SELPLG and infection: To determine if we could generate viruses through HEK293T transfection that were more similar to the viruses produced through infection, we generated additional virus stocks that were produced through co-transfection with 10- and 100-fold less PSGL-1 pDNA than what was used for the PSGL-1Low virus (0.25 and 0.025 ng; Additional file 1: Figure S2).