Table 2.

Proportion of strains with recombinant genomes among VAPP case isolates in Romania, 1980 to 1990

Polio-vaccine serotypeaRFLP assaybCategory of recombinant (genotype)cNo. of strains (% of recombinants)Total no. of strains% Recombinants in each serotype
1 + P23D1 + 3D-3′
S1S1S1∼∼S1∼∼5 (0)50
S2S2∼∼S2∼∼9 (0)9
S2S3S2/S39 (23)
S2S2S1S2/S124 (62)
S2/S3S1S2/S3/S11 (2)3981
S2WS2/W5 (13)
S3S3∼∼S3∼∼7 (0)7
S3S3S1S3/S19 (32)2880
S3S2S3/S219 (68)
TotalSn/Sn + S2/W67 (76)88d 76
  • a S1, S2, S3, Sabin PV vaccine-derived type 1, 2, and 3, respectively.

  • b Characteristics of the genomes according to RFLP assays 1 and 3D1. In some cases, RFLP P2 and 3D-3′ assays were also used (see Materials and Methods). S2/S3, intertypic recombinant genome in which the 5′ part is derived from S2 and the 3′ part is derived from S3; W, wild (non-vaccine).

  • c Sn, Sabin strain of any serotype; ∼∼S(n)∼∼, nonrecombinant Sabin strain; S2/W, V/W recombinants.

  • d The analysis is based only on the 88 strains isolated in Romania during an 11-year period (1980 to 1990).