An investigation of the concurrency of anti-Neospora antibody and parasitemia in water buffalo (Bubalus bubalis) in the northwest of 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, 83 serum samples were collected from buffaloes in the northwest of Iran. Plates were coated with 2 × 106 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 0.50 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 NC5 gene without the DNA isolation process. A total number of 83 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 0.50 or above (16 samples, 19.27%) were also positive for Neospora DNA. All samples with OD less than 0.50 (34 samples, 40.96%) were negative for Neospora DNA. However, 33 samples with the S/P ratio of bellow 0.50 (39.75%) showed a significant level of antibody. A 100% 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.