TABLE 1

Frequency of particular gene combinations incorporated in progeny viruses resulting from 10-plasmid competitive transfection assays

Plasmids in competition between Udorn and PR8Incorporated genesaNo. of viruses identified (% within expt)bSum of viruses (avg % ± SD)c
Expt 1Expt 2Expt 3
HA and PB1PR8 HA PR8 PB134 (92)25 (71)21 (68)80 (77 ± 13)
PR8 HA Udorn PB11 (3)5 (14)4 (13)10 (10 ± 6)
Udorn HA PR8 PB12 (5)5 (14)5 (16)12 (12 ± 6)
Udorn HA Udorn PB10 (0)0 (0)1 (3)1 (1 ± 2)
NA and PB1PR8 NA PR8 PB128 (64)13 (30)22 (42)63 (45 ± 17)
PR8 NA Udorn PB14 (9)9 (20)6 (12)19 (14 ± 6)
Udorn NA PR8 PB14 (9)5 (11)5 (10)14 (10 ± 1)
Udorn NA Udorn PB18 (18)17 (39)19 (37)44 (31 ± 12)
  • a Competitive 10-plasmid transfections were established with plasmids expressing all eight PR8 gene segments plus two plasmids expressing either Udorn HA and Udorn PB1 gene segments (top part of the table) or Udorn NA and Udorn PB1 gene segments (bottom of the table). The origins of the HA and PB1 or the NA and PB1 gene segments in the progeny viruses were determined by gene-specific RT-PCR.

  • b The number of viruses with a particular gene combination is indicated, with the frequency of this gene combination in an individual experiment shown in parentheses.

  • c The total number of viruses with a given gene combination in the three experiments is indicated, with the average of the frequencies ± standard deviation in parentheses.