Chapter 6
Alphavirus-Based Antigen Preparation
Kenneth Lundstrom
Abstract
Alphavirus-based vectors present an efficient approach for antigen preparation applied for vaccine development. Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been engineered
for high-level expression of antigens targeting infectious diseases and tumors. Alphaviruses possess a large
application range as vectors can be delivered as naked RNA replicons, recombinant viral particles, and
layered DNA plasmids. Immunization studies in animal models have provided protection against challenges
with lethal doses of pathogenic infectious agents and tumor cells. So far, a limited number of clinical trials
have been conducted for alphavirus vectors in humans.
Key words Alphavirus vectors, Immunization, Viral vaccines, Cancer vaccines, Protection against
lethal challenges
1 Introduction
Alphaviruses belong to the family Togaviridae consisting of a positive sense single-stranded RNA (ssRNA) genome encapsulated in a
capsid protein covered by a membrane envelope structure [1]
(Fig. 1). Among the approximately 30 alphaviruses, Semliki Forest
virus (SFV) [2], Sindbis virus (SIN) [3], and Venezuelan equine
encephalitis virus (VEE) [4] have been engineered as vectors for
recombinant gene expression. Typically, three types of expression
vector systems have been developed, represented by replicationdeficient viral particles, replication-proficient viral particles, and
layered DNA/RNA plasmid vectors [5]. The common feature of
all three systems relates to the presence of the alphavirus nonstructural genes, which makes these vectors self-replicating and resulting
in high-level RNA replication in infected cells with extreme transgene expression. In the case of recombinant particles, in vitro RNA
is transcribed from plasmid DNA, electroporated into mammalian
host cells, preferentially baby hamster kidney (BHK) cells, and
mature viral particles are harvested. In contrast, layered
DNA/RNA vectors where the SP6 RNA polymerase promoter
Blaine A. Pfeifer and Andrew Hill (eds.), Vaccine Delivery Technology: Methods and Protocols, Methods in Molecular Biology,
vol. 2183, https://doi.org/10.1007/978-1-0716-0795-4_6, © Springer Science+Business Media, LLC, part of Springer Nature 2021
63
Alphavirus-Based Antigen Preparation
Kenneth Lundstrom
Abstract
Alphavirus-based vectors present an efficient approach for antigen preparation applied for vaccine development. Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been engineered
for high-level expression of antigens targeting infectious diseases and tumors. Alphaviruses possess a large
application range as vectors can be delivered as naked RNA replicons, recombinant viral particles, and
layered DNA plasmids. Immunization studies in animal models have provided protection against challenges
with lethal doses of pathogenic infectious agents and tumor cells. So far, a limited number of clinical trials
have been conducted for alphavirus vectors in humans.
Key words Alphavirus vectors, Immunization, Viral vaccines, Cancer vaccines, Protection against
lethal challenges
1 Introduction
Alphaviruses belong to the family Togaviridae consisting of a positive sense single-stranded RNA (ssRNA) genome encapsulated in a
capsid protein covered by a membrane envelope structure [1]
(Fig. 1). Among the approximately 30 alphaviruses, Semliki Forest
virus (SFV) [2], Sindbis virus (SIN) [3], and Venezuelan equine
encephalitis virus (VEE) [4] have been engineered as vectors for
recombinant gene expression. Typically, three types of expression
vector systems have been developed, represented by replicationdeficient viral particles, replication-proficient viral particles, and
layered DNA/RNA plasmid vectors [5]. The common feature of
all three systems relates to the presence of the alphavirus nonstructural genes, which makes these vectors self-replicating and resulting
in high-level RNA replication in infected cells with extreme transgene expression. In the case of recombinant particles, in vitro RNA
is transcribed from plasmid DNA, electroporated into mammalian
host cells, preferentially baby hamster kidney (BHK) cells, and
mature viral particles are harvested. In contrast, layered
DNA/RNA vectors where the SP6 RNA polymerase promoter
Blaine A. Pfeifer and Andrew Hill (eds.), Vaccine Delivery Technology: Methods and Protocols, Methods in Molecular Biology,
vol. 2183, https://doi.org/10.1007/978-1-0716-0795-4_6, © Springer Science+Business Media, LLC, part of Springer Nature 2021
63