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

Risk analysis and seroprevalence of bovine ephemeral fever virus in Punjab, Pakistan

Bovine ephemeral fever (BEF) is a vector-borne viral disease caused by the RNA virus which belongs to the genus Ephemerovirus and the family Rhabdoviridae. To evaluate the effect of the risk factors like the breed of cattle and buffaloes, age, sex, lactation, housing and region on the bovine ephemeral fever virus (BEFV) prevalence, ELISA and virus neutralisation (VN) tests (n = 600) were performed for the BEFV prevalence. The seroprevalence in cattle was 45.6% and 42% by ELISA and VN, respectively (P = 0.001). The breed-wise seropositive ratio was (55-64%) in cattle and (22.5-18.3%) in buffaloes by VN and ELISA. The sex-wise prevalence was (40-49.4%) in females and (35.8-46%) in males by VN and ELISA in cattle and a similar prevalence was reported in buffaloes. The age-wise prevalence in bovines by ELISA was 5.33, 22.66 and 17.66% in the age group < 1 year, 1-3 years and > 3 years, respectively. The disease prevalence was higher in the age group of 1-3 years. The prevalence was higher during the 3rd lactation in bovines. The region-wise prevalence was higher in the 07 districts while lower (18-21%) in Rawalpindi District by VN and ELISA, respectively (P = 0.001). Commercial dairy farms of cattle showed a higher disease prevalence (52% and 44%) than non-commercial farms (38% and 36%) by ELISA and VN, respectively (P = 0.227). Exotic cows showed higher disease prevalence (76.67% and 70%) by ELISA and VN. The mortality in bovines was 5% (7.7% and 2.3%) in the cattle and buffaloes. The case fatality of BEFV in bovines was 12.25%. There was a significant effect of the risk factors like the breed, age, sex, lactation, housing and region on the BEFV prevalence. This is the first comprehensive study of BEFV in Pakistan.

Whole genome characterization and evolutionary analysis of bovine ephemeral fever virus isolated in Iran

Bovine ephemeral fever virus (BEFV) is an economically important arthropod-borne virus of cattle and water buffaloes which is enzootic in Africa, Australia, and Asia. We characterized the entire length of BEFV BA/RZ/IR strain genome isolated in Iran and compared to the all BEFV full genomes available in the GenBank. The BEFV genomes were phylogenetically classified as 4 lineages including the Middle Eastern, East Asian, Australian, and South African lineages. The Iranian BA/RZ/IR strain, which displayed maximum sequence identity (96.72%) to the Chinese JT02L strain was clustered as a separate branch in the East Asian lineage of the virus. Using Shannon entropy analysis, amino acid variations were detected in the all proteins encoded by BEFV genomes. Particularly, the polymerase L and the accessory proteins Gns, α2 and β exhibited the highest amino acid variations suggesting their significance in the viral replication efficiency. Our bioinformatics analyses also predict the occurrence of recombination event within the East Asian lineage of BEFV genomes. Our data show that the Chinese Henan 1 may be a hybrid strain constructed of the Chinese JT02L and Iranian BA/RZ/IR BEFV strains as the major and minor parents, respectively. These computational analyses suggest that the homologous recombination may be an evolutionary mechanism for BEFV as a member of the Rhabdoviridae family.

Emergence and genomic analysis of a novel sublineage of bovine ephemeral fever virus in Southwest China

Introduction

Bovine ephemeral fever virus (BEFV), belonging to the genus Ephemerovirus under the family Rhabdoviridae, is the etiological cause for the bovine ephemeral fever (BEF) in cattle and water buffalo.

Methods

In this study, we report recent BEF outbreaks in Southwest China and sequence the complete genome sequence of one BEFV isolate BEFV/CQ1/2022.

Results and Discussion

Comparative genomic analyses between BEFV/CQ1/2022 and isolates available in GenBank revealed remarkable inter-isolate divergence. Meanwhile, the sequence divergence was related to the evolutionary relationships and geographical distribution of the isolates. Phylogenetic analysis indicated that the global BEFV isolates can be divided into 4 distinct lineages. The East Asia lineage was the most diverse and could be subdivided into 4 sublineages. Notably, BEFV/CQ1/2022 and other 10 recent isolates from Mainland China were found to be clustered in sublineage 2. Additionally, recombination analysis provided evidence of BEFV recombination among East Asian isolates for the first time. Taken together, a novel sublineage of the East Asian BEFV emerged in Southwest China, and large divergence and potential recombination among BEFV strains were investigated in this study, which may improve understanding of BEFV epidemiology and evolution.

