Evaluation of Immunoglobulin M Antibody capture Elisa Kits for Diagnosis of Japanese Encephalitis

Abstract

Japanese encephalitis (JE) is the most common cause of viral encephalitis. It is caused by the JE virus (JEV), belonging to the family flaviviridae. It is endemic in many partsof Asia, including Nepal.This study conducted at the National Public HealthLaboratory, in 2010 is concerned with the evaluation of two commercially availableMAC ELISA assays; the Panbio JE-Dengue IgM Combo ELISA and the XCytonELISA developed and available for the diagnosis of the JE against the well establishedin house AFRIMS (Armed Forces Research Institute of Medical Sciences) ELISA. Thesensivity,specificity,predictive value positive, predictive value negative and efficiencyof the kits were evaluated along with percentage cross reactivity of the kits to denguepositive serum samples. Two hundred fifty one serums and three hundred twenty nine CSF samples were testedusing thePanbioIgM Combo ELISA and XCyton ELISA respectively. Besides a panelof samples containing 30 positive and 30 negative CSF sample was tested using thePanbioELISA and a panel of samples containing 30 positive and 33negative sampleswas tested using the XCyton ELISAThe Panbio kit had sensitivity ranging from 59-76% and the specificity ranging from 84-90 %. The XCyton kit had sensitivity rangingfrom 83-85% and specificity ranging from 95-100%. The efficiency of the XCyton kitwas greater than the Panbio kit for any type of sample tested. The percentages crossreactivity against the denguepositive serumsamples using both the kits was 4% and32% respectively. The p values obtained were statistically significant at 5% level ofsignificance for chi-square test. The overall sensitivity and specificity of the XCyton kitwas higher than that of thePanbiokit. ThePanbiokit includes antigen for both JE andDengue and has additional advantage where both JE and dengue co-circulate. Key words: JE, MAC ELISA, sensitivity, specificity, PVP, PVN