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Culicoides sonorensis (Wirth & Jones) is the principal North American vector of bluetongue virus (BTV). BTV infection of livestock is distinctly seasonal (late summer and fall) in temperate regions of the world such as California, which has led to speculation regarding vertical transmission of the virus within the midge vector as a potential mechanism for interseasonal maintenance ("overwintering") of the virus. To evaluate potential vertical transmission of BTV in its midge vector, we fed adult midges BTV-spiked blood and used a BTV-specific quantitative reverse transcriptase polymerase chain reaction assay to evaluate parent, egg, and progeny stages of laboratory-reared C. sonorensis for the presence of viral nucleic acid. Whereas BTV nucleic acid was weakly detected in egg batches of virus-fed female midges, virus was never detected in subsequent progeny stages (larvae, pupae, and F1 generation adults). Similarly, BTV was not detected in pools of larvae collected from the waste-water lagoon of a BTV-endemic dairy farm in northern California during the seasonal period of virus transmission. Collectively, these results indicate that BTV is not readily transmitted vertically in C. sonorensis, and that persistence of the virus in long-lived parous female midges is a more likely mechanism for overwintering of BTV in temperate regions.

The availability of rapid, highly sensitive and specific molecular and serologic diagnostic assays, such as competitive enzyme-linked immunosorbent assay (cELISA), has expedited the diagnosis of emerging transboundary animal diseases, including bluetongue (BT) and African horse sickness (AHS), and facilitated more thorough characterisation of their epidemiology. The development of assays based on real-time, reverse-transcription polymerase chain reaction (RT-PCR) to detect and identify the numerous serotypes of BT virus (BTV) and AHS virus (AHSV) has aided in-depth studies of the epidemiology of BTV infection in California and AHSV infection in South Africa. The subsequent evaluation of pan-serotype, real-time, RT-PCR-positive samples through the use of serotype-specific RT-PCR assays allows the rapid identification of virus serotypes, reducing the need for expensive and time-consuming conventional methods, such as virus isolation and serotype-specific virus neutralisation assays. These molecular assays and cELISA platforms provide tools that have enhanced epidemiologic surveillance strategies and improved our understanding of potentially altered Culicoides midge behaviour when infected with BTV. They have also supported the detection of subclinical AHSV infection of vaccinated horses in South Africa. Moreover, in conjunction with whole genome sequence analysis, these tests have clarified that the mechanism behind recent outbreaks of AHS in the AHS-controlled area of South Africa was the result of the reversion to virulence and/or genome reassortment of live attenuated vaccine viruses. This review focuses on the use of contemporary molecular diagnostic assays in the context of recent epidemiologic studies and explores their advantages over historic virus isolation and serologic techniques.

Zika virus (ZIKV) is an arbovirus that causes birth defects, persistent male infection, and sexual transmission in humans. The purpose of this study was to continue the development of an ovine ZIKV infection model; thus, two experiments were undertaken. In the first experiment, we built on previous pregnant sheep experiments by developing a mid-gestation model of ZIKV infection. Four pregnant sheep were challenged with ZIKV at 57-64 days gestation; two animals served as controls. After 13-15 days (corresponding with 70-79 days of gestation), one control and two infected animals were euthanized; the remaining animals were euthanized at 20-22 days post-infection (corresponding with 77-86 days of gestation). In the second experiment, six sexually mature, intact, male sheep were challenged with ZIKV and two animals served as controls. Infected animals were serially euthanized on days 2-6 and day 9 post-infection with the goal of isolating ZIKV from the male reproductive tract. In the mid-gestation study, virus was detected in maternal placenta and spleen, and in fetal organs, including the brains, spleens/liver, and umbilicus of infected fetuses. Fetuses from infected animals had visibly misshapen heads and morphometrics revealed significantly smaller head sizes in infected fetuses when compared to controls. Placental pathology was evident in infected dams. In the male experiment, ZIKV was detected in the spleen, liver, testes/epididymides, and accessory sex glands of infected animals. Results from both experiments indicate that mid-gestation ewes can be infected with ZIKV with subsequent disruption of fetal development and that intact male sheep are susceptible to ZIKV infection and viral dissemination and replication occurs in highly vascular tissues (including those of the male reproductive tract).

Zika virus (ZIKV) is a vertically and sexually transmissible virus resulting in severe congenital malformation. The goal of this study was to develop an ovine model of ZIKV infection. Between 28-35 days gestation (DG), four pregnant animals were infected with two doses of 6 × 10 6 PFU of ZIKV; four control animals received PBS. Animals were evaluated for 45 days (D) post-infection (PI) and necropsies were performed. Viral RNA was detected in infected ewe peripheral blood mononuclear cells (PBMC) during the first week PI; however, all fluids and tissues were negative upon culture. Anti-ZIKV IgM (1:400) and neutralizing antibodies were detected in all infected animals. Clinical disease, virus, or ZIKV antibodies were not detected in control ewes. After two weeks PI, fetal loss occurred in two infected animals, and at necropsy, three infected animals had placental petechiation and ecchymosis and one had hydramnion. Fetal morphometrics revealed smaller cranial circumference to crown-rump length ratios ( p < 0.001) and relative brain weights ( p = 0.038) in fetuses of infected animals compared with control fetuses. Immunophenotyping indicated an increase in B cells ( p = 0.012) in infected sheep. Additionally, in vitro experiments using both adult and fetal cell lines demonstrated that ovine cells are highly permissive to ZIKV infection. In conclusion, ZIKV infection of pregnant sheep results in a change in fetal growth and gestational outcomes.