Development and validation of a DIVA ELISA for differentiating BEFV infected from vaccinated animals

Inactivated vaccine is considered safe and used for prevention of bovine ephemeral fever in several endemic countries. To differentiate between BEFV-infected and vaccinated animals, we developed an ELISA capable of detecting infection-related antibodies against BEFV. Recombinant proteins, including N, P, M, L, G_NS, α2, β and γ, were expressed in E. coli and screened by Western blotting and ELISA. The results showed G_NS, α2 and β specifically reacted with sera from BEFV infected cattle but not sera from vaccinated cattle. A DIVA ELISA based on a C-terminal truncated form of G_NS was developed, with 100% sensitivity and 98.0% specificity at a sample to positive-control optical density ratio (S/P) threshold of 0.18. Specificity analysis showed that the assay has no cross-reactivity with antisera of other common bovine viruses. Anti-G_NS antibody appears at 3-4 days post infection (dpi) and persists up to 240-300 dpi in the experimentally infected cattle. Sero-epidemiological survey using sera collected from vaccinated cattle in an endemic area in Jiangsu Province revealed sero-positive rate of 2.36% (6/254), indicating that the DIVA ELISA could be used as a reliable diagnostic tool for differentiating BEFV infected from vaccinated animals.

Identification of Cytotoxic T lymphocyte (CTL) Epitope and design of an immunogenic multi-epitope of Bovine Ephemeral Fever Virus (BEFV) Glycoprotein G for Vaccine Development

Bovine ephemeral fever (BEF), a vector-borne disease of cattle and water buffalo, is enzootic in tropical and subtropical zones of Asia, Australia, and Africa. Since cytotoxic T lymphocytes (CTL) responses may play a key role in the control of bovine ephemeral fever virus (BEFV) infection, it is important to identify and characterize the CTL target epitopes of BEFV antigens. The current study has been designed to identify and characterize the potential CTL epitopes using the Immuno-informatics tools, and it helped find the potent vaccine candidates against BEF. Antigenicity, toxicity, allergenicity, and immunogenicity testing of predicted CTL epitopes was done. Total four CTL epitopes for BEFV G protein, have been identified as potential epitopes. Prediction of the 3D structure of multi-epitope (final structure) was performed using I-TASSER server. Model 1 was selected as the best model with C-Score: -3.71. The modeled G protein structure and multi-epitope structure were validated by the Ramachandran plots Prosa and Verify 3D server. Epitopic regions of 3D protein structure were identified by Chimera UCSF software. Physicochemical properties of the Multi epitope were evaluated using ProtParam server. This is the first report of CTL epitope in the G protein of BEFV. In this manner, they would play an important role in evoking the immune response as well as vaccine development. However, in vitro and in vivo experimental studies are required for suggested epitopes verification. The multi-epitope was designed from regions of the G protein sequence that lacked mutation and genomic diversity. Therefore, it can be introduced as a protein vaccine from all strains of BEFV as a vaccine candidate for design.

Genomic Analysis Illustrated a Single Introduction and Evolution of Israeli Bluetongue Serotype 8 Virus Population 2008-2019

Outbreaks of the European Bluetongue virus (BTV) serotype 8 (BTV-8), which are characterized by activity cycles separated by years of inactivity, may be influenced by genetic changes of the virus or by herd immunity. BTV activity in Israel is characterized by similar dynamics, but differs from European countries in its vector population, environmental conditions, and lack of cattle vaccination against this serotype. Comparison of these two geographical systems and characterization of their epidemiological connection is therefore of high interest in-order to better understand the factors influencing BTV-8 evolution. BTV-8, closely related to the European strain, was introduced to Israel in 2008. It was at the center of BT outbreaks in 2010 and 2015–2016 and thereafter was lastly isolated in Israel in 2019. We performed genetic analyses of twelve BTV-8 Israeli strains isolated between 2008 and 2019 and compared them with published sequences of BTV-8 isolated in other countries. The analysis revealed a single introduction of BTV-8 into Israel and thereafter extensive occurrence of genomic drifts and multiple reassortments with local BTV strains. Comparison of the Israeli and Cypriot BTV-8 from 2015 to 2016 suggests transmission of the virus between the two countries and a separate and parallel development from European or other Israeli BTV-8 strains. The parallel development of other BTV-8 strains was demonstrated by the identification of the Israeli BTV-8 ISR-1194/1/19 strain, which exhibited common origin with reassorted Israeli BTV-8 strains from 2010 and additional reassortment of seven segments. In order to reveal the source of BTV-8 introduction into Israel we performed BEAST analysis which showed that a probable common ancestor for both European and Israeli BTV-8 presumably existed in 2003–2004. In 2019, a possible new introduction occurred in Israel, where a novel BTV-8 strain was detected, sharing ~95% identity by segments 2 and 6 with Nigerian BTV-8NIG1982/07 and European–Middle Eastern strains. The results of the study indicate that Israel and neighboring countries consist a separate environmental and evolutionary system, distinct from European ones.

