Construction of an attenuated Tian Tan vaccinia virus strain by deletion of TA35R and TJ2R genes

Advances in vaccinia virus-based vaccine vectors, with applications in flavivirus vaccine development

Historically, virulent variola virus infection caused hundreds of millions of deaths. The smallpox pandemic in human beings has spread for centuries until the advent of the attenuated vaccinia virus (VV) vaccine, which played a crucial role in eradicating the deadly contagious disease. Decades of exploration and utilization have validated the attenuated VV as a promising vaccine vehicle against various lethal viruses. In this review, we focus on the advances in VV-based vaccine vector studies, including construction approaches of recombinant VV, the impact of VV-specific pre-existing immunity on subsequent VV-based vaccines, and antigen-specific immune responses. More specifically, the recombinant VV-based flaviviruses are intensively discussed. Based on the publication data, this review aims to provide valuable insights and guidance for future VV-based vaccine development.

An improved system for constructing marker-free recombinant goatpox viruses to express foreign proteins

Goatpox virus (GTPV), belonging to the genus Capripoxvirus in the family Poxviridae, causes a contagious disease affecting goats and sheep. Homologous recombination as a conventional method is commonly used to construct recombinant GTPVs but generally with genetic markers, such as enhanced green fluorescent protein (eGFP) and guanine phosphoribosyl transferase (gpt). We have previously constructed a recombinant GTPV, which can efficiently express the EG95 antigen of Echinococcus granulosus, but contains eGFP and gpt markers in viral genome. In this study, our previous GTPV-generating system was modified by reconstruction of a Loxp-containing transfer plasmid for deleting markers using the Cre/Loxp system. Meanwhile, the previous method was significantly improved by introduction of an immortalized goat testis cell line as a substitute for primary cells. Based on the latest system, a marker-free recombinant GTPV was reconstructed for expressing the EG95 antigen, and showed neither a significant difference in replication kinetics from its parental virus nor mutations in the foreign sequence during serial 10 passages in vitro.

Construction of recombinant capripoxviruses as vaccine vectors for delivering foreign antigens: Methodology and application

Goatpox (GTP), sheeppox (SPP) and lumpy skin disease (LSD) are three severe diseases of goat, sheep and cattle. Their typical clinical symptoms are characterized by vesicles, papules, nodules, pustules and scabs on animal skins. The GTP, SPP and LSD are caused by goatpox virus (GTPV), sheeppox virus (SPPV) and lumpy skin disease virus (LSDV), respectively, all of which belong to the genus Capripoxvirus in the family Poxviridae. Several capripoxvirus (CaPV) isolates have been virulently attenuated through serial passaging in vitro for production of live vaccines. CaPV-based vector systems have been broadly used to construct recombinant vaccines for delivering foreign antigens, many of which have been demonstrated to induce effective immune protections. Homologous recombination is the most commonly used method for constructing recombinant CaPVs. Here, we described a methodology for generation of recombinant CaPVs by the homologous recombination, and further reviewed CaPV-vectored vaccines for delivering foreign antigens.