Abstract. Cattle in western Uruguay that were eating Solanum bonariense developed periodic episodes of ataxia, hypermetria, hyperesthesia, head and thoracic limb extension, opisthotonus, nystagmus, and falling to the side or backward. Similar clinical signs were experimentally reproduced in cattle by administration of S. bonariense via rumen cannula at a dose of 1,024 g/kg body mass. No significant gross lesions were observed in field cases or experimentally induced cases. Spontaneous and induced histologic lesions were similar and included vacuolation, degeneration, and loss of Purkinje cells. Axonal spheroids, microcavitations, and other changes of wallerian-type degeneration in cerebellar white matter were also observed. Ultrastructural changes included increased number of electron-dense residual storage bodies in membrane-bound vesicles in affected Purkinje cells, and similar vesicles and mitochondria in axonal spheroids. No histologic lesions were detected in the other examined tissues. The Purkinje-cell swelling and vacuolation with subsequent cerebellar degeneration are suggestive of Purkinje-cell specific toxin that produces abnormal lysosome function and cell specific axonal transport. This is the first report of S. bonariense toxicity.

The objective of this study was to test the effectiveness of ivermectin for the treatment of mouse hepatitis virus (MHV), a type 2 family RNA coronavirus similar to SARS-CoV-2. Female BALB/cJ mice were infected with 6,000 PFU of MHV-A59 (group infected, n = 20) or infected and then immediately treated with a single dose of 500 µg/kg ivermectin (group infected + IVM, n = 20) or were not infected and treated with PBS (control group, n = 16). Five days after infection/treatment, the mice were euthanized and the tissues were sampled to assess their general health status and infection levels. Overall, the results demonstrated that viral infection induced typical MHV-caused disease, with the livers showing severe hepatocellular necrosis surrounded by a severe lymphoplasmacytic inflammatory infiltration associated with a high hepatic viral load (52,158 AU), while mice treated with ivermectin showed a better health status with a lower viral load (23,192 AU; p < 0.05), with only a few having histopathological liver damage (p < 0.05). No significant differences were found between the group infected + IVM and control group mice (P = NS). Furthermore, serum transaminase levels (aspartate aminotransferase and alanine aminotransferase) were significantly lower in the treated mice than in the infected animals. In conclusion, ivermectin diminished the MHV viral load and disease in the mice, being a useful model for further understanding this therapy against coronavirus diseases.

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SARS-CoV2 is a single strand RNA virus member of the type 2 coronavirus family, responsible for causing COVID-19 disease in humans. The objective of this study was to test the ivermectin drug in a murine model of coronavirus infection using a type 2 family RNA coronavirus similar to SARS-CoV2, the mouse hepatitis virus (MHV). BALB/cJ female mice were infected with 6,000 PFU of MHV-A59 (Group Infected; n=20) and immediately treated with one single dose of 500 ug/kg of ivermectin (Group Infected + IVM; n=20), or were not infected and treated with PBS (Control group; n=16). Five days after infection/treatment, mice were euthanized to obtain different tissues to check general health status and infection levels. Overall results demonstrated that viral infection induces the typical MHV disease in infected animals, with livers showing severe hepatocellular necrosis surrounded by a severe lymphoplasmacytic inflammatory infiltration associated with a high hepatic viral load (52,158 AU), while ivermectin administration showed a better health status with lower viral load (23,192 AU; p<0.05) and few livers with histopathological damage (p<0.05), not showing statistical differences with control mice (P=NS). Furthermore, serum transaminase levels (aspartate aminotransferase and alanine aminotransferase) were significantly lower in treated mice compared to infected animals. In conclusion, ivermectin seems to be effective to diminish MHV viral load and disease in mice, being a useful model for further understanding new therapies against coronavirus diseases.