The role of wildlife in the epidemiology and control of Foot-and-mouth-disease And Similar Transboundary (FAST) animal diseases: A review

Transboundary Animal Diseases (TADs) are notifiable diseases which are highly transmissible and have the potential for rapid spread regardless of national borders. Many TADs are shared between domestic animals and wildlife, with the potential to affect both livestock sector and wildlife conservation and eventually, public health in the case of zoonosis. The European Commission for the Control of Foot-and-Mouth Disease (EuFMD), a commission of the Food and Agriculture Organization of the United Nations (FAO), has grouped six TADs as 'Foot-and-mouth disease (FMD) And Similar Transboundary animal diseases' (FAST diseases). FAST diseases are ruminant infections caused by viruses, for which vaccination is a control option. The EuFMD hold-FAST strategy aims primarily at addressing the threat represented by FAST diseases for Europe. Prevention and control of FAST diseases might benefit from assessing the role of wildlife. We reviewed the role of wildlife as indicators, victims, bridge hosts or maintenance hosts for the six TADs included in the EuFMD hold-FAST strategy: FMD, peste des petits ruminants, lumpy skin disease, sheep and goatpox, Rift Valley fever and bovine ephemeral fever. We observed that wildlife can act as indicator species. In addition, they are occasionally victims of disease outbreaks, and they are often relevant for disease management as either bridge or maintenance hosts. Wildlife deserves to become a key component of future integrated surveillance and disease control strategies in an ever-changing world. It is advisable to increase our knowledge on wildlife roles in relevant TADs to improve our preparedness in case of an outbreak in previously disease-free regions, where wildlife may be significant for disease surveillance and control.

Isolation and genetic characterization of bovine ephemeral fever virus from epidemic-2020 in Turkey

Bovine ephemeral fever virus (BEFV) infection occurs seasonally in many tropical and subtropical regions of Africa, Asia (including the Middle East), and Australia while it is exotic in Europe. In this study, the epidemiology of BEFV infection in Turkey that bridges southeastern Europe and Asia, geographically, was investigated according to the comparison of the nucleotide sequences of the virus caused the last epidemic in 2020 with those of the strains previously detected in Turkey as well as BEFV strains from other countries. In the phylogenetic analysis, based on an alignment of full-length G gene sequences, BEFVs from epidemic-2020 were located in Middle Eastern lineage and appear to represent most closely related BEFVs from India-2018 and 2019. The findings will contribute to a better understanding of BEFV epidemiology in Turkey.

Endemic and Emerging Arboviruses in Domestic Ruminants in East Asia

Epizootic congenital abnormalities caused by Akabane, Aino, and Chuzan viruses have damaged the reproduction of domestic ruminants in East Asia for many years. In the past, large outbreaks of febrile illness related to bovine ephemeral fever and Ibaraki viruses severely affected the cattle industry in that region. In recent years, vaccines against these viruses have reduced the occurrence of diseases, although the viruses are still circulating and have occasionally caused sporadic and small-scaled epidemics. Over a long-term monitoring period, many arboviruses other than the above-mentioned viruses have been isolated from cattle and Culicoides biting midges in Japan. Several novel arboviruses that may infect ruminants (e.g., mosquito- and tick-borne arboviruses) were recently reported in mainland China based on extensive surveillance. It is noteworthy that some are suspected of being associated with cattle diseases. Malformed calves exposed to an intrauterine infection with orthobunyaviruses (e.g., Peaton and Shamonda viruses) have been observed. Epizootic hemorrhagic disease virus serotype 6 caused a sudden outbreak of hemorrhagic disease in cattle in Japan. Unfortunately, the pathogenicity of many other viruses in ruminants has been uncertain, although these viruses potentially affect livestock production. As global transportation grows, the risk of an accidental incursion of arboviruses is likely to increase in previously non-endemic areas. Global warming will also certainly affect the distribution and active period of vectors, and thus the range of virus spreads will expand to higher-latitude regions. To prevent anticipated damages to the livestock industry, the monitoring system for arboviral circulation and incursion should be strengthened; moreover, the sharing of information and preventive strategies will be essential in East Asia.

