Full-Length Genomic RNA of Foot-and-Mouth Disease Virus Is Infectious for Cattle by Injection

Figures

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  Figure 1. Inoculation of cell cultures with heat-treated FMDV. For each treatment temperature, the percentage of replicate wells that developed CPE 72 h after inoculation with the previously heated virus suspension is shown: (a) heat-inactivated virus preparation on BHK-21 cells, with and without RNase treatment after heating; (b) heat-inactivated virus preparation on LFBK-αVβ6 cells.

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  Figure 2. Clinical findings in the first animal experiment after injection of naked FMDV RNA into the tongue: (a) rectal body temperatures; (b) clinical scores. See Tables S1 and S2 in the Supplemental Material for the raw data summarized in this figure.

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  Figure 3. FMDV RT-q-PCR results after injection of naked FMDV RNA in the first animal trial: (a) saliva samples; (b) serum samples. See Table S3 in the Supplemental Material for the raw data summarized in this figure.

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  Figure 4. Postmortem findings after injection of naked FMDV RNA into the tongue. All six cattle in the first animal trial developed severe clinical signs of FMD and pathognomonic findings were made at necropsy (arrows): (a) lesions on the tongue, corresponding to the areas of injection, and on the upper gums; (b) lesions on the tongue, the upper and lower gums; (c) large, mostly intact lesion in the interdigital space; (d) the true extent of the lesion is revealed after manipulation.

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  Figure 5. Pathohistological findings after injection of naked FMDV RNA into the tongue in the first animal trial ((a–c), tongue, 5× magnification; d–f, interdigital space, 10× magnification). (a) Animal 249, tongue, H.E. staining. The lingual mucosa shows characteristic vesiculopustular lesions containing neutrophils and sloughed epithelial cells (asterisk). The adjacent mucosa is infiltrated by neutrophils (arrows) and reveals clear intercellular spaces between swollen and degenerating keratinocytes (arrowheads). (b) Animal 249, tongue, anti-FMDV immunohistochemistry. Associated with the lesions as described in a), FMDV-antigen-positive cells (red–brown signal, arrows) were detected throughout the lingual mucosal epithelium. The inset shows positively stained cells at higher magnification. (c) Animal 249, tongue, pre-immune serum immunohistochemistry (negative control). To confirm the specificity of the anti-FMDV antibody staining, tissue sections were incubated with pre-immune serum. Unspecific binding was excluded as no positively labeled cells were detected. (d) Animal 260, interdigital space, H.E. staining. Overview of a large vesicle in the interdigital cleft. A large intraepidermal…