Bluetongue (BT) and epizootic hemorrhagic disease (EHD) are globally re-emerging diseases of domestic and wild ruminants, respectively caused by BT virus (BTV) and EHD virus. Both viruses are transmitted by hematophagous midges; however, newly recognized BTV serotypes may be transmitted horizontally without requirement for any biological vector. The global range of these viruses and/or their associated diseases have changed remarkably in recent years, most notably with the invasion of Europe by multiple serotypes of BTV since 1998. Although not zoonoses, the unanticipated emergence of BT and EHD in several different areas of the world provides a uniquely sobering and unambiguous reminder of the potential consequences of climate change on the distribution and severity of vector-borne diseases. Recent experiences with these viruses have also emphasized the need for effective, DIVA-compatible vaccines to combat anticipated future incursions, as existing vaccines have serious inherent deficiencies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Congenital infections of domestic animals with viruses in several families, including Bunyaviridae, Flaviridae, Parvoviridae, and Reoviridae, are the cause of naturally occurring teratogenic central nervous system and/or musculoskeletal defects (arthrogryposis) in domestic animals. Congenital infections of ruminant livestock with bluetongue virus (BTV) and some related members of the genus Orbivirus (family Reoviridae) have clearly shown the critical role of gestational age at infection in determining outcome. Specifically, fetuses infected prior to mid-gestation that survive congenital BTV infection are born with cavitating central nervous system defects that range from severe hydranencephaly to cerebral cysts (porencephaly). Generally, the younger the fetus (in terms of gestational age) at infection, the more severe the teratogenic lesion at birth. Age-dependent virus infection and destruction of neuronal and/or glial cell precursors that populate the developing central nervous system are responsible for these naturally occurring virus-induced congenital defects of animals, thus lesions are most severe when progenitor cells are infected prior to their normal migration during embryogenesis. Whereas congenital infection is characteristic of certain BTV strains, notably live-attenuated (modified-live) vaccine viruses that have been passaged in embryonating eggs, transplacental transmission is not characteristic of many field strains of the virus and much remains to be determined regarding the genetic determinants of transplacental transmission of individual virus strains., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Bluetongue (BT) is an economically important, non-zoonotic arboviral disease of certain wild and domestic species of cloven-hooved ungulates. Bluetongue virus (BTV) is the causative agent and the occurrence of BTV infection is distinctly seasonal in temperate regions of the world, and dependent on the presence of vector biting midges (e.g. Culicoides sonorensis in much of North America). In recent years, severe outbreaks have occurred throughout Europe and BTV is endemic in most tropical and temperate regions of the world. Several vaccines have been licensed for commercial use, including modified live (live-attenuated) and inactivated products, and this review summarizes recent strategies developed for BTV vaccines with emphasis on technologies suitable for differentiating naturally infected from vaccinated animals. The goal of this review is to evaluate realistic vaccine strategies that might be utilized to control or prevent future outbreaks of BT., (Copyright © 2017 Elsevier B.V. All rights reserved.)

African horse sickness (AHS) is a fatal disease of equids relevant to the global equine industry. Detection of AHS virus (AHSV) during outbreaks has become more rapid and efficient with the advent of group specific reverse transcriptase quantitative polymerase chain reaction (GS RT-qPCR) assays to detect AHSV nucleic acid. Use of GS RT-qPCR together with recently described type specific (TS RT-qPCR) assays cannot only expedite diagnosis of AHS but also facilitate further evaluation of the dynamics of AHSV infection in the equine host. A potential limitation to the application of these assays is that they detect viral nucleic acid originating from any AHS live attenuated vaccine (LAV), which is the vaccine type routinely administered to horses in South Africa. The aim of this study was to contrast the dynamics and duration of the RNAaemia to the serological responses of horses following immunization with a commercial polyvalent AHSV-LAV using GS and TS RT-qPCR assays and serum neutralisation tests. The results of the study showed extended RNAemia in vaccinated horses, and that more horses tested positive on GS RT-qPCR with lower Cq values after receiving the AHSV-LAV containing types 1, 3 and 4 prior to the vaccine containing types 2, 6, 7 and 8, rather than when the vaccine combinations were reversed. Furthermore, lower Cq values were obtained when vaccines were administered 4weeks apart as compared with a longer interval or 12weeks apart. These findings are of particular relevance in regions where AHSV-LAVs are used as the use of these vaccines may complicate the accurate interpretation of diagnostic testing results., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

African horse sickness (AHS) is a hemorrhagic viral fever of horses. It is the only equine disease for which the World Organization for Animal Health has introduced specific guidelines for member countries seeking official recognition of disease-free status. Since 1997, South Africa has maintained an AHS controlled area; however, sporadic outbreaks of AHS have occurred in this area. We compared the whole genome sequences of 39 AHS viruses (AHSVs) from field AHS cases to determine the source of 3 such outbreaks. Our analysis confirmed that individual outbreaks were caused by virulent revertants of AHSV type 1 live, attenuated vaccine (LAV) and reassortants with genome segments derived from AHSV types 1, 3, and 4 from a LAV used in South Africa. These findings show that despite effective protection of vaccinated horses, polyvalent LAV may, paradoxically, place susceptible horses at risk for AHS.

The global distribution of bluetongue virus (BTV) has been changing recently, perhaps as a result of climate change. To evaluate the risk of BTV infection and transmission in a BTV-endemic region of California, sentinel dairy cows were evaluated for BTV infection, and populations of Culicoides vectors were collected at different sites using carbon dioxide. A deterministic model was developed to quantify risk and guide future mitigation strategies to reduce BTV infection in California dairy cattle. The greatest risk of BTV transmission was predicted within the warm Central Valley of California that contains the highest density of dairy cattle in the United States. Temperature and parameters associated with Culicoides vectors (transmission probabilities, carrying capacity, and survivorship) had the greatest effect on BTV's basic reproduction number, R0. Based on these analyses, optimal control strategies for reducing BTV infection risk in dairy cattle will be highly reliant upon early efforts to reduce vector abundance during the months prior to peak transmission., Competing Interests: The authors have declared that no competing interests exist.

Within Northern California, Culicoides sonorensis is the major vector of Bluetongue virus (BTV) and annual infection of livestock is distinctly seasonal (typically July‑November). Our recent studies compare the population dynamics of C. sonorensis midges with occurrence of BTV infection of C. sonorensis and sentinel dairy cattle throughout both the seasonal and interseasonal ('overwintering') periods of BTV activity. Spring emergence and seasonal abundance of adult C. sonorensis on the sampled farms coincided with rising vernal temperature. Intensive surveillance confirmed widespread infection of both sentinel cattle and vector midges during the August‑November period of seasonal BTV transmission. Bluetongue virus infection of parous female midges captured in traps set during daylight hours was also detected during the interseasonal period of virus activity, whereas there was no concurrent active infection of sentinel cattle during the overwintering period. The finding of BTV‑infected vector midges during mid‑Winter suggests that BTV can overwinter in Northern California by infection of long‑lived female C. sonorensis midges that were infected during the prior seasonal period of virus transmission and which, then, entered a quiescence in the fall (Autumn) and re‑emerged sporadically during the overwintering period. Notably, vertical transmission of BTV was not detected among progeny of midges infected in the laboratory nor in field‑collected larvae. In addition to defining the mechanism of BTV over‑wintering in a temperate region, the studies reviewed in this article also provide precise documentation of temporal changes in the annual abundance, dispersal and dynamics of BTV infection of Culicoides midges. Collectively these findings are critical to the creation of accurate predictive models of BTV infection in livestock and to development of sound abatement strategies.