South African bovine ephemeral fever virus glycoprotein sequences are phylogenetically distinct from those from the rest of the world

Bovine ephemeral fever virus (BEFV) is an economically important arbovirus affecting cattle and water buffalo. Currently, isolates can be separated into three phylogenetic groups, differentiated by the place of isolation, namely, East Asia, Australia, and the Middle East. BEFV surface glycoprotein (G) genes from 14 South African field strains collected between 1968 and 1999 were sequenced and compared to 154 published sequences. The BEFV isolates from South Africa were found to be phylogenetically distinct from those from other parts of the world.

Prevalence and risk factors of some arthropod-transmitted diseases in cattle and sheep in Jordan

Aims:

The objectives of this study were to determine the prevalence and associated risk factors of bluetongue virus (BTV) in sheep and bovine ephemeral fever virus (BEFV) in dairy cattle in Jordan.

Materials and Methods:

A simple randomized study was designed to collect 600 serum samples from sheep and 300 serum samples from dairy cattle located in the Northwestern parts of Jordan. In addition, data regarding farm management were collected using a pre-tested questionnaire through personal interview to determine potential risk factors. The seroprevalences of BEF and BTVs were determined using serum neutralization test and BTV group-specific competitive enzyme-linked immunosorbent assay, respectively.

Results:

The overall seroprevalence of neutralizing antibodies against BEFV in dairy cattle was 45.37%. The overall seroprevalence of BTV group-specific antibodies in sheep was 47.8% (54% true seroprevalence). Logistic regression analysis identified geographic location (Irbid) (odds ratio [OR]=1.0; confidence interval [CI]=0.5-2.1), no use of disinfectants on the farm (OR=1.0; CI=0.05-0.1), and lack of veterinary services (OR=10; CI=3.5-13.2) as risk factors associated with high seropositivity against BTV in sheep. Geographic location (Jarash) (OR=3; CI=1.0-5.5), age of the animal (1-2 years of age (OR=1; CI=0.3-1.9), and lack of veterinary services (OR=9; CI=4-11) were identified as risk factors associated with high seroprevalence against BEFV in dairy cattle.

Conclusion:

Results of this study indicate that BEFV in dairy cattle and BTV in sheep are endemic in Northwestern regions of Jordan. Implementation of appropriate control measures is, therefore, required to reduce the adverse effects of these diseases on animal health and productivity.

Bovine Ephemeral Fever in Asia: Recent Status and Research Gaps

Bovine ephemeral fever is an arthropod-borne viral disease affecting mainly domestic cattle and water buffalo. The etiological agent of this disease is bovine ephemeral fever virus, a member of the genus Ephemerovirus within the family Rhabdoviridae. Bovine ephemeral fever causes economic losses by a sudden drop in milk production in dairy cattle and loss of condition in beef cattle. Although mortality resulting from this disease is usually lower than 1%, it can reach 20% or even higher. Bovine ephemeral fever is distributed across many countries in Asia, Australia, the Middle East, and Africa. Prevention and control of the disease mainly relies on regular vaccination. The impact of bovine ephemeral fever on the cattle industry may be underestimated, and the introduction of bovine ephemeral fever into European countries is possible, similar to the spread of bluetongue virus and Schmallenberg virus. Research on bovine ephemeral fever remains limited and priority of investigation should be given to defining the biological vectors of this disease and identifying virulence determinants.

