Fetal bovine serum (FBS) is the most widely used growth supplement added to in vitro cell cultures. It has been in use for over fifty years, outperforming both synthetic and natural growth supplements. FBS is employed across a variety of research and industrial applications, including vaccine production.
Traditionally, vaccines are made from a weakened or dead form of a disease-causing microorganism that stimulates the immune system and creates antibodies that protect against stronger versions of the pathogen. To create large batches of vaccine to inoculate thousands of people, the vaccine component must be produced in high quantities. Viruses cannot replicate outside of a host; therefore, a host animal or cell type must be provided.
Is fetal bovine serum used in vaccines?
The production of many vaccines relies on the successful culture of cells, which act as hosts for viral replication. During vaccine development, these viruses are either attenuated (weakened) or inactivated (killed), allowing them to promote an immune response without causing illness in a patient [1]. The growth of weakened pathogen strains using cells requires specific growth media, and often, animal-derived products. |
FBS has proven especially effective as a supplement to cell culture media for promoting viral replication. When used in media at concentrations between 2–10%, FBS is highly effective at promoting cell growth due to the presence of nutritional, hormonal, growth, and attachment factors. In addition, FBS contains lower levels of growth-inhibiting factors (e.g., antibodies) and can also act as a buffer against environmental changes (e.g., pH shifts).
Due to these benefits, FBS is often used as part of the culture medium in which viruses are studied, grown, and harvested for use in vaccines. However, FBS does not actually exist within the final vaccine itself; rather, its macromolecular proteins are broken down by the cells for use as nutrients, and its growth factors stimulate proliferation of the desired cells.
A history of vaccines
Before vaccinations, epidemics were one of the most prolific killers of Homo sapiens; therefore, vaccine development has been a pivotal area of human history and ingenuity [2].
The earliest inoculations
Evidence suggests that the Chinese used inoculation as far back as 1000 CE [3]. Ayurveda texts also indicate the early use of inoculation in India [4]. During the 1500s, the practice of inoculation began to spread west, eventually reaching Türkiye, Africa, and Europe [5].
The beginning of modern vaccinations
The credit for modern western human vaccination is attributed to English physician Edward Jenner, who in 1796 injected a young boy, James Phipps, with material from a cowpox vesicle sourced from Sarah Nelmes, a milkmaid. Two months later, young James was inoculated with smallpox and developed no symptoms [3]. However, the use of cowpox inoculation did not become common until the 1840s [6].
The second generation of vaccines
The famous Louis Pasteur introduced the second generation of vaccines in the 1880s. Whereas Jenner’s breakthrough came about with the realization that those who survived cowpox were immune to smallpox, Pasteur, considered one of the fathers of germ theory, was the first to artificially weaken a disease and create a vaccine. One of the most well-known accomplishments of Pasteur was the development of a rabies vaccine, which in 1885, was used to prevent rabies infection in a child. This was the first example of successful rabies vaccination in a human patient [7].
Cell-based vaccine production
Historically, vaccines were commonly produced using live animals or animal products (e.g., chicken eggs). However, over time, cell-based vaccines (i.e., vaccines produced using cultured cell lines) have become more common [1,8]. The use of cell lines allows vaccines to be rapidly produced without relying on the supply of certain animal products. In addition, viruses may be attenuated within cell culture by adapting them to growth conditions that differ from those in the human body (e.g., culturing them at lower temperatures). This way, once the vaccine is injected into a patient, these viruses can promote an immune response but are unable to cause disease symptoms under physiological conditions [1].
The importance of fetal bovine serum in vaccine production
Although produced in cells grown with fetal bovine serum, viral particles that are used in the vaccine are purified from the cell culture. Nevertheless, researchers have been looking to develop vaccine manufacturing methods in a more controllable environment.
Researchers have explored a variety of avenues, including chemically defined and serum-free media, to find what provided the greatest efficacy while reducing exposure to the ‘unknown’ components in FBS. However, due to its proven success as a source of growth-promoting factors for cultured cells fetal bovine serum remains a robust and critical component of many vaccine manufacturing protocols [9,10].
Safety and quality of fetal bovine serum in vaccines
Strict guidelines set forth by global government agencies (i.e., USDA, FDA, DEFRA, ANVISA, etc.) exert a high measure of quality control on FBS products. Disease status of animals are monitored by the World Organization for Animal Health (OIE) [10,11].
Thermo Fisher Scientific has also incorporated extra measures to help ensure the integrity of FBS products. One such method is fingerprinting technology developed in conjunction with Oritain , which can be used to determine and confirm the origin of FBS. FBS origin is especially important for the manufacture of vaccines as this information is needed for submissions to the FDA or other regulatory authorities [9].
Fetal bovine serum has been used in vaccine production for over 50 years, and it has proven itself as an extremely effective growth supplement. Although customers would ideally prefer to be in a world where serum is synthetic, there is currently still a long way until we reach that point.
- How are vaccines made? Human Cell Strains in Vaccine Development. History of Vaccines. College of Physicians of Philadelphia.
- How are vaccines made? Vaccines for Pandemic Threats. History of Vaccines. College of Physicians of Philadelphia.
- Vaccine Timeline: Before Jenner and After COVID-19. Timeline. History of Vaccines. College of Physicians of Philadelphia.
- History of Medicine. Medicine and surgery before 1800. Traditional medicine and surgery in Asia. Britannica. Encyclopædia Britannica, Inc.
- Vaccine Timeline: Before Jenner and After COVID-19. Overview. History of Vaccines. College of Physicians of Philadelphia.
- Smith KA. (2011) Edward Jenner and the Small Pox Vaccine. Front Immunol 2:21.
- Louis Pasteur, ForMemRS: The Father of Germ Theory Timeline. History of Vaccines. College of Physicians of Philadelphia.
- Influenza. Prevent Flu. How Influenza (Flu) Vaccines Are Made. Centers for Disease Control and Prevention (CDC).
- Bovine Derived Materials Used in Vaccine Manufacturing Questions and Answers. U.S. Food & Drug Administration (FDA).
- Hawkes PW. (2015) Fetal bovine serum: geographic origin and regulatory relevance of viral contamination. Bioresour and Bioprocess 2(34).
- The ISIA Journey. January 2020. International Serum Industry Association.
Resources
Fetal Bovine Serum Basics
Learn the basics of FBS for cell culture, including information on the FBS uses, components, and the market dynamics driving this industry.
Cell Culture Basics
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Gibco iMatch Sera Lot Matching Tool
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