The diagnostic significance of the polymerase chain reaction and isoelectric focusing in herpes simplex virus encephalitis

In this study, serum and CSF samples of 55 neurological patients have been examined to confirm the diagnosis of herpes simplex virus encephalitis (HSVE). Different methods were applied, including serological titer evaluations, determination of intrathecally‐produced HSV‐specific antibodies by isoelectric focusing with affinity immunoblotting (IEF), as well as HSV‐specific ELISA and HSV‐specific polymerase chain reaction (PCR). The results of IEF and PCR have been compared and contrasted to develop general directions for virological diagnosis of HSVE. Of 14 patients suffering from clinically diagnosed HSVE, HSVE was confirmed in 12 cases by the demonstration of PCR or IEF positivity. A HSV‐specific CNS infection could be excluded in 2 of these 14 patients. In 17 patients suffering from non‐HSVE, PCR and IEF results were negative. Twenty‐four patients, suffering from other neurological diseases, serving as a control group, were PCR‐ and HSV‐IEF‐negative. The study indicated that there are two possibilities for unequivocal demonstration of HSV‐specific CNS involvement: first, performance of PCR especially in the acute phase of disease and in sus‐picious relapses, and second, performance of HSV‐specific IEF for determination of intrathecally synthesized HSV‐specific antibodies. It is suggested that these two methods should be introduced in routine diagnosis of viral encephalitis.