Endemic and emerging arboviral diseases of livestock in Nigeria: a review

Arthropod-borne viruses (arboviruses) are the largest biologic group of vertebrate viruses and constitute important emerging infectious disease agents globally. Arthropod transmission provides a way for viruses to cross species barriers since the same arthropod may bite animals that rarely or never come into close contact in nature. In Nigeria, arboviruses have, over several decades, caused severe diseases in livestock resulting in great economic losses and, sometimes, infection of humans leading to morbidity and mortality. In the present review, a computerized search of existing literature was conducted using the Google search engine and PubMed electronic database to identify and review relevant publications on arboviral diseases of livestock in Nigeria. The keywords used were 'arbovirus', 'arthropod-borne viral diseases' or 'livestock diseases' and 'Nigeria' while the Boolean operator 'OR' was used to combine and narrow the searches. Additional information was obtained by searching the veterinary libraries for journals not listed in the database. The available publications were thereafter reviewed and findings qualitatively described. Our findings revealed that although there were several studies on arboviruses and the livestock diseases they cause in Nigeria, most of such reports were made four to six decades ago, with only a few reported recently. Consequently, the true economic and public health impact of these diseases are likely to be underestimated, mainly due to under-reporting or lack of awareness of them. Thus, it is essential to update information on arboviral diseases in Nigeria in order to increase awareness of the diseases and facilitate their prompt identification and reporting. The importance of routine surveillance for arbovirus livestock diseases and sentinel herd monitoring as basis for development of an early warning and alert system to prevent future outbreaks is discussed.

Source-receptor probability of atmospheric long-distance dispersal of viruses to Israel from the eastern Mediterranean area

Viruses that affect the health of humans and farm animals can spread over long distances via atmospheric mechanisms. The phenomenon of atmospheric long-distance dispersal (LDD) is associated with severe consequences because it may introduce pathogens into new areas. The introduction of new pathogens to Israel was attributed to LDD events numerous times. This provided the motivation for this study which is aimed to identify all the locations in the eastern Mediterranean that may serve as sources for pathogen incursion into Israel via LDD. This aim was achieved by calculating source-receptor relationship probability maps. These maps describe the probability that an infected vector or viral aerosol, once airborne, will have an atmospheric route that can transport it to a distant location. The resultant probability maps demonstrate a seasonal tendency in the probability of specific areas to serve as sources for pathogen LDD into Israel. Specifically, Cyprus' season is the summer; southern Turkey and the Greek islands of Crete, Karpathos and Rhodes are associated with spring and summer; lower Egypt and Jordan may serve as sources all year round, except the summer months. The method used in this study can easily be implemented to any other geographic region. The importance of this study is the ability to provide a climatologically valid and accurate risk assessment tool to support long-term decisions regarding preparatory actions for future outbreaks long before a specific outbreak occurs.

Resurgence of bovine ephemeral fever in mainland Japan in 2015 after a 23-year absence

In September and October 2015, suspected cases of bovine ephemeral fever (BEF) were reported in the mainland region of Kagoshima Prefecture and on Tanegashima Island. The genome of the BEF virus (BEFV) was detected in the diseased cows and the cows that had recovered. The serum obtained from the affected cows contained high titers of BEFV-neutralizing antibody. In total, 18 affected cows were demonstrated to be infected with BEFV during the outbreak. Our findings showed evidence that BEF occurred in mainland Japan after a 23-year absence. Phylogenetic analysis based on the surface glycoprotein (G) gene revealed that BEFVs detected in the affected cows were genetically distinct from previous Japanese BEFVs, but were close to BEFVs circulating in Taiwan and mainland China in recent years. Amino acid substitution in the neutralizing epitope domains of the G protein was limited between the detected viruses and the vaccine strain (YHL isolate), and high titers of the neutralizing antibody against the YHL isolate were induced in the infected cattle during the disease occurrences. Therefore, current BEF vaccines probably elicit protective immunity against the BEFVs detected in 2015, although their effectiveness should be assessed. Since the BEFV vaccination rates are estimated to be low, a BEF outbreak should be considered a possibility in mainland Japan.

Monitoring for bovine arboviruses in the most southwestern islands in Japan between 1994 and 2014

Background

In Japan, epizootic arboviral infections have severely impacted the livestock industry for a long period. Akabane, Aino, Chuzan, bovine ephemeral fever and Ibaraki viruses have repeatedly caused epizootic abnormal births and febrile illness in the cattle population. In addition, Peaton, Sathuperi, Shamonda and D’Aguilar viruses and epizootic hemorrhagic virus serotype 7 have recently emerged in Japan and are also considered to be involved in abnormal births in cattle. The above-mentioned viruses are hypothesized to circulate in tropical and subtropical Asia year round and to be introduced to temperate East Asia by long-distance aerial dispersal of infected vectors. To watch for arbovirus incursion and assess the possibility of its early warning, monitoring for arboviruses was conducted in the Yaeyama Islands, located at the most southwestern area of Japan, between 1994 and 2014.

