Comparison of suspension MDCK cells, adherent MDCK cells, and LLC-MK2 cells for selective isolation of influenza viruses to be used as vaccine seeds

Influenza Other Respir Viruses. 2020 Mar;14(2):204-209. doi: 10.1111/irv.12694. Epub 2019 Oct 25.


Background: Cell-based influenza vaccines can solve the problem of the frequent occurrence of egg adaptation-associated antigenic changes observed in egg-based vaccines. Seed viruses for cell-based vaccines can be prepared from clinical specimens by cell culture; however, clinical samples risk harboring respiratory viruses other than influenza virus. Therefore, it is necessary to investigate the patterns of co-infection in clinical samples and explore whether cell culture technology can selectively propagate influenza viruses from samples containing other respiratory viruses.

Methods: A total of 341 clinical specimens were collected from patients with influenza or influenza-like illness and analyzed by ResPlex II assay to detect 18 respiratory viruses. The patterns of co-infection were statistically analyzed with Fisher's exact test. The samples with double or triple infections were passaged in suspension MDCK cells (MDCK-S), adherent MDCK cells (MDCK-A), and LLC-MK2D cells. Cell-passaged samples were analyzed by ResPlex II assay again to investigate whether each cell line could amplify influenza viruses and eliminate other respiratory viruses.

Results: Double infections were detected in 8.5% and triple infections in 0.9% of the collected clinical specimens. We identified four pairs of viruses with significant correlation. For all samples with double and triple infection, MDCK-S and MDCK-A could selectively propagate influenza viruses, while eliminating all contaminating viruses. In contrast, LLC-MK2D showed lower isolation efficiency for influenza virus and higher isolation efficiency for coxsackievirus/echovirus than MDCK-S and MDCK-A.

Conclusions: Both MDCK-S and MDCK-A are considered suitable for the preparation of influenza vaccine seed viruses without adventitious agents or egg-adaptation mutations.

Keywords: Madin-Darby canine kidney cell line; adventitious virus; cell-based vaccine; influenza; vaccine seed virus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Dogs
  • Humans
  • Madin Darby Canine Kidney Cells / virology*
  • Orthomyxoviridae / growth & development
  • Orthomyxoviridae / isolation & purification*
  • Viral Vaccines
  • Virus Cultivation / methods*


  • Viral Vaccines