Rapid Detection of Herpes Simplex Virus and Varicella-Zoster Virus Infections by Real-Time PCR

Abstract

The herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) and varicella-zoster virus (VZV) can cause life-threatening infections of the central nervous system and lead to severe infections in immunocompromised subjects and newborns. In these cases, rapid diagnosis is crucial. We developed three different real-time PCR assays based on TaqMan chemistry for the LightCycler instrument to detect HSV-1, HSV-2, and VZV. When the TaqMan assays were compared to our in-house nested PCR assays, the test systems had equal sensitivities of <10 plasmid copies per assay. When clinical samples were investigated by TaqMan PCR to detect HSV-1, HSV-2, and VZV DNA, 95, 100, and 96% of the samples determined to be positive by nested PCR, respectively, were positive by the real-time PCR assays. The specificities of all PCR assays were almost 100%. Furthermore, the TaqMan PCR assays could be performed within 2.5 h, whereas nested PCR results were available after 9 h. In addition to offering more rapid results, the TaqMan PCR assays appear to be less expensive than nested PCR assays due to less hands-on time. In summary, TaqMan PCR is an excellent alternative to conventional nested PCR assays for the rapid detection of HSV-1, HSV-2, and VZV in clinical samples.Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) cause a variety of clinical symptoms in the central nervous system (CNS). In immunocompromised patients, the virus leads to severe clinical outcomes, including mucocutaneous disease and pneumonia. At delivery, HSV can be transmitted to the newborn and, following this exposure, can cause severe disseminated infections and death.The varicella-zoster virus (VZV)-the causative agent of chicken pox and shingles-can also cause severe systemic infections of the CNS and the respiratory tract in immunocompetent individuals as well as in immunocompromised patients. The latter may also suffer from disseminated diseases of multiple organ systems.Rapid laboratory diagnosis is urgently needed to distinguish HSV from VZV infections when the CNS is involved, especially in cases with clinically confusing dermal manifestations. Furthermore, rapid diagnosis of HSV and VZV infections is crucial in neonates to prevent a lethal outcome of disease (8, 9). Today, effective therapy of HSV and VZV infections is possible with antiviral drugs such as acyclovir. However, therapy must be initiated very early after the onset of disease to decrease lethality and to minimize the number of patients sustaining persistent neurological damage (15). Thus, the ability to rapidly diagnose HSV and VZV infections is a key feature in the virology laboratory. Molecular diagnostic assays using PCR are the standard for detecting herpesvirus infections of the CNS (1, 2, 10). Modifications of the basic PCR technique have been used to increase the sensitivity of detection of the viruses, e.g., by using nested PCR assays. Although very sensitive, this technique has the disadvantage of being highly susceptible to contamination, potentially leading to false-positive results (...

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Cathelicidin deficiency predisposes to eczema herpeticum

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