Results

Blood sampling was conducted once a year, in the autumn, in 40 to 60 healthy cattle from the Yaeyama Islands. Blood samples were tested for arboviruses. A total of 33 arboviruses including Akabane, Peaton, Chuzan, D’ Aguilar, Bunyip Creek, Batai and epizootic hemorrhagic viruses were isolated from bovine blood samples. Serological surveillance for the bovine arboviruses associated with cattle diseases in young cattle (ages 6–12 months: had only been alive for one summer) clearly showed their frequent incursion into the Yaeyama Islands. In some cases, the arbovirus incursions could be detected in the Yaeyama Islands prior to their spread to mainland Japan.

Conclusions

We showed that long-term surveillance in the Yaeyama Islands could estimate the activity of bovine arboviruses in neighboring regions and may provide a useful early warning for likely arbovirus infections in Japan. The findings in this study could contribute to the planning of prevention and control for bovine arbovirus infections in Japan and cooperative efforts among neighboring countries in East Asia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0747-z) contains supplementary material, which is available to authorized users.

Experimental infection with bovine ephemeral fever virus and analysis of its antibody response cattle

Bovine ephemeral fever (BEF) is an arthropod-borne viral disease that occurs throughout mainland China. LS11 obtained in the 2011 BEF epidemic was a wild strain, and its virulence and antibody response have never been studied in China. Therefore, the issues were investigated in this work. Experimental cattle were intravenously infected with different doses of BEF virus, and some non-infected cattle were simultaneously monitored. Blood and serum samples were collected from all animals over the course of our study. Infected cattle were challenged for a second time with BEF virus to determine protective period of the antibodies. BEF virus was detected in blood samples from infected cattle, but not in monitored cattle. The neutralizing antibodies (nAbs) against BEFV were easier to be detected and persisted for longer periods in cattle infected with higher doses of BEFV than in those infected with lower doses. When the titer of nAbs was equal to 5 or 6, re-infected cattle still could mount a challenge against BEFV. However, after 3 or 6months, when nAbs were no longer apparent, re-infected cattle displayed typical symptoms of BEF. Our findings indicated that vaccination should be performed once the titer of nAb decreased to 5 or 6.

Risk analysis and seroprevalence of bovine ephemeral fever virus in cattle in the Kingdom of Saudi Arabia

Bovine ephemeral fever virus (BEFV) is an arthropod-borne rhabdovirus that causes disabling clinical signs and major economic losses in cattle and water buffalo. The disease is well documented in Asia, Africa, and the Middle East; however, the seroprevalence of BEFV in different regions and bovine breeds in the Kingdom of Saudi Arabia (KSA) is unknown. The aim of this study was to analyze risk factors which affect the prevalence of antibodies against BEFV in small herds of cattle in four geographical regions of KSA. A total of 1480 serum samples from non-BEFV vaccinated small herds of cattle were collected from the Eastern, Jizan, Qasim, and Riyadh regions (370 samples per region) during the summer of 2010. Serum neutralization test was used to detect antibodies against BEFV. There was a significant effect of region, breed, sex, and age on the seroprevalence of BEFV. Seropositive ratios were 18, 18, 26, and 12 % for the Eastern, Jizan, Qasim, and Riyadh regions, respectively (P = 0.00002); 23.2 % for dairy and 13.7 % for non-dairy breeds (P = 0.00004); 24.4 % for males and 14.6 % for females (P = 0.00004); and 15.4, 29.1, and 11.4 % for animals <1 year, 1-3 years, and >3 years, respectively (P < 0.001). Risk analysis showed a significant effect of different regions of KSA on the seroprevalence of BEFV. Host risk factors (age, sex, and breed) showed also a significant effect on the seroprevalence of BEFV. This indicates active circulation of this virus in small herds of cattle. Insect control strategies and BEFV vaccination programs during the spring are recommended to reduce the spread of BEFV and minimize subsequent economic losses as this is adopted in many enzootic countries.

