Immunoreactivity of sera from naturally and experimentally infected cows (Nc-6 Argentina, Nc-1) to Neospora caninum immunodominant antigens

CAMPERO L.M.; MINKE L.; HECKER Y.; BACIGALUPE D.; RAMBEAUD M. ; MOORE D.P.; CAMPERO C.M.; SCHARES G.; VENTURINI M.C.

Lisboa

Congreso; Apicomplexa in Farm Animals. International Meeting. Lisbon. 25-28 October, 2012; 2012

Neospora caninum is a protozoan parasite that causes abortion and important economic loss in argentinian cattle. The accurate diagnosis of N. caninum infection is essencial for control. The aim of this study was to determine and compare immunoreactivity of sera from naturally (NI) and experimentally infected cows (EI) (Nc-6 Argentina, Nc-1) to N. caninum immunodominant antigens by Immunoblot (IB) and Immunofluorescence Antibody Test (IFAT). Serum samples were obtained from NI (n=266), EI Nc-6 (n= 18) and Nc-1 (n=30) cows. Sera were analyzed by IFAT in two-fold dilutions and IB performed in non-reduced conditions with Nc-1and sera dilution of 1:100. Animals were classified as seropositive by IFAT more than 1:50 and IB whenever 2 or more immunodominant antigens (IDA) were detected. A very good agreement between IFAT and IB (k=0.85, p less than 0,001) was observed. Based on the frequency and intensity of recognition, five IDA (19, 29, 30, 33, and 37 kDa) were recognized by sera from all studied groups. IDA were recognised at high dilutions in most EI sera but also at low titres in NI cows. A 37 kDa and 29 kDa antigens were detected in 100% and 96% of seropositive animals, respectively. The 30 and 33 kDa antigens were recognised with higher frequency and intensity in IFAT samples with titres more or equal to 1:400. The 17 kDa protein was only recognized in IFAT samples with titres more or equal to 1:100 and a protein ~26 kDa was present in IFAT titres more or equal to 1:3200. A clear relationship between increasing IFAT titre and more intense and frequent antigen recognition was observed. Similar immunoblotting patterns were observed in NI and EI cows. In conclusion, the 37 kDa and 29 kDa proteins are suitable antigens for immunodiagnosis of neosporosis in cattle. In addition, there were no differences in immunoreactivity of sera from cows infected with the studied isolates and those present in the field in Argentina.