Problem: Infection of naïve pregnant cows with non-cytopathic (ncp) bovine viral diarrhea virus (BVDV) results in transplacental infection of the fetus. Infection of the pregnant cow with ncp BVDV late in gestation (after day 150) results in transient infection (TI), as both the dam and fetus can mount an immune response to the virus. In contrast, if the fetus is infected with ncp BVDV early in gestation (before day 150), the fetal immune system is undeveloped and unable to recognize the virus as foreign. This results in induction of immune tolerance to the infecting BVDV strain and persistent infection (PI).
Methods: Infection of naïve pregnant heifers with ncp BVDV2 on day 75 was hypothesized to induce differential gene expression in white blood cells of the dams and their fetuses, adversely affecting development and antiviral immune responses in PI fetuses.
Results: Gene expression differed in maternal blood cells in the presence of PI versus uninfected fetuses. PI adversely affected fetal development and antiviral responses, despite protective immune responses in the dam.
Conclusion: Fetal PI with BVDV alters maternal immune function, compromises fetal growth and immune responses, and results in expression of maternal blood biomarkers that can be used to identify cows carrying PI fetuses.