Invasion of exotic bovine ephemeral fever virus into Taiwan in 2013-2014

Bovine ephemeral fever virus is a member of the family Rhabdoviridae and bovine ephemeral fever has frequently affected cattle population in Taiwan since 1967. During the outbreaks in 2013 and 2014, exotic bovine ephemeral fever viruses were detected by reverse transcription polymerase chain reaction and nucleotide sequencing. Sequence comparison showed that the exotic viruses shared 99.0-99.4% nucleotide identities (99.4-100.0% amino acid identities) with Chinese viruses and, on the contrary, 96.2-97.2% nucleotide identities (97.8-98.6% amino acid identities) with indigenous Taiwanese viruses. Additionally, our phylogenetic analysis also supported that the newly invaded bovine ephemeral fever viruses were closely related to the Chinese strains. These exotic 2013-2014 viruses have become prevalent and displaced indigenous virus strains since their appearance.

Epidemiology and control of bovine ephemeral fever

Bovine ephemeral fever (or 3-day sickness) is an acute febrile illness of cattle and water buffaloes. Caused by an arthropod-borne rhabdovirus, bovine ephemeral fever virus (BEFV), the disease occurs seasonally over a vast expanse of the globe encompassing much of Africa, the Middle East, Asia and Australia. Although mortality rates are typically low, infection prevalence and morbidity rates during outbreaks are often very high, causing serious economic impacts through loss of milk production, poor cattle condition at sale and loss of traction power at harvest. There are also significant impacts on trade to regions in which the disease does not occur, including the Americas and most of Europe. In recent years, unusually severe outbreaks of bovine ephemeral fever have been reported from several regions in Asia and the Middle East, with mortality rates through disease or culling in excess of 10–20%. There are also concerns that, like other vector-borne diseases of livestock, the geographic distribution of bovine ephemeral fever could expand into regions that have historically been free of the disease. Here, we review current knowledge of the virus, including its molecular and antigenic structure, and the epidemiology of the disease across its entire geographic range. We also discuss the effectiveness of vaccination and other strategies to prevent or control infection.

Using Synoptic Systems' Typical Wind Trajectories for the Analysis of Potential Atmospheric Long-Distance Dispersal of Lumpy Skin Disease Virus

Lumpy skin disease virus (LSDV) is an infectious, arthropod-borne virus that affects mostly cattle. Solitary outbreaks have occurred in Israel in 1989 and 2006. In both years, the outbreaks occurred parallel to a severe outbreak in Egypt, and LSDV was hypothesized to be transmitted from Egypt to Israel via long-distance dispersal (LDD) of infected vectors by wind. The aim of this study was to identify possible events of such transport. At the first stage, we identified the relevant synoptic systems that allowed wind transport from Egypt to Israel during the 3 months preceding each outbreak. Three-dimensional backwards Lagrangian trajectories were calculated from the receptor sites in Israel for each occurrence of such relevant synoptic system. The analysis revealed several events in which atmospheric connection routes between the affected locations in Egypt and Israel were established. Specifically, during the 1989, Damietta and Port Said stand out as likely sources for the outbreak in Israel. In 2006, different locations acted simultaneously as potential sources of the outbreak in Israel. These locations were situated in the Nile delta, the Suez Canal and in northern Sinai. The analysis pointed out Sharav low and Shallow Cyprus low to the North to be the most likely systems to enable windborne transport from Egypt to Israel. These findings are of high importance for the analysis of the risk of transmission of vectorborne viruses in the eastern Mediterranean region.

Safety, immunogenicity and duration of immunity elicited by an inactivated bovine ephemeral fever vaccine

Bovine ephemeral fever (BEF) is an economically important viral vector-borne cattle disease. Several live-attenuated, inactivated and recombinant vaccines have been tested, demonstrating varying efficacy. However, to the best of our knowledge, duration of immunity conferred by an inactivated vaccine has never been reported. In the last decade, Israel has faced an increasing number of BEF outbreaks. The need for an effective vaccine compatible with strains circulating in the Middle East region led to the development of a MONTANIDE™ ISA 206 VG (water-in-oil-in-water), inactivated vaccine based on a local strain. We tested the safety, immunogenicity and duration of immunity conferred by this vaccine. The induced neutralizing antibody (NA) response was followed for 493 days in 40 cows vaccinated by different protocols. The vaccine did not cause adverse reactions or a decrease in milk production. All cows [except 2 (6.7%) which did not respond to vaccination] showed a significant rise in NA titer of up to 1:256 following the second, third or fourth booster vaccination. Neutralizing antibody levels declined gradually to 1:16 up to 120 days post vaccination. This decline continued in cows vaccinated only twice, whereas cows vaccinated 3 or 4 times showed stable titers of approximately 1:16 for up to 267 days post vaccination. At least three vaccinations with the inactivated BEF vaccine were needed to confer long-lasting immunity. These results may have significant implications for the choice of vaccination protocol with inactivated BEF vaccines. Complementary challenge data should however be added to the above results in order to determine what is the minimal NA response conferring protection from clinical disease.

