Comparison of diagnostic tests for diagnosis of infectious bovine rhinotracheitis in natural cases of bovine abortion.

Rapid and precise diagnosis plays a pivotal role in implementing suitable control measures in natural field cases of bovine abortion due to infection with bovine herpesvirus (BHV)-1. In the present study, serology, virus isolation, histopathology, immunohistochemistry (IHC) and real-time polymerase chain reaction (PCR) for amplification of the gene encoding glycoprotein B were applied for diagnosis of infectious bovine rhinotracheitis (IBR) in cases of abortion. The seroprevalence of IBR in the population studied was 26.3% as determined by indirect enzyme-linked immunosorbent assay. BHV-1 abortions occurred between 4 and 8 months of gestation with an average gestational age of 6 months. Affected placentae showed necrosis of chorionic villi and of the endothelium of small villous blood vessels with characteristic intranuclear (IN) acidophilic inclusion bodies. Similar inclusions were also seen in most of the tissues examined. BHV-1 antigen was identified immunohistochemically in necrotic foci in the liver, the endothelium of placental blood vessels, the bronchial epithelium and hepatocytes. Lesions in the brain also had IN inclusion bodies that labelled positively by IHC. Eighteen samples (nine of stomach content, two of placental cotyledons, five of pooled fetal tissue and two of vaginal discharge) out of 84 tested were positive by real-time PCR for BHV-1.