Maria Ventosa's research while affiliated with Universidad Autónoma de Madrid and other places

Background: Friedreich's ataxia (FA) is an autosomal recessive neurodegenerative disease caused by mutations in the frataxin gene (FXN), which lead to reduced levels of the essential mitochondrial protein frataxin. Currently there is no effective cure. Methods: With the aim of developing a gene therapy for FA neuropathology, here we describe the construction and preliminary characterization of a high capacity nonreplicative genomic herpes simplex virus type 1 vector (H24B-FXNlac vector) carrying a reduced version of the human FXN genomic locus, comprising the 5 kb promoter and the FXN cDNA with the inclusion of intron 1. Results: We show that the transgene cassette contains the elements necessary to preserve physiological neuronal regulation of human FXN expression. Transduction of cultured fetal rat dorsal root ganglion neurons with the H24B-FXNlac vector results in sustained expression of human FXN transcripts and frataxin protein. Rat footpad inoculation with the H24B-FXNlac vector results in human FXN transgene delivery to the dorsal root ganglia, with expression persisting for at least 1 month. Conclusions: Our results support the feasibility of using this vector for sustained neuronal expression of human frataxin for FA gene therapy.

Nonreplicative Herpes simplex virus type-1 (HSV-1) genomic vectors have already entered into clinical trials for neurological gene therapy thanks to their scalable growth in permissive cells. However, the small transgene capacity of this type of HSV-1 vectors currently used in the clinic represents an important limiting factor as a gene delivery system. To develop high capacity nonreplicative genomic HSV-1 vectors, in this study we have characterized a series of multiply deleted mutants which we have constructed in bacterial artificial chromosomes (BACs), removing up to 24 kb of unstable or dispensable genomic sequences to allow insertion of transgenes up to this size. We show that synergistic effects of deletions of: the HSV-1 replication origins oriS and oriL, the HSV-1 internal repeat region, the remaining ICP4 gene copy and the genes encoding for ICP27, UL56, UL55, can severely reduce the growth of these HSV-1 vectors. Given that several of these elements have been characterized as 'non-essential' for viral growth in cell culture by single deletion experiments of wild-type HSV-1, our study highlights the need to re-evaluate their functional contribution in the context of multiply deleted nonreplicative HSV-1 genomic vectors. Our BAC mutants described here can serve as useful starting platforms to accelerate HSV-1 vector development.Gene Therapy accepted article preview online, 29 May 2017. doi:10.1038/gt.2017.43.

The majority of humans have been infected with Herpes Simplex Virus Type 1 (HSV-1) and harbor its viral DNA in the latent form within neurons for lifetime. This, combined with the absence of serious adverse effects due to HSV-1 derived vectors in clinical trials so far, highlight the potential to use this virus to develop neuronal gene transfer vectors which are transparent to the host, allowing the effects of the transgene to act without interference from the transfer system eg., for functional genomics in basic neuroscience or gene therapy of neurological disorders. On the other hand, other HSV-1 derived vectors which also have a promising perspective in the clinic, are designed to have enhanced cytotoxicity in certain cell types, as in the case of oncolytic vectors. Understanding virus-host interactions is fundamental not only to the success of these gene therapy vectors but also with respect to identifying and minimizing biohazards associated with their use. In this review we discuss characteristics of HSV-1 and gene therapy vectors derived from this virus which are useful to consider in the context of biosafety risk assessment and risk management.