A comparative study of serological techniques for detection of West Nile virus antibodies

This study was conducted to compare different serological techniques namely enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition (HI), indirect immunofluorescence (IFT) and plaque reduction neutralization (PRNT), for detection of West Nile virus (WNV) antibodies in sera collected from inhabitants of a flooded village (Begiram, Minufiya Governorate). ELISA showed 45% while HI and IFT indicated 37.6 and 26.4% positive sera among the tested 178 sera taken from the flooded village, respectively. The results obtained by ELISA, HI and IFT of only 55 randomly chosen sera were compared with their PRNT results. ELISA was found to be more sensitive (83.8%) while IFT and HI were more specific (88.9% and 83.3%, respectively). The positive predictive values for the 3 tests were more than 80% while the negative predictive values were different for these tests: 66.7% for ELISA, 44.1% and 37% for HI and IFT, respectively. From this study it is concluded that for screening of population in an endemic area, two serological tests in combination can be used starting with ELISA (the more sensitive) followed by HI and/or IFT (the more specific) to exclude the false positive results.