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Upstream processing for viral vaccines–General aspects
Published in Amine Kamen, Laura Cervera, Bioprocessing of Viral Vaccines, 2023
Lars Pelz, Sven Göbel, Karim Jaen, Udo Reichl, Yvonne Genzel
After infection, the viruses utilize the host cells to replicate their genome and synthesize viral proteins. The assembly and release of progeny virions completes a replication cycle. Infectious viruses released then infect uninfected cells until preferably the whole cell population is infected. Virus particles accumulate in the vessel and highest virus titers are reached, depending on the replication time of the virus, between 2−4 days after TOI (Figure 5.6). Typically, the infectious virus titer peaks earlier than the total virus titer (infectious plus non-infectious virus particles), and the total virus titer remains more or less constant after reaching its maximum, whereas the infectious titer often decreases with time depending on the virus stability. This is important for generation of seed virus and when infectious virus material is the product (e.g., live-attenuated vaccines, viral vectors, oncolytic viruses). For lytic viruses, the cytopathic effect leads to the termination of the process due to cell death. Depending on titers and the level of contaminating by-products (e.g., host cell DNA, proteins), the virus harvest is collected, clarified (depth filtration, centrifugation) and inactivated by (e.g., formaldehyde, β-propiolactone or binary ethyleneimine (BEI) for manufacturing of inactivated vaccines). Subsequently, it is subjected to DSP and formulation (Figure 5.1). After sterilization of the equipment or exchange of the single-use equipment, a new batch cycle can be conducted. Monitoring of the production process is carried out by measuring the concentrations of cells and metabolites, pH value, total and infectious virus titer, DNA and (host cell) protein levels (see also chapter 8). Most of these measurements still rely on manual sampling. For off-line analytics, samples are stored at −80°C and should only be thawed once for titrations as viruses are sensitive to freeze-thaw cycles. For other assays, heat or other inactivation of samples should be considered with respect to biosafety and virus contaminations of equipment.
Incorporating viruses into soil ecology: A new dimension to understand biogeochemical cycling
Published in Critical Reviews in Environmental Science and Technology, 2023
Xiaolong Liang, Mark Radosevich, Jennifer M. DeBruyn, Steven W. Wilhelm, Regan McDearis, Jie Zhuang
Though not meeting the technical definition of self-replication, viruses are the most diverse life forms globally and represent the largest genetic reservoir on the planet. Largely due to the nature of viruses (e.g., living or non-living controversy, RNA or DNA composing genome, and no common genomic sequence shared), viral classification is imperfect and widely debated. Generally, viruses can be classified based on the characteristics of viral particles and their infecting host (Dion et al., 2020; Kimura et al., 2008). Specifically, the properties of viral protein capsid, e.g., icosahedral, helical, envelope structure, contractile tail, and non-contractile tail, are used for viral classification (Fig. 1). Viral genomes vary in genetic material (DNA or RNA) and the structure (i.e., single- or double-stranded, circular or linear, and compact or segmented). While soil viral ecology studies have mostly focused on DNA viruses, RNA viruses are also widely distributed and an important part of soil ecology. Recent studies suggested that soil contains abundant and diverse RNA viruses that primarily infect fungi and bacteria (Hillary et al., 2022; Starr et al., 2019). Soil RNA viruses may also infect vertebrates and plants and potentially affect soil nutrient cycling. Difficulties in extracting sufficient viral RNA genomic materials from soil samples and computational analysis of the generated large metatranscriptome datasets have impeded efforts of studying soil RNA viruses.
Disinfecting Efficacy of an Ozonated Water Spray Chamber: Scientific Evidence of the Total and Partial Biocidal Effect on Personal Protective Equipment and in Vitro Analysis of a Viral Experimental Model
Published in Ozone: Science & Engineering, 2023
Fabricia Oliveira, Laerte Marlon Conceição Dos Santos, Eduardo Santos da Silva, Leticia de Alencar Pereira Rodrigues, Paulo Roberto Freitas Neves, Greta Almeida Fernandes Moreira, Gabriela Monteiro Lobato, Carlos Nascimento, Marcelo Gerhardt, Alex Alisson Bandeira Santos, Luis Alberto Brêda Mascarenhas, Bruna Aparecida Souza Machado
Regarding the action of O3 on viruses, according to the literature, inactivation occurs mainly by peroxidation of lipids and proteins (Cristiano 2020; Jiang et al. 2019). In the case of non-enveloped viruses, O3 can cause damage to the viral capsid, interrupting virus contact with target cells. In enveloped viruses, O3 diffuses to the viral protein coating, causing damage to the genetic material – both DNA and RNA (Jiang et al. 2019; Wigginton and Kohn 2012). Ozonated water has proven effective in inactivating Norwalk virus, poliovirus 1, and bacteriophage MS2, as detected by viral infection and RT-PCR assays. O3 has kinetic activity of viral inactivation in two stages, with 99–99.5% of the poliovirus inactivation occurring in the first 8 seconds or less (Jiang et al. 2019). Concentrations equal to or greater than 1.5 mg/L increased the inactivation rate in the second stage (Shin and Sobsey 2003). Additionally, Brié et al. (2018) demonstrated through their studies the microbial action of ozonated water in murine norovirus and hepatitis A virus, at a concentration ranging from 3 to 5 mg/L.
Epidemiology, virology and clinical aspects of hantavirus infections: an overview
Published in International Journal of Environmental Health Research, 2022
Sima Singh, Arshid Numan, Dinesh Sharma, Rahul Shukla, Amit Alexander, Gaurav Kumar Jain, Farhan Jalees Ahmad, Prashant Kesharwani
The hantavirus genome synthesis of viral RNAs includes transcription and replication. Transcription helps to produce to produce viral protein-encoding mRNAs and replication to produce viral genomic RNA as shown in Figure 3. The viral RNA-dependent RNA polymerase (RdRp) is responsible for all of these functions (Sironen and Plyusnin 2011). Hantavirus is replicated in macrophages and vascular endothelial cells in patients, especially in the lungs and kidneys (Yanagihara and Silverman 1990). Moreover, thus, cultures of endothelial cells are used for hantavirus infection as in vitro models. The entry of hantaviruses into cells is thought to be mediated by certain host cell surface proteins. The replication cycle starts by attaching pathogens to the receptor of the host cell surface (Markotić et al. 2007). Several findings clearly indicate that the viral Gn protein interacts with integrin receptors on the surface of host cells to mediate binding (Mir and Panganiban 2010). Integrins are a heterodimeric protein family that contain α-chain and β-chain. It promotes cell-cell adhesion as well as cell-extracellular matrix adhesion (Takagi and Springer 2002; Campbell and Humphries 2011).