Simultaneous detection of five notifiable viral diseases of cattle by single-tube multiplex real-time RT-PCR

From forests to fields: investigating Culicoides (Diptera: Ceratopogonidae) abundance and diversity in cattle pastures and adjacent woodlands

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are hematophagous flies that feed on wild and domestic ruminants. They can transmit arboviruses, such as bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV), which circulate in the United States. Larvae occupy a range of aquatic and semiaquatic habitats, and disperse short distances from their development sites. In the southeastern United States, there are limited studies on the abundance and diversity of Culicoides in wooded and adjacent livestock pasture habitats. In this study, we characterized Culicoides diversity and abundance within these distinct habitat types. BG-Sentinel and CDC miniature suction traps baited with CO2 or UV-light were placed in wooded and pasture habitats at 2 locations on a university beef farm in Savoy, Arkansas. Traps were set once per week for 9 wk during August-October of 2021 and 2022. Fifteen species were collected during this study, and the 2 most abundant species were Culicoides haematopotus Malloch and Culicoides stellifer Coquillett. There was a significant effect of site and location on C. haematopotus collections, and a significant effect and interaction of site and trap on C. stellifer collections. In the woods, significantly more C. stellifer were collected from CDC-UV traps, while in the pasture significantly more were collected in CDC-CO2 traps. These data suggest that C. stellifer, a putative vector of BTV and EHDV in the southeast, may be traveling into the pasture to host-seek, while C. haematopotus remains primarily in wooded areas. This study reveals community differences between these habitat types and implications for Culicoides control.

The Molecular Epidemiology of Epizootic Hemorrhagic Disease Viruses Identified in Israel between 2015 and 2023

Epizootic hemorrhagic disease (EHD) is an infectious, non-contagious viral disease seriously affecting cattle and some wild ruminants and has a worldwide distribution. All viruses can be subdivided into "Eastern" and "Western" topotypes according to geographic distribution via the phylogenetic analysis of internal genes. In Israel, during the last decade, three outbreaks were registered: caused by EHDV-6 in 2015, by EHDV-1 in 2016, and by EHDV-7 in 2020. Additionally, RNA of EHDV-8 was found in imported calves from Portugal in 2023. During the same period in other countries of the region, non-Israeli-like EHDV-6 and EHDV-8 were identified. Full genome sequencing, BLAST, and phylogenetic analyses of the locally and globally known EHDV genomes allowed us to presume the probable route and origin of these viruses detected in Israel. Thus, EHDV-6 has probably been circulating in the region for a long period when EHDV-1 and -8 appeared here for the last years, while their route of introduction into the new areas was probably natural; all of them belonged to the "Western" topotype. In contrast, EHDV-7 probably had the "Eastern", anthropogenic origin. Data from the study can facilitate the evaluation of the appearance or reappearance of EHDVs in the Mediterranean area and enhance the planning of prevention measures.

A novel bluetongue virus serotype 2 strain isolated from a farmed Florida white-tailed deer (Odocoileus virginianus) arose from reassortment of gene segments derived from co-circulating serotypes in the Southeastern USA

Bluetongue disease is a reportable animal disease that affects wild and farmed ruminants, including white-tailed deer (WTD). This report documents the clinical findings, ancillary diagnostics, and genomic characterization of a novel reassortant bluetongue virus serotype 2 (BTV-2) strain isolated from a dead Florida farmed WTD in 2022. Our analyses support that this BTV-2 strain likely stemmed from the acquisition of genome segments from co-circulating BTV strains in Florida and Louisiana. In addition, our analyses also indicate that genetically uncharacterized BTV strains may be circulating in the Southeastern USA; however, the identity and reassortant status of these BTV strains cannot be determined based on the VP2 and VP5 genome sequences. Hence, continued surveillance based on complete genome characterization is needed to understand the genetic diversity of BTV strains in this region and the potential threat they may pose to the health of deer and other ruminants.

