In vivo gene transfer to the brain cortex using a single injection of HSV-1 vector into the medial septum.

This study shows that an ICP4-replication-deficient herpes simplex virus containing the Moloney murine leukaemia virus LTR fused with the coding sequence for the beta-galactosidase gene can be used as a very effective vector for delivering the beta-galactosidase reporter gene into the rat brain septum. F344 rats received bilateral stereotaxic injections into the nucleus of the diagonal band and into the medial septum. The X-gal stain was used to detect the activity of the expressed beta-galactosidase enzyme. The delivered reporter gene was expressed successfully not only in the neuronal cells of the injected areas but also in cells that project to the injection area such as cortex cells about 6 mm away from the injection sites. Expression was visible at 1, 3 and 9 weeks following injection. We conclude that this vector can effectively deliver genes into different regions of the mature mammalian brain and also to areas distant from the injection site.

Gene transfer into the central nervous system using herpes simplex virus-1 vectors.

Manipulation of gene expression in developing or in mature central nervous systems (CNS) holds a promise for the resolution of many compelling neurobiological questions, including the feasibility of gene therapy to treat diseases of the brain. In this context, a number of viral vectors have been used in recent years to introduce and express genes into the CNS. This article discusses a gene transfer system based on the Herpes Simplex Virus-1 (HSV-1). We describe here the use of non-replicating, non-toxic HSV-1 vector, 8117/43, in a series of studies carried in our joint program. This vector proves further the utility of HSV-1 as a delivery vehicle to a number of distinct sites within the CNS.

Mutagenesis of a cAMP response element within the latency-associated transcript promoter of HSV-1 reduces adrenergic reactivation.

Mutagenesis of a cyclic AMP response element (CRE) within the LAT promoter of HSV-1 reduces the ability of LAT expression to be induced in transient assays, but has only a minimal impact on reactivation of the virus in in vitro systems. Here we show that a CRE mutation results in a significant reduction of adrenergically induced reactivation in vivo in the rabbit eye model. Spontaneous reactivation frequencies were also reduced. In addition, we demonstrate that this mutation has no effect on the amount of LAT expressed during latency when compared with the parent, 17syn+, and the rescuant. These results indicate a greater effect of CRE on induced reactivation in vivo than in in vitro systems, but also suggest that the CRE in the LAT promoter is not autonomous in conducting the reactivation signal.

A cAMP response element within the latency-associated transcript promoter of HSV-1 facilitates induced ocular reactivation in a mouse hyperthermia model.

Herpes simplex virus type 1 (HSV-1) recombinant strain 17CRE contains a site-directed mutation in the 7-bp CRE consensus sequence located 38 nucleotides upstream of the transcription start site. Scarified mouse corneas received inoculations of 17syn+ (parent), 17CRE, and rescue 17CREr. Slit lamp examination of herpetic lesions and tear film swabs containing infectious virus showed that 17CRE had the same acute phenotype as 17syn+ and 17CREr. At 4 weeks, when the corneas had healed and latency was established, mice received hyperthermic shock. Eye swabs taken 24 h after hyperthermia showed that 17CRE reactivated significantly less than 17syn+ and 17CREr, while no significant differences were found in HSV-1 DNA genome copy numbers and latent virus in the trigeminal ganglia. These results are evidence that this CRE site in the LAT promoter facilitates ocular HSV-1 reactivation in mice.