Figure 5.

Preventing 5′-UTR Exchange by Recombination with Co-circulating Enteroviruses

(A) Schematic of recombination assay (i). Sabin2 or nOPV2 strains were used to coinfect HEp2C cells together with poliovirus type 3 (PV3). After co-infection, type 2 poliovirus recombinants were selected using antibodies directed against poliovirus type 3 and two rounds of replication in L20B at 37°C that selects for high fitness, temperature-resistance variants. Co-infection in HEp2c was repeated five times to increase the chance of recombination. Type 2 strains tested (ii) were as follows: Sabin2; S2/S15 domV, which does not revert by single point mutations, but potentially can acquire a more thermostable domV by recombination with PV3; and S2/S15 domV/cre5, in which 2C cre has been relocated into the 5′-UTR.

(B) After five rounds of co-infection and L20B selection, virus populations were sequenced, and the proportion of reads corresponding to PV3 or Sabin2 variants was calculated across the genome. Recombination between PV3 and (i) Sabin2, (ii) S2/S15, and (iii) S2/S15/cre5.