2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) and Bovine herpesvirus 1 infection in cattle: an epidemiological analysis in Campania Region (Italy)

Introduction: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), commonly known as dioxin, is a toxic and persistent environmental contaminant which induces immune suppression and increased susceptibility to infectious agents. Bovine herpesvirus 1 (BHV-1), a cattle pathogen, can provoke infectious bovine rhinotracheitis (IBR), genital infections, conjunctivitis, abortions, encephalitis or other fatal diseases in newborns. BHV-1 induced immune suppression which may lead to secondary bacterial infections that can cause pneumonia. Hence, BHV- 1 infection might cause substantial economic loss in the cattle industry. Following BHV-1 infection in bovine cells (MDBK), we previously showed that TCDD influences the infection by increasing virus replication. Moreover, TCDD anticipates BHV-1- induced apoptosis, by accelerating the down-regulation of telomerase activity when virus-induced apoptosis occurred, and by anticipating in the cytoplasm the presence of bICP0, the main transcriptional regulatory protein of BHV-1. Furthermore, TCDD enhances the free intracellular iron availability, which might promote the onset of BHV-1 infection and render bovine cells more vulnerable to the virus. Objectives: Herein, we performed an epidemiological analysis on prevalence of IBR in some areas where high levels of TCDD have been detected in dairy products. Materials and Methods: We collected serum and plasma samples to detect antibodies for IBR from cattle raised on farms in Campania Region (Italy), by using IBR-gB and IBR-gE E.L.I.S.A. kit, which represents the test procedure of choice in many European IBR programs. Results: We revealed a significant prevalence of IBR on samples collected from farms in contaminated areas compared to uncontaminated areas. Discussion and Conclusions: Very low doses of TCDD cause the damage previously showed in bovine cells. In addition, herein we provided evidence that TCDD influences BHV-1 infection, promoting the prevalence of IBR in cattle. Thus, TCDD may act as an additional risk factor for progression of BHV-1 infection in cattle. We suggest that this risk should be given adequate consideration in the care of farm animal health.