What Are Vero Cells and Why Are They Used in Science?

Vero cells are a continuous line of cells used in research and pharmaceutical manufacturing, particularly in virology. Their unique characteristics allow for the large-scale production of viruses and other biological products. This makes them a standardized system for developing and testing new vaccines and therapies.

Discovery and Origin of Vero Cells

The Vero cell line was established in 1962 by scientists Yasumura and Kawakita at Chiba University in Japan. These cells were isolated from the kidney epithelial tissue of a healthy, adult African green monkey. The name “Vero” is an abbreviation of “Verda Reno,” which means “green kidney” in Esperanto, referencing their origin.

Unlike primary cells, which have a finite lifespan, continuous cell lines can be propagated indefinitely in a laboratory setting. This provides researchers with a consistent biological system for experiments, eliminating the variability associated with using primary animal tissues.

Unique Biological Properties

One of the defining features of Vero cells is their high susceptibility to a wide range of viruses. This is because they are deficient in the genes that produce interferon, a group of proteins that healthy cells release to inhibit viral replication. Lacking this natural antiviral defense mechanism, Vero cells become efficient factories for growing large quantities of viruses.

Vero cells are also characterized by aneuploidy, an abnormal number of chromosomes. This deviation from normal cells does not impede their growth in culture or their ability to support viral replication. These cells are also adherent, meaning they grow attached to the surface of a culture flask, which is advantageous for laboratory handling and scaling up production.

Applications in Science and Healthcare

The most prominent use for Vero cells is manufacturing human vaccines. The World Health Organization approved them as the first continuous cell line for this purpose, and they have been used to produce vaccines for diseases including:

• Polio
• Rabies
• Rotavirus
• Smallpox
• Influenza
• COVID-19

Beyond vaccine development, Vero cells are a standard model in virology research. Scientists use them to study how viruses infect cells, replicate, and cause disease. They are also employed to screen the effectiveness of new antiviral drugs, cultivate certain intracellular parasites, and to test the toxicity of various compounds.

Safety and Handling Considerations

The use of Vero cells for human therapeutics is subject to strict regulatory oversight. Because they are a continuous and aneuploid cell line, they can form tumors if injected into immunosuppressed animals. This tumorigenic potential necessitates rigorous purification processes for any product, like a vaccine, manufactured using these cells.

Regulatory bodies mandate that manufacturers demonstrate the effective removal of residual host cell components. These purification steps are designed to eliminate virtually all Vero cell DNA and proteins from the final product, ensuring its safety. Vaccines produced in Vero cells have a long history of safe application in millions of people.