Detection of Akabane Viral Antigens in Spontaneous Lymphohistiocytic Encephalomyelitis in Cattle

Abstract

A 5-month-old Japanese black bull calf and twenty-seven 1-27-day-old calves exhibiting neurological signs between August and October 1998 were examined. The bull calf exhibited rapid breathing, fever, hypersensitivity, and ataxia and was euthanized 4 days after the onset of symptoms. The 27 calves primarily exhibited ataxia, and 15 had arthrogryposis. Histological examination of the bull calf revealed perivascular infiltraction by mononuclear cells, diffuse to multifocal gliosis, and neuronal necrosis in the brain and spinal cord. Multiple malacic foci were found in the midbrain in 5 cases. In contrast, in the 15 calves necropsied in October, there were fewer inflammatory changes, but there was neuronal cell loss in the ventral horn and a decrease in myelinated axons in the lateral and ventral funiculi. Immunohistochemical examination using a rabbit antiserum against Akabane virus strain OBE-1 revealed a large amount of viral antigen in the degenerating neurons and glial cells of the bull calf, mainly in the spinal gray matter. Small amounts of viral antigen in swollen axons and a few glial cells were found in 5 of 27 calves. Thirteen of the 27 calves had high neutralization antibody titers against the Akabane virus, whereas there was no significant antibody titer in most of the calves necropsied during August. The present study revealed that viral antigen detection was very useful for the diagnosis of Akabane diseases in the 5-month-old bull calf that was suspected to be infected postnatally, while it had limited usefulness in the other young calves.

Encephalomyelitis Associated with Akabane Virus Infection in Adult Cows

“…12,15 In July 1998, a severe outbreak of congenital abnormalities in calves was reported in most areas of Japan; a 5-month-old bull calf and 27 calves ranging from 1 to 27 days of age were examined, and their cases were diagnosed as AV infection. 19 Here, we describe an outbreak of natural AV infection in adult cows as revealed through histopathology, immunohistochemistry, neutralizing antibody assay, and reverse transcription polymerase chain reaction (RT-PCR) analysis.Between August and September 2000, 5 adult cows in Wonju City ranging from 2 to 7 years of age developed neurologic signs, including hypersensitivity, tremor, locomotor ataxia, or lameness. The cows were from five different farms where the morbidity was about 30%.…”

“…12,15 In July 1998, a severe outbreak of congenital abnormalities in calves was reported in most areas of Japan; a 5-month-old bull calf and 27 calves ranging from 1 to 27 days of age were examined, and their cases were diagnosed as AV infection. 19 Here, we describe an outbreak of natural AV infection in adult cows as revealed through histopathology, immunohistochemistry, neutralizing antibody assay, and reverse transcription polymerase chain reaction (RT-PCR) analysis.…”

“…The pattern and distribution of histologic lesions observed in the five cows were very similar to those in previous reports on AV infection. 19 AV has a tropism for motor neurons in the spinal cord, as detected through immunohistochemistry, and causes neurogenic skeletal muscle atrophy or dysplasia that is believed to be the cause of the lameness and locomotor problem exhibited by these cows. 4 Severe muscular atrophies were observed in two cows examined.…”

“…The neutralization antibody titers represented the highest dilution rate of examined sera that inhibited a cytopathic effect for the cultured cells. 19 The SN test for BEFV, Ibaraki disease virus, BVDV, and Japanese encephalitis virus, an indirect fluorescent antibody test for Chlamydia psittaci and N. caninum, and an enzyme-linked immunosorbent assay for Aujeszky's disease were also performed using standard methods. 9,13 Direct fluorescent antibody (FA) tests for IBRV, BVDV, and rabies virus were conducted with specific conjugates on frozen sections of brain and spinal cord.…”

“Schmallenberg” virus: likely epidemiological scenarios and data needs

“…The malformations induced by viruses of the Simbu serogroup are designated arthrogryposis hydranencephaly syndrome (AHS) (Coverdale et al, 1979;Inaba and Matumoto, 1981). In some cases, varying degrees of encephalitis may occur in both acute infections and newborns infected with Akabane Virus (Uchida et al, 2000;Kono et al, 2008).…”