Characterization of HIV/HA pseudoviral particle release mediated by NA
. A, relative infectivity of the pseudovirions determined by luciferase activity (relative light units, RLUs) from infected 293T and A549 target cells. Pseudovirions generated in the absence of NA represent background luciferase levels. As a positive control, HA and HIV plasmids were first introduced into 293T producer cells and the transfected cells were then treated with a commercial neuraminidase twice during pseudovirion production (+bNA). Experiments were performed in triplicates and repeated several times. Error bars indicate standard deviations. B, hemagglutination activity from titrated NAA and NAH pseudovirion populations mixed with chicken red blood cells. PBS serves as a negative control. C, neuraminidase activity of NAA and NAH proteins measured by the release of fluorogenic substrate 4-MUNANA (arbitrary units). Experiments were performed in triplicates and repeated several times, and error bars indicate standard deviations.