Comparison of dengue virus plaque reduction neutralization by macro and "semi-micro' methods in LLC-MK2 cells

A simplified "semi-micro' plaque reduction neutralization test (PRNT) for dengue antibody in LLC-MK2 cells in disposable tissue culture plates is described. The assay compares favorably with the standard PRNT in glass prescription bottles, with relative sensitivity and specificity both 100% at a 1:40 screening dilution by 70% plaque reduction criteria. The assay is easy to perform, economical of time, expense, and storage space, and is suitable for study of sera available in small volumes, such as those obtained on filter paper or by the capillary method. The LLC-MK2 semi-micro PRNT is an acceptable alternative to the standard PRNT, particularly in laboratories that use these cells routinely for other tissue culture work and for flavivirus vaccine development.