ISOLATIONS OF AKABANE VIRUS FROM SENTINEL CATTLE AND CULICOIDES BREVITARSIS

SUMMARY A total of 14 isolations of Akabane virus were made from the blood of five cattle during sub-clinical infection. The serial isolation of this virus from four of these animals suggests a viraemia of at least 3 or 4 days. Neutralising antibody to Akabane virus in the serum of infected calves reached an initial peak titre of 32 to 256 four to five days after the viraemia but later rose further to a range of 64 to 512. Three isolations of Akabane virus were made from Culicoides brevitarsis collected nearby in the same period. C. brevitarsis was the dominant haematophagous midge present during that time. These findings strengthen the case for C. brevitarsis to be considered as a vector of Akabane virus.     

Hemagglutination-inhibition test applied to the study of akabane virus infection in domestic animals

Some factors affecting the hemagglutination-inhibition (HI) reaction with Akabane virus were investigated and an HI test developed. The test was proven to be useful in studies of antibody responses in cattle and other domestic animals infected with Akabane virus. HI antibody titers of individual animals were shown to be closely correlated with their neutralizing antibody titers and to remain undiminished for a relatively long time. In some early sera from domestic animals infected with Akabane virus, HI antibody sensitive to 2-mercaptoethanol was demonstrated.     

Antibodies to Akabane virus in horses,sheep and goats in Japan

High prevalences of neutralizing (NT) antibody to Akabane virus were obtained with horse (72%), sheep (38%) and goat (67%) serum samples collected in Chiba Prefecture, where outbreaks of abortion and congenital deformities caused by Akabane virus occurred among cattle. In these animal sera, titers of hemagglutination-inhibiting (HI) antibody to Akabane virus and of NT antibody were closely correlated.     

Akabane virus infection in the pregnant ewe. 1. Growth of virus in the foetus and the development of the foetal immune response

Three different pools of the CSIRO 16 strain of Akabane virus differing in their laboratory passage histories were used to inoculate 39 ewes between 32 and 36 days pregnant; 22 pregnant ewes received inocula containing no virus. There was no difference in the development, duration and titre of the viraemia and neutralising antibody response between the three infected groups of ewes. Both infected and control ewes had 141% foetuses when autopsied at 69 to 105 days gestation. Of the 55 foetuses from infected ewes 44 (80%) had gross developmental abnormalities.At autopsy of the dams Akabane virus was isolated only from the uterine caruncle. From foetal samples virus was isolated from a wide range of tissues, from one foetus at 69 days and from the blood of four foetuses at 95 to 106 days gestation. Virus was also isolated from 24 of the choriolllantoic fluid samples and from 37 placentomes of the 44 foetuses with developmental defects, in concentrations ranging from 10² to 10^5.5 TCID₅₀/ml or/g. No virus was isolated from the tissues of the control ewes or their foetuses.Neutralising antibody to Akabane virus was detected in 78% of the foetal sera from the infected group, titres ranging from 2 to 64. IgM and IgG₁ and neutralising antibody were detected in sera of 40 foetuses with developmental abnormalities including three that were of 76 to 78 days gestation. Neutralising antibody was detected only in serum that contained IgG₁ but may also have been associated with IgM in infected foetuses. IgM was detected in the serum of most foetuses including the non-infected controls, but sera from the control foetuses did not contain IgG₁ or neutralising antibody to Akabane virus. No IgG₂ or IgA were detected in any foetal serum.     

Encephalitis of cattle caused by Iriki isolate, a new strain belonging to Akabane virus

A disease characterized by nervous signs was found in 10 calves in two districts in Kagoshima Prefecture, Japan, from October to November, 1984. Histopathological changes of nonpurulent encephalitis were found in every case. An agent, named Iriki isolate, was isolated from the cerebellum of a calf in HmLu-1 cell cultures. All of the affected calves possessed neutralizing antibody to the virus. A high seropositive rate to the virus in cohabiting cattle and cattle kept in the epizootic area, and seroconversion to the virus in 1984, were disclosed. Experimental infection of calves with Iriki isolate produced severe nervous signs and histopathological changes similar to those of the natural infection. These seroepidemiological findings and animal experiments established that Iriki isolate is the causative agent of the disease. Iriki isolate was considered as a variant of Akabane virus since the virus showed cross reaction with Akabane virus in virus neutralization tests.     

