Isolation and Pathogenicity of an Emerging Highly Virulent CSFV 2.1c Strain in South China

Figures

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  Figure 1. Clinical symptoms of a pig farm in Guangdong.

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  Figure 2. (A) IFA revealing the reactivity of a monoclonal antibody against the CSFV E2 protein from GD-2024 at 24, 48, and 72 h post-infection. Scale bars indicate 100 µm. (B) GD-2024 viral titer detection at 12, 24, 36, 48, 60, 72, 84, and 96 hpi. (C) Growth kinetics of GD-2024.

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  Figure 3. Phylogenetic tree based on the complete E2 sequences of 33 CSFV strains, constructed using the NJ method in MEGA 11.0 software.

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  Figure 4. 5′UTR sequence comparison of GD-2024 isolate and nine reference isolates. Some mutations or deletion regions of these isolates are indicated by red boxes and are described in detail in the text.

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  Figure 5. 3′UTR sequence comparison of GD-2024 isolate and eight reference isolates. Some mutations or deletion regions of these isolates are indicated by red boxes (□) and are described in detail in the text.

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  Figure 6. Amino acid sequence comparison of the E2 gene between the GD-2024 isolate and nine reference isolates. Some mutations or deletion regions of these isolates are indicated by red boxes (□) and are described in detail in the text.

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  Figure 7. (A) Clinical scores of piglets after challenge throughout the experiment. (B) Body temperature changes in piglets in each group after challenge. (C–E) Viral load detection in the blood, oral swabs, and fecal swabs. (F) Changes in body weight of piglets in each group after challenge. (G) Survival rate of pigs in each group during the challenge study. Each bar represents the mean ± standard deviation in each group. (H) Quantification of CSFV genomic RNA in the CSFV GD-2024 strain-challenged pigs. Data are presented as mean ± standard error (n = 5 per group). Two-way ANOVA was used for analysis. Significant differences are marked with asterisks: ** p < 0.01 compared with the negative control group.

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  Figure 8. Representative gross lesions in the pigs inoculated with the CSFV GD-2024 strain. The ocular lesions observed in the GD-2024 challenge group exhibited solid lesions in the lungs, infarcts in the spleen, and hemorrhages in the lymph nodes. In contrast, the control group did not exhibit any lesions. The white arrow indicates the location of the tissue lesion.

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  Figure 9. Histopathologic lesion results in organs of pigs infected with the CSFV GD-2024 strain. The GD-2024 challenge group exhibited interstitial pneumonia, splenic erythrocyte leaching, and lymphocyte necrosis, whereas the control group did not display any lesions. The black arrow indicates the location of the lesion. Scale bars indicate 250 µm.