Gamma interferon (IFN-Γ) production has been ascribed a role in protecting cows infected with Neospora caninum against abortion. The present study analyzes the interaction between IFN-Γ production and levels of plasma pregnancy-associated glycoprotein-1 (PAG-1), as a marker of placental/fetal well-being, throughout gestation in naturally Neospora-infected dairy cows. Data were obtained from 88 pregnant Holstein-Friesian cows in two herds: 62 seropositive and 26 seronegative for the parasite. Blood samples were collected on Days 40, 90, 120, 150, 180 and 210 of gestation. Plasma was tested for antibodies against N. caninum, PAG-1 and IFN-Γ . Twenty five (28.4%) pregnancies were recorded after AI using Holstein-Friesian semen (19 in seronegative and 6 in seropositive animals), and 63 (71.6%) after AI using Limousin semen (7 in seronegative and 56 in seropositive animals). Gamma interferon was detected in the plasma of 14 (22.6%) of the 62 Neospora-seropositive cows and could not be detected in any of the 26 seronegative animals. All 14 cows producing IFN-Γ became pregnant using Limousin semen. Our GLM repeated measures analysis revealed no effects of herd, lactation number, milk production at the time of pregnancy diagnosis and Neospora-seropositivity on plasma PAG-1 concentrations. Significant positive effects were observed of both the day of gestation (P<0.0001) and the interaction between day of gestation and breed of sire (P = 0.001) on PAG-1 values. Cows carrying twins had higher (P = 0.002) PAG-1 concentrations throughout gestation than cows carrying singletons. Interactions between breed of sire and Neospora-seropositivity (P<0.0001), and between IFN-Γ production and Neospora-seropositivity (P = 0.04) were also detected. Thus, Neospora-seronegative cows inseminated with Limousin and Neospora-seropositive cows showing no IFN-Γ production, exhibited higher PAG-1 concentrations during gestation than seropositive cows inseminated with Limousin semen and producing IFN-Γ , respectively. Our data indicate that the production of IFN-Γ correlates negatively and the production of antibodies against N. caninum is uncorrelated with plasma PAG-1 concentrations during gestation in Neospora-infected dairy cows. Our results also suggest that augmented Th1 cell-mediated immunity is related to a lower risk of abortion and therefore higher resistance to the parasite in cows inseminated with Limousin versus Holstein-Friesian semen. © 2009 Nova Science Publishers, Inc. All rights reserved.
|Title of host publication||Pregnancy Protein Research|
|Number of pages||13|
|Publication status||Published - 1 Feb 2009|
- Dairy cows.
- Gamma interferon
- Neospora caninum
- Pregnancy associated glycoprotein