Practice question

Routine animal cell culture including work with established human lines like HeLa, HEK293, and CHO must be performed at Biosafety Level 2 according to international guidelines. Even well-characterized lines may harbor endogenous retroviruses, latent herpesviruses such as Epstein-Barr virus, human cytomegalovirus, or adventitious agents introduced via bovine serum or mycoplasma contamination. Furthermore, cell line cross-contamination, as historically documented for HeLa overgrowth, poses risks. BSL-2 provides appropriate containment without impairing workflow: access restricted to trained personnel, use of Class II BSC for trypsinization, media changes, pipetting that generates aerosols, mandatory PPE including gloves and lab gowns, biosafety training records, biohazard labels on incubators, and decontamination of liquid waste with bleach or autoclaving. BSL-1 is limited to defined non-pathogenic organisms such as E. coli K-12, while BSL-3 and BSL-4 are reserved for agents causing serious airborne disease like Mycobacterium tuberculosis or Ebola. Therefore BSL-2 represents standard for mammalian cell culture. Certification of cabinets annually and training logs documented in laboratory biosafety manual reinforce adherence. This knowledge strengthens laboratory safety, protocol reproducibility, and regulatory compliance critical for translational research and clinical applications, ensuring reliable data and workforce protection.