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Use of HEp-2 cells for improved isolation and passage of Chlamydia pneumoniae
P M Roblin1, W Dumornay, M R Hammerschlag
1Department of Pediatrics, State University of New York Health Science Center, Brooklyn 11203.
Abstract:
Chlamydia pneumoniae has proved to be difficult to isolate and propagate in cell culture. We compared the growth of three strains of C. pneumoniae, TW-183 and two clinical isolates from Brooklyn, N.Y., in five cell lines, including HeLa 229, McCoy, HL, HEp-2, and HTED, an immortalized human tracheal cell line. HEp-2 was the most sensitive cell line tested. When 10-fold dilutions of three C. pneumoniae strains at known titers were inoculated into the different cell lines, the mean number of inclusion-forming units per milliliter was 1 to 2 log units higher in the HEp-2 than in the other cell lines. This difference was statistically significant. Omission of pretreatment with DEAE-dextran resulted in larger inclusions than those seen in pretreated cells, with the exception of McCoy and HTED cells. Retrieval of clinical specimens previously cultured on HeLa 229 cells and comparison of mean inclusion counts in fresh clinical specimens simultaneously inoculated on HeLa 229 and HEp-2 cells suggested that culture in HEp-2 cells may require only the initial inoculation and one passage, compared with three to four passages, as required by culture in HeLa 229 cells.
Insights
HEp-2 cells show superior sensitivity for culturing Chlamydia pneumoniae (C. pneumoniae), requiring fewer passages than HeLa 229 cells. This finding improves C. pneumoniae isolation and propagation for research.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Chlamydia pneumoniae (C. pneumoniae) isolation and propagation in cell culture present significant challenges.
- Optimizing cell culture methods is crucial for studying C. pneumoniae pathogenesis and developing treatments.
Purpose of the Study:
- To compare the growth efficiency of different C. pneumoniae strains across various cell lines.
- To identify the most sensitive cell line for C. pneumoniae isolation and propagation.
- To evaluate the impact of DEAE-dextran pretreatment on C. pneumoniae inclusion formation.
Main Methods:
- Three C. pneumoniae strains (TW-183 and two clinical isolates) were cultured in five cell lines: HeLa 229, McCoy, HL, HEp-2, and HTED.
- Inclusion-forming units (IFUs) per milliliter were quantified after inoculating 10-fold dilutions of C. pneumoniae.
- The effect of DEAE-dextran pretreatment on inclusion size was assessed.
Main Results:
- HEp-2 cells demonstrated the highest sensitivity, yielding 1-2 log units higher mean IFUs/mL compared to other cell lines.
- Excluding McCoy and HTED cells, omitting DEAE-dextran pretreatment resulted in larger C. pneumoniae inclusions.
- Culture in HEp-2 cells required fewer passages (initial inoculation + one passage) compared to HeLa 229 cells (three to four passages).
Conclusions:
- HEp-2 cells are significantly more sensitive for C. pneumoniae isolation and propagation than the tested cell lines.
- Optimized cell culture techniques using HEp-2 cells can reduce passage requirements, facilitating C. pneumoniae research.
- Understanding optimal culture conditions is vital for accurate diagnosis and study of C. pneumoniae infections.