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Design and production of vaccines against COVID-19 using established vaccine platforms
Published in Amine Kamen, Laura Cervera, Bioprocessing of Viral Vaccines, 2023
Ryan Kligman, Jesús Lavado-García, Amine Kamen
When it comes to vaccine safety, there are many elements to consider. However, one that should be mentioned is a phenomenon called antibody dependent enhancement (ADE). ADE occurs when antibodies produced against a vaccine pathogen are unable to effectively neutralize the virus and end up exacerbating the natural infection. It is caused by the Fc antibody portion of the virus-antibody complex binding more efficiently to cells with Fc receptors like macrophages and dendritic cells, thus increasing viral cell-entry [6,22]. This is especially important for potential vaccines against SARS-CoV-2, because this phenomenon was previously seen in SARS-CoV, MERS-CoV, and other respiratory viruses such as RSV and measles [23]. Even though ADE is particularly a concern for inactivated vaccines, it must be kept in mind for all other vaccine platforms [21].
COVID-19 Vaccine Development and Applications
Published in Yashwant V. Pathak, Gene Delivery Systems, 2022
The detailed biological characteristics of SARS-CoV-2 are still unknown, and whether it infects only the respiratory tract or both respiratory and intestinal tracts is yet to be established; furthermore, the route of dissemination of SARS-CoV-2 to the lungs is not clear yet. Elucidation of these biological characteristics is a very crucial factor in the development of potential treatments and preventive strategies. Antibody-dependent enhancement (ADE) of coronavirus infections following vaccination is also a major concern in developing vaccines against COVID-19. Although the mechanism behind ADE is not yet clear, this may occur due to sub-neutralizing antibodies that do not have the capacity to completely neutralize the virus but instead cause enhanced uptake and spread of the viruses by entering Fc receptor–expressing cells (98). Another challenge in the developmental process of COVID-19 vaccines is the lack of suitable animal models to test vaccine efficacy and safety because none of the animal models appropriately mimic human COVID-19 infection and the potential correlates of infection (99). Furthermore, the genetic instability of the virus can result in limited effectiveness of the vaccines against it, which may eventually need an update in the composition of current COVID-19 vaccines to ensure the levels of protection against newly evolved variants. Therefore, it is important to create a secure and reliable vaccine in advance of future outbreaks of SARS-CoV-2 variants (100). Rapid large-scale manufacturing and distribution of billions of doses of COVID-19 vaccines still remains a challenge, with lots of uncertainty to meet the demand of a pandemic.
Effects of freeze-drying and microwave vacuum freeze-drying on the activity of IgY: From the perspective of protein structure
Published in Drying Technology, 2023
Zhe Wang, Xu Duan, Linlin Li, Guangyue Ren, Tiantian Wu, Junliang Chen, Yuan Ang, Jingfang Guo, Mengyue Zhao
Immunoglobulin of yolk (IgY), a natural polyclonal antibody, is an immunoglobulin commonly found in birds, reptiles, and amphibians. It usually transfers and accumulates from chicken serum to egg yolk, providing acquired immunity to chicks.[1] IgY is like a phylogenetic progenitor of mammalian immunoglobulin E (IgE), immunoglobulin A (IgA), and immunoglobulin G (IgG) but it has advantages of low cost and is more in line with ethical issues such as animal welfare.[2] Immunization of hens leads to the transfer of specific antibodies to egg yolks, making eggs a source of oral IgY for humans.[3] When used as a therapeutic antibody, IgY will not bind to the human complement system or Fc receptors, reducing the risk of antibody dependent enhancement (ADE). IgY is currently used in a variety of commercial foods, such as yogurt, candies, etc., which plays a role in passive immunization or prevention of human diseases caused by pathogens. Leiva et al reported that the use of IgY instead of mammalian polyclonal antibodies could neutralize the bee venom in vivo.[4] Furthermore, IgY has a broad role and potential value in the diagnosis, prevention, and treatment of the COVID-19 epidemic.[1]