Establishment of an analyzing method for a Japanese encephalitis virus neutralization test in Vero cells.

We established a 50% plaque reduction analyzing method of neutralizing antibody for human serum to Japanese encephalitis virus (JEV) in Vero cells, called the '3 points least-squares regression method' (3LSRM). Our method shows a high correlation with the chick embryo cell method (the current standard method for human serum), using the chart method established by the National Institute of Infectious Diseases of Japan, which is an equation made with retrospective data obtained with the 50% plaque reduction method as a standard measurement method for neutralizing antibody titers to JEV. Our new method is much simpler and more reliable than the current method in that it uses an established cell line, Vero cells, and its results are computed by the 3LSRM.