Table 2.

Vectors packaged by PD223 cells use the same receptor as does MDEVa

LAPSN pseudotypecLAPSN titer (FFU/ml)b on:
dunni/N2dunni/N2+MDEVNIH 3T3PD223
PA3171 × 106 1 × 106 2 × 105 2 × 105
PD2236 × 104 <2.52 × 103 20
MDEVNDd ND2 × 103  5
  • a Data are from two separate experiments, each of which was repeated with nearly identical results. The first experiment included the dunni and dunni/N2+MDEV cells and the second included NIH 3T3 and PD223 cells as targets for infection. All cells were cultured in Dulbecco’s modified Eagle’s medium with 10% FBS except for GL8c16 cells, which were used to produce the LAPSN (MDEV) virus and which were cultured in McCoy’s medium with 15% FBS. Titration was performed as described previously (11) on D17 cells.

  • b The titers are the means of duplicate assays in which each value varied by no more than 17% of the mean, except for the values 20 and 5 which represent only a few foci.

  • c The LAPSN vector with a PA317 (amphotropic) pseudotype was made by using PA317 cells (6) containing the LAPSN vector. The LAPSN vector with a PD223 pseudotype was made by using PD223/LAPSN cells and had a titer of 3 × 105AP+ FFU/ml on D17 cells. MDEV pseudotype LAPSN vector was harvested from the GL8c16 clone of G355/LAPSN+MDEV cells. This particular virus stock had a lower titer than usual and thus gave a titer on NIH 3T3 cells equivalent to that of LAPSN(PD223) virus, although the GL8c16 virus titer is usually about 10-fold higher.

  • d ND, not determined.