Herpesviruses and SARS-CoV-2: Viral Association with Oral Inflammatory Diseases

The oral cavity is a niche for diverse microbes, including viruses. Members of the Herpesviridae family, comprised of dsDNA viruses, as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an ssRNA virus, are among the most prevalent viruses infecting the oral cavity, and they exhibit clinical manifestations unique to oral tissues. Viral infection of oral mucosal epithelia triggers an immune response that results in prolonged inflammation. The clinical and systemic disease manifestations of HHV have been researched extensively, and several recent studies have illuminated the relationship between HHV and oral inflammatory diseases. Burgeoning evidence suggests the oral manifestation of SARS-CoV-2 infection includes xerostomia, dysgeusia, periodontal disease, mucositis, and opportunistic viral and bacterial infections, collectively described as oral post-acute sequelae of COVID-19 (PASC). These diverse sequelae could be a result of intensified immune responses initially due to the copious production of proinflammatory cytokines: the so-called "cytokine storm syndrome", facilitating widespread oral and non-oral tissue damage. This review explores the interplay between HHV, SARS-CoV-2, and oral inflammatory diseases such as periodontitis, endodontic disease, and peri-implantitis. Additionally, the review discusses proper diagnostic techniques for identifying viral infection and how viral diagnostics can lead to improved overall patient health.

Blood analytes of clinically normal and diseased neonatal and weaned farmed white-tailed deer (Odocoileus virginianus) fawns

Recent research focused on farmed deer has exposed many knowledge gaps regarding health assessment protocols for white-tailed deer (WTD). The objectives of this study were to establish de novo blood analyte reference intervals for farmed WTD fawns at birth (1-2 days of age; n = 84) and again at weaning (76-125 days of age; n = 28), to compare data at birth and at weaning to understand how these analytes are affected by the intrinsic factors age and sex in clinically normal WTD fawns, and to compare between clinically normal and sick WTD weanlings (respiratory disease n = 12; orbivirus-infected n = 6). Reference intervals were established for WTD fawns at birth and weaning. Female WTD neonates had significantly higher red blood cell counts, hematocrit, and hemoglobin compared to males. Most blood analytes were significantly different in clinically normal WTD neonates compared to weanlings, suggesting an effect of age. The observed sex- and age-related variations in WTD highlight the need to establish reference intervals that account for intrinsic factors. The comparison of clinically normal and sick WTD weanlings in this study identified higher MCHC and absolute monocytes in sick weanlings but these findings were presumably not biologically relevant given the small sample size for sick fawns. While the reference interval data presented herein will be useful for the veterinary care of WTD fawns at critical time periods in a high-density farm setting, this study also demonstrates the need to identify more sensitive and specific biomarkers for the assessment of health status in farmed WTD with specific underlying diseases.

Characterization of two novel reassortant bluetongue virus serotype 1 strains isolated from farmed white-tailed deer (Odocoileus virginianus) in Florida, USA

Hemorrhagic diseases caused by epizootic hemorrhagic disease virus or by bluetongue virus (BTV) are the most important orbivirus diseases affecting ruminants, including white-tailed deer (WTD). Bluetongue virus is of particular concern for farmed WTD in Florida, given its lethality and its wide distribution throughout the state. This study reports the clinical findings, ancillary diagnostics, and genomic characterization of two BTV serotype 1 strains isolated from two farmed WTD, from two different farms in Florida in 2019 and 2022. Phylogenetic and genetic analyses indicated that these two novel BTV-1 strains were reassortants. In addition, our analyses reveal that most genome segments of these strains were acquired from BTVs previously detected in ruminants in Florida, substantiating their endemism in the Southeastern U.S. Our findings underscore the need for additional research to determine the genetic diversity of BTV strains in Florida, their prevalence, and the potential risk of new BTV strains to WTD and other ruminants.

