Immune response to Neospora caninum in naturally infected heifers and heifers vaccinated with inactivated antigen during the second trimester of gestation

The objective of this study was to compare the immune response to Neospora caninum in naturally infected heifers and heifers inoculated with a killed whole N. caninum tachyzoite preparation during the second trimester of gestation. Nine Holstein heifers were used in this study; three naturally infec...

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Bibliographic Details
Published in:Veterinary parasitology 2005-06, Vol.130 (1), p.29-39
Main Authors: Moore, D.P., Leunda, M.R., Zamorano, P.I., Odeón, A.C., Romera, S.A., Cano, A., de Yaniz, G., Venturini, M.C., Campero, C.M.
Format: Article
Language:English
Subjects:
Animals
Animals, Newborn
Antibodies, Protozoan - blood
antibody detection
antibody formation
antigens
Bovine
calves
Cattle
Cattle Diseases - immunology
Cattle Diseases - parasitology
Cattle Diseases - prevention & control
Cattle Diseases - transmission
Cell Proliferation
Coccidiosis - immunology
Coccidiosis - parasitology
Coccidiosis - prevention & control
Coccidiosis - veterinary
Enzyme-Linked Immunosorbent Assay - veterinary
Female
Fluorescent Antibody Technique, Indirect - veterinary
Immunoglobulin Isotypes - immunology
Immunology
inactivated vaccines
Infectious Disease Transmission, Vertical - prevention & control
Infectious Disease Transmission, Vertical - veterinary
Interferon-gamma - immunology
interferons
lymphocyte proliferation
Male
Neospora - immunology
Neospora caninum
neosporosis
pregnancy
Protozoan Vaccines - immunology
Protozoan Vaccines - therapeutic use
Random Allocation
seroprevalence
T-Lymphocytes - cytology
T-Lymphocytes - immunology
tachyzoites
vaccination
Vaccination - veterinary
Vaccine
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Summary:The objective of this study was to compare the immune response to Neospora caninum in naturally infected heifers and heifers inoculated with a killed whole N. caninum tachyzoite preparation during the second trimester of gestation. Nine Holstein heifers were used in this study; three naturally infected heifers were born from seropositive dams, and six seronegative heifers were born from seronegative dams. Four seronegative heifers were subcutaneously vaccinated with a killed whole N. caninum tachyzoite preparation at weeks 13, 15 and 17 of gestation. A killed whole N. caninum tachyzoite preparation containing 45 mg of protein/5 ml dose was formulated with 70% of mineral oil adjuvant (13% consisting of Arlacel C, 85% Marcol 52 and 2% Tween-80). Similarly, two seronegative heifers (negative controls) were inoculated with mock-infected bovine monocytes in oil adjuvant. Humoral immune responses were tested by using an indirect fluorescent antibody test (IFAT) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting isotype specific antibodies. Cellular immune responses were assessed by lymphocyte proliferation test (LPT) and IFN-γ production. N. caninum-specific antibody responses increased in immunized cattle by week 15 of gestation (mean reciprocal antibody titers 450 ± 252), peaked at week 23 (mean 16,000 ± 6400). Maximum antibody response in naturally infected heifers was observed at week 19 of gestation (mean: 3467 ± 2810). Mean serum IFAT titers were significantly higher in immunized heifers compared with those in naturally infected heifers from weeks 17 to 25 ( P < 0.05). Analysis of isotype specific antibodies in naturally infected heifers revealed a predominant IgG1 response in one heifer and a predominant IgG2 response in the other two. Similar titers of IgG1 and IgG2 occurred in immunized heifers. Control heifers remained seronegative throughout the study by IFAT and ELISA. Significant antigen-specific proliferation responses were only detected in naturally infected heifers in week 19 of gestation. Peripheral mononuclear blood cells (PMBC) from immunized animals produced IFN-γ in similar concentrations to those of infected animals ( P > 0.05). No abortion was seen in any experimental group; however, one calf from a vaccinated heifer died due to dystocia. All calves from vaccinated and control heifers were seronegative by IFAT at 6 months of age; in contrast, calves born from naturally infected heifers remained seropositive with titers
ISSN:0304-4017
1873-2550
DOI:10.1016/j.vetpar.2005.03.010