Circulation of bovine ephemeral fever in the Middle East--strong evidence for transmission by winds and animal transport

Bovine ephemeral fever virus (BEFV) is an economically important arbovirus of cattle. The main routes of its transmission between countries and continents are not completely elucidated. This study aimed to explore BEFV transmission in the Middle-East. A phylogenetic analysis was performed on the gene encoding the G protein of BEFV isolates from Israel from 2000 and 2008 with isolates from Turkey (2008), Egypt (2005), Australia (1968-1998) and East Asia (1966-2004). Calf sera collected during the years 2006-2007 were tested by serum neutralization in order to explore for recent exposure to BEFV before 2008. These were followed by a meteorological analysis, aimed to reveal movement of air parcels into Israel in the two weeks preceding the first case of BEF in Israel in 2008. The 2008 Israeli and Turkish isolates showed 99% identity and formed a new cluster with the 2000 Israeli isolate. The serological survey showed no new exposure to BEFV during 2006 and 2007. These results coincided with the meteorological analysis, which revealed that air parcels originating in Southern Turkey had reached the location of outbreak onset in Israel nine days before the discovery of the index case. The Egyptian isolate clustered phylogenetically with the Taiwanese isolates, coinciding with data on importation of cattle from China to the Middle East in the year preceding the isolation of the Egyptian isolates. These results suggest that both winds and animal transport may have an important role in trans-boundary transmission of BEFV.     

Theoretical epidemiology on bovine ephemeral fever outbreaks in Tanegashima Island, Kagoshima Prefecture of Japan in 1988.

From the end of September to November 1988, a compact scale of bovine ephemeral fever (BEF) outbreaks occurred suddenly in Tanegashima island of Kagoshima Prefecture, southern part of Kyusyu island of Japan. The BEF outbreak pattern showed epidemical characteristics as follows; (1) outbreak spread from few foci to zone during one month, and (2) the disease might be transmitted in farms with a fixed probability of adequate contact. By using the above aspects, we attempted to analyze the disease theoretically with the application of Poisson distribution and Reed-Frost model. The BEF incidence in farms was in well accord with the Poisson distribution. As the very rare event occurred in unit time or in unit area in this epidemic, the cattle population at risk were equivalently susceptible to BEF virus in this island, due to the influence of no vaccination to BEF control before the first outbreak. Similarly, the epidemic curve of the Reed-Frost model was proved to fit well the incidence observed in a farm, and the probability of adequate contact was induced as p = 0.226. If the cattle population is less than 5 in this farm, the outbreak would not occur in the first instance.     

牛流行热研究进展

牛流行热,又称为三日热,是由虫媒弹状病毒牛流行热病毒(BEFV)引起的牛和水牛的一种传染病.该病会导致牛发热、四肢僵硬、跛行,通常又会完全恢复.其会引起感染动物的死亡,母牛流产,致使奶牛产奶量下降、公牛体重和生殖能力下降.作者结合国内外对牛流行热病毒的研究,从发病历史、流行病学、病原学、临床症状、致病机理、诊断、防控等方面阐述了牛流行热的研究进展,旨在为该病的深入研究提供参考.     

Genetic and antigenic analysis of Chlamydia pecorum strains isolated from calves with diarrhea

Chlamydia pecorum (designated 22–58) was isolated in 2010 in HmLu-1 cells from the jejunum of a calf which died of necrotizing enterocolitis in Yamaguchi Prefecture, Japan. Immunohistochemical staining identified C. pecorum positive reactions in the jejunal villi. C. pecorum, designated 24–100, was isolated from the feces of a calf with diarrhea in another farm in Yamaguchi Prefecture in 2012. A significant increase in neutralizing antibody titers against C. pecorum was confirmed in paired sera. Nucleotide sequence identities of omp1 genes of the 2 isolates were 100%. The isolates were genetically and antigenically more closely related to C. pecorum Bo/Yokohama strain isolated from cattle with enteritis in Japan than to the other prototype strains, Bo/Maeda isolated from cattle with pneumonia and Ov/IPA isolated from sheep with polyarthritis. These results indicate that C. pecorum strains similar to 22–58 and 24–100 might be endemic in Yamaguchi Prefecture and cause enteric disease in cattle.     

