Evaluation of Immunodiagnostic Performances of INeospora caninum/I Peroxiredoxin 2 Recombinant Proteins for Bovine Neosporosis

Bovine neosporosis is a widespread and economically impactful disease affecting the dairy and meat industries globally. With no effective drug or vaccine available, the disease’s control relies on accurate detection methods. This study assessed the performance of three Neospora caninum proteins—NcPrx2, NcMIC4, and NcSAG1—as immunodiagnostic tools for identifying IgG antibodies against N. caninum. Comparisons were made with the indirect fluorescent antibody test (IFAT). The findings indicate that NcSAG1 exhibited the highest sensitivity and specificity, followed by NcMIC4. In contrast, NcPrx2 demonstrated lower sensitivity and specificity compared with IFAT. This study highlights that NcSAG1 is helpful as antigen marker and that NcPrx2 and NcMIC4 have potential in immunodiagnosis for detecting N. caninum infections in field samples. These findings could contribute to improved treatment management, surveillance, and risk assessment of neosporosis in livestock in the future. Bovine neosporosis is among the main causes of abortion in cattle worldwide, causing serious economic losses in the beef and dairy industries. A highly sensitive and specific diagnostic method for the assessment of the epidemiology of the disease, as well as it surveillance and management, is imperative, due to the absence of an effective treatment or vaccine against neosporosis. In the present study, the immunodiagnostic performance of Neospora caninum peroxiredoxin 2 (NcPrx2), microneme 4 (NcMIC4), and surface antigen 1 (NcSAG1) to detect IgG antibodies against N. caninum in cattle were evaluated and compared with that of the indirect fluorescent antibody test (IFAT). The results revealed that NcSAG1 had the highest sensitivity and specificity, with values of 88.4% and 80.7%, respectively, followed by NcPrx2, with a high sensitivity of 87.0% but a low specificity of 67.0%, whereas NcMIC4 showed sensitivity and specificity of 84.1% and 78.9%, respectively, when compared with IFAT. A high degree of agreement was observed for NcSAG1 (k = 0.713) recombinant protein, showing the highest diagnostic capability, followed by NcMIC4 (k = 0.64) and NcPrx2 (k = 0.558). The present study demonstrates that NcSAG1 is helpful as an antigen marker and also demonstrates the potential immunodiagnostic capabilities of NcPrx2 and NcMIC4, which could serve as alternative diagnostic markers for detecting N. caninum infection in cattle. These markers may find utility in future treatment management, surveillanc