Trans-Encapsidation of Foot-and-Mouth Disease Virus Genomes Facilitates Escape from Neutralizing Antibodies

Figures

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  Figure 1. Establishment of a serotype-specific PCR assay. (a) Plasmids containing infectious DNA copies of the FMDV-O, FMDV-A, FMDV-SAT1, and FMDV-SAT2 genomes were mixed in equimolar amounts in the indicated combinations. Mixtures of plasmids were subjected to PCR analysis using primer sets specific for FMDV-O (b), FMDV-A (c), FMDV-SAT1 (d), or FMDV-SAT2 (e).

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  Figure 2. Trans-encapsidation between O and A serotype viruses enables escape from neutralizing antibodies. (a) Schematic diagram of the experimental workflow. ZZ-R 127 cells were either co-infected with FMDV-O and FMDV-A at an MOI of 1 per virus or infected with each virus separately for 16 h. Supernatants were collected, and those from the two separate infections were combined in a single tube. Aliquots of these samples were then incubated in the presence of anti-O, anti-A, or anti-O + anti-A antisera for 1 h prior to infection (MOI 0.05) of a fresh monolayer of ZZ-R 127 cells. After 16 h, RNA was prepared from the cells and RT-PCR was performed using primers specific for FMDV-O or FMDV-A. (b) Viruses obtained from the separate infections and the co-infection were titered by plaque assay. (c) Viruses obtained from the separate infections and the co-infection were subjected to RT-PCR analysis using FMDV-O or FMDV-A specific primer sets to confirm the presence of both genomes prior to incubation with antisera. (d) RT-PCR analysis of RNA purified from cells exposed to viruses obtained from separate combined infections incubated with either anti-O, anti-A, or anti-O plus anti-A antisera…

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  Figure 3. Trans-encapsidation between SAT1 and SAT2 serotype viruses enables escape from neutralizing antibodies. ZZ-R 127 cells were either co-infected with FMDV-SAT1 and FMDV-SAT2 or infected with each virus separately and processed as described in Figure 2a. (a) Viruses obtained from the separate infections and the co-infection were titered by plaque assay. (b) Viruses obtained from the separate infections and combined were subjected to RT-PCR analysis along with the products of the co-infection using FMDV-SAT1 (1) or FMDV-SAT2 (2) specific primer sets to confirm the presence of both genomes prior to incubation with antisera. (c) RT-PCR analysis of RNA purified from cells exposed to viruses obtained from the separate combined infections and incubated with anti-SAT1, anti-SAT2, or anti-SAT1 + anti-SAT2 antisera using SAT1 or SAT2 specific primers. (d) RT-PCR analysis of RNA purified from cells exposed to viruses from the co-infection incubated with anti-SAT1, anti-SAT2, or anti-SAT1 + anti-SAT2 antisera using SAT1 or SAT2 specific primers. (e) RT-PCR analysis of RNA from cells exposed to viruses incubated without antisera.