Effect of pH and NaCl on Vero cell VRP titer

aPhosphate: 20 mM sodium phosphate buffer + 5.5% sucrose at designated pH used to titrate VRP packaged with indicated VEE GP coat.bTris: 20 mM trishydroxymethylaminomethane + 5.5% sucrose at designated pH used to titrate VRP packaged with indicated VEE GP coat.cInfectious unit (IU) titer determined on Vero cells.dGenome equivalent (GE) titer determined by quantitative reverse transcription PCR.