Viruses isolated from Culicoides midges in South Africa during unsuccessful attempts to isolate bovine ephemeral fever virus

Five viruses, unrelated to bovine ephemeral fever virus (BEFV), were isolated from Culicoides biting-midges collected during the summer months of the years 1968-69 and 1969-70 near a cattle herd in which cases of BEF occurred and at an open horse stable at Onderstepoort. These viruses were investigated by means of serological, electron-microscopical and physicochemical tests. It was established that 2 isolates, Cul. 1/69 and Cul. 2/69, were related to each other and belonged to the Palyam subgroup of the genus Orbivirus, that isolate Cul. 3/69 belonged to the equine encephalosis subgroup of the genus Orbivirus, while Cul. 1/70 was related to Akabane virus, which belongs to the Simbu subgroup of the family Bunyaviridae. One isolate, Cul. 5/69, though prevalent in the cattle population, could not be identified at this point. A brief serological survey indicated that the cattle in the nearby herd possessed antibodies against all the isolates except Cul. 3/69. BEFV could not be isolated in mice or in cultured cells from the wild-caught Culicoides.     

A comparison of the epidemiology of bovine ephemeral fever in South Korea and south-western Japan

SUMMARY Bovine ephemeral fever (BEF) outbreaks were investigated in South Korea and Japan from 1953 to 1991, retrospectively. The epidemics occurred contemporaneously several times; particularly, those of 1988 and 1991. The initial outbreaks in the Fukuoka Prefecture, Japan, in 1988 and 1991 occurred about 1 month after those in Korea. Meteorological analysis showed that a low-level jet stream through Jeonnam Province in Korea struck the Fukuoka Prefecture of Japan during the epidemic. The BEF epidemics of Fukuoka Prefecture may have originated from infected vectors carried on the low-level jet stream.     

Bovine ephemeral fever in Taiwan.

Bovine ephemeral fever (BEF) is a vector-borne disease of cattle, spanning tropical and subtropical zones of Asia, Australia, and Africa, caused by Ephemerovirus of the Rhabdoviridae. Taiwan has had 3 BEF epizootics, occurring in 1989, 1996, and 1999, since the vaccination regimen was initiated in 1984, given once a year in the spring with a single-dose formaldehyde-inactivated vaccine using the 1983 isolate as the seed virus. This study evaluated the 1999 population immunity against BEF virus in Taiwanese dairy cows with a neutralization test and whether the recent BEF virus isolates have mutated significantly from the vaccine virus. In March 1999, before vaccination, 94% of the animals studied were already seropositive, suggestive of an endemic or persistent infection from the previous year. By June 1999, when 51% of herds had been vaccinated, the antibody level rose, and by September 1999, the serum-neutralizing antibody (SNA) level fell to a minimum, preceding the outbreak of BEF in October 1999, during which the antibody levels of vaccinated cows continued to decline while those of unvaccinated cows rose sharply. The results suggest that, in 1999, vaccine-induced immunity was partially protective against BEE Because the current single-dose vaccination regimen resulted in minimal population immunity by September, a booster vaccination given in late summer may be advisable for future disease control. Analysis of the glycoprotein gene of Taiwanese isolates between 1983 and 1999 showed a 97.4-99.6% homology, with an alteration of 4 amino acids in antigenic sites G1, G3b, and G3c. Phylogenetic analysis of Taiwanese isolates revealed at least 2 distinct clusters: the 1983-1989 isolates and the 1996-1999 isolates. Both were distinct from 2 Japanese strains and the Australian BB7721 strain. Thus, at least 2 distinct BEF viruses, which had diverged before 1983, existed in Taiwanese dairy cows.     

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.     

Retrospective epidemiological investigation of an outbreak of bovine ephemeral fever in 1991 affecting dairy cattle herds on the Mediterranean coastal plain

From August to October 1991 bovine ephemeral fever (BEF) occurred sporadically in two localities in Israel. The morbidity and mortality rates reached 2.6% and 0.1%, respectively. Only 12/50 dairy cattle herds were clinically infected with BEF in the dairy community. The total morbidity rate reached 0.8%. The lowest morbidity rate was recorded in young heifers (5.5%) and the highest in adult cows (75%). Only heifers over the age of three months were clinically affected. The spread of the disease apparently followed the local prevailing night winds, which blow from east to west, i.e., from the land toward the sea. The morbidity period lasted 61 days. The low incidence and morbidity rates were possibly due to the low virulence of the virus strain involved in the 1991 epidemic. Retrospective analysis indicates that vectors - apparently mosquitoes - infected with BEF virus could have been overwintering.     

