Th2-like response in the spleen and pancreas; decreased recruitment of activated CD8؉ T-cells to islets, accompanied by diminished CCR5 expression on CD8 ؉ T-cells; and regulatory T-cell activity in the draining pancreatic lymph nodes. Thus, inflammatory responses that target islet ␤-cells are suppressed by CCL4, which implicates the use of CCL4 therapeutically to prevent type 1 diabetes. Diabetes 56: 809 -817, 2007 D evelopment of type 1 diabetes depends upon the selective recruitment of pathogenic leukocytes to pancreatic islets by chemokines and their receptors (1-5). Previously, we demonstrated in nonobese diabetic (NOD) mice that treatment with interleukin (IL)-4 elevates intrapancreatic CCL4 levels that correlate with decreased intraislet CCR5 expression and protection from type 1 diabetes (4). Increased intrapancreatic CCL4 expression is associated with enhanced recruitment of insulin B-chain reactive regulatory CD4ϩ T-cells to the pancreas and prevention of destructive insulitis upon oral insulin administration (6), and protection from type 1 diabetes by a neutralizing anti-IL-16 monoclonal antibody depends on CCL4 activity. These results suggest that enhanced CCL4 expression in secondary lymphoid organs and the pancreas blocks the development of type 1 diabetes.In this study, we tested whether CCL4 protects against type 1 diabetes using a gene transfer approach. A plasmid vector stabilized by the Epstein-Barr virus EBNA1/oriP episomal maintenance replicon was utilized to sustain CCL4 expression in vivo. We demonstrate that intradermal gene transfer of CCL4 prevents type 1 diabetes and that antibody-mediated CCL4 blockade reverses the ability of T-cells from IL-4 -treated NOD mice to transfer protection against type 1 diabetes. This is the first demonstration that IL-4 -mediated protection against type 1 diabetes relies upon CCL4 activity in vivo and that CCL4 inhibits progression to type 1 diabetes. RESEARCH DESIGN AND METHODSNOD/Del, NOD.Scid (from Dr. Len Schultz; The Jackson Laboratories, Bar Harbor, ME) and NOD8.3 TCR transgenic mice were bred in a specific pathogen-free barrier facility at the Robarts Research Institute (7,8). Mice were maintained in a specific pathogen-free facility at the University of Western Ontario according to institutional guidelines. IL-4 treatment, cell transfer, and CCL4 neutralization. One hundred nanograms (1,000 units) of recombinant mIL-4 (Immunex, Seattle, WA...

HIV infection results in severe immune dysfunction with ensuing sequelae that includes characteristic opportunistic infections. Pneumocystis pneumonia (PCP) is one of the most common of these infections and is routinely treated with sulphamethaxazole (SMX). Although this drug is known to cause hypersensitivity adverse drug reactions (ADRs) in 0.1% of the general population, the incidence of these ADRs increases tenfold in the HIV-positive population. The HIV-1 trans-activator of transcription (HIV-1 Tat) together with the drug metabolite sulphamethaxazole-hydroxylamine (SMX-HA) have both been reported to be factors in these hypersensitivity ADRs. In this study, we use an inducible, Tat-expressing vector system to show that the level of Tat expression contributes to the cellular sensitivity of Jurkat T cells to SMX-HA. We further demonstrated that apoptosis is the likely mechanism by which this occurs. Thus, our data provide insight into the significant increase of SMX-related ADRs during the transition between HIV-1 infection and AIDS.