A glycoprotein H (gH)-deleted herpes simplex virus type 2 (HSV-2) was evaluated as a vaccine for the prevention of HSV-induced disease. This virus, which we term a DISC (disabled infectious single cycle) virus, can only complete one replication cycle in normal cells and should thus be safe yet still able to stimulate broad humoral and cell-mediated antiviral immune responses. A gH-deleted HSV-2 virus that has been tested as a vaccine in the guinea pig model of recurrent HSV-2 infection was constructed. Animals vaccinated with DISC HSV-2 showed complete protection against primary HSV-2-induced disease, even when challenged 6 months after vaccination. In addition, the animals were almost completely protected against recurrent disease. Even at low vaccination doses, there was a high degree of protection against primary disease. A reduction in recurrent disease symptoms was also observed following therapeutic vaccination of animals already infected with wild type HSV-2.

No abstract

The panel of safety studies provided evidence that DISC-hGMCSF will be unable to replicate and cause disease, and has low toxicity in man. These data were presented to the Medicines Control Agency and the Gene Therapy Advisory Committee as part of the regulatory submissions for a clinical trial in melanoma patients. These submissions have been approved, and DISC-hGMCSF has now entered a phase I clinical trial in the UK by direct intratumoural injection.

No abstract

Bombesin-related peptides stimulate a rapid increase in polyphosphoinositide hydrolysis in Swiss-mouse 3T3 cells. These peptides generate an increase in the efflux of 45Ca2+ from pre-labelled cells, a response consistent with an inositol trisphosphate-mediated mobilization of intracellular Ca2+. The bombesin-stimulated release of cellular 45Ca2+ is inhibited by tumour-promoting phorbol esters (e.g. 12-0-tetradecanoylphorbol 13-acetate, TPA). Although there are several possible sites of action at which this effect might occur, our results indicate that TPA induces an uncoupling of bombesin-stimulated hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) without decreasing cellular binding of bombesin. In cultured cells, protein kinase C can be down-modulated by a prolonged incubation of the cells with phorbol esters. Such pretreatment greatly decreased the inhibitory effect of TPA on bombesin-stimulated PIP2 hydrolysis, suggesting that this action of the phorbol ester is mediated via protein kinase C. Since diacylglycerol is an endogenous activator of protein kinase C and a direct product of PIP2 hydrolysis, these results suggest that protein kinase C inhibition of polyphosphoinositide hydrolysis may function as a negative-feedback pathway. Cells in which protein kinase C has been down-modulated show elevated basal and bombesin-stimulated production of inositol phosphates, providing evidence that such a feedback loop limits polyphosphoinositide turnover in both unstimulated and mitogen-stimulated cells.