When comparing neutralization susceptibility with virus density for JFH1-based viruses with Core-NS2 of genotypes 1a to 6a, only 2a virus displayed increased neutralization at higher densities. JFH1-based viruses with Core-NS2 of genotypes 1 to 6 (virus with genotypes 1a, 2a, 3a, 4a, 5a, and 6a) from centrifugation fractions with different densities were neutralized with four dilutions of H06 serum as described in Materials and Methods. Neutralization data are shown as the means of three replicates with the SEM related to mean of 6 replicates of virus only.