Detection of herpesvirus genomes by polymerase chain reaction in cerebrospinal fluid and clinical findings

Abstract

Background: The viruses of the Herpesviridae family, in particular herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), cytomegalovirus (CMV), Epstein–Barr virus (EBV), varicella zoster virus (VZV), and human herpesvirus 6 (HHV-6), are responsible for numerous infections of the central nervous system (CNS). These infections manifest as diverse clinical signs, many of which are not specific. The diagnosis of these infections is necessary to make it possible to adapt treatment appropriately, as treatment is specific for the particular virus concerned. Objectives: To apply a polymerase chain reaction (PCR) technique for the diagnosis in a single reaction of the six herpesviruses most frequently detected in the cerebrospinal fluid (CSF) and to analyse clinical events in patients presenting positive results in PCR for herpesviruses. Study design: We studied 141 patients, from whom 180 CSF samples were collected. The clinical files of the patients were consulted retrospectively, and a list of clinical signs was recorded. After testing by targeted PCR, at the clinician's demand, we tested these samples by herpes consensus PCR, which detects six herpesviruses (HSV-1, HSV-2, CMV, EBV, VZV, HHV-6), in a single PCR. Results: Targeted PCR tests identified 25 CSF samples (13.9%), corresponding to 18 patients (12%), as positive. The herpes consensus PCR test detected 49 samples (27.2%) as positive, resulting in the identification of 54 individual viruses (four samples displayed co-infection) from 39 patients (27%). 130 CSF samples, from 101 patients, tested negative by both techniques. 23 HIV-positive patients (30.6%), three HIV-negative immunocompromised patients (27%), and 14 immunocompetent patients (25%) were CSF PCR-positive. In HIV-positive patients, CMV was the virus most frequently identified (13%), followed by EBV (10.6%), VZV (5.3%) and finally HSV-1 and HSV-2 (both 1.3%). We did not detect HHV-6 in any of these samples. We detected only HSV-2, EBV and VZV in the 11 HIV-negative immunocompromised patients. CSF samples of immunocompetent patients contained mostly VZV (9%) and HSV-1 (7.3%). Conclusions: The herpes consensus PCR for a given virus was more sensitive than the standard, targeted PCR used in our laboratory. The clinical signs presented by patients infected with HSV-1, HSV-2 and CMV were similar to those reported in previous studies. For VZV, we report the possibility of mild, transient cerebral viral reactivation. Our data on the detection of EBV by PCR suggest that the PCR test is of predictive value for cerebral lymphoma in immunocompromised patients. The possible role of HHV-6 in a subacute neurological disorder merits further investigation.

Introduction

Attacks on the central nervous system (CNS) by viruses of the Herpesviridae family, resulting in illnesses of the meningoencephalitis or meningitis type, are well documented. It is widely accepted that the clinical signs of these infections are not specific. Cerebral biopsy has been abandoned, and polymerase chain reaction (PCR) diagnosis from the cerebrospinal fluid (CSF) is now the reference method (Cinque et al., 1995, Cinque et al., 1998). The diagnosis of these infections is necessary for appropriate treatment, as treatment is specific for the virus concerned.

We have developed a PCR technique (Herpes consensus) for the diagnosis of viral infections of CNS and have demonstrated that, with this technique, the six most frequently encountered viruses—herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), cytomegalovirus (CMV), Epstein–Barr virus (EBV), varicella zoster virus (VZV), and human herpesvirus 6 (HHV-6)—can be detected in a single PCR (Minjolle et al., 1999). We then investigated the correlation between the results obtained with this technique and clinical data.