Bluetongue (BT) is a mild to severe disease of domestic and wild ruminants caused by the Bluetongue virus (BTV) and generally transmitted by Culicoides biting midges. Its occurrence also determines a livestock trade ban in affected countries with severe economic consequences on national and international trade. For this reason, in May 2011, the OIE encouraged the OIE Reference Laboratories to establish and maintain a BT network to provide expertise and training to the OIE and OIE Member Countries for BT diagnosis, surveillance and control. The network is constantly sustained by world leading scientists in the field of virology, epidemiology, serology, entomology and vaccine development. The website, available at http://oiebtnet.izs.it/btlabnet/, hosts an Information System containing data on BTV outbreaks and strains and a WebGIS that distributes maps on BTV occurrence. In this paper we describe the applications and present the benefits derived from the use of the WebGIS in the context of BT international surveillance network.

This is a report of the complete genome sequences of plaque-selected isolates of each of the four virus strains included in a South African commercial tetravalent African horse sickness attenuated live virus vaccine., (Copyright © 2015 Guthrie et al.)

Blood samples collected as part of routine diagnostic investigations from South African horses with clinical signs suggestive of African horse sickness (AHS) were subjected to analysis with an AHS virus (AHSV) group specific reverse transcription quantitative polymerase chain reaction (AHSV RT-qPCR) assay and virus isolation (VI) with subsequent serotyping by plaque inhibition (PI) assays using AHSV serotype-specific antisera. Blood samples that tested positive by AHSV RT-qPCR were then selected for analysis using AHSV type specific RT-qPCR (AHSV TS RT-qPCR) assays. The TS RT-qPCR assays were evaluated using both historic stocks of the South African reference strains of each of the 9 AHSV serotypes, as well as recently derived stocks of these same viruses. Of the 503 horse blood samples tested, 156 were positive by both AHSV RT-qPCR and VI assays, whereas 135 samples that were VI negative were positive by AHSV RT-qPCR assay. The virus isolates made from the various blood samples included all 9 AHSV serotypes, and there was 100% agreement between the results of conventional serotyping of individual virus isolates by PI assay and AHSV TS RT-qPCR typing results. Results of the current study confirm that the AHSV TS RT-qPCR assays for the identification of individual AHSV serotypes are applicable and practicable and therefore are potentially highly useful and appropriate for virus typing in AHS outbreak situations in endemic or sporadic incursion areas, which can be crucial in determining appropriate and timely vaccination and control strategies., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Bluetongue (BT) was first recognized and described in Southern Africa, and only later elsewhere. It is now known that the causative agent of BT [BT virus (BTV)] occurs throughout temperate and tropical regions of the world. Previous OIE symposia in 1984, 1991 and 2003 clarified the global distribution of BTV and its epidemiology, pathogenesis, and diagnosis. Since the 3rd symposium in 2003, however, there have been significant developments. Notably, BT has emerged in Northern Europe and novel BTV serotypes have appeared in other endemic areas raising substantial questions regarding the environmental and anthropogenic drivers of emergence of BTV, including the invasion and spread of laboratory propagated viruses. Additional BTV serotypes with novel properties have recently been identified in Europe and the Middle East. Recent studies also confirm the importance of the Culicoides vector as the essential overwintering reservoir of BTV in temperate regions such as California and not ruminant livestock, proving wrong the prevailing thesis circulated prior to the 1st symposium in 1984. The challenge for participants of this 4th symposium is to predict collectively what the future might hold in terms of emergence of BTV globally, and what strategies are likely to be most feasible, justified, and effective for its control.

Background: Pathogen manipulation of host behavior can greatly impact vector-borne disease transmission, but almost no attention has been paid to how it affects disease surveillance. Bluetongue virus (BTV), transmitted by Culicoides biting midges, is a serious disease of ruminant livestock that can cause high morbidity and mortality and significant economic losses. Worldwide, the majority of surveillance for Culicoides to assess BTV transmission risk is done using UV-light traps. Here we show that field infection rates of BTV are significantly lower in midge vectors collected using traps baited with UV light versus a host cue (CO2)., Methods: We collected Culicoides sonorensis midges in suction traps baited with CO2, UV-light, or CO2 + UV on three dairies in southern California to assess differences in the resulting estimated infection rates from these collections. Pools of midges were tested for BTV by qRT-PCR, and maximum likelihood estimates of infection rate were calculated by trap. Infection rate estimates were also calculated by trapping site within a dairy. Colonized C. sonorensis were orally infected with BTV, and infection of the structures of the compound eye was examined using structured illumination microscopy., Results: UV traps failed entirely to detect virus both early and late in the transmission season, and underestimated virus prevalence by as much as 8.5-fold. CO2 + UV traps also had significantly lower infection rates than CO2-only traps, suggesting that light may repel infected vectors. We found very high virus levels in the eyes of infected midges, possibly causing altered vision or light perception. Collecting location also greatly impacts our perception of virus activity., Conclusions: Because the majority of global vector surveillance for bluetongue uses only light-trapping, transmission risk estimates based on these collections are likely severely understated. Where national surveillance programs exist, alternatives to light-trapping should be considered. More broadly, disseminated infections of many arboviruses include infections in vectors' eyes and nervous tissues, and this may be causing unanticipated behavioral effects. Field demonstrations of pathogen-induced changes in vector behavior are quite rare, but should be studied in more systems to accurately predict vector-borne disease transmission.

This is a report of the complete genome sequences of plaque-selected isolates of each of the three virus strains included in a South African commercial trivalent African horse sickness attenuated live virus vaccine., (Copyright © 2015 Guthrie et al.)

