Rapid in vitro micro-cytotoxicity tests for the detection and quantitation of neutralizing antibodies to both viruses and toxins.

A generally applicable method was developed for the rapid and quantitative detection of both toxin- and virus neutralizing antibodies. The method was optimized for three different biological agents, i.e., Shigella toxin, influenza viruses (A/Beying, A/Taiwan and B/Yamagata) and Chikungunya virus. The in vitro micro-cytotoxicity tests developed for the detection and quantitation of neutralizing antibodies are based on the inhibition of the virus- or toxin-induced cytotoxic effect by antibodies. As a result of the cytotoxicity, infected cells are no longer attached to the solid phase and can be easily removed. Thereafter, the proteins of the remaining living cells are stained. After removing the excess dye, the remaining dye is dissolved and the absorbance values are measured. The neutralization titers are determined from the absorbance values. Since the tests are performed in wells of microtiter plates, the in vitro micro-cytotoxicity tests are less laborious and consume less reagent in comparison with classical neutralization tests.