Monoclonal antibodies to flavivirus antigens induced by a vaccinal strain of yellow fever

: Monoclonal antibodies (MABs) YEL-2 induced by the vaccine FNS Dakar yellow fever (YF) virus were characterized for their capacity to enter into serological reactions and to react with heterologous flaviviruses. YEL-2 MABs belong to the IgG2a class of immunoglobulins, possess the antihemagglutination properties, are active in indirect IF test but do not activate complement and have no neutralizing properties. The inability to enter into CFT in the presence of antihemagglutinating properties suggests that YEL-2 MABs are directed for the structural E glycoprotein. YEL-2 MABs reacted similarly with the vaccine 17D strain and the FNS Dakar strain by which they had been induced. In addition to YF virus, YEL-2 MABs reacted with Tyuleniy, Rosio, Ilheus, Uganda S, Karshi, and Sokuluk viruses, the reaction with Tyuleniy virus reaching the same titer as with the homologous virus but was of one-way nature. No reaction of YEL-2 MABs was observed with the viruses of the tick-borne encephalitis complex, Japanese encephalitis, West Nile, Dengue 2 and 4 viruses. These results specify the antigenic classification of flaviviruses.