Preferential infection of neuronal and astroglia cells by Akabane virus in primary cultures of fetal bovine brain

Akabane virus is a member of the genus Bunyavirus; it is pathogenic for ruminants and transmitted by arthropod vectors. Infection of adult cattle and sheep causes a transient viremia without obvious clinical signs, while infection of pregnant animals often causes fetal abnormalities including hydranencephaly, poliomyelitis and arthrogryposis. Infectious virus or viral antigens is present in the brain, spinal cord and skeletal muscle of infected fetuses. To understand the interaction between Akabane virus and bovine brain cells, we investigated the viral tropism using primary cultures of fetal bovine brain. The cultured neuronal cells, astroglia cells and microglia cells were distinguished by cell type specific antisera. Akabane virus was found to infect neuronal cells and astroglia cells, which led to degenerative death. No microglia cells were found infected. In some brain cultures, we observed different sensitivities of the cells to two Akabane virus strains: an attenuated strain infected and spread more readily than wild type virus. This difference was not observed in a hamster fibroblast cell line. Both viral and host determinants might be involved in the different susceptibility of brain cells to Akabane virus infection.     

A serological survey of Akabane virus infection in cattle and sheep in northwest China

Purpose

Akabane disease characterized mainly by fetal damage is a ruminant disease caused by insect-transmitted Akabane virus infection.

Methods

We investigated Akabane disease using serum neutralization tests in 446 blood samples collected from 187 cattle and 259 sheep of Xinjiang province, northwest China.

Results

(1) The overall prevalence rate of neutralizing antibody was 19.06?% (85/446), (2) the prevalence rates of Akabane disease in cattle and sheep were 20.32?% (38/187) and 18.15?% (47/259), respectively, (3) the disease prevalence rates were not significantly different between cattle and sheep, but significantly different among samples collected from different sampling months, (4) the disease was most prevalent in July when mosquitoes and culicoides were most active, and (5) the disease prevalence rates were significantly different between individuals with abortion experience and without abortion experience (P?<?0.05), suggesting that Akabane virus infection may significantly increase abortion risk in cattle and sheep.

Conclusions

To our knowledge, this is the first report confirming that Akabane virus infection is common in cattle and sheep of Xinjiang province, northwest China and providing useful epidemiological information for cattle and sheep abortion prevention and control.     

Detection of Akabane viral antigens in spontaneous lymphohistiocytic encephalomyelitis in cattle.

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.     

鹿流行性出血病病毒双抗夹心ELISA方法的建立

为建立鹿流行性出血病病毒(EHDV)病原学检测方法,用纯化的抗EHDV特异性单克隆抗体包被ELISA板,用兔抗EHDV IgG作为夹心抗体,IgG作为夹心抗体建立EHDV双抗夹心ELISA方法,并对该方法的特异性和敏感性进行了试验.用ELISA分别检测EHDV、蓝舌病病毒(BTV)、水疱性口炎病毒(VSV)、赤羽病病毒...     

A SURVEY OF ANTIBODY TO AINO VIRUS IN CATTLE AND OTHER SPECIES IN AUSTRALIA

SUMMARY A serological survey of healthy cattle in Australia showed that antibodies to Aino virus were present in serums from cattle in northern Australia and down the east coast as far as central New South Wales in 1975, 1976 and 1977, but occurred with a lower frequency than antibodies to Akabane virus. in contrast to the findings with Akabane virus, no neutralising antibodies to Aino virus were detected in serums from camels, dogs or horses. Antibodies to both viruses were detected in buffaloes and sheep, but not in humans or any of the Australian indigenous species so far tested. All positive serums originated from within the known range of Culicoides brevitarsis.     

Isolation of Akabane virus from the biting midge Culicoides oxystoma in Japan

Akabane virus was isolated from the biting midge, Culicoides oxystoma, collected in a cowshed in Kagoshima on Kyushu Island of Japan. This is the first report on the isolation of Akabane virus from biting midges of the genus Culicoides in Japan. Two calves kept as bait in the cowshed seroconverted to Akabane virus. These results strongly suggest that C. oxystoma may be a vector of Akabane virus.     

