Detection of bovine herpesvirus 5 DNA in aborted fetal nervous system

MARIN, M; MORREL, E; PÉREZ, S; VERNA, A; LEUNDA, M; ODEÓN, A

Santiago de Chile

Congreso; XXVI Congreso Mundial de Buiatría; 2010

Bovine herpesviruses 1, 4 and 5 (BoHV-1, 4 and 5) have all been implicated as a cause of bovine reproductive disease and abortions. However, the role of BoHV-5 in abortion has not been definitively demonstrated. This study describes a case of a bovine abortion in which BoHV-5 DNA was detected in the fetal nervous system. The case occured in a farm at General Alvarado country (Buenos Aires, Argentina). Samples from a 7 - 8 month-old aborted bovine fetus, paired serum samples from aborted cows and sera from pregnant and calved cows were submitted to the Specialized Veterinary Diagnostic Service of INTA Balcarce for diagnosis of infectious agents. Virus isolation from fetal spleen and brain on MDBK cells, a multiplex PCR and seroneutralization for BoHV-1 and 5 were carried out. For Neospora caninum, indirect immunofluorescence (IF) test from fetal fluids and serum was performed to evaluate antibodies. Even though BoHV was not isolated, BoHV-5 DNA specific sequence was detected in fetal nervous tissue by multiplex PCR. IF failed to detect N. caninum specific antibodies in fetal fluids. However, 70% of sera from aborted cows and 25% of sera from pregnant or calved cows were serum positive to this protozoan. No other reproductive pathogen was identified (Brucella abortus, Campylobacter fetus, Leptostira spp, Tricomonosis, BVDV). Histopathological analysis revealed the presence of focal, non-suppurative encephalitis characterized by congestion, hemorrages, gliosis and focal necrosis in the base and cortex of the fetal brain. Bovine abortion of undetermined cause is frequent and, in many cases microscopic findings in fetal tissues suggest an infectious cause. This fact highlights the need for improved diagnostic techniques. This study demonstrated the presence of BoHV-5 DNA in aborted fetal nervous system, being the first description of this virus associated with bovine abortion. The microscopic lesions in the fetal nervous tissues were compatible with BoHV-5 infection and because, some features of the changes overlap with those provoked by N. caninum a careful microscopic evaluation should be carried out when CNS lesions appear. Thus, this implies that BoHV-5 infection should also be considered when bovine fetal neurologic lesions are found. Although the involvement of the protozoan should also be considered due to the high seroprevalence in aborted cows in the herd, these results demonstrate the participation of BoHV-5 in a case of bovine abortion.