Genetic and pathogenic characterization of Akabane viruses isolated from cattle with encephalomyelitis in Korea

A large-scale outbreak of Akabane viral encephalomyelitis in cattle was reported in the southern part of Korea in 2010. Fifteen Akabane virus (AKAV) strains were isolated from the brain and spinal cord samples by using BHK-21 and/or HmLu-1 cells. To examine the genetic relationships and characteristics of the isolates, nucleotide sequences of the S, M, and L segments of the 15 isolates were determined and analyzed. Complete sequence analysis of the 15 AKAV isolates showed 99.9-100% amino acid identities, indicating that the 15 isolates originated from a single strain. The S and M RNA segments of a representative isolate (AKAV-7/SKR/2010) were also compared with the segments of representative reference sequences. This AKAV-7/SKR/2010 strain showed the highest identity with the Iriki and KM-1/Br/06 strains. Neighbor-joining phylogenetic trees of S and M RNA segments were constructed. Four representative AKAV isolates were classified into subgroup Ia, which contains the Iriki and KM-1/Br/06 strains recognized to cause encephalomyelitis in calves and adult cattle in Japan. Moreover, experimental intraperitoneal infection was performed using the AKAV-7/SKR/2010 and AKAV-17/SKR/2010 strains to assess pathogenesis in suckling mice. The 2 isolates, genetically related to the Iriki strain, were neurovirulent and caused neurological signs in suckling mice. In contrast, the 93FMX strain and the K0505 strain, related to the OBE-1 strain, were avirulent in mice. The present results indicate that these isolates most likely had originated from the Iriki strain and are closely related to the Iriki strain both genetically and pathogenically.     

徐州地区牛流行热病毒的分离与鉴定

1991年夏秋之交徐州市各奶牛场暴发牛流行热。为确诊该病,采集了发病高热期抗凝血,进行了病毒分离和鉴定试验。病料经处理后,直接接种于BHK_21细胞,传至第二代可见典型的CPE。电镜下观察到80—150nm弹状病毒颗粒。分离毒的理化特性、核酸类型及中和试验结果均与标准BEFV相一致,证实该分离病毒为牛流行热病毒。     

牛流行热病的诊治

牛流行热(又名三日热)是由牛流行热病毒(Bovine Ephemeral Fever Virus,BEFV,又名牛暂时热病毒)引起的一种急性热性传染病。其特征为突然高热,呼吸促迫,流泪和消化器官的严重卡他炎症和运动障碍。感染该病的大部分病牛经2~3日即恢复正常,故又称三日热或暂时热。该病病势迅猛,但多为良性经过。过去曾将该病误认为是流行性感冒。该病能引起牛大群发病,明显降低乳牛的产乳量。     

The effect of anti-inflammatory agents on the clinical expression of bovine ephemeral fever

The effect of two anti-inflammatory drugs on the development and persistence of clinical signs in cattle experimentally infected with bovine ephemeral fever (BEF) virus was investigated by their administration, either before or after the commencement of fever. A total of 16 cattle was given phenylbutazone sodium (PBZ). The drug prevented fever and other clinical signs in six cattle when given daily during the incubation period, and at 8-h intervals for 5 days when clinical disease might be expected. When treatment with PBZ was deferred until 2-4 h after the commencement of fever, the rectal temperature returned to normal within 4 h in four of six cattle and the development of other clinical signs was suppressed. Clinical signs of ephemeral fever occurred in four untreated cattle infected at the same time. Viraemia, the development of neutralizing antibodies (at 8-11 days), resistance to subsequent challenge with BEF virus, neutrophilia, lymphopenia and a rise in plasma fibrinogen occurred in all BEF-infected animals whether treated or untreated, despite different clinical appearances. The mean peak of plasma fibrinogen in the untreated cattle was 6.9 g l-1; 3.2 g l-1 when treated 2-4 h after fever developed and 3.8 g l-1 when treated from 18-h post-infection. BEF virus was isolated from leucocytes of each of the cattle, but the frequency of isolation was lower in the treated group. The results indicate that treatment with PBZ blocked the host response which produces the clinical signs and did not have an anti-viral effect. In a similar experiment, a long-acting anti-inflammatory drug, flunixin meglumine, failed to prevent BEF or to modify the clinical signs once they had developed, except for the rectal temperature which returned to normal within 2-4 h of the administration of the drug. The efficacy of this drug was not improved by increasing the dosage to two or three times the recommended level.     

