CHARACTERIZATION OF LANGAT VIRUS ANTIGENIC DETERMINANTS DEFINED BY MONOCLONAL-ANTIBODIES TO E,NS1 AND PREM AND IDENTIFICATION OF A PROTECTIVE, NONNEUTRALIZING PREM-SPECIFIC MONOCLONAL-ANTIBODY

Hybridomas secreting monoclonal antibodies (MAb) to the tick-borne enc ephalitis (TEE) group virus, Langat virus (LGTV), were prepared. Of mo re than 200 MAb screened, 19 antibodies, which cross-reacted with the etiologic agent of Central European encephalitis, were selected for fu rther characterization. Of these MAb, 14 were specific for LGTV E glyc oprotein, two for the NS1 protein, and three for preM protein. The two NS1-specific MAb and two of the E-specific MAb reacted with all six o f the other TEE group viruses tested while the remainder of the E-spec ific MAb failed to recognize at least one of the viruses. None of the MAb neutralized LGTV in cell culture assays, but one of the preM-speci fic MAb protected weanling mice against a virulent LGTV challenge. Alt hough protective antibodies to E and NS1 proteins of TEE viruses were reported, our data provided the first evidence for protection by a non -neutralizing antibody to the preM or M protein of any of the tick-bor ne flaviviruses.