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A substantial risk in using live attenuated, multiply deleted viruses as vaccines against AIDS is their potential to induce AIDS. A mutant of the simian immunodeficiency virus (SIV) with large deletions in nef and vpr and in the negative regulatory element induced AIDS in six of eight infant macaques vaccinated orally or intravenously. Early signs of immune dysfunction were seen in the remaining two offspring. Prolonged follow-up of sixteen vaccinated adult macaques also showed resurgence of chronic viremia in four animals: two of these developed early signs of disease and one died of AIDS. We conclude that this multiply deleted SIV is pathogenic and that human AIDS vaccines built on similar prototypes may cause AIDS.

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mda-7 is a novel tumor suppressor with cytokine properties. Adenoviral mda-7 (Ad-mda7) induces apoptosis and cell death selectively in tumor cells. The molecular mechanisms underlying the anti-tumor activity of Ad-mda7 in breast and lung cancer lines were investigated. Microarray analyses implicated both the beta-catenin and the PI3K signaling pathways. Ad-mda7 treatment increased protein expression from tumor suppressor genes, including E-cadherin, APC, GSK-3beta, and PTEN, and decreased expression of proto-oncogenes involved in beta-catenin and PI3K signaling. Ad-mda7 caused a redistribution of cellular beta-catenin from the nucleus to the plasma membrane, resulting in reduced TCF/LEF transcriptional activity, and upregulated the E-cadherin-beta-catenin adhesion complex in a tumor cell-specific manner. Expression of the PI3K pathway members (p85 PI3K, FAK, ILK-1, Akt, and PLC-gamma) was downregulated and expression of the PI3K antagonist PTEN was increased. Consistent with this result, pharmacological inhibition of PI3K by wortmannin did not abrogate killing by Ad-mda7. Killing of breast cancer cells by Ad-mda7 required both MAPK and MEK1/2 signaling pathways, whereas these pathways were not essential for MDA-7-mediated killing in lung cancer cells. Thus, in breast and lung tumor cells MDA-7 protein expression modulates cell-cell adhesion and intracellular signaling via coordinate regulation of the beta-catenin and PI3K pathways.

Similarities, although somewhat limited, between KP4 and scorpion toxins led us to investigate the possibility that the toxic effects of KP4 may be mediated by inhibition of cation channels. Our results suggest that certain properties of fungal Ca2+ channels are homologous to those in mammalian cells. KP4 may, therefore, be a new tool for studying mammalian Ca2+ channels and current mammalian Ca2+ channel inhibitors may be useful lead compounds for new anti-fungal agents.

Biological maintenance of cells under variable conditions should affect gene expression of only certain genes while leaving the rest unchanged. The latter, termed "housekeeping genes," by definition must reflect no change in their expression levels during cell development, treatment, or disease state anomalies. However, deviations from this rule have been observed. Using DNA microarray technology, we report here variations in expression levels of certain housekeeping genes in prostate cancer and a colorectal cancer gene therapy model system. To highlight, differential expression was observed for ribosomal protein genes in the prostate cancer cells and beta-actin in treated colorectal cells. High-throughput differential gene expression analysis via microarray technology and quantitative PCR has become a common platform for classifying variations in similar types of cancers, response to chemotherapy, identifying disease markers, etc. Therefore, normalization of the system based on housekeeping genes, such as those reported here in cancer, must be approached with caution.

We have succeeded in stably maintaining the entire genome of SIVmac239 as a plasmid clone. Supercoiled proviral plasmid DNA was inoculated intramuscularly into two adult rhesus macaques and into a neonate. All three animals became viremic and seroconverted. Viral kinetics were followed prospectively by quantitative competitive reverse transcriptase polymerase chain reaction (QC-RT-PCR), measurement of proviral DNA load in peripheral blood mononuclear cells (PBMCs) by PCR, and virus isolation by cocultivation. The infant developed high virus loads and succumbed to AIDS and SIV-associated nephropathy at 10 weeks postinoculation. Both adults are still living but have progressed to AIDS; one adult has also developed severe thrombocytopenia. We conclude that infection through intramuscular inoculation of cloned plasmid DNA encoding the entire proviral genome is reproducible and will provide a useful tool for studying viral pathogenesis.

The env gene of three simian immunodeficiency virus (SIV) variants developed convergent mutations during disease progression in six rhesus macaques. The monkeys had been inoculated with supercoiled plasmids encoding infectious proviruses of SIVmac239 (a pathogenic, wild-type strain), SIVdelta3 (the live attenuated vaccine strain derived from SIVmac239), or SIVdelta3+ (a pathogenic progeny virus that had evolved from SIVdelta3). All six monkeys developed immunodeficiency and progressed to fatal disease. Although many divergent mutations arose in env among the different hosts, three regions consistently mutated in all monkeys studied; these similar mutations developed independently even though the animals had received only a single infectious molecular clone rather than standard viral inocula that contain viral quasispecies. Together, these data indicate that the env genes of SIVmac239, SIVdelta3, and SIVdelta3+, in the context of different proviral backbones, evolve similarly in different hosts during disease progression.