2.8 Quantification of lentiviral vector physical titre
The LV physical titre was measured using the Simple Plex HIV-1 Gag p24
ELISA kit (Protein Simple, San Jose, California) following
manufacturer’s instructions. The vector samples were diluted according
to the estimated p24 concentration to ensure they were in the linear
range of the assay. The first dilution was performed with 0.5% Triton X
Lysis buffer (Sigma-Aldrich, St. Louis, Missouri, United States). To
ensure lysis, the sample preparations were incubated for 1 hour at 37°C
in a 5% (v/v) CO2 humidified incubator. A second
dilution was then performed with SD30 dilution buffer (Protein Simple,
San Jose, California) prior to loading the samples on the cartridge.
Samples was analysed in triplicate and read using the Ella microfluidic
device (Protein Simple, San Jose, California). The p24 concentration was
calculated relative to the factory-calibrated standard curve supplied
with the kit. The LV specific infectivity was calculated as the ratio
between infectious titer and physical titre.