Poxviruses as Gene Therapy Vectors: Generating Poxviral Vectors Expressing Therapeutic Transgenes

Abstract

Treatments with poxvirus vectors can have long-lasting immunological impact in the host, and thus they have been extensively studied to treat diseases and for vaccine development. More importantly, the oncolytic properties of poxviruses have led to their development as cancer therapeutics. Two poxviruses, vaccinia virus (VACV) and myxoma virus (MYXV), have been extensively studied as virotherapeutics with promising results. Vaccinia virus vectors have advanced to the clinic and have been tested as oncolytic therapeutics for several cancer types with successes in phase I/II clinical trials. In addition to oncolytic applications, MYXV has been explored for additional applications including immunotherapeutics, purging of cancer progenitor cells, and treatments for graft-versus-host diseases. These novel therapeutic applications have encouraged its advancement into clinical trials. To meet the demands of different treatment needs, VACVand MYXV can be genetically engineered to express therapeutic transgenes. The engineering process used in poxvirus vectors can be very different from that of other DNA virus vectors (e.g., the herpesviruses). This chapter is intended to serve as a guide to those wishing to engineer poxvirus vectors for therapeutic transgene expression and to produce viral preparations for preclinical studies.

Novel approaches for vaccine development

“…This replacement serves dual purpose: (1) rendering the virus replication-incompetent or less virulent for safety purposes, and (2) freeing space to insert genes without significantly changing the inherent genome size (Lee et al, 2017). Over the past several decades, different viruses have been developed into vectors including Ads (Barouch and Picker, 2014;Ertl, 2016), cytomegaloviruses (Barouch and Picker, 2014), adeno-associated viruses (AAVs) (El Andari and Grimm, 2020), poxviruses (Conrad and Liu, 2019), herpesviruses (Artusi et al, 2018), and retroviruses (Chen et al, 2018b;Luis, 2020;Stephenson et al, 2016). For the purposes of this review, we will focus on the current state of Ad vector development.…”

The use of viral vectors in vaccine development

“…Poxvirus vectors are usually produced via homologous recombination in poxvirus infected cells. Commonly used cell lines include the kidney epithelial cells CV-1, Vero, and BSC-40 cells 82 . Poxvirus infected cells are transfected with the recombinant transfer plasmid and the produced recombinant vector can be further propagated in susceptible cells.…”

Bioprocessing and the Production of Antiviral Biologics in the Prevention and Treatment of Viral Infectious Disease

“…Bovine, porcine, murine and canine adenoviruses have been applied in the production of adenoviral vaccine vectors [ 69 ]. Due to their highly immunogenic nature, poxviruses are another viral vector candidate which have been used to produce vaccines against HIV-1 and malaria and can produce multi-antigen vaccines against different pathogens [ 70 ]. Poxviral vectors are generated via homologous recombination in cells including kidney epithelial cells, Vero cells and African green monkey-derived cells (BSC-40 cells) [ 71 ], and are replication-deficient or rendered deficient in avian cells [ 72 ].…”