Hefer valley virus: a novel ephemerovirus detected in the blood of a cow with severe clinical signs in Israel in 2022

A novel ephemerovirus was identified in a Holstein-Friesian cow in the Hefer Valley, Israel, that showed severe and fatal clinical signs resembling an arboviral infection. A sample taken during the acute phase tested negative for important endemic arboviral infectious cattle diseases. However, sequencing from blood revealed the full genome sequence of Hefer Valley virus, which is likely to represent a new species within the genus Ephemerovirus, family Rhabdoviridae. Archived samples from cattle with comparable clinical signs collected in Israel in 2021 and 2022 tested negative for the novel virus, and therefore, the actual distribution of the virus is unknown. As this is a recently identified new viral infection, the viral vector and the prevalence of the virus in the cattle population are still unknown but will be the subject of future investigations.

Comparative Molecular and Epidemiological Analyses of Israeli Bluetongue Viruses Serotype 1 and 9 Causing Outbreaks in 2018-2020

Israel is endemic to bluetongue virus (BTV). The introduction of novel-for-the-region arboviruses have been recorded annually in recent years. In 2019, previously non-reported in-the-country BTV-1 and BTV-9 were identified. BTV-1 caused a single-season outbreak, probably linked to mild infection in ruminants. BTV-9 was retrospectively detected in the field samples collected from August 2018 until 2020. It was the dominant serotype in 2019, out of the six serotypes recorded during that calendar year. Clinical manifestation of the disease in cases diagnosed with BTV-9 were compared to those in cases determined to have BTV-1. BLAST and phylogenetic analyses of BTV-1 showed that the nucleotide (nt) sequence coding the viral outer protein 1 (VP2) determining the serotype is closely related to BTV-1 isolated in Sudan in 1987, and the coding sequence of the outer protein 2 (VP5) is related to South African BTV-1 from 2017. A probable common ancestor with Libyan BTV-9 strains isolated in 2008 was seen in an analysis of Israeli BTV-9 nt sequences. Notably, the outbreak-caused BTV-9 strains collected in 2019 exhibited a distinct level of genetic reassortment with local Israeli strains compared to BTV-9 strains registered in 2018 and 2020.

Identification of Novel Reassortant Shuni Virus Strain in Clinical Cases of Israeli Ruminants, 2020–2021

The Shuni virus (SHUV) causes an endemic viral infection in Israel and South Africa. It belongs to the Simbu serogroup within the order Bunyavirales, family Peribunyaviridae, genus Orthobunyavirus. Recently, it has been identified in aborted cases of domestic ruminants, young cattle and horses manifesting neural signs and acute death, symptomatic cows, and in carcasses of wild animals. Moreover, SHUV was isolated and identified in humans. In this study, we describe clinical cases of SHUV infection in Israeli domestic ruminants in 2020–2021, which represented clinical manifestations of simbuviral infection including abortions, a neural lethal case in a fattening calf, and an acute symptomatic case in a beef cow. In all cases, SHUV was confirmed by complete or partial viral genome sequencing. There is a significant difference of M and L segments of the novel strains compared with those of all known SHUV strains, while the S segments have more than 99% nucleotide (nt) identity with Israeli and African “Israeli-like” strains previously circulated in 2014–2019. This indicates a reassortment origin of the strain. At the same time, M and S segment nt sequences showed about 98–99% nt identity with some South African strains collected in 2016–2018. Nevertheless, the viral origin and the geographical place of the reassortment stayed unknown.

Co-circulation of Orthobunyaviruses and Rift Valley Fever Virus in Mauritania, 2015

Ngari virus (NRIV) has been mostly detected during concurrent outbreaks of Rift Valley fever virus (RVFV). NRIV is grouped in the genus Orthobunyavirus within the Bunyaviridae family and RVFV in the genus Phlebovirus in the family Phenuiviridae. Both are zoonotic arboviruses and can induce hemorrhagic fever displaying the same clinical picture in humans and small ruminants. To investigate if NRIV and its parental viruses, Bunyamwera virus (BUNV) and Batai virus (BATV), played a role during the Mauritanian RVF outbreak in 2015/16, we analyzed serum samples of sheep and goats from central and southern regions in Mauritania by quantitative real-time RT-PCR, serum neutralization test (SNT) and ELISA. 41 of 458 samples exhibited neutralizing reactivity against NRIV, nine against BATV and three against BUNV. Moreover, complete virus genomes from BUNV could be recovered from two sheep as well as two NRIV isolates from a goat and a sheep. No RVFV-derived viral RNA was detected, but 81 seropositive animals including 22 IgM-positive individuals were found. Of these specimens, 61 samples revealed antibodies against RVFV and at least against one of the three orthobunyaviruses. An indirect ELISA based on NRIV/BATV and BUNV derived Gc protein was established as complement to SNT, which showed high performance regarding NRIV, but decreased sensitivity and specificity regarding BATV and BUNV. Moreover, we observed high cross-reactivity among NRIV and BATV serological assays. Taken together, the data indicate the co-circulation of at least BUNV and NRIV in the Mauritanian sheep and goat populations.