Sero-survey on Aino, Akabane, Chuzan, bovine ephemeral fever and Japanese encephalitis virus of cattle and swine in Korea

Vector-borne arboviruses produce mild to severe symptoms in domestic animals. Bovine ephemeral fever (BEF), Akabane, Aino, and Chuzan virus have been primarily attributed to reproductive disorders or febrile diseases in cattle, and Japanese encephalitis virus (JEV) is mainly associated with reproductive failures in swine. We investigated antibody titers from domestic swine against four bovine arboviruses (BEF, Akabane, Aino, and Chuzan virus) and from cattle against JEV in Korea. While the positive rates for Akabane and BEF were 37.4% and 15.7%, the positive incidence of Chuzan and Aino were relatively low, with positive rates of 3.04% and 0.4%, respectively, based on a virus neutralization assay. Antibody titers against more than one virus were also frequently detected in domestic swine. The incidence of JEV was 51.3% among domestic cattle. In addition, one positive case was detected in the thoracic fluids from 35 aborted calves, based on the hemagglutination inhibition test. Our results indicate that swine are susceptible hosts of bovine arboviruses without showing clinical symptoms in a natural environment. Moreover, we confirmed that JEV could be associated with reproductive failure in pregnant cattle, as were other vector-borne bovine arboviruses assessed in this study.     

赤羽病病毒的纯化及其单克隆抗体的制备

将人工繁殖、纯化的赤羽病病毒作为免疫原,通过常规杂交瘤技术,制备亲和性强、特异性好的小鼠抗赤羽病病毒单克隆抗体,并进行相应的纯化和标记工作。以澳大利亚进口的试剂盒进行验证,结果证明:进口单抗与我们制备的AAK纯品及AAK-HRP显示同样结果;且质控结果表明,AAK纯品及其衍生物AAK-HRP的特异性和亲和性均基本满足进行封闭ELISA检测方法的要求,为制备国产化ELISA试剂盒提供了基础。     

赤羽病间接ELISA检测方法的建立和标化

应用赤羽病病毒(AKV)OBE-1株和牛标准阴阳性血清，以蔗糖密度梯度离心纯化细胞毒为包被抗原，在国内首次建立了检测AKV抗体的间接ELISA方法。该方法与中和试验相关系数0．7614，特异性和重复性良好。应用此方法对南京、上海附近奶牛抽样检测，阳性率分别为26．7％和32．7％。对澳大利亚、加拿大、美国进口牛13600头份进行检测，全部阴性。     

Seroprevalence of five arboviruses in sentinel cattle as part of nationwide surveillance in South Korea, 2009?2012

To investigate the possible circulation of arboviruses in South Korea, nationwide surveillance of five arbovirues was conducted in sentinel calves during 2009−2012. We used serum neutralization tests to investigate the presence of antibodies for the Aino virus, Akabane virus, bovine ephemeral fever virus, Chuzan virus and Ibaraki virus. In 2009, 2011 and 2012, the seropositive rates for these five arboviruses were all less than 14.1%. In 2010, however, the seropositive rates for Aino virus and Akabane virus were 33.2% and 40.2%, respectively. High seropositive rates were also associated with a large-scale outbreak of Akabane viral encephalomyelitis in cattle in southern Korea in 2010. Continued seroprevalence surveillance will be useful for monitoring natural arboviral diseases.     

Prevalence of neutralising antibodies to Akabane virus in the Arabian peninsula

Serum-neutralising antibodies to Akabane virus were found in a wide range of domestic animals in all countries of the Arabian Peninsula but the virus does not seem to be endemic there. Sentinel herds in Oman and N. Yemen did not detect any Akabane activity between August 1984-November 1986 and May 1983-November 1984, respectively. However, there is strong evidence to suggest that Akabane virus incursions have recently taken place in Kuwait, Saudi Arabia and Bahrain as neutralising antibodies were detected in 1-year-old cattle bled during 1986 in each of these countries. The possibility of windborne infected vectors, from virus-endemic areas, initiating these incursions into the Arabian Peninsula is discussed.     

Detection of antibodies against Akabane virus in bovine sera by enzyme-linked immunosorbent assay

An enzyme-linked immunonosorbent assay was established for detection of antibodies to Akabane virus in bovine sera. The assay was shown to be a useful serological tool for studies on Akabane virus infection.     

