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1.
Vet Parasitol ; 157(3-4): 182-95, 2008 Nov 07.
Article in English | MEDLINE | ID: mdl-18814972

ABSTRACT

Bovine reproductive failure caused by the parasite Neospora caninum is a major problem and is responsible for severe economic losses worldwide. Currently, appropriate control measures depend on the predominant transmission route in a particular herd. Therefore, the development of diagnostic tools capable of discriminating between primo-infection, recrudescence, re-infection, and chronic infection is a major challenge in the serodiagnosis of bovine neosporosis. Here, two recombinant protein-based ELISAs utilizing the immunodominant NcGRA7 dense granule protein and the NcSAG4 bradyzoite stage-specific protein were developed and showed good diagnostic performances. Their usefulness for discerning between primo-infection, recrudescence, re-infection, and chronic infection was also studied by analyzing an appropriate panel of serum samples belonging to different groups of experimentally and naturally infected bovines. Our results suggest that anti-rNcGRA7 antibody levels may be indicative of acute infection (primo-infection, re-infection, and recrudescence), whereas the presence of anti-rNcSAG4 antibodies may be associated with chronic infection and could be a good indicator of infection establishment (tachyzoite-bradyzoite conversion). Moreover, primo-infection associated with a Neospora-associated epidemic abortion pattern is characterized by the detection of anti-rNcGRA7 antibodies together with the absence or detection of anti-rNcSAG4 antibody levels around the cut-off point. In contrast, the detection of antibody levels directed against both recombinant proteins may be quite indicative of recrudescence or re-infection associated with abortion and/or vertical transmission in herds with a Neospora-associated endemic abortion pattern. In conclusion, both serological tests developed in the present study offer additional information to conventional avidity tests and, consequently, improve the diagnosis of bovine neosporosis with perspectives for control measures.


Subject(s)
Cattle Diseases/diagnosis , Coccidiosis/veterinary , Enzyme-Linked Immunosorbent Assay/veterinary , Neospora , Animals , Cattle , Cattle Diseases/parasitology , Cattle Diseases/pathology , Chronic Disease , Coccidiosis/diagnosis , Coccidiosis/parasitology , Coccidiosis/pathology , Enzyme-Linked Immunosorbent Assay/methods , Female , Male , Recurrence
2.
Vet Parasitol ; 142(1-2): 187-91, 2006 Nov 30.
Article in English | MEDLINE | ID: mdl-16884852

ABSTRACT

It has been suggested that the abortion herd pattern could influence bovine foetal neosporosis. Here, a comparison of (i) Neospora caninum DNA-detectability by PCR, (ii) N. caninum-associated lesions and (iii) parasite loads in target organs was made between epidemic and endemic abortion cases. We observed that N. caninum DNA was predominantly detected in more than one organ in the foetuses from herds with epizootic rather than endemic abortion cases (P<0.05, Fisher F-test). The highest parasite burdens were found in the heart in foetuses from outbreaks of epidemic abortion and in the brain in endemic cases (P<0.05, Kruskal-Wallis H-test). Moreover, foetuses from epidemic outbreaks had significantly higher parasite burdens in heart (P<0.05, Mann-Whitney U-test) than endemic abortion cases. Epidemic abortion cases showed higher lesion frequencies in liver (P<0.05, Fisher F-test). This report confirms that the abortion herd pattern is an important factor that influences pathogenesis in natural N. caninum infections.


Subject(s)
Abortion, Veterinary/parasitology , Cattle Diseases/parasitology , Coccidiosis/veterinary , Neospora/isolation & purification , Pregnancy Complications, Parasitic/veterinary , Animals , Cattle , Cattle Diseases/pathology , Coccidiosis/parasitology , Coccidiosis/pathology , DNA, Protozoan/analysis , Female , Fetus/parasitology , Fetus/pathology , Heart/parasitology , Liver/parasitology , Liver/pathology , Organ Specificity , Polymerase Chain Reaction/veterinary , Pregnancy , Pregnancy Complications, Parasitic/parasitology , Pregnancy Complications, Parasitic/pathology
3.
J Vet Diagn Invest ; 17(5): 442-50, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16312235

ABSTRACT

Avidity serological tests (avidity enzyme-linked immunosorbent assay [ELISA] and avidity Western blot) were developed and used to differentiate between acute (primary infection, reinfection, and recrudescence) and chronic Neospora caninum infection in cattle. In addition, the pattern of immunoglobulin G (IgG) avidity maturation against different specific antigens of N. caninum tachyzoites was studied. Sequential serum samples were collected from cattle naturally and experimentally infected with N. caninum. Four groups of experimentally infected cattle were included in the study and were representative of primary infection, reinfection, chronic infection, and noninfection. Serum samples were also collected from naturally infected cattle classified into nonaborting and aborting cows on the basis of clinical findings and serological profiles, and a third group composed of seronegative cows that seroconverted during the course of the experiment. All samples were tested by avidity ELISA and avidity Western blot. The IgG avidity ELISA allowed the discrimination between primary and chronic infection because all experimentally primary-infection cows showed low avidity indexes at week 4 postinfection (p.i.) compared with the high avidity values found at week 20 postinfection. However, this test did not allow the discrimination of reinfection or recrudescence from chronic infection. Regarding IgG avidity Western blot results, no antigenic markers correlating with acute (primary infection, recrudescence, and reinfection) or chronic infection were recognized. However, the 17-kD immunodominant antigen was mostly responsible for high avidity values obtained by avidity ELISA because it was intensively recognized by high-avidity antibodies in all chronically infected animals after urea treatment.


Subject(s)
Blotting, Western/veterinary , Cattle Diseases/parasitology , Coccidiosis/veterinary , Enzyme-Linked Immunosorbent Assay/veterinary , Neospora/immunology , Abortion, Veterinary/microbiology , Abortion, Veterinary/prevention & control , Acute Disease , Animals , Antibodies, Protozoan/blood , Antibodies, Protozoan/immunology , Antibody Affinity , Blotting, Western/methods , Blotting, Western/standards , Cattle , Cattle Diseases/diagnosis , Chronic Disease , Coccidiosis/diagnosis , Coccidiosis/parasitology , Enzyme-Linked Immunosorbent Assay/methods , Enzyme-Linked Immunosorbent Assay/standards , Epitopes/immunology , Female , Immunoglobulin G/immunology , Pregnancy
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