Hossein Rezvan - Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamadan, Iran
Amir Khaki - Department of Clinical Sciences, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran
Mehdi Namavari - Razi Vaccine and Serum Research Institute, Shiraz, Iran
Roya Abedizadeh - PhD Student, Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamadan, Iran

Neospora caninum is an obligate intracellular parasite causing abortion and reproductive failure in ruminants. Here, the seroprevalence of Neospora DNA and anti-Neospora antibodies and the correlation between the DNA and the antibody using polymerase chain reaction (PCR) and a new developed whole cell-based enzyme-linked immunosorbent assay (ELISA) in water buffalo (Bubalus bubalis) were investigated. To determine the level of anti-Neospora antibody, ۸۳ serum samples were collected from buffaloes in the northwest of Iran. Plates were coated with ۲ × ۱۰۶ whole Neospora tachyzoites and the anti-Neospora antibody level was determined by calculating the ratio of sample/positive control (S/P) optical densities (ODs) in the ELISA. All samples with the ration of ۰.۵۰ or above were accounted as positive. To confirm the presence of Neospora DNA, the serum samples were directly subjected to PCR and nested PCR for detection of Neospora NC۵ gene without the DNA isolation process. A total number of ۸۳ buffalo serum samples were examined for the presence of anti-N. caninum immunoglobulin G and Neospora DNA. All samples with the S/P ratio of ۰.۵۰ or above (۱۶ samples, ۱۹.۲۷%) were also positive for Neospora DNA. All samples with OD less than ۰.۵۰ (۳۴ samples, ۴۰.۹۶%) were negative for Neospora DNA. However, ۳۳ samples with the S/P ratio of bellow ۰.۵۰ (۳۹.۷۵%) showed a significant level of antibody. A ۱۰۰% correlation was observed between high levels of the anti-Neospora antibody and Neospora DNA in the serum of water buffalo, and the whole N. caninum tachyzoites have the potency to be used as antigens for detection of the parasite in ELISA.

Antibody, ELISA, Neospora caninum, Polymerase chain reaction, Water buffalo