Constitutive and Inducible Innate Responses in Cells Infected by HSV-1-Derived Amplicon Vectors

Eliza Tsitoura , Alberto L Epstein*
Université de Lyon, Lyon, F-69003, France; CNRS, UMR5534, Centre de Génétique Moléculaire et Cellulaire, Villeurbanne, F-69622, France

© Tsitoura and Epstein; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http: // which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Centre de Génétique Moléculaire et Cellulaire CGMC - UMR 5534 - CNRS Université Claude Bernard Lyon 1 Bâtiment Grégoire Mendel, 16 rue Raphaël Dubois, 69622 Villeurbanne Cedex, France; Tel: (33) 4 72 43 13 25; Fax: (33) 4 72 43 26 85; E-mail:


Amplicons are helper-dependent herpes simplex virus type 1 (HSV-1)-based vectors that can deliver very large foreign DNA sequences and, as such, are good candidates both for gene delivery and vaccine development. However, many studies have shown that innate constitutive or induced cellular responses, elicited or activated by the entry of HSV-1 particles, can play a significant role in the control of transgenic expression and in the induction of inflammatory responses. Moreover, transgene expression from helper-free amplicon stocks is often weak and transient, depending on the particular type of infected cells, suggesting that cellular responses could be also responsible for the silencing of amplicon-mediated transgene expression. This review summarizes the current experimental evidence underlying these latter concepts, focusing on the impact on transgene expression of very-early interactions between amplicon particles and the infected cells, and speculates on possible ways to counteract the cellular protective mechanisms, thus allowing stable transgene expression without enhancement of vector toxicity.

Keywords:: HSV-1, amplicon vectors, innate responses, IFN, gene silencing..