Occurrence of malformed calves in April-May 2021 indicates an unnoticed 2020 emergence of Schmallenberg virus in Denmark

During the European emergence of Schmallenberg virus (SBV) in 2011, examination of Culicoides spp. showed that SBV-infected midges were present across Denmark. However, SBV-associated malformations in ruminant species have not been reported in Denmark. In April 2021, seven calves with severe congenital generalized arthrogryposis and reduced body weight originating from a narrow region of the Jutlandic peninsula were submitted for examination. Analysis of fetal brain tissue for SBV viral RNA and pleural effusion for fetal anti-SBV antibodies identified SBV as the cause of the congenital syndrome. Backwards calculation from the calving dates indicated the occurrence of an unnoticed emergence of SBV in Denmark from early August 2020 and during the late summer and autumn. As SBV-associated malformations may lead to severe dystocia requiring fetotomy or caesarean section, veterinarians performing obstetric intervention are first-line personnel in recognition of SBV emergence in domestic ruminants.

Identification and Genetic Characterization of Viral Pathogens in Ruminant Gestation Abnormalities, Israel, 2015-2019

Infectious agents including viruses are important abortifacients and can cause fetal abnormalities in livestock animals. Here, samples that had been collected in Israel from aborted or malformed ruminant fetuses between 2015 and 2019 were investigated for the presence of the following viruses: the reoviruses bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV), the flaviviruses bovine viral diarrhea virus (BVDV) and border disease virus (BDV), the peribunyaviruses Shuni virus (SHUV) and Akabane virus (AKAV), bovine herpesvirus type 1 (BoHV-1) and bovine ephemeral fever virus (BEFV). Domestic (cattle, sheep, goat) and wild/zoo ruminants were included in the study. The presence of viral nucleic acid or antigen could be confirmed in 21.8 % of abnormal pregnancies (213 out of 976 investigated cases), with peribunyaviruses, reoviruses and pestiviruses being the most prevalent. At least four different BTV serotypes were involved in abnormal courses of pregnancy in Israel. The subtyping of pestiviruses revealed the presence of two BDV and several distinct BVDV type 1 strains. The peribunyaviruses AKAV and SHUV were identified annually throughout the study period, however, variation in the extent of virus circulation could be observed between the years. In 2018, AKAV even represented the most detected pathogen in cases of small domestic ruminant gestation abnormalities. In conclusion, it was shown that various viruses are involved in abnormal courses of pregnancy in ruminants in Israel.

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.

A Mortality-Based Description of EHDV and BTV Prevalence in Farmed White-Tailed Deer (Odocoileus virginianus) in Florida, USA

