Herpesvirus 5 DNA in aborted fetal nervous system

MARIN M ; MORRELL E2,; PÉREZ SE; VERNA A; LEUNDA MR; ODEÓN AC

Congreso; XXVI World Buiatrics Congress; 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 describe a case of a bovine abortion in which BoHV-5 DNA was detected in the fetal nervous system. The outbreak 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 analysis 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) from fetal fluids and serum was performed. Even though BoHV was not isolated, BoHV-5 DNA specific sequence was detected in fetal nervous tissue. Diagnostic methods failed to detect N. caninum in fetal fluids. However, 70% of sera from aborted cows and 25% of sera from pregnant or calved cows resulted positive to this protozoan. No other reproductive pathogens were 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, histopathological examination of fetal tissues suggests an infectious origin. This highlights the need for improved diagnostic techniques. This study demonstrated the presence of BoHV-5 DNA in aborted fetal nervous system. This is the first description of BoHV-5 associated with bovine abortion. The microscopic lesions in the fetal nervous tissues were compatible with BoHV-5 infection and, in some cases, overlaps with the lesions provoked by N. caninum. Thus, this implies that BoHV-5 infection should also be considered when bovine fetal neurologic lesions are found. Although the involvement of the protozoan cannot be ruled out in this case due to the high seroprevalence in aborted cows in the herd, these results demonstrate the participation of BoHV-5 in the outbreak of bovine abortion. It is concluded that this virus might play a role in some reproductive disorders in cattle, including abortions.