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Published in Norman Begg, The Remarkable Story of Vaccines, 2023
A critical aspect of vaccine manufacture is to produce a vaccine that is capable of stimulating the immune system, but without producing any symptoms of the disease. Traditionally, this is done by either inactivation (killing the virus or bacterium) or attenuation (weakening it to make it harmless). The oldest method is inactivation, using a chemical such as formalin. Formalin is a solution of formaldehyde with a characteristic strong, irritating smell. It is widely used for long-term storage of animal and organ specimens; if you have an aquarium, you probably used it to kill the parasites that live in fish. Formalin inactivation is a very reliable method still used today for many vaccines. Some of the most widely used vaccines in the world still use this method, such as polio and influenza. The other most common method is attenuation, where the virus or bacterium is grown repeatedly in cell cultures, which has the effect of weakening them. The attenuated organisms are still able to replicate, but they have lost their ability to cause disease. Measles, mumps, rubella and yellow fever are all examples of live attenuated vaccines.
Photocatalytic Inactivation of Pathogenic Viruses Using Metal Oxide and Carbon-Based Nanoparticles
Published in Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji, Viral and Antiviral Nanomaterials, 2022
Lan Ching Sim, Wei Qing Wee, Shien Yoong Siow, Kah Hon Leong, Jit Jang Ng, Pichiah Saravanan
The use of a photocatalyst is environmental-friendly and sustainable because of the employment of renewable energy as the energy source of the photocatalytic viral inactivation. This chapter provides a review on the development of photocatalytic inactivation of viruses using metal oxide NPs and carbon-based NPs. Despite recent advances, some potential research is yet to be explored to overcome new challenges provoked by viral pandemic cases. Future work should explore the coating of photocatalysts on face masks or other surfaces to control the viral spread of Coronavirus 2 (SARS-CoV-2) via fomite and aerosol. Further, molecular imprinting could be used to selectively adsorb viruses and concentrate them near photocatalytic sites for inactivation. It has been proven to be effective in waterborne viral inactivation. There is lack of investigation on the viral inactivation mechanism using a combination of quantitative analytical tools since the foremost discovery by Wigginton et al. (2012). This approach helps to identify and quantify the extent of modifications in the virus genome or proteins by measuring the damage at well-defined levels of inactivation (Wigginton et al. 2012). Most of the viral inactivation methods are reported by using UVC light at 254 nm, which is harmful to skin and eyes. Hence, it is suggested to use far-UVC light (207–222 nm) or visible light (390–750 nm) to reduce the negative effects of UVC light. And for that, it will be necessary to develop a photocatalyst material that could harvest more visible light.
Vaccine Development Strategies and the Current Status of COVID-19 Vaccines
Published in Debmalya Barh, Kenneth Lundstrom, COVID-19, 2022
Mohsen Akbarian, Kenneth Lundstrom, Elrashdy M. Redwan, Vladimir N. Uversky
Various methods of inactivation based on radiation (γ-radiation, X-ray, and UV) and chemicals (methanol, formalin, and β-propiolactone), have been used on viruses to preserve their antigenic properties while reducing or eliminating their infectivity. Inactivated vaccines have been used successfully to control the spread of viruses, such as polio, influenza, and hepatitis A. It should be emphasized here that these types of vaccines do not typically have problems, such as re-activation of a virus and/or mutation into new, more virulent variants [19]. However, unexpected or poor immune responses, the need for the administration of high and repeated vaccine doses, and in some cases, pulmonary inflammation have also been reported [34]. In addition to inactivated viral vaccines, attenuated viral vaccines have been developed. The advantages of these vaccines, which are relatively inexpensive, include long-lasting and strong immune responses. Furthermore, there is no need for adjuvant use. Nonetheless, they also show some disadvantages, for example, potential reactivation of virus and reduced safety compared to inactivated viral vaccines.
Approaches for the discovery of drugs that target K Na 1.1 channels in KCNT1-associated epilepsy
Published in Expert Opinion on Drug Discovery, 2022
Barbara Miziak, Stanisław J Czuczwar
When membrane depolarization is persistently present, due to various inactivating mechanisms (e.g. slow cessation of transmission upon activation), the channels go into a non-conducting state. It is important to remember that inactivation is not the same as the reverse process of activation. In inactivation, the stimuli that activate the channel are still present, but the channels no longer conduct ions efficiently [39]. N-type inactivation binds to the intracellular region at the amino-terminal acting, resulting in pore closure. The entire process occurs within a few milliseconds. In case of C-type inactivation, it has been shown to be voltage independent over a range of −25 to +50 mV, and is partially coupled to N-type inactivation. Furthermore, the kinetics of this type of inactivation will vary depending on the alternatively spliced carboxy-terminal regions in the channels involved [40]. C-type inactivation has been shown to play an important role in modulating the firing of action potentials in neurons and cardiac muscle by regulating the availability of functional Kv channels [41].
In vitro strain specific reducing of aflatoxin B1 by probiotic bacteria: a systematic review and meta-analysis
Published in Toxin Reviews, 2022
Alireza Emadi, Majid Eslami, Bahman Yousefi, Anna Abdolshahi
Numerous studies were investigated about preventing/inhibiting aflatoxin production, reducing/detoxifying aflatoxin in contaminated products, and inhibiting the absorption of aflatoxin at the gastrointestinal tract (Afshar et al.2020). Efforts have been prepared to eliminate toxins from contaminated sources or cut down into fewer toxic complexes (Zaki et al.2012). There were different approaches to decrease aflatoxin bioavailability in foods. The most important techniques can be biological decontamination and chemical inactivation (Lili et al.2018, Sadiq et al.2019, Afshar et al.2020). Based on consumer demands for safe foods and avoiding the chemical process, it must establish effective specified methods that are cost-effective, environment according, applicable, available, and safe. In this regard, the biodegradation of aflatoxin using nonpathogenic microorganisms and their derivates have been considered as a relevant strategy (Oliveira et al.2013, Kim et al.2017).
Charge effect of water-soluble porphyrin derivatives as a prototype to fight infections caused by Acinetobacter baumannii by aPDT approaches
Published in Biofouling, 2022
Carolina da Silva Canielles Caprara, Livia da Silva Freitas, Bernardo Almeida Iglesias, Lara Beatriz Ferreira, Daniela Fernandes Ramos
Another important point to be discussed is that the photoinactivation of Gram-negative bacteria has been more laborious due to their outer membrane barrier preventing the uptake of anionic compounds, regardless if they are antibiotics or photosensitizing agents (Theuretzbacher et al. 2020; Fekrirad et al. 2021). This has had repercussions, including less success in developing new antimicrobials compared to Gram-positive strains (Theuretzbacher et al. 2020). Given this scenario, bacterial photoinactivation was evaluated as an antimicrobial strategy against different A. baumannii strains using visible light irradiation for up to 90 min. Thus, even if antibacterial photodynamic inactivation is a therapeutic option used to treat infectious diseases, the following factors were considered: photosensitizers, light, and oxygen to remove highly metabolically active cells. Since the first reports of the photodynamic process, the choice of photosensitizers has taken into account not only the selectivity for bacteria over host tissue but also the combination of an overall cationic charge and water solubility (Dai et al. 2009; da Fonseca et al. 2021).