Hemorrhagic disease (HD) caused by bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) is the most important viral disease of farmed and wild white-tailed deer (WTD; Odocoileus virginianus) and can cause substantial mortality in susceptible hosts. Captive cervid farming is an emerging industry in Florida, an HD-enzootic region. Morbidity and mortality due to HD are major concerns among deer farmers, but the impact of HD on Florida’s cervid farming industry is unknown. Our primary objective was to determine the prevalence of epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) among WTD submitted to the University of Florida Institute of Food and Agricultural Sciences Cervidae Health Research Initiative (CHeRI) for post-mortem diagnostics. Our secondary objectives were to identify the predominant circulating EHDV serotypes during each sampling year and to determine the age class with the greatest proportion of EHDV- and BTV-positive post-mortem specimens. From 2016 to 2020, spleen samples from 539 farmed WTD with unexplained mortality were tested for the presence of EHDV and BTV by RT-qPCR. Overall, the prevalence of EHDV, BTV, or EHDV/BTV coinfection was 26%, 16%, and 10%, respectively, and 44% of deer (237/539) were diagnosed with HD by RT-qPCR. The predominant circulating EHDV serotype varied by year. Overall, EHDV-2 was the most commonly identified serotype (55% of PCR-positive cases), and EHDV-1 was the least frequently identified serotype (16% of PCR-positive cases). The greatest proportion of EHDV/BTV positives among mortality cases was observed in young WTD aged 3–6 months (50%–82% positive). There was a significant difference in the prevalence of EHDV/BTV by age when comparing specimens from WTD over 1 year old (p = 0.029, n = 527). Among these samples, the number of reported mortalities and the prevalence of EHDV/BTV were highest in yearling animals (56%). These data provide the first estimate of EHDV and BTV prevalence and virus serotypes among farmed WTD in Florida, identify the WTD age groups with the greatest proportions of EHDV- and BTV-positive specimens, and suggest that HD caused by these two viruses may be a major source of mortality challenging the captive cervid farming industry in Florida.

Epizootic Hemorrhagic Disease Virus and Bluetongue Virus Seroprevalence in Wild White-Tailed Deer (Odocoileus virginianus) in Florida, USA

A wild population of white-tailed deer (Odocoileus virginianus) was surveyed for evidence of past or current epizootic hemorrhagic disease virus (EHDV) and current bluetongue virus (BTV) infections. We collected 121 blood samples from hunter-harvested or live-captured deer from two state-managed properties in northwest Florida, US; live captures were in support of a movement ecology study. Blood samples were tested for antibodies against titers to three EHDV serotypes (EHDV-1, EHDV-2, and EHDV-6), and multiplex quantitative reverse transcription PCR was used to identify the presence of EHDV or BTV viral RNA. Of these samples, 81% (98/121) tested seropositive for at least one of three serotypes of EHDV. Of those testing seropositive, 33% (40/121) contained antibodies for two serotypes, and 19% (24/121) contained antibodies for all three EHDV serotypes. Furthermore, results of generalized linear models indicated that the probability of infection by EHDV serotypes 1 and 6 increased with an animal's age. Our findings indicate that seroprevalence may be high for multiple serotypes in regions where these orbiviruses are endemic. These results could prove useful for managing disease risk in naïve deer populations.

Vector Competence of Florida Culicoides insignis (Diptera: Ceratopogonidae) for Epizootic Hemorrhagic Disease Virus Serotype-2

Epizootic hemorrhagic disease virus (EHDV; family Reoviridae, genus Orbivirus) is an arthropod-borne virus of ungulates, primarily white-tailed deer in North America. Culicoides sonorensis, the only confirmed North American vector of EHDV, is rarely collected from Florida despite annual virus outbreaks. Culicoides insignis is an abundant species in Florida and is also a confirmed vector of the closely related Bluetongue virus. In this study, oral challenge of C. insignis was performed to determine vector competence for EHDV serotype-2. Field-collected female midges were provided bovine blood spiked with three different titers of EHDV-2 (5.05, 4.00, or 2.94 log₁₀PFUe/mL). After an incubation period of 10 days or after death, bodies and legs were collected. Saliva was collected daily from all females from 3 days post feeding until their death using honey card assays. All samples were tested for EHDV RNA using RT-qPCR. Our results suggest that C. insignis is a weakly competent vector of EHDV-2 that can support a transmissible infection when it ingests a high virus titer (29% of midges had virus positive saliva when infected at 5.05 log₁₀PFUe/mL), but not lower virus titers. Nevertheless, due to the high density of this species, particularly in peninsular Florida, it is likely that C. insignis plays a role in the transmission of EHDV-2.