LABORATORY AND FIELD STUDIES WITH A BOVINE EPHEMERAL FEVER VACCINE

Bovine ephemeral fever (BEF) virus vaccines, prepared from the brains of suckling mice infected with strain 525 BEF virus, were evaluated in housed cattle and in the field. The virus in lyophilised preparations was stable for 6 months at -50 degrees C. Thirty-four calves, 5 to 18 months old, were used in laboratory vaccination trials. An increase in serum neutralising antibody was detected in 13 of 14 calves initially free of serum antibody, and all 13 failed to develop clinical illness following challenge with virulent BEF virus. Vaccination resulted in no detectable serum antibody increase in 4 calves, 5 months old, with pre-existing antibody of presumed maternal origin. Seven animals, 18 months of age with serum antibody presumed due to previous BEF infection, developed increased antibody titres following vaccination. In 3 animals vaccinated but not challenged, vaccine-induced antibodies decreased to low levels over 5 months. In contrast, the antibody titres following infection with virulent virus in 2 calves were maintained over 5 months. Field trials, involving 236 animals initially free of serum antibody, were conducted on 5 properties near Mackay and 4 properties near Brisbane. Most of 164 animals were vaccinated with a single dose of lyophilised vaccine containing aluminium hydroxide adjuvant. Only 4 animals failed to develop serum antibody and no adverse reactions to vaccination were reported. Natural infection with BEF occurred in 4 herds at Mackay and clinically mild BEF occurred in 3 of 109 vaccinated and 3 of 46 control animals. On the basis of measured serum antibody titres it was assumed that 8 of 53 animals receiving full vaccine volume, 20 of 40 animals receiving half vaccine volume and 18 of 40 control animals became infected with BEF virus. Two dairy herds in Brisbane became naturally infected with virulent BEF virus 7 months after vaccination. Clinical BEF was observed in 8 of 11 control animals and in 3 of 26 animals which received 2 doses of vaccine. Two strains of BEF virus were isolated from unvaccinated animals that developed clinically mild BEF in the field. These strains either failed to infect, or produced subclinical or very mild BEF, when inoculated intravenously into susceptible calves. The anitbody response to natural infection with apparently mild viruses was short-lived, similar to that produced by vaccination.     

Isolation of Fukuoka virus, a member of the Kern Canyon serogroup viruses of the family Rhabdoviridae, from cattle.

Four virus strains with identical antigenic properties were isolated from blood samples of 4 sentinel calves having a fever and leukopenea in cultures of HmLu-1 cells derived from baby hamster lung. The virus was identified as Fukuoka virus, classified as a member of the Kern Canyon serogroup viruses of the family Rhabdoviridae, on the basis of its antigenic properties.     

Antigenic diversity of bovine viral diarrhea-mucosal disease (BVD-MD) viruses recently isolated from persistently infected cattle and mucosal disease, and serologic survey on bovine sera using antigenically different BVD-MD viruses

Twenty nine recent isolates of bovine viral diarrhea-mucosal disease (BVD-MD) virus, 17 from persistently infected cattle and 12 from mucosal disease, were compared antigenically with the reference strains by a serum neutralization test. The reference viruses were divided into 2 groups, tentatively designated as N and K, based on the antigenic relationships in the cross-neutralization test. Antigenic properties of recent isolates were considerably different with the sources of virus isolation. Seventeen isolates recovered from persistently infected cattle were divided into 3 groups in the neutralization test using antisera to the reference strains; 12 and 2 were considered as the possible members of groups K and N, respectively, and the others belonged to neither group. On the other hand, 10 of 12 isolates recovered from mucosal disease were considered as the possible members of group N, and the others were classified into neither group. Interestingly, none of BVD-MD viruses isolated from cases of mucosal disease belonged to group K. The results of serologic survey on sera collected from 713 cattle at the Hokkaido provinces in 1974 to 1988 indicated that infections of cattle with BVD-MD viruses other than group K were prominent before 1981. Cattle infected with group K BVD-MD virus were first detected in 1982, and increased in number thereafter. The results obtained in this study suggested that BVD-MD viruses with various antigenic properties spread widely among cattle herds, and also a possibility that clinical manifestations in cattle infected with BVD-MD viruses may differ with their antigenic properties.     

