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Quality and lifecycle management
Published in Sarfaraz K. Niazi, Biosimilars and Interchangeable Biologics, 2016
Viruses contamination comes from the host cell, the culture medium, and infections during manufacture. The host cell may contain a genomic virus or virus vectors used to transform the cell line. The type of viral genome and/or vector depends on the cell line history. Continuous cell lines are extensively characterized but chronic or latent viruses may be present. The retroviruses associated with continuous cell lines are noninfectious, but oncogenic. Epstein-Barr virus or Sendai virus are often used for cell transformations. Contaminants such as BVDV, IBR, reovirus, PI-3, bovine leukemia virus, bovine polyoma virus should be expected from serum supplemented media. Virus control is executed on several levels. The cell line history reveals all information on the origin and identity of the cell line and the host genome vectors used to establish the cell line. The master cell bank is extensively characterized using viral identity tests, in vitro tests, and in vivo tests to assure freedom of adventitious viruses. The end of production test of the cell culture is carried out to assure that the cells are free of viruses. Viruses are brought into the process from the environment either because of contaminated equipment, infected raw materials, water, or because of non-sterile handling procedures. Working in closed systems and avoidance of raw materials of animal origin will help reduce the risk of infection. Strict control of equipment cleaning and sanitization procedures during processing will also help reducing contamination risk. Removal Viruses may be inactivated by heat, radiation, chemical compound, or low pH, or removed by chromatography or filtration techniques. Due to molecular diversity no specific chromatographic purification method can be recommended, and virus reduction factors must be determined for selected unit operations. Nanofiltration is a very efficient virus removal step often resulting in logarithmic reduction factors of 5–8. A commonly used reagent for cleaning of chromatographic media is 0.1–1 M NaOH. Viruses can be destroyed successfully with peracetic acid (make sure that equipment, filters, and chromatographic media are not affected by NaOH or peracetic acid). A variety of purity analyses are available: monolayer cultures, test for pathogen viruses not able to grow in cell cultures in both animals and eggs, test for retroviruses, endogenous viruses or viral nucleic acid, test for selected viruses using mouse, rat, and hamster antibody production tests. It is necessary to document utilization of adequate virus removal and inactivation strategies to ensure the exclusion of contaminating viruses. Different modes of action should ensure overlapping and complementary levels of protection. The purification process is validated with respect to virus removal and inactivation. The final product is rarely tested if continuous mammalian cell lines have been used as an expression system.
Prevalence of Bovine Leukemia Virus (BLV) and Bovine Adenovirus (BAdV) genomes among air and surface samples in dairy production
Published in Journal of Occupational and Environmental Hygiene, 2020
Agata Stobnicka-Kupiec, Małgorzata Gołofit-Szymczak, Rafał L. Górny, Marcin Cyprowski
Bovine leukemia virus (BLV), a member of Deltaretrovirus genus, is widespread in the dairy cattle population around the world. It causes a chronic infection of lymphocyte-B subpopulation in cows, which is accompanied by presence of viral genomes in their body fluids (Murtaugh et al. 1991; Reyes and Cockerell 1996; Romero et al. 1983; Yamada et al. 2013). Most of the BLV-infected animals remain clinically healthy but they carry the virus, with blood and body secretions, including milk (Khudhair et al. 2016). Several publications indicate that BLV may be harmful for humans revealing possible correlation between BLV infection and breast cancer development in women and entailing a higher risk of developing hematopoietic neoplastic diseases (Buehring et al. 2014, 2015, 2017; Donham et al. 1980; Giovanna et al. 2013; Ochoa Cruz et al. 2006; Svec et al. 2005; Tsai et al. 2014).