New Vaccine Technologies to Combat Outbreak Situations

Abstract

Ever since the development of the first vaccine more than 200 years ago, vaccinations have greatly decreased the burden of infectious diseases worldwide, famously leading to the eradication of small pox and allowing the restriction of diseases such as polio, tetanus, diphtheria, and measles. A multitude of research efforts focuses on the improvement of established and the discovery of new vaccines such as the HPV (human papilloma virus) vaccine in 2006. However, radical changes in the density, age distribution and traveling habits of the population worldwide as well as the changing climate favor the emergence of old and new pathogens that bear the risk of becoming pandemic threats. In recent years, the rapid spread of severe infections such as HIV, SARS, Ebola, and Zika have highlighted the dire need for global preparedness for pandemics, which necessitates the extremely rapid development and comprehensive distribution of vaccines against potentially previously unknown pathogens. What is more, the emergence of antibiotic resistant bacteria calls for new approaches to prevent infections. Given these changes, established methods for the identification of new vaccine candidates are no longer sufficient to ensure global protection. Hence, new vaccine technologies able to achieve rapid development as well as large scale production are of pivotal importance. This review will discuss viral vector and nucleic acid-based vaccines (DNA and mRNA vaccines) as new approaches that might be able to tackle these challenges to global health.

The outbreak of SARS-CoV-2 pneumonia calls for viral vaccines

“…As a cause of respiratory tract infection and as demonstrated by the findings of SARS-CoV-2 in stools 1,21 , administration of vaccines by oral or aerosol routes will induce mucosal immune responses and are possible modes of SARS-CoV-2 vaccine immunization. A safe DNA vector for preparation of DNA vaccines 22 , an attenuated virus strain for design of chimeric viral vaccines 23 , and engineered safe bacteria for production of membrane vesicle-vaccines 24 could be explored for vaccine delivery and are worth investigating in the near future.…”

“…Received: 11 February 2020; Accepted: 21 February 2020; 12,14 Viral vector vaccines Safety; induces high cellular and humoral immune responses Possibly present pre-existing immunity 12 DNA vaccines Easier to design; high safety; high-titer neutralizing antibodies Lower immune responses in humans; repeated doses may cause toxicity 23 mRNA vaccines Easier to design; high degree of adaptability; induce strong immune responses…”

Disease X: accelerating the development of medical countermeasures for the next pandemic

“…2 Although viral pathogens represent a small proportion of the pathogens that account for emerging infectious disease events, the most devastating recent emergence events-namely, HIV, influenza H1N1 and H5H1, severe acute respiratory syndrome coronavirus, Lassa virus, Ebola virus, and Middle East respiratory syndrome coronavirus-have involved RNA viruses. 3,4 They can replicate in numerous host species, and their errorprone reverse transcriptase enables high mutability resulting in the evasion of host responses. Further, 94% of zoonotic viruses affecting humans are RNA viruses.…”

COVID-19 from veterinary medicine and one health perspectives: What animal coronaviruses have taught us

“…One of the main issues is that most experimental vaccines triggered an antibody-dependent enhancement (ADE) mechanism, which causes a more severe disease in immunised animals than in control cats after virus challenge (German et al, 2004). ADE is triggered by antibody-mediated virus entry into macrophages via Ig Fc receptors and might represent an obstacle to the development of SARS-CoV-2 specific vaccines (Rauch et al, 2018). An alternative mechanism for ADE has been described recently for MERS-CoV, for which neutralizing antibodies bind to the spike protein, triggering a conformational change of the spike and mediating viral entry into IgG Fc receptor-expressing cells through canonical viral-receptordependent pathways (Wan et al, 2020).…”