Efficacy of cordycepin against Neospora caninum infection in vitro and in vivo

Neospora caninum (N. caninum) is an obligate intracellular Apicomplexa parasite that causes abortions in dairy cows and incurs substantial to significant economic losses in the global dairy farming industry. Cordycepin, a nucleoside antibiotic derived from Chinese medicine Cordyceps militaries, exhibits diverse biological activities. However, it remains unclear whether cordycepin possesses inhibitory effects against N. caninum infection. Therefore, this study aimed to establish both in vivo and in vitro models of N. caninum to investigate the potential impact of cordycepin against N. caninum infection. We successfully established an in vitro model of N. caninum infection in RAW264.7 cells, followed by qRT- PCR analysis to detect the content of N. caninum DNA within the cells. The effects of cordycepin on N. caninum was observed using the Giemsa method on RAW264.7, and the rate of cell infection was calculated. Cordycepin exhibited inhibitory effects on N. caninum tachyzoites in vitro, preserving cellular integrity and reducing the rate of cell infection. In mice, we established an in vivo model of N. caninum infection and detected N. caninum presence in tissues using. Real-time fluorescence quantitative PCR. Histopathological changes were observed through Hematoxylin-eosin staining. Liver function was assessed by using glutamic acid aminotransferase (ALT) and aspartic acid aminotransferase (AST) kits. Oxidative stress status was measured using catalase (CAT), malondialdehyde (MDA), and glutathione (GSH) kits. Compared with the model group, mice treated with cordycepin showed reduced clinical symptoms, increased food intake, and their body weight (P=0.0143, P=0.0068) was significantly higher than those in the model group. Furthermore, cordycepin treatment significantly alleviated hepatic cord disorders, hepatocellular swelling, detachment, and vacuolization; duodenal epithelial detachment and shortening of villi caused by N. caninum infection. Cordycepin administration reduced the increase in ALT (P=0.01, P=0.008) and AST (P<0.001) levels caused by N. caninum infection, while ameliorating hepatocyte swelling, necrosis, and detachment as well as inflammatory cell infiltration within mice liver; it also led to shortened or even disappeared duodenal villi along with and oedema of the submucosa. Analysis of oxidative stress showed that cordycepin ameliorated the damage caused by N. caninum by reducing MDA (P=0.03, P=0.02, P=0.005) and increasing CAT (P=0.004, P<0.001) and GSH (P=0.004, P<0.001) levels. In conclusion, this study reports for the first time on cordycepin’s efficacy against N. caninum infection providing a potential candidate drug for neosporosis treatment.