Construction of a bivalent vaccine against anthrax and smallpox using the attenuated vaccinia virus KVAC103

Highly attenuated poxvirus-based vaccines against emerging viral diseases

Although one member of the poxvirus family, variola virus, has caused one of the most devastating human infections worldwide, smallpox, the knowledge gained over the last 30 years on the molecular, virological and immunological mechanisms of these viruses has allowed the use of members of this family as vectors for the generation of recombinant vaccines against numerous pathogens. In this review, we cover different aspects of the history and biology of poxviruses with emphasis on their application as vaccines, from first- to fourth-generation, against smallpox, monkeypox, emerging viral diseases highlighted by the World Health Organization (COVID-19, Crimean-Congo haemorrhagic fever, Ebola and Marburg virus diseases, Lassa fever, Middle East respiratory syndrome and severe acute respiratory syndrome, Nipah and other henipaviral diseases, Rift Valley fever and Zika), as well as against one of the most concerning prevalent virus, the Human Immunodeficiency Virus, the causative agent of AcquiredImmunodeficiency Syndrome. We discuss the implications in human health of the 2022 monkeypox epidemic affecting many countries, and the rapid prophylactic and therapeutic measures adopted to control virus dissemination within the human population. We also describe the preclinical and clinical evaluation of the Modified Vaccinia virus Ankara and New York vaccinia virus poxviral strains expressing heterologous antigens from the viral diseases listed above. Finally, we report different approaches to improve the immunogenicity and efficacy of poxvirus-based vaccine candidates, such as deletion of immunomodulatory genes, insertion of host-range genes and enhanced transcription of foreign genes through modified viral promoters. Some future prospects are also highlighted.

Engineered Extracellular Vesicle-Delivered CRISPR/CasRx as a Novel RNA Editing Tool

Engineered extracellular vesicles (EVs) are considered excellent delivery vehicles for a variety of therapeutic agents, including nucleic acids, proteins, drugs, and nanomaterials. Recently, several studies have indicated that clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) delivered by EVs enable efficient DNA editing. However, an RNA editing tool delivered by EVs is still unavailable. Here, a signal peptide-optimized and EVs-delivered guide RNA (gRNA) and CRISPR/CasRx (Cas13d) system capable of rapidly inhibiting the expression of targeted genes with quick catabolism after performing their functions is developed. EVs with CRISPR/CasRx and tandem gRNAs targeting pivotal cytokines are further packed whose levels increase substantially over the course of acute inflammatory diseases and find that these engineered EVs inhibit macrophage activation in vitro. More importantly, this system attenuates lipopolysaccharide (LPS)-triggered acute lung injury and sepsis in the acute phase, mitigating organ damage and improving the prognosis in vivo. In summary, a potent tool is provided for short-acting RNA editing, which could be a powerful therapeutic platform for the treatment of acute diseases.

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.