Experimental infection with Neospora caninum in pregnant buffaloes (Bubalus bubalis) in Argentina

KONRAD, J.L.; CRUDELI, G.; CASPE, G.; MOORE, D.P.; CANO, D.; LEUNDA, M.; ODEÓN, A.; CAMPERO, C.M.

Buenos Aires

Congreso; World Association for the Advancement of Veterinary Parasitology (WAAVP); 2011

Seroprevalence of Neospora caninum in buffaloes (Bubalus bubalis) was characterized by our research group and a high prevalence was proved in the Northeast of Argentina. To characterize the pathogenesis of the disease an experimental infection was carried out with N. caninum in pregnant buffaloes. Twelve Mediterranean buffaloes ranged from 4 to 14 years old and seronegative to N. caninum were used. The buffaloes were kept in the ranges under extensive systems until slaughter. The female buffaloes were oestrus synchronised using the Ovsynch protocol. After that they were kept in natural service for 72 hours with 3 male buffaloes clinically and genitally fit. The pregnancy was confirmed by ultrasound. Buffaloes of 70 (n = 3) and 90 (n = 6) days of gestation (dg), respectively were inoculated intravenously with 10 8 tachyzoites of Nc-1 strain; and 2 animals were not inoculated. The buffaloes were slaughtered at 28 days post inoculation (dpi) with 98 and 118 dg (n = 8), and then at 42 (n = 4) dpi with 132 dg. No abortions were observed during those periods. The fetuses were necropsied and tissue samples and fetal fluids from cavities were obtained. 1/10 fetuses was not viable at the time of autopsy and presented moderate autolysis. DNA was extracted (Qiagen® kit) from tissues and detection of parasite DNA was performed by a nested-PCR on the ITS-1 region of N. caninum and amplification product was in the in 2% agarose electrophoresis gel. The fetal cavity fluids were analyzed by indirect immunofluorescence (IFI) to dilutions 1/10, 1/16 and 1/25. The presence of DNA from N. caninum inoculated in 10/10 fetuses was confirmed. The 2 fetuses from non inoculated female were negative. At 132 days of gestation, the IFI fetal fluid was positive in all dilutions in only 2/4 inoculated fetuses.The higher gestational age fetuses were confirmed positive by IFI fetal immunocompetence. The negative result of the control animals suggests the absence of horizontal transmission. In this study, the pathogenic effect of N. caninum and the transmission of the strain used in females pregnant buffaloes inoculated intravenously at 70 and 90 days of gestation were determined.