Deletion Mutants of the Attenuated Recombinant ASF Virus, BA71ΔCD2, Show Decreased Vaccine Efficacy

Figures

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  Figure 1. Schematic representation of the recombinant parental virus BA71∆CD2f (A) and the EP153R and DP96R gene regions deleted by homologous recombination in recombinant viruses BA71∆CD2EP153R and BA71∆CD2DP96R (B). Dotted lines indicate the homologous regions between the parental virus and the correspondent transfer plasmid.

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  Figure 2. Comparative infection kinetics of the three recombinant viruses, BA71∆CD2f, BA71∆CD2EP153R and BA71∆CD2DP96R, in PAMs. (A) Percentage of infected cells analyzed by flow cytometry and (B) ASFV DNA amount found in the supernatant of infected PAMs at different time points after infection.

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  Figure 3. Rectal temperature and ASFV DNA amount found in sera after immunization with BA71∆CD2f (A,B) BA71∆CD2EP153R (C,D) or BA71∆CD2DP96R (E,F) in each individual animal. Average and standard deviation values from control pigs immunized with PBS are shown. ASFV DNA amounts are plotted on a logarithmic scale as GEC per milliliter of serum, 103 GEC/mL being the limit of detection of the assay.

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  Figure 4. Survival rates after Georgia2007/1 challenge. Pigs were immunized with either BA71∆CD2f, BA71∆CD2DP96R or BA71∆CD2EP153R and then challenged 24 days later with a lethal dose of Georgia 2007/1.

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  Figure 5. ASF compatible clinical signs observed after challenge. Color palette indicates normal (green), mild (yellow) and high (>41 °C; orange) rectal temperature, while euthanized animals are indicated in red. Clinical scores are indicated with numbers; 1 being low-grade fever (<41 °C) as the only clinical observation.

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  Figure 6. Rectal temperatures measured and ASFV DNA amount found in sera of immunized and control pigs after Georgia2007/1 challenge. Data plotted correspond to individual animals showing rectal temperatures (A,C,E) and virus loads in serum (B,D,F). Upper panels show data corresponding to BA71∆CD2f immunized pigs, middle panels to BA71∆CD2EP153R and lower panels to BA71∆CD2DP96R. Average and standard deviation values obtained from control animals are also depicted. Virus titers are plotted on a logarithmic scale as GEC per milliliter of serum, 103 GEC/mL serum being the limit of detection of the assay. * Day of the death of the animals. Last data recorded for pig 75 correspond to day 6pc (death date).

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  Figure 7. ASFV-specific antibodies detected in serum of pigs immunized with BA71∆CD2f (A), BA71∆CD2EP153R (B) and BA71∆CD2DP96R (C), before and after Georgia2007/1 challenge. Individual ELISA optical density (OD) values are shown for each immunization group. Average and standard deviation OD values obtained from the control group are also shown in each figure panel.

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  Figure 8. IFNγ-secreting specific T cells found in peripheral blood mononuclear cells (PBMCs) in vitro. Any sample scoring ≥300 spots/500,000 PBMCs received a score of 300, which was considered the limit of our assay resolution.