Comparative study between chemiluminescence assay and two different sensitive polymerase chain reactions on the diagnosis of serial herpes simplex virus encephalitis

Objective-A prospective study was undertaken on the diagnosis of herpes sim plex encephalitis (HSVE) by comparing chemiluminescence assay (CL) and two different sensitive polymerase chain reactions (PCRs). Methods-The materials comprised 53 serial CSF samples from 31 patients with acute encephalitis with suspected HSVE. Each CSF was distributed to three independent laboratories to perform quantitative measurements by CL, the lo w sensitive (single) PCR, and high sensitive (nested) PCR. The CL provided a method of detecting HSV itself and the small fragment with HSV antigenici ty which was composed of viral component proteins. The serial CSFs were fou nd retrospectively to comprise 24 samples from 11 patients with HSVE due to HSV1 and 29 samples from 20 patients with non-HSVE. Results- the CL showed 50 to 48 000 pfu/ml in all samples of HSVE (except o ne) taken from the 3rd to the 25th day. The low sensitive PCR demonstrated 50 to 47 000 pfu/ml in only six samples of HSVE. The high sensitive PCR dis closed less than 100 to 120 000 copies/ml in 11 samples of HSVE. At the acu te stage from the Ist to 7th day, the sensitivities of CL and the high sens itive PCR were 100%, but that of the low sensitive PCR was 75%. The sensiti vity of CL was significantly higher than those of both PCRs after the acute stage on the 15th to 32nd day. The specificities and positive predictive v alues of the three methods were 100%. However, the negative predictive valu e of CL was significantly higher than that of the low sensitive PCR. Conclusions-The sensitivity of CL is equivalent to that of the high sensiti ve PCR during the acute stage and significantly higher than that of the hig h sensitive PCR after the acute stage. A clear difference in sensitivity ex ists between the different PCRs. A combination of the PCR, chemiluminescenc e assay, and serological antibody diagnosis is currently considered the mos t effective approach for the clinical diagnosis of HSVE.