Complete genome sequencing and assessment of mutation-associated protein dynamics of the first Indian bovine ephemeral fever virus (BEFV) isolate

BackgroundBovine ephemeral fever (BEF) is a re-emerging disease caused by bovine ephemeral fever virus (BEFV). Although it poses a huge economic threat to the livestock sector, complete viral genome information from any South Asian country, including India, lacks.AimGenome characterization of the first Indian BEFV isolate and to evaluate its genetic diversity by characterizing genomic mutations and their associated protein dynamics.Materials and MethodsOf the nineteen positive blood samples collected from BEF symptomatic animals during the 2018-19 outbreaks in India, one random sample was used to amplify the entire viral genome by RT-PCR. Utilizing Sanger sequencing and NGS technology, a complete genome was determined. Genome characterization, genetic diversity and phylogenetic analyses were explored by comparing the results with available global isolates. Additionally, unique genomic mutations within the Indian isolate were investigated, followed by in-silico assessment of non-synonymous (NS) mutations impacts on corresponding proteins’ secondary structure, solvent accessibility and dynamics.ResultsThe complete genome of Indian BEFV has 14,903 nucleotides with 33% GC with considerable genetic diversity. Its sequence comparison and phylogenetic analysis revealed a close relatedness to the Middle Eastern lineage. Genome-wide scanning elucidated 30 unique mutations, including 10 NS mutations in the P, L and G_NS proteins. The mutational impact evaluation confirmed alterations in protein structure and dynamics, with minimal effect on solvent accessibility. Additionally, alteration in the interatomic interactions was compared against the wild type.ConclusionThese findings extend our understanding of the BEFV epidemiological and pathogenic potential, aiding in developing better therapeutic and preventive interventions.     

Isolation of bovine adenovirus type 4 from cattle in Oregon.

Four isolates of bovine adenovirus type 4 were recovered from Oregon cattle. One isolate was recovered from a 1-week-old calf with pneumoenteritis, and 1 isolate from an 8-month-old bull with fever and respiratory disease. Two isolates were recovered as latent viruses in testicular cell cultures. All 4 isolates of the virus were shown to have certain physical, chemical, biologic, and antigenic characteristics similar to previously described strains of bovine adenovirus type 4. Of 246 adult beef and dairy cattle in Oregon, 51% had serum-viral neutralizing antibodies to the type 4 virus at the 1:8 dilution level.     

An epizootic of bovine ephemeral fever in New South Wales in 2008 associated with long-distance dispersal of vectors

Objective To report the rapid transmission of bovine ephemeral fever ( BEF) virus from north-western New South Wales south to the Victorian border in January 2008 and to present data that suggests an uncommon meteorological event caused this rapid southward dispersal of vectors. Procedure The locations of reported clinical cases, data from sentinel herds and results from a survey of cattle in the southern affected area were examined to delineate the distribution of virus transmission. Synoptic weather charts for January 2008 were examined for meteorological conditions that may have favoured movement of vectors in a southerly direction. Results Cases of BEF and exposure to BEF virus in NSW were confirmed west of the Great Dividing Range, extending from the Queensland border to Finley, on the far North Coast and around the Hunter Valley. A low-pressure system moved south across the state on 18–19 January 2008, preceding the first cases of BEF in the south of NSW by 1–2 days. Conclusion Heavy rainfall in December 2007 provided a suitable environment for vector breeding, resulting in the initiation of and support for continuing BEF virus transmission in north-western NSW. The movement of a low-pressure system south across central western NSW in mid-January 2008 after the commencement of BEF virus transmission in the north-west of the state provided a vehicle for rapid southward movement of infected vectors.     

Transmission of virus from serosal fluids and demonstration of antigen in neutrophils and mesothelial cells of cattle infected with bovine ephemeral fever virus

Following intravenous injection of bovine ephemeral fever (BEF) virus 6 cattle were autopsied after clinical disease became evident. Fluid from serosal cavities with serofibrinous inflammatory changes showed large increases in neutrophil numbers. BEF virus was detected for the first time in pericardial, thoracic and abdominal fluids. Virus was also detected in synovial fluids, confirming an earlier report of transmission with a synovial fluid sample. Using a direct fluorescent antibody technique, BEF virus antigen was identified for the first time in synovial, pericardial, thoracic and abdominal fluids, in synovial membranes and epicardium. In synovial membranes and epicardium, specific fluorescence was observed in two cell types, mesothelial cells and neutrophils. In the fluids, fluorescence was restricted to neutrophils, the predominant cell type. Specific fluorescence was observed in blood smears from only one animal although blood samples collected at autopsy from all animals contained infective virus.