Serial changes of intrathecal viral loads evaluated by chemiluminescence assay and nested PCR with aciclovir treatment in herpes simplex virus encephalitis

Objective We assessed the potential for estimating the effects of antiviral therapy on the clearance of intrathecal herpes simplex virus (HSV) antigens as evaluated by the chemiluminescence assay (CL) and on that of intrathecal HSV-DNA as evaluated by the nested polymerase chain reaction (PCR) in serial patients with herpes simplex virus encephalitis (HSVE). Methods The materials comprised serial cerebrospinal fluid (CSF) samples from 18 patients with HSVE. All patients were diagnosed as having HSVE retrospectively based on the detection of intrathecal HSV antigens by the CL, that of HSV-DNA by the nested PCR, and also serological confirmation of intrathecal antibody production. The relationships between the days of aciclovir therapy and serial HSV viral loads as evaluated by the CL and nested PCR in the serial CSFs were assessed. Results The serial intrathecal viral loads evaluated by the CL and nested PCR declined after the commencement of aciclovir administration in all patients. The serial alterations of the intrathecal viral load evaluated by the CL in each patient were similar to those of the intrathecal viral load evaluated by the nested PCR. The initial and maximum viral loads evaluated by the CL and nested PCR showed a wide distribution in the CSF samples taken from the patients with poor and good outcomes. Differences in the means of the viral loads in the CSF samples taken from the patients between a poor outcome and a good outcome were not evident. A transient increase of viral load as evaluated by these two methods was noted in the same 4 patients. The viral loads in these 4 patients also declined in the subsequent CSF samples. The outcome of these 4 patients was good in one patient and poor in the others. Conclusion Evaluation of intrathecal viral antigens by the CL has a potential for estimating the effects of antiviral therapy, as does evaluation of the intrathecal HSV-DNA by the nested PCR. The intrathecal viral loads evaluated by CL and nested PCR were not a predictor of outcome in HSVE.