Neutralization profile of anti-CHIKV envelope monoclonal antibodies (mAbs).

Six anti-CHIKV E1 mAbs [clones 3D11 (red), 11E11 (brown), 13H11 (orange), 15B2 (blue), 19B8 (gray), and RC5-3 (green)] were tested for their neutralization activity. CK47, which was previously shown to exhibit neutralizing activity in this system, was used as a positive control (black), while 24B3, an anti-capsid protein antibody, was used as a negative control (pink). Four-fold serial dilutions (ranging from 1:200 to 1:51200) of each mAb were incubated with Asian-genotype CHIKV-pseudotyped lentiviral particles prior to infection of U251 cells. Luciferase activity (expressed as relative luciferase units, RLUs), reflecting infectivity of pseudotyped lentiviruses, was measured at 72 hours post-infection. The graph displays the mean relative infectivity of pseudotyped lentiviruses following pre-incubation with various dilutions of mAbs. Error bars indicate standard error of the mean (SEM) from three independent experiments, each performed in duplicate.