Cell Lines for Viral Culture in Suspected Respiratory Virus Infection
For the 4-year-old patient with suspected respiratory viral infection, the sputum specimen should be processed using multiple cell lines including MDCK, LLC-MK2, and HEp-2 cells in a shell vial assay format for optimal detection of respiratory viruses. 1, 2
Optimal Cell Line Selection
The clinical presentation of fever, respiratory symptoms, and infiltrate on chest X-ray during January strongly suggests a viral respiratory infection, likely influenza. Based on the evidence, a combination of cell lines provides the best diagnostic yield:
- MDCK (Madin-Darby Canine Kidney): Optimal for influenza virus isolation 3
- LLC-MK2 (Rhesus Monkey Kidney): Excellent for parainfluenza viruses 3, 2
- HEp-2 (Human Epithelial): Particularly good for respiratory syncytial virus (RSV) 2
Shell Vial Assay Approach
A shell vial assay using a combination of these cell lines (CoHLM SV assay) is recommended as it:
- Detects 94.1% of respiratory viruses within 48 hours (compared to 6 days for traditional culture) 2
- Requires less technical expertise than conventional culture methods 4
- Provides faster results while maintaining good sensitivity 5
Additional Cell Lines to Consider
For comprehensive coverage of potential respiratory pathogens, additional cell lines that may be included are:
- Vero E6: Useful for various respiratory viruses
- RD-18S: Enhances detection of enteroviruses
- GMK: Improves isolation rates for certain viruses 1
Clinical Context Considerations
The timing of this patient's presentation in January increases the likelihood of influenza or RSV infection, which should guide the prioritization of appropriate cell lines 6. The patient's clinical presentation with fever, cough, and right lower lobe infiltrate is classic for viral pneumonia, with influenza being a leading consideration during winter months.
Modern Diagnostic Approach
While cell culture remains valuable, it's important to note that nucleic acid amplification testing (NAT) is now considered the reference standard for respiratory virus detection by the American Academy of Pediatrics and CDC due to:
- Higher sensitivity
- Faster turnaround time
- Ability to detect multiple viruses simultaneously 6
Practical Implementation
For this patient's sputum specimen:
- Process the sample promptly in viral transport media to maintain virus viability
- Use a shell vial assay with MDCK, LLC-MK2, and HEp-2 cells
- Consider adding additional cell lines if available for broader coverage
- Examine for cytopathic effects at 24-48 hours
- Confirm viral identification with immunofluorescence or other specific tests
This approach balances diagnostic yield with turnaround time, which is critical for appropriate management of this pediatric patient with respiratory distress.