Characteristic features of human catalytic light chain, 22F6, showing the suppression of influenza virus infection by the different way

We found unique human catalytic light chains in which #4 clone showed a substantial effect on the suppression of infectivity of influenza virus A type (H1N1). Interestingly, 22F6 clone also showed a unique characteristic to prevent from the infection of influenza virus by the quite different way. Generally, in vitro assay, the virus and the antibody was first mixed and then the solution was incubated for one hour with MDCK cells in medium. Then, the plaques were counted for estimating the infection efficacy. In this study, we employed a new method in which only antibody was incubated with MDCK cells for one hour. After that, the medium solution containing the antibody was discarded and the well was washed out with the medium. Then the influenza virus dissolved in the medium without an antibody was put into the wells, followed by counting the number of plaques. C179 monoclonal antibody has been used in world widely as a famous neutralizing mAb against influenza virus H1N1 and H2N2 types. For the general in vitro assay, the mAb could completely suppress the infection of the virus against MDCK cells as expected but not in our new method. #4 clone showed the similar result. Surprisingly, 22F6 clone could lower the infectivity of the virus in our method. Namely, the functional mechanism of 22F6 clone is quite different from the neutralizing activity of C179 mAb and the catalytic activity of #4 clone.