EVIDENCE OF EPIZOOTIC HEMORRHAGIC DISEASE VIRUS AND BLUETONGUE VIRUS EXPOSURE IN NONNATIVE RUMINANT SPECIES IN NORTHERN FLORIDA

Epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) are vector-borne viruses of ruminants nearly worldwide. They can affect white-tailed deer (WTD; Odocoileus virginianus), the ranching industry, and nonindigenous hoof stock species managed for conservation. One potential risk factor for ranched WTD is commingling with nonindigenous species on high-fenced properties. Nonindigenous species provide novel viewing and hunting opportunities; however, their presence may create disease hazards. Furthermore, animals within conservation properties may be at a risk from commingling exotics and adjacent wild WTD. Currently, knowledge about EHDV and BTV seroprevalence and transmission is limited in nonindigenous populations in the southeastern United States. The authors conducted a serological survey of 10 Bovidae and 5 Cervidae species residing within two properties in northern Florida. The first site was a conservation property breeding threatened nonindigenous species for conservation. The second property was a private high-fenced game preserve managing WTD and nonindigenous species for breeding, sale, and harvest. Blood samples were tested for titers to three EHDV serotypes (1, 2, and 6) and active circulating viral EHDV and BTV. The private ranch had evidence of EHDV or BTV in one of three (33.3%) Bovidae species and four of five (80%) Cervidae species sampled. At the conservation property, evidence of EHDV infection was found in four of seven (57.1%) Bovidae and one of one (100%) Cervidae species sampled. The presence of antibodies in many nonindigenous species sampled might indicate these species are potential viral hosts and may be a risk to ranched WTD and other species within the same property. Nonindigenous species within the private ranch and conservation properties are at risk of contracting EHDV and BTV, and herd managers should reduce vector-host interactions and consider increased biosecurity measures when translocating animals.

Three New Orbivirus Species Isolated from Farmed White-Tailed Deer (Odocoileus virginianus) in the United States

We report the detection and gene coding sequences of three novel Orbivirus species found in six dead farmed white-tailed deer in the United States. Phylogenetic analyses indicate that the new orbiviruses are genetically closely related to the Guangxi, Mobuck, Peruvian horse sickness, and Yunnan orbiviruses, which are thought to be solely borne by mosquitos. However, four of the six viruses analyzed in this work were found as co-infecting agents along with a known cervid pathogen, epizootic hemorrhagic disease virus-2 (EHDV-2), raising questions as to whether the new viruses are primary pathogens or secondary pathogens that exacerbate EHDV-2 infections. Moreover, EHDV-2 is known to be a Culicoides-borne virus, raising additional questions as to whether Culicoides species can also serve as vectors for the novel orbiviruses, if mosquitoes can vector EHDV-2, or whether the deer were infected through separate bites by the insects. Our findings expand knowledge of the possible viral pathogens of deer in the United States. Moreover, due to the close genetic relatedness of the three new orbiviruses to viruses that are primary pathogens of cattle and horses, our findings also underscore a crucial need for additional research on the potential role of the three new orbiviruses as pathogens of other animals.

Characterization of bluetongue virus serotype 28

Bluetongue virus (Reoviridae; Orbivirus, BTV), which is usually transmitted by biting midges, affects wild and domestic ruminants worldwide, thereby causing an economically important disease. Recently, a putative new BTV strain was isolated from contaminated vaccine batches. In this study, we investigated the genomic and clinical characteristics of this isolate, provisionally designated BTV-28. Phylogenetic analysis of BTV-28 segment 2 (Seg-2) showed that it is related to Seg-2 from BTV serotypes 4, 10, 11, 17, 20 and 24, sharing 64%-66% identity in nucleotide sequences (nt) and 59%-62% in amino acid (aa) sequences of BTV VP2. BTV-28 Seg-6 is related to the newly reported XJ1407 BTV isolate, sharing 76.70% nt and 90.87% aa sequence identity. Seg-5 was most closely related to a South African BTV-4 strain, and all other segments showed close similarity to BTV-26. Experimental infection by injection of 6-month-old ewes caused clinical signs in all injected animals, lasting from 2 to 3 days to several weeks post-infection, including high body temperature, conjunctivitis, nasal discharge and rhinitis, facial oedema, oral hyperaemia, coronitis, cough, depression and tongue cyanosis. Naïve control animals, placed together with the infected sheep, displayed clinical signs and were positive for viral RNA, but their acute disease phase was shorter than that of BTV-injected ewes. Control animals that were kept in a separated pen did not display any clinical signs and were negative for viral RNA presence throughout the experiment. Seroconversion was observed in the injected and in one of the two contact-infected animals. These findings demonstrate that BTV-28 infection of sheep can result in clinical manifestation, and the clinical signs detected in the contact animals suggest that it might be directly transmitted between the mammalian hosts.

