Today, cell culture media can be divided in different types based on their content of animal-derived products. Serum-free media (SFM) do not require the addition of serum for optimal cell growth but may contain other additives derived from animals such as lactalbumin, casein, insulin, lipids or sterols [ 12]. Animal-component-free media (ACFM) are media in which none of the components are animal-derived [ 11]. Protein-free media (PFM) are free of supplemental polypeptide factors but may contain hydrolyzed peptide fragments from animal or plant sources. Finally, chemically defined media (CDM) comprise well-characterized constituents of low molecular weight and are, in most cases, free of proteins [ 11, 12]. BHK21 cells have already been adapted to grow in serum-free or animal-component-free cell media for rabies vaccine production [ 13, 14]. With adaption to serum-free conditions, BHK21 cells switch from anchorage-dependent to suspension growth [ 13, 14] and fundamental changes in cell structure take place [ 15, 16]. On the other hand, selective pressures during the adaption of viral strains to BHK21 cells, whether as adherent or as suspension cells, can lead to capsid alterations that influence the antigenicity and stability of the virus particle. Anand P, Stahel VP (May 2021). "Review the safety of Covid-19 mRNA vaccines: a review". Patient Safety in Surgery. 15 (1): 20. doi: 10.1186/s13037-021-00291-9. PMC 8087878. PMID 33933145. William T. Stearn: Botanical Latin. History, Grammar, Syntax, Terminology and Vocabulary. David & Charles, 3rd ed., 1983. Quote: "Virus: virus (s.n. II), gen. sing. viri, nom. pl. vira, gen. pl. vīrorum (to be distinguished from virorum, of men)." Hull, Roger (2002). "12". Matthews' Plant Virology (4thed.). Academic Press. pp.555–56. ISBN 978-0123611604 . Retrieved 21 February 2022. Hall AJ, Jepson PD, Goodman SJ, Harkonen T (2006). "Phocine distemper virus in the North and European Seas– data and models, nature and nurture". Biological Conservation. 131 (2): 221–29. doi: 10.1016/j.biocon.2006.04.008.

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Further Reading

Hilleman MR (October 2004). "Strategies and mechanisms for host and pathogen survival in acute and persistent viral infections". Proceedings of the National Academy of Sciences of the United States of America. 101 (Suppl 2): 14560–66. Bibcode: 2004PNAS..10114560H. doi: 10.1073/pnas.0404758101. PMC 521982. PMID 15297608.

Schiffman M, Castle PE, Jeronimo J, Rodriguez AC, Wacholder S (September 2007). "Human papillomavirus and cervical cancer". Lancet. 370 (9590): 890–907. doi: 10.1016/S0140-6736(07)61416-0. PMID 17826171. S2CID 20196938.Han Q, Lin Q, Jin S, You L (April 2020). "Coronavirus 2019-nCoV: A brief perspective from the front line". The Journal of Infection. 80 (4): 373–77. doi: 10.1016/j.jinf.2020.02.010. PMC 7102581. PMID 32109444. Virus infection kinetics were performed to compare the pace of viral growth and the overall yield, estimated by endpoint titration, in adherent and suspension BHK cells in serum-containing growth medium and animal-component-free-growth medium. The progression of cell death together with the viral titer was documented to find the best time point for virus harvest in the different cell media systems. None of this came up in the statement that Tedros gave on January 30, two days after meeting Xi in person during a visit to Beijing and ten days after the first U.S. case of the coronavirus was confirmed. Instead, Tedros praised China’s commitment to “transparency” and to “protecting the world’s people.” He congratulated China on its containment measures, calling them “very impressive, and beyond words.” He said that China was “setting a new standard for outbreak response.” In declaring the coronavirus a public-health emergency of international concern, he said that “this declaration is not a vote of no confidence in China. On the contrary, WHO continues to have confidence in China’s capacity to control the outbreak.” A pandemic is a worldwide epidemic. The 1918 flu pandemic, which lasted until 1919, was a category 5 influenza pandemic caused by an unusually severe and deadly influenza A virus. The victims were often healthy young adults, in contrast to most influenza outbreaks, which predominantly affect juvenile, elderly, or otherwise-weakened patients. [157] Older estimates say it killed 40–50million people, [158] while more recent research suggests that it may have killed as many as 100million people, or 5% of the world's population in 1918. [159] Genzel Y, Fischer M, Reichl U. Serum-free influenza virus production avoiding washing steps and medium exchange in large-scale microcarrier culture. Vaccine. 2006;24:3261–72.