Pramod N P, Thyagarajan S P, Mohan K V, Anandakannan K
Department of Microbiology, University of Madras, Taramani, Chennai, India.
Can J Ophthalmol. 2000 Apr;35(3):134-40. doi: 10.1016/s0008-4182(00)80006-x.
Herpetic ocular disease is a major cause of blindness. Rapid and accurate diagnosis is essential for prompt, proper treatment. We evaluated the usefulness of detection of herpes simplex virus (HSV) DNA by polymerase chain reaction (PCR) in the laboratory diagnosis of herpetic keratitis.
A retrospective study was conducted involving 234 patients who attended the cornea clinic at the Regional Ophthalmic Institute, Chennai, India, between March 1995 and September 1997. Inclusion in the study was based on clinical diagnosis of herpetic keratitis. Oligonucleotide primers directed against the HSV-I thymidine kinase gene were used, yielding a 110 base pair amplicon. The utility of PCR analysis was assessed against other diagnostic markers: HSV isolation on cell culture, HSV antigen detection by indirect immunofluorescence, detection of anti-HSV IgG by enzyme-linked immunosorbent assay (ELISA) and detection of HSV-specific tear secretory IgA (sIgA) by ELISA. These tests showed overall sensitivity values of 22.4%, 39.8%, 30.4% and 20.3% respectively.
In epithelial keratitis all 35 specimens from which virus was cultured were positive by PCR. PCR gave a positive result in 23 (82.1%) of the 28 specimens in which HSV antigen was detected and in 4 (57.1%) of the 7 specimens that showed HSV-specific IgG. In addition, PCR detected HSV DNA in 5 of the 30 cases in which these three tests gave a negative result. PCR of two pooled tear samples (collected 1 week apart from the same patient) from 40 patients with stromal keratitis gave a positive result in 12 cases (30%). In stromal keratitis the sensitivity of PCR in detecting HSV DNA in tear samples was 85.7% with culture, indirect immunofluorescence and detection of anti-HSV IgG as the gold standard, and 80% with detection of sIgA as the gold standard.
The results confirm the good correlation with the clinical picture that can be obtained with PCR analysis. They also highlight the diagnostic utility of PCR in detecting HSV DNA in tear samples. This is particularly important in herpetic stromal keratitis, in which collection of corneal scrapings is not advised and, hence, conventional techniques such as virus isolation and antigen detection become difficult.
疱疹性眼病是导致失明的主要原因。快速准确的诊断对于及时、恰当的治疗至关重要。我们评估了聚合酶链反应（PCR）检测单纯疱疹病毒（HSV）DNA在疱疹性角膜炎实验室诊断中的实用性。
进行了一项回顾性研究，纳入了1995年3月至1997年9月期间在印度钦奈地区眼科研究所角膜门诊就诊的234例患者。纳入研究基于疱疹性角膜炎的临床诊断。使用针对HSV-1胸苷激酶基因的寡核苷酸引物，产生一个110碱基对的扩增子。将PCR分析的实用性与其他诊断标志物进行评估：细胞培养分离HSV、间接免疫荧光检测HSV抗原、酶联免疫吸附测定（ELISA）检测抗HSV IgG以及ELISA检测HSV特异性泪液分泌型IgA（sIgA）。这些检测的总体敏感性值分别为22.4%、39.8%、30.4%和20.3%。
在上皮性角膜炎中，所有35份培养出病毒的标本经PCR检测均为阳性。在28份检测到HSV抗原的标本中，PCR在23份（82.1%）中呈阳性结果；在7份显示HSV特异性IgG的标本中，PCR在4份（57.1%）中呈阳性结果。此外，在这三项检测结果均为阴性的30例病例中，PCR在5例中检测到HSV DNA。对40例基质性角膜炎患者的两份泪液混合样本（相隔1周从同一患者采集）进行PCR检测，12例（30%）呈阳性结果。在基质性角膜炎中，以培养、间接免疫荧光和检测抗HSV IgG为金标准时，PCR检测泪液样本中HSV DNA的敏感性为85.7%；以检测sIgA为金标准时，敏感性为80%。
结果证实了PCR分析与临床情况具有良好的相关性。它们还突出了PCR在检测泪液样本中HSV DNA的诊断实用性。这在疱疹性基质性角膜炎中尤为重要，因为不建议采集角膜刮片，因此病毒分离和抗原检测等传统技术变得困难。