Evolution of bovine ephemeral fever virus in the Australian episystem

Bovine ephemeral fever virus (BEFV) is an arthropod-borne rhabdovirus that causes a debilitating disease of cattle in Africa, Asia, and Australia; however, its global geodynamics are poorly understood. An evolutionary analysis of G gene (envelope glycoprotein) ectodomain sequences of 97 BEFV isolates collected from Australia during 1956 to 2012 revealed that all have a single common ancestor and are phylogenetically distinct from BEFV sampled in other geographical regions. The age of the Australian clade is estimated to be between 56 and 65 years, suggesting that BEFV has entered the continent on few occasions since it was first reported in 1936 and that the 1955-1956 epizootic was the source of all currently circulating viruses. Notably, the Australian clade has evolved as a single genetic lineage across the continent and at a high evolutionary rate of ∼10(-3) nucleotide substitutions/site/year. Screening of 66 isolates using monoclonal antibodies indicated that neutralizing antigenic sites G1, G2, and G4 have been relatively stable, although variations in site G3a/b defined four antigenic subtypes. A shift in an epitope at site G3a, which occurred in the mid-1970s, was strongly associated with a K218R substitution. Similarly, a shift at site G3b was associated primarily with substitutions at residues 215, 220, and 223, which map to the tip of the spike on the prefusion form of the G protein. Finally, we propose that positive selection on residue 215 was due to cross-reacting neutralizing antibody to Kimberley virus (KIMV). This is the first study of the evolution of BEFV in Australia, showing that the virus has entered the continent only once during the past 50 to 60 years, it is evolving at a relatively constant rate as a single genetic lineage, and although the virus is relatively stable antigenically, mutations have resulted in four antigenic subtypes. Furthermore, the study shows that the evolution of BEFV in Australia appears to be driven, at least in part, by cross-reactive antibodies to KIMV which has a similar distribution and ecology but has not been associated with disease. As BEFV and KIMV are each known to be present in Africa and Asia, this interaction may occur on a broader geographic scale.

A large-scale outbreak of bovine ephemeral fever in Turkey, 2012

Regional cases of bovine ephemeral fever (BEF) were documented previously in Turkey. Previous cases were confirmed in South-East Turkey with low cow mortality. Recent BEF-suspected outbreaks with high mortality were documented in many regions of Turkey in 2012. The aim of study was the epidemiological examination of the outbreak and molecular characterization of the viruses detected from the outbreak. For this reason, blood samples were collected from BEF-suspected outbreak regions. From the results of RT-PCR, high rate of BEF-suspected samples (48/60 or 80%) was found positive for BEF virus (BEFV) RNA. The nucleotide sequences of the G₁ region of G gene of BEFV in the current study during the 2012 outbreak were grouped into cluster II of BEFV. It was suggested that BEFV may be spread out to other neighbor countries in the future years.

Phylogenetic relationships of the glycoprotein gene of bovine ephemeral fever virus isolated from mainland China, Taiwan, Japan, Turkey, Israel and Australia

Background

The glycoprotein (G) gene sequences of bovine ephemeral fever virus (BEFV) strains derived from mainland China have not been compared with those of the isolates from other countries or areas. Therefore, the G genes of four BEFV isolates obtained from mainland China were amplified and sequenced. A phylogenetic tree was constructed in order to compare and analyze the genetic relationships of the BEFV isolates derived from mainland China and different countries and areas.

Results

The complete BEFV G gene was successfully amplified and sequenced from four isolates that originated from mainland China. A total of fifty-one BEFV strains were analyzed based on the G gene sequence and were found to be highly conserved. A phylogenetic tree showed that the isolates were grouped into three distinct lineages depending on their source of origin. The antigenic sites of G₁, G₂ and G₃ are conserved among the isolates, except for several substitutions in a few strains.

Conclusions

The phylogenetic relationships of the BEFV isolates that originated from mainland China, Taiwan, Japan, Turkey, Israel and Australia were closely related to their source of origin, while the antigenic sites G₁, G₂ and G₃ are conserved among the BEFV isolates used in this work.