Summary Bluetongue (BT) is an arthropod-transmitted viral disease of non-African ungulates, principally sheep. The disease results from vascular injury analogous to that of human haemorrhagic viral fevers, with characteristic tissue infarction, haemorrhage, vascular leakage, oedema, and hypovolaemic shock. Importantly, BT is not zoonotic. Bluetongue virus (BTV) infection of ruminants and vector Culicoides midges is endemic throughout many tropical and temperate regions of the world; however, within this global range the virus exists within relatively discrete ecosystems (syn. episystems) where specific constellations of BTV serotypes are spread by different species of biting Culicoides midges. Recently discovered goat-associated BTVs, notably BTV serotype 25 (BTV-25) in central Europe, appear to have distinctive biological properties and an epidemiology that is not reliant on Culicoides midges as vectors for virus transmission. Bluetongue virus infection of ruminants is often subclinical, but outbreaks of severe disease occur regularly at the upper and lower limits of the virus's global range, where infection is distinctly seasonal. There have been recent regional alterations in the global distribution of BTV infection, particularly in Europe. It is proposed that climate change is responsible for these events through its impact on vector midges. However, the role of anthropogenic factors in mediating emergence of BTV into new areas remains poorly defined; for example, it is not clear to what extent anthropogenic factors were responsible for the recent translocation to northern and eastern Europe of live attenuated vaccine viruses and an especially virulent strain of BTV-8 with distinctive properties. Without thorough characterisation of all environmental and anthropogenic drivers of the recent emergence of BT in northern Europe and elsewhere, it is difficult to predict what the future holds in terms of global emergence of BTV infection. Accurate and convenient laboratory tests are available for the sensitive and specific serological and virological diagnosis of BTV infection and confirmation of BT in animals. Prevention and control strategies for BT are largely reactive in nature, and typically are reliant on vaccination of susceptible livestock and restrictions on animal trade and movement.

Summary Epizootic haemorrhagic disease (EHD) is an arthropod-transmitted viral disease of certain wild ungulates, notably North American white-tailed deer and, more rarely, cattle. The disease in white-tailed deer results from vascular injury analogous to that caused by bluetongue virus (BTV), to which EHD virus (EHDV) is closely related. There are seven serotypes of EHDV recognised, and Ibaraki virus, which is the cause of sporadic disease outbreaks in cattle in Asia, is included in EHDV serotype 2. The global distribution and epidemiology of BTV and EHDV infections are also similar, as both viruses occur throughout temperate and tropical regions of the world where they are transmitted by biting Culicoides midges and infect a wide variety of domestic and wild ungulates. However, the global distribution and epidemiology of EHDV infection are less well characterised than they are for BTV. Whereas most natural and experimental EHDV infections (other than Ibaraki virus infection) of livestock are subclinical or asymptomatic, outbreaks of EHD have recently been reported among cattle in the Mediterranean Basin, Reunion Island, South Africa, and the United States. Accurate and convenient laboratory tests are increasingly available for the sensitive and specific serological and virological diagnosis of EHDV infection and confirmation of EHD in animals, but commercial vaccines are available only for prevention of Ibaraki disease and not for protection against other strains and serotypes of EHDV.

Bluetongue (BT) and epizootic hemorrhagic disease (EHD) are noncontagious, insect-transmitted diseases of domestic and wild ruminants caused by related but distinct viruses. There are significant gaps in our scientific knowledge and available countermeasures to control an outbreak of orbivirus-induced disease, whether BT or EHD. Both BT virus (BTV) and EHD virus (EHDV) cause hemorrhagic fevers in susceptible ruminants; however, BT is principally a disease of domestic livestock whereas EHD is principally a disease of certain species of wild, non-African ungulates, notably white-tailed deer. The live-attenuated (modified live virus [MLV]) vaccines available in the United States for use in small ruminant livestock do provide good protection against clinical disease following infection with the homologous virus serotype. Although there is increasing justification that the use of MLV vaccines should be avoided if possible, these are the only vaccines currently available in the United States. Specifically, MLVs are used in California to protect sheep against infection with BTV serotypes 10, 11, and 17, and a MLV to BTV serotype 10 is licensed for use in sheep throughout the United States. These MLV vaccines may need to continue to be used in the immediate future for protective immunization of sheep and goats against BT. There are currently no licensed vaccines available for EHD in the United States other than autogenous vaccines. If there is a need to rapidly develop a vaccine to meet an emerging crisis associated with either BTV or EHDV infections, development of an inactivated virus vaccine in a conventional adjuvanted formulation will likely be required. With two doses of vaccine (and in some instances just one dose), inactivated vaccines can provide substantial immunity to the epizootic serotype of either BTV or EHDV. This strategy is similar to that used in the 2006-2008 BTV serotype 8 outbreaks in northern Europe that provided vaccine to the field within 2 years of the initial incursion (by 2008). Further research and development are warranted to provide more efficacious and effective vaccines for control of BTV and EHDV infections.

Orbiviruses are members of the Reoviridae family and include bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). These viruses are the cause of significant regional disease outbreaks among livestock and wildlife in the United States, some of which have been characterized by significant morbidity and mortality. Competent vectors are clearly present in most regions of the globe; therefore, all segments of production livestock are at risk for serious disease outbreaks. Animals with subclinical infections also serve as reservoirs of infection and often result in significant trade restrictions. The economic and explicit impacts of BTV and EHDV infections are difficult to measure, but infections are a cause of economic loss for producers and loss of natural resources (wildlife). In response to United States Animal Health Association (USAHA) Resolution 16, the US Department of Agriculture (USDA), in collaboration with the Department of the Interior (DOI), organized a gap analysis workshop composed of international experts on Orbiviruses. The workshop participants met at the Arthropod-Borne Animal Diseases Research Unit in Manhattan, KS, May 14-16, 2013, to assess the available scientific information and status of currently available countermeasures to effectively control and mitigate the impact of an outbreak of an emerging Orbivirus with epizootic potential, with special emphasis given to BTV and EHDV. In assessing the threats, workshop participants determined that available countermeasures are somewhat effective, but several weaknesses were identified that affect their ability to prevent and control disease outbreaks effectively.

