Background: Diagnosis of Herpes simplex virus (HSV) infections is achieved by detecting the antigen and isolating the virus from the specimen, which requires 7-28 days. With the recently introduced molecular biological technique of polymerase chain reaction (PCR), the diagnosis of HSV infections has been made more rapid and specific.
Objective: We evaluated PCR in comparison with the standard laboratory methods on different types of clinical specimens referred to in our laboratory.
Study design: A total of 54 specimens, from 54 patients, were investigated. Antigen detection on direct smears was carried out using fluorescent antibody test (FAT) and virus isolation was performed using conventional tube culture method. PCR was carried out with the DNA extracted from various specimens using primers, which coded for the DNA polymerase gene giving a 179 base pair (bp) product.
Results: The primers were specific for HSV-1 and HSV-2, and the sensitivity of the primers was found to be 0.5 and 0.2 fg in the detection of HSV-1 and HSV-2 DNA, respectively. Of the 50 specimens (excluding 4 archival formalin fixed tissue specimens, which were not subjected to virological methods of detection) HSV was detected by virological methods and PCR in nine specimens, and by PCR alone in 15 additional specimens, thus increasing the analytical sensitivity significantly by 30% (McNemar test: P = 0.0001). The positivity of PCR in all nine virologically positive specimens and the 4 archival specimens obtained from proven lesions of HSV infections further confirmed the specificity of the PCR.
Conclusion: PCR, in our study, was found to be a rapid, specific and highly sensitive method for the detection of HSV in clinical specimens.