赤羽病琼脂免疫扩散试验诊断方法的研究

应用引自美国和日本的羽病毒和标准阳性血甭,制备了琼脂免疫扩散试验（ＡＧＩＤ）抗原和高免阳性血清,建立了赤羽病ＡＧＩＤ诊断方法。应用此方法对上海、杭州、广州等地的１３８３头牛进行了检疫,ＡＧＩＤ抗体阳性牛７４６头,阳笥率５４．０％,与流行情况相符。同时对从澳大利亚、美国、新西兰和加拿大等国进口的牛、羊、猪血清１６２头份进行了检疫,全部为ＡＧＩＤ抗体阴性。     

Appearance of slow-reacting and complement-requiring neutralizing antibody in cattle infected with Akabane virus

Slow-reacting complement-requiring neutralizing (NT) antibody was detected in sera from cattle 2 weeks after infection with Akabane virus. Bovine sera obtained 3 or 4 weeks after infection contained slow-reacting noncomplement-requiring NT antibody. The slow-reacting complement-requiring NT antibody was sensitive to 2-mercaptoethanol (2-ME), whereas the slow-reacting noncomplement-requiring NT antibody was resistant to 2-ME. The initial phase may represent the IgM response and the later phase a change to IgG. A NT test was developed in which virus-serum mixtures were incubated at 4 degrees C for 48 h and then with complement at 37 degrees C for 60 min; this gave an improved sensitivity over the previous incubation at 37 degrees C for 60 min.     

Neutralising antibodies to Akabane virus in ruminants in Cyprus

Summary Neutralising antibodies to Akabane virus, a cause of arthrogryposis and hydranencephaly, were demonstrated in serum samples from 33 sheep, 3 goats and 1 bovine among 285 serum samples collected in south-eastern Cyprus from December 1970 onwards. Twenty-four of the 29 sheep having positive antibodies came from one farm in Liopetri. No positive sera came from animals born after 1969, no association with abortions or stillbirths was noted and no arthrogryposis or hydranencephaly was observed in Cypriot animals in 1969 or before. It is suggested that Akabane virus was carried to Cyprus from the eastern Mediterranean mainland by infected midges on the wind in 1969 and possibly also in 1968, but that no disease was observed since infection took place after 50 days of gestation when damage to the foetus was unlikely.

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Anticuerpos Neutralizantes Del Virus Akabane En Rumiantes En Chipre

Resumen Se encontraron anticuerpos neutralizantes del virus Akabane, la causa de artrogriposis e hidranencefália, en muestras de suero de 33 ovejas, 3 cabras y 1 bovino, entre 285 muestras en total colectadas en la región suroriental de Chipre. El muestreo empezó en Diciembre de 1970. Veinticuatro de las 29 ovejas positivas se sangraron en una granja de Liopetri.No se encontraron anticuerpos específicos en animales nacidos después de 1969; tampoco se encontró asociación alguna con abortos o daños fetales. No se observó artrogriposis o hidranencefália en animales chipriotas en 1969 o anterior a esa fecha. Esto sugiere, que el virus Akabane llegó a Chipre de la región oriental mediterránea, en insectos del ordenDiptera, en 1969 y posiblemente también en 1968. La enfermedad en esa época no se vió, posiblemente debido a que la infección ocurrió después de los 50 días de gestación, cuando el feto es poco susceptible al virus.

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Anticorps Neutralisants, Specifiques Du Virus Akabane, Chez Des Ruminants A Chypre

Résumé Des anticorps neutralisants, spécifiques du virus Akabane, agent de l'arthrogrypose et de l'hydrocéphalie, ont été mis en évidence dans des échantillons de sérum, provenant de 33 moutons, 3 chevres et 1 vache, sur 285 échantillons sérologiques prélevés dans la partie orientale de Chypre depuis décembre 1970.24 des 29 moutons positifs venaient d'une ferme de Liapetri. Aucun sérum ne provenait d'animaux nés en 1969 ou avant; de même aucun syndrome d'avortement ou de mortinatalité associé à des cas d'arthrogrypose ou d'hydrocéphalie n'avait été décelé chez les animaux de Chypre en 1969 on avant. On pense que le virus Akabane a pu être importé à Chypre depuis les rivages de la Méditerranée orientale par des moucherons infectés transportés par le vent en 1969 peut être aussi en 1968 mais qu'aucun cas n'avait été observé puisque l'infection s'était déclarée après 50 jours de gestation alors que l'atteinte du foetus était devenue peu probable.