ImageJ is an open-source software tool used for a variety of scientific objectives including cell counting, shape analysis and image correction. This technology has previously been used to estimate mosquito abundance in surveillance efforts. However, the utility of this application for estimating abundance or parity in the surveillance of Culicoides spp. (Diptera: Ceratopogonidae) has not yet been tested. Culicoides sonorensis (Wirth and Jones), a biting midge often measuring 2.0-2.5 mm in length, is an economically important vector of ruminant arboviruses in California. Current surveillance methods use visual sorting for the characteristics of midges and are very time-intensive for large studies. This project tested the utility of ImageJ as a tool to assist in gross trap enumeration as well as in parity analysis of C. sonorensis in comparison with traditional visual methods of enumeration using a dissecting microscope. Results confirmed that automated counting of midges is a reliable means of approximating midge numbers under certain conditions. Further evaluation confirmed accurate and time-efficient parity analysis in comparison with hand sorting. The ImageJ software shows promise as a tool that can assist and expedite C. sonorensis surveillance. Further, these methods may be useful in other insect surveillance activities., (© 2014 The Royal Entomological Society.)

Bluetongue virus (BTV) is the cause of an economically important arboviral disease of domestic and wild ruminants. The occurrence of BTV infection of livestock is distinctly seasonal in temperate regions of the world, thus we determined the dynamics of BTV infection (using BTV-specific real time reverse transcriptase polymerase chain reaction) among sentinel cattle and vector Culicoides sonorensis (C. sonorensis) midges on a dairy farm in northern California throughout both the seasonal and interseasonal (overwintering) periods of BTV activity from August 2012 until March 2014. The data confirmed widespread infection of both sentinel cattle and vector midges during the August-November period of seasonal BTV transmission, however BTV infection of parous female midges captured in traps set during daylight hours also was detected in February of both 2013 and 2014, during the interseasonal period. The finding of BTV-infected vector midges during mid-winter suggests that BTV may overwinter in northern California by infection of long-lived female C. sonorensis midges that were infected during the prior seasonal period of virus transmission, and reemerged sporadically during the overwintering period; however the data do not definitively preclude other potential mechanisms of BTV overwintering that are also discussed.

The advent of recombinant DNA technology, development of infectious cDNA clones of RNA viruses, and reverse genetic technologies have revolutionized how viruses are studied. Genetic manipulation of full-length cDNA clones has become an especially important and widely used tool to study the biology, pathogenesis, and virulence determinants of both positive and negative stranded RNA viruses. The first full-length infectious cDNA clone of equine arteritis virus (EAV) was developed in 1996 and was also the first full-length infectious cDNA clone constructed from a member of the order Nidovirales. This clone was extensively used to characterize the molecular biology of EAV and other Nidoviruses. The objective of this review is to summarize the characterization of the virulence (or attenuation) phenotype of the recombinant viruses derived from several infectious cDNA clones of EAV in horses, as well as their application for characterization of the molecular basis of viral neutralization, persistence, and cellular tropism., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Bluetongue is a potentially fatal arboviral disease of domestic and wild ruminants that is characterized by widespread edema and tissue necrosis. Bluetongue virus (BTV) serotypes 10, 11, 13, and 17 occur throughout much of the United States, whereas serotype 2 (BTV-2) was previously only detected in the southeastern United States. Since 1998, 10 other BTV serotypes have also been isolated from ruminants in the southeastern United States. In 2010, BTV-2 was identified in California for the first time, and preliminary sequence analysis indicated that the virus isolate was closely related to BTV strains circulating in the southeastern United States. In the current study, the whole genome sequence of the California strain of BTV-2 was compared with those of other BTV-2 strains in the Americas. The results of the analysis suggest co-circulation of genetically distinct viruses in the southeastern United States, and further suggest that the 2010 western isolate is closely related to southeastern strains of BTV. Although it remains uncertain as to how this novel virus was translocated to California, the findings of the current study underscore the need for ongoing surveillance of this economically important livestock disease.

African horse sickness (AHS) is typically a highly fatal disease in susceptible horses and vaccination is currently used to prevent the occurrence of disease in endemic areas. Similarly, vaccination has been central to the control of incursions of African horse sickness virus (AHSV) into previously unaffected areas and will likely play a significant role in any future incursions. Horses in the AHSV-infected area in South Africa are vaccinated annually with a live-attenuated (modified-live virus [MLV]) vaccine, which includes a cocktail of serotypes 1, 3, 4 (bottle 1) and 2, 6-8 (bottle 2) delivered in two separate doses at least 21 days apart. In this study, the neutralising antibody response of foals immunized with this polyvalent MLV AHSV vaccine was evaluated and compared to the response elicited to monovalent MLV AHSV serotypes. Naïve foals were immunized with either the polyvalent MLV AHSV vaccine, or a combination of monovalent MLV vaccines containing individual AHSV serotypes 1, 4, 7 or 8. There was a marked and consistent difference in the immunogenicity of individual virus serotypes contained in the MLV vaccines. Specifically, foals most consistently seroconverted to AHSV-1 and responses to other serotypes were highly variable, and often weak or not detected. The serotype-specific responses of foals given the monovalent MLV vaccines were similar to those of foals given the polyvalent MLV preparation suggesting that there is no obvious enhanced immune response through the administration of a monovalent vaccine as opposed to the polyvalent vaccine., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Infection of ruminants with most (but not all) serotypes of bluetongue virus (BTV) leads to a highly blood cell-associated viremia that may be prolonged but not persistent. Furthermore, recovered animals are resistant to reinfection with the homologous virus serotype, which is the basis for vaccination strategies to prevent BTV infection and the clinical disease (bluetongue) that it causes in domestic livestock. BTV infection is initiated at the site of virus inoculation and the associated draining lymph node, from where the virus is then spread in lymph cells to the systemic circulation and secondary sites of replication. Replication of BTV in target cells, notably mononuclear phagocytic cells (dendritic cells and macrophages) and endothelium, leads to the generation of the innate and adaptive immune responses that mediate both initial virus clearance and subsequent resistance to infection with the homologous virus serotype. The goal of this review is to summarize current understanding of these innate and adaptive immune responses of animals to BTV infection., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The Sacramento (northern Central) Valley of California (CA) has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV) and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012- to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice) along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the "overwintering" of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual abundance and dispersal of Culicoides midges is essential for the creation of models to predict BTV infection of livestock and to develop sound abatement strategies.

Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids. There has been significant recent progress in understanding the molecular biology of EAV and the pathogenesis of its infection in horses. In particular, the use of contemporary genomic techniques, along with the development and reverse genetic manipulation of infectious cDNA clones of several strains of EAV, has generated significant novel information regarding the basic molecular biology of the virus. Therefore, the objective of this review is to summarize current understanding of EAV virion architecture, replication, evolution, molecular epidemiology and genetic variation, pathogenesis including the influence of host genetics on disease susceptibility, host immune response, and potential vaccination and treatment strategies., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Reasons for Performing Study: African horse sickness is an insect-transmitted, noncontagious disease of equids caused by African horse sickness virus (AHSV). Mortality can exceed 90% in fully susceptible horse populations. A live-attenuated (modified live) cell-culture-adapted (MLV) polyvalent AHSV vaccine is widely used to control African horse sickness in endemic areas in southern Africa. Field studies detailing antibody responses of vaccinated horses are lacking., Objectives: To determine antibody titres to the 9 known serotypes of AHSV in a cohort of broodmares that were regularly vaccinated with the MLV AHSV vaccine and to measure the passive transfer and rate of decay of maternal antibody to the individual virus serotypes in foals., Methods: Serum was collected from 15 mares before foaling and from their foals after foaling and monthly thereafter for 6 months. Antibody titres to each of the 9 AHSV serotypes were determined by serum virus neutralisation assay., Results: There was marked variation in the antibody response of the mares to individual AHSV serotypes even after repeated vaccination, with consistently higher titre responses to some virus serotypes. Likewise, the duration of maternally derived antibodies in foals differed among serotypes., Conclusions: Data from this study confirm variation of the neutralising antibody response of individual mares to repeated vaccination with polyvalent AHSV vaccine. Virus strains of individual AHSV serotypes included in the vaccine may vary in their inherent immunogenicity. Passively acquired maternal antibodies to AHSV vary markedly among foals born to vaccinated mares, with further variation in the duration of passive immunity to individual AHSV serotypes., Potential Relevance: These data are relevant to the effective utilisation of live-attenuated AHSV vaccines in endemic regions, and potentially to the use of vaccines in response to future incursions of AHSV into previously free regions. Further studies involving a larger population will be required to determine the optimal time for vaccinating foals., (© 2012 EVJ Ltd.)

Bluetongue (BT) is a non-zoonotic arboviral disease of certain wild and domestic species of cloven-hoofed ungulates. The causative agent, bluetongue virus (BTV), is spread through temperate and tropical regions of the world by biting Culicoides midges. Control of BTV infection is complicated by the plurality of virus serotypes and the ubiquity and opportunistic feeding behavior of its midge vector. The global distribution of BTV infection has recently altered, perhaps driven in part by climatic influences on midge species resident in different regions. The goal of this review is to evaluate realistic strategies that might be utilized to control or prevent future outbreaks of BT and other Culicoides-transmitted diseases. Importantly, optimal control of emerging, rapidly evolving arbovirus diseases such as BT will require integrated countermeasures that mitigate all aspects of the virus's transmission cycle. This will best be accomplished using preventative, rather than purely reactive strategies., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Blood samples collected from 503 suspect cases of African horse sickness (AHS) and another 503 from uninfected, unvaccinated South African horses, as well as 98 samples from horses from an AHS free country, were tested with an AHS virus (AHSV) specific duplex real-time reverse transcription quantitative PCR (RT-qPCR) assay and virus isolation (VI). The diagnostic sensitivity and specificity of this AHSV RT-qPCR assay and VI were estimated using a 2-test 2-population Bayesian latent class model which made no assumptions about the true infection status of the tested animals and allowed for the possibility of conditional dependence (correlation) in test results. Median diagnostic sensitivity and specificity of the AHSV RT-qPCR were 97.8% and 99.9%, respectively. Median diagnostic specificity of virus isolation was >99% whereas the estimated diagnostic sensitivity was 44.2%. The AHSV RT-qPCR assay provides for rapid, high-throughput analysis of samples, and is both analytically and diagnostically sensitive and specific. This assay is potentially highly useful for demonstrating freedom or infection of horses with AHSV, thus it is appropriate that its reproducibility be evaluated in other laboratories as a global standard for detection of AHSV., (Copyright © 2012 Elsevier B.V. All rights reserved.)

To determine whether subclinical cases, together with clinical cases, of African horse sickness (AHS) occur in immunised horses in field conditions, whole blood samples were collected and rectal temperatures recorded weekly from 50 Nooitgedacht ponies resident in open camps at the Faculty of Veterinary Science, University of Pretoria, Onderstepoort, during 2008-2010. The samples were tested for the presence of African horse sickness virus (AHSV) RNA by a recently developed real-time RT-PCR. It was shown that 16% of immunised horses in an AHS endemic area were infected with AHSV over a 2 year period, with half of these (8%) being subclinically infected. The potential impact of such cases on the epidemiology of AHS warrants further investigation., (© 2012 EVJ Ltd.)

