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editorial
. 1998 Mar;36(3):852. doi: 10.1128/jcm.36.3.852-852.1998

Rapid Detection and Typing of Herpes Simplex Virus DNA in Clinical Specimens by the Hybrid Capture II Signal Amplification Probe Test

Frank, J Michalski 1
PMCID: PMC104646  PMID: 9508333

In a recent study by Cullen et al. in which DNA hybridization by the Hybrid Capture II method (HC-II) was compared with cell culture for detection of herpes simplex virus (HSV) DNA (1), the culture system missed 7 of 44 (15.9%) of the consensus HSV-positive specimens from symptomatic ulcerative genital lesions. This raises questions about the sensitivity of the culture method. The Discussion section states that three of the negatives were due to greater sensitivity of HC-II and four were due to differences in sampling or inhibitions of culture.

In the culture method referenced in the Materials and Methods section, that of Gleaves et al. (2), HSV antigen is detected by fluorescein-labeled monoclonal antibody in MRC-5 cells cultured for 16 and 36 h and then fixed by acetone on coverslips. However, Cullen et al. state that in their study HSV was detected by an enzyme-linked immunosorbent assay with centrifuged cultures. No detail or reference for their method is given.

Two apparently contradictory statements were also found. In Results it is stated that one of the seven culture-negative patients had no lesions but generalized symptoms suggestive of herpes, while in Materials and Methods it is stated that specimens were from ulcerative lesions. Secondly, the Discussion section states that it takes 3 to 7 days to obtain routine culture results, while in the introduction and in Materials and Methods a period of 2 to 3 days is cited.

It is difficult to evaluate the results of the new method of diagnosis due to confusion over comparative culture methods.

REFERENCES

  • 1.Cullen A, Long C, Lorincz A. Rapid detection and typing of herpes simplex virus DNA in clinical specimens by the Hybrid Capture II signal amplification probe test. J Clin Microbiol. 1997;35:2275–2278. doi: 10.1128/jcm.35.9.2275-2278.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Gleaves C A, Wilson D J, Wold A D, Smith T F. Detection and serotyping of herpes simplex virus in MRC-5 cells by use of centrifugation and monoclonal antibodies 16 h postinoculation. J Clin Microbiol. 1985;21:29–32. doi: 10.1128/jcm.21.1.29-32.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
J Clin Microbiol. 1998 Mar;36(3):852.

AUTHORS’ REPLY

Attila Lörincz 1, Allison Cullen 1, Carole Long 1

Dr. Michalski raises a salient point regarding the sensitivity of our culture method. Culture is often considered the “gold standard” for such comparisons; however, culture is subject to variations in sensitivity related to interlaboratory technique. This variability is one reason a test system like the Hybrid Capture II (HC-II) is attractive, as it offers sensitive and reproducible DNA detection.

It is generally accepted that amplified-nucleic acid tests are equivalent in sensitivity to or more sensitive than traditional culture. We have shown that HC-II is more sensitive than either rapid or traditional culture for cytomegalovirus (1-3) and Chlamydia trachomatis (1-1). Thus, it is not surprising that this study showed HC-II to be at least equivalent in sensitivity to culture.

The reference for our HSV culture was a study by Gleaves et al. (1-2), which compared a shell vial HSV antigen detection method with traditional cell culture for HSV. It was our intention that the traditional culture method described by Gleaves et al. be taken as a general reference for HSV culture. For our study, cultures were grown for 2 to 3 days and were then centrifuged; this was followed by an enzyme-linked immunosorbent assay to detect HSV. We regret any confusion that our incomplete description may have caused.

Dr. Michalski identifies two apparent contradictions in our paper. The first is regarding the description of one patient as having generalized symptoms suggestive of herpes but no lesions; however, the study population was described as patients with lesions. In cases where herpes was suspected but no lesions were present, a swab of the cervix was collected. There were only a few patients meeting these criteria. In the case mentioned, HC-II detected HSV from a cervical swab whereas culture did not.

The second apparent contradiction relates to a statement in the introduction that culture detects most cases of HSV in 2 to 3 days but that cultures are routinely held for up to 7 days in order to detect low titers or asymptomatic infection. In our study, we did not perform culture for 7 days, as noted in Materials and Methods. However, the general comment that culture can take between 3 and 7 days is not inaccurate.

Lastly, we appreciate Dr. Michalski’s desire for assessing the true performance of the HC-II test in comparison with culture. We intend to subject the HC-II HSV test to more rigorous clinical evaluations in the future.

REFERENCES

  • 1-1.Cullen A P, Arthur P A, He L, Long C D, Shook D, Hook III E W, Smith K, Lorincz A T. Evaluation of the Digene Hybrid Capture® II CT/GC test for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in clinical specimens. Presented at the International Congress of Sexually Transmitted Diseases, Seville, Spain, 21 October 1997. 1997. [Google Scholar]
  • 1-2.Gleaves C A, Wilson D J, Wold A D, Smith T F. Detection and serotyping of herpes simplex virus in MRC-5 cells by use of centrifugation and monoclonal antibodies 16 h postinoculation. J Clin Microbiol. 1985;21:29–32. doi: 10.1128/jcm.21.1.29-32.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 1-3.Veal N, Payan C, Fray D, Sarol L, Blanchet O, Kouyoumdjian S, Lunel F. Novel DNA assay for cytomegalovirus detection: comparison with conventional culture and pp65 antigenemia assay. J Clin Microbiol. 1996;34:3097–31. doi: 10.1128/jcm.34.12.3097-3100.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]

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