Bluetongue (BT) is an important viral disease of ruminants that is transmitted by hematophagous Culicoides midges. We examined the seasonal patterns of abundance and infection of Culicoides sonorensis at four dairy farms in the northern Central Valley of California to develop estimates of risk for bluetongue virus (BTV) transmission to cattle at each farm. These four farms were selected because of their similar meteorological conditions but varying levels of vector abundance and BTV infection of cattle. C. sonorensis midges were collected weekly at each farm during the seasonal transmission period, using three different trapping methods: traps baited with either carbon dioxide (CO(2)) alone or traps with CO(2) and UV light, and by direct aspiration of midges from sentinel cattle. Analysis of BTV-infected midges using group and serotype-specific quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) assays confirmed that BTV serotypes 10, 11, 13 and 17 are all present in the region, but that midge infection rates and the number of BTV serotypes circulating differed markedly among the individual farms. Furthermore, more serotypes of BTV were present in midges than in sentinel cattle at individual farms where BTV circulated, and the virus was detected at each farm in midges prior to detection in cattle. BTV infection rates were remarkably lower among female C. sonorensis midges collected by CO(2) traps with UV light than among midges collected by either animal-baited aspirations or in CO(2) traps without light. A subsample of female midges examined from each collection method showed no overall differences in the proportion of female midges that had previously fed on a host. Findings from this study confirm the importance of using sensitive surveillance methods for both midge collection and virus detection in epidemiological studies of BTV infection, which is especially critical if the data are to be used for development of mathematical models to predict the occurrence of BTV infection of livestock., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of a variety of pathogens including African horse sickness virus (AHSV), a member of the family Reoviridae, genus Orbivirus. AHSV causes African horse sickness (AHS), an endemic disease of equids with an extremely high mortality rate in horses in sub-Saharan Africa. Culicoides (Avaritia) imicola Kieffer is considered to be the principal vector of AHSV and is the dominant Culicoides species in South Africa. Due to the global distribution of Culicoides vectors, there is a potential risk of AHS spreading from endemic areas to areas traditionally free of the disease, which could have a severe economical impact on the affected equine industry. As part of any risk assessment it is essential to monitor known vectors as well as potential vector species. In the present study, sampling of Culicoides insects was compared using overnight collections in the conventional Onderstepoort light trap and mechanical aspiration of midges at sunset from bait horses. Culicoides imicola was confirmed as the predominant species using both trapping methods. Other species, mainly Culicoides (Avaritia) bolitinos Meiswinkel and Culicoides (Avaritia) gulbenkiani Caeiro, were highly underrepresented in the light trap collections, but made a significant contribution to the mechanical aspiration catches. The time for optimal collection differed between the trapping methods, leading to the conclusion that mechanical aspiration is a useful addition to conventional light trap collection and possibly the better choice when investigating insect vectors. An infection rate of 1.14% was calculated for the midge population based on real-time quantitative reverse-transcription polymerase chain reaction (RT-qPCR) assays of collected Culicoides midges, which exceeds previous estimates. This is probably due to the increased sensitivity of the RT-qPCR assay used in this study as compared to the virus isolation assays used in previous studies. RT-qPCR-positive midges were present in midge pools obtained from both light trap and mechanical aspiration. Seven of the positive pools consisted of C. imicola only, four contained mixed species and one pool contained no C. imicola, suggesting the presence of AHSV in midges of other species., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Bluetongue is an economically important arboviral disease of ruminants that is transmitted by hematophagous Culicoides midges. In light of dramatic recent changes in the global distribution of bluetongue virus (BTV), the goals of this study were to re-evaluate the prevalence of BTV infection of cattle and abundance of Culicoides midges on individual dairy farms in California. A serosurvey of adult dairy cattle confirmed that BTV infection is prevalent throughout much of the state, although the coastal northwestern region remains free of infection and prevalence varies markedly among farms in the remainder of the state. Intensive sampling for one year of 4 farms in the northern Central Valley of California showed that the abundance of Culicoides midges was markedly different and coincided with the prevalence of BTV infection of sentinel cattle on each farm. Mean maximum and minimum temperatures and other meteorological parameters were similar on all 4 farms, thus we speculate that particular management practices were responsible for both the increased midge abundance and prevalence of BTV infection of cattle at individual farms. Specifically, it is concluded that variation in vector abundance at individual farms most likely is the result of waste-water lagoon and irrigation management practices, leading to higher BTV infection rates among livestock held on farms with more waste-water lagoons and greater acreage of land for waste-water irrigation., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Bluetongue is an arthropod-transmitted viral disease of ruminants and certain other animals that was recognized and described more than 100 years ago in southern Africa. Bluetongue virus (BTV) infection of ruminants and vector Culicoides insects is enzootic throughout tropical and temperate regions of the world; however, there have been drastic recent regional alterations in the global distribution of BTV infection, particularly in Europe since 1998. Multiple novel BTV serotypes also have been detected since 1998 in the south-eastern United States, apparently encroaching from the adjacent Caribbean ecosystem, and novel serotypes of BTV have been identified recently in other historically enzootic regions of the world, including the Middle East and Australia. It has been proposed, but certainly not proven, that global climate change is responsible for these events. BTV infection of ruminants is often subclinical, but outbreaks of severe disease occur with regular frequency especially at the upper and lower limits of the virus' global range where infection is highly seasonal - occurring in the late summer and autumn. Bluetongue disease results from vascular injury, likely through a process analogous to that of human hemorrhagic viral fevers in which production of vasoactive mediators from virus-infected macrophages and dendritic cells results in enhanced endothelial paracellular permeability with subsequent vascular leakage and hypovolemic shock., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Equine herpesvirus-2 (EHV-2) infection has been implicated as a cause of a variety of clinical disorders in young horses, including upper respiratory tract disease, generalized malaise, fever, pharyngeal lymphoid hyperplasia, and lymphadenopathy. Considerable sequence heterogeneity has been demonstrated previously among EHV-2 strains, and individual horses can be concurrently infected with more than one virus strain. In this study, the temporal variation of the viral load and genomic diversity of the glycoprotein B (gB) gene of EHV-2 in the nasal secretions of a cohort of foals was characterized during the first 5 months of life. The viral load in nasal secretions of foals peaked when the foals were approximately 3 months old, and there was notable genetic heterogeneity of the gB gene, both among foals and within individuals. Furthermore, there was evidence of positive selection of EHV-2 variants with unique amino acid sequences at specific sites of gB., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been especially dramatic, with spread of multiple serotypes of the virus throughout extensive portions of Europe and invasion of the south-eastern USA with previously exotic virus serotypes. Although climate change has been incriminated in the emergence of BTV infection of ungulates, the precise role of anthropogenic factors and the like is less certain. Similarly, although there have been somewhat less dramatic recent alterations in the distribution of EHDV, AHSV, and EEV, it is not yet clear what the future holds in terms of these diseases, nor of other potentially important but poorly characterized Orbiviruses such as Peruvian horse sickness virus., (© INRA, EDP Sciences, 2010.)

Equid herpesvirus-2 (EHV-2) infection is ubiquitous in horses. Although EHV-2 infection has been associated with several disease syndromes, its true pathogenic significance in horses remains uncertain. Epstein-Barr virus (EBV), another gammaherpesvirus, has been shown to cause febrile illness in humans related to its immunopathologic effects. Thus, the purpose of this study was to describe the ontogeny of the immune response of a cohort of 9 foals to natural infection with EHV-2 by evaluating serial complete blood counts, lymphocyte morphology, cytokine gene expression in peripheral blood mononuclear cells (PBMC), viral load in nasal swabs and blood, and antigen-specific cellular immune responses of PBMC, in conjunction with clinical evaluation of the foals. The occurrence of fever in foals was not related to lymphocytosis or specific changes in lymphocyte morphology, cytokine gene expression, or viral load, but tended to be associated (P

Bluetongue virus (BTV) is the cause of bluetongue (BT), an emerging, arthropod-transmitted disease of ungulates. The cellular tropism of BTV in ruminants includes macrophages, dendritic cells and endothelial cells (ECs), and fulminant infection is characterized by lesions consistent with those of so-called viral hemorrhagic fevers. Specifically, BT is characterized by vascular injury with hemorrhage, tissue infarction and widespread edema. To further investigate the pathogenesis of vascular injury in BT, we evaluated the responses of cultured bovine pulmonary artery EC (bPAEC) and monocyte-derived macrophages (bMDM) to BTV infection by measuring transcript levels of genes encoding molecules important in mediating EC activation and/or endothelial barrier dysregulation. The data confirm that BTV infection of bPAEC resulted in increased transcription of genes encoding chemokine ligand 2 (CCL2) and E-selectin, and BTV infection of bMDM resulted in increased transcription of genes encoding TNF-alpha, IL-1beta, IL-8, and inducible nitric oxide synthase (iNOS). The data from these in vitro studies provide further evidence that cytokines and other vasoactive substances produced in macrophages potentially contribute to vascular injury in BTV-infected ruminants, along with direct effects of the virus itself on ECs., (Copyright 2010 Elsevier B.V. All rights reserved.)

There have been substantial recent changes in the global distribution and nature of bluetongue virus (BTV) infection of ungulates, perhaps as a result of climate change. To evaluate the epidemiology of BTV infection in California, an area historically endemic for the virus, we monitored newborn dairy calves at different sites for 1 year for the presence of BTV RNA and virus-specific antibodies. The data confirm both localized, vector-mediated, seasonal transmission of BTV as well as dissemination of BTV and/or viral nucleic acid to newborn calves following ingestion of colostrum.

Nucleotide sequences of 52 South African isolates of African horse sickness virus (AHSV) collected during 2004-2005 and including viruses of all nine AHSV serotypes, were used to design and develop a duplex real-time reverse transcription quantitative PCR (RT-PCR) assay targeting the VP7 (S8) and NS2 (S9) genes of AHSV. The assay was optimized for detection of AHSV in fresh and frozen blood of naturally infected horses. Assay performance was enhanced using random hexamers rather than gene-specific primers for RT, and with denaturation of double-stranded RNA in the presence of random hexamers. The assay was efficient with a linear range of at least five orders of magnitude. The analytical sensitivity of the assay was 132 copies of the target genes (4125 copies per ml of blood), and the assay was at least 10-fold more sensitive than virus isolation on BHK-21 cells. The assay was also highly specific because it did not detect related orbiviruses, such as bluetongue and equine encephalosis viruses., (Copyright 2010 Elsevier B.V. All rights reserved.)

Bluetongue virus (BTV) is the cause of bluetongue, an emerging, arthropod-transmitted disease of ungulates. Bluetongue is characterized by vascular injury with hemorrhage, tissue infarction and widespread edema, lesions that are consistent with those of the so-called viral hemorrhagic fevers. To further investigate the pathogenesis of vascular injury in bluetongue, we utilized an electrical impedance assay and immunofluorescence staining to compare the effects of BTV infection on cultured bovine endothelial cells (bPAEC) with those of inducers of cell death (Triton X-100) and interendothelial gap formation (tissue necrosis factor [TNF]). The data confirm that the adherens junctions of BTV-infected bPAECs remained intact until 24h post-infection, and that loss of monolayer impedance precisely coincided with onset of virus-induced cell death. In contrast, recombinant bovine TNF-alpha caused rapid loss of bPAEC monolayer impedance that was associated with interendothelial gap formation and redistribution of VE-cadherin, but without early cell death. The data from these in vitro studies are consistent with a pathogenesis of bluetongue that involves virus-induced vascular injury leading to thrombosis, hemorrhage and tissue necrosis. However, the contribution of cytokine-induced interendothelial gap formation with subsequent edema and hypovolemic shock contributes to the pathogenesis of bluetongue remains to be fully characterized., (Copyright 2010 Elsevier B.V. All rights reserved.)

Bluetongue (BT) is an important disease of ruminant livestock that is currently emerging in previously unaffected regions, most notably extensive portions of Europe. The epidemiology of BT virus (BTV) infection is poorly defined in much of the world, including extensive portions of Asia and the Middle East. Thus, the objective of this study was to describe the distribution and seroprevalence of BTV infection of sheep in West Azerbaijan Province of Iran, and to identify demographic and climatological factors associated with exposure of these sheep to BTV infection. BTV infection was widespread in the province as 400 of 1153 (34.7%) of the sheep sera evaluated contained antibodies to BTV, as determined by competitive ELISA, and 172 of 184 flocks included BTV seropositive sheep (93.5%). Multivariable logistic analyses failed to identify specific demographic or animal management practices that were predictive of BTV serological status of the sheep flocks. The virus serotypes and vector insects that occur within the region remain unknown.

This pilot study evaluated protection of an equine autogenous bacterin-toxoid vaccine against Corynebacterium pseudotuberculosis infection. Twenty-four BALB/c mice were inoculated with two doses of bacterin-toxoid vaccine or two injections of a placebo. Clinical, microbiologic, and pathologic outcomes were assessed after intradermal infection with one of two equine-origin C. pseudotuberculosis strains. Mice receiving bacterin-toxoid from fast-growing C. pseudotuberculosis showed significant protection from challenge infection, as evidenced by a higher survival rate, fewer gross and histopathologic lesions, and lower bacterial levels on culture. Successful protection via a vaccine against equine internal abscesses might provide supplementary management options against an important, potentially fatal disease.