Molecular characterization of a novel reassortment Mammalian orthoreovirus type 2 isolated from a Florida white-tailed deer fawn

Mammalian orthoreovirus (MRV) is the type species of the genus Orthoreovirus and causes a range of significant respiratory, nervous or enteric diseases in humans and animals. In 2016 a farmed white-tailed deer (Odocoileus virginianus) fawn became ill, displaying clinical signs of lethargy, dehydration, and profuse foul-smelling diarrhea. A necropsy was performed after the three-week-old fawn died and various tissue samples were submitted to the University of Florida's Cervidae Health Research Initiative for diagnostic evaluation. Aliquots of homogenized heart, liver, and spleen tissues were inoculated onto Vero E6 cells. After virus-specific cytopathic effects (CPE) were detected in Vero cells inoculated with spleen homogenate, infected cells were fixed in glutaraldehyde and analyzed by transmission electron microscopy (TEM), which revealed icosahedral virus particles approximately 75 nm in diameter with morphologies consistent with those of reoviruses within the cytoplasm of the infected cells. RNA extracted from virions in the spent media of infected cells with advanced CPE was used to prepare a cDNA library, which was sequenced using an Illumina MiSeq sequencer. Complete coding sequences for ten separate reovirus segments were attained, and these indicated the isolated agent was a MRV. Genetic and phylogenetic analyses based on the outer capsid sigma-1 (σ1) protein gene sequences supported the Florida white-tailed fawn isolate as a type 2 MRV that branched as the sister group to a MRV-2 strain previously characterized from the urine of a moribund lion (Panthera leo) in Japan. However, analyses based on 7/10 genes (L1-L2, M2-M3, S2-S4) supported the white-tailed deer MRV as the closest relative to a type 3 MRV strain isolated from a dead mink in China. These data suggest the white-tailed deer MRV may have resulted from the natural reassortment of MRVs originating from multiple wildlife species. To our knowledge, this is the first detection of MRV-2 infection in a white-tailed deer. Continued surveillance efforts are needed to determine whether this MRV-2 strain poses a health threat to farmed white-tailed deer populations.

Epidemiology of Bluetongue Virus and Epizootic Hemorrhagic Disease Virus in Beef Cattle on a Ranch in South-Central Florida

Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) infect a variety of wild and domestic ruminant hosts in the United States, with outcomes ranging from subclinical infection to clinical disease resulting in mortality. Because cattle have been suggested as a temporary reservoir for both BTV and EHDV, ongoing national surveillance for these viruses may benefit from inclusion of domestic cattle as a supplement to current programs, such as surveillance of wild white-tailed deer. To better understand the prevalence of BTV and EHDV in cattle, we surveyed for viral RNA (vRNA) in the blood of 1,604 beef cattle on a south-central Florida cattle ranch over 3 years. While overall prevalence of vRNA in blood was low (<2% for either virus), the occurrence of vRNA was much higher in young animals: in 2016, 24% of animals 2 years old were positive by PCR for either BTV or EHDV. Our results suggest that cattle are a likely temporary reservoir for these viruses in Florida, and could provide additional information on the spatial distribution, viral diversity, and timing of emergence of these viruses, particularly if surveillance was restricted to cattle ≤2 years of age.

Field data implicating Culicoides stellifer and Culicoides venustus (Diptera: Ceratopogonidae) as vectors of epizootic hemorrhagic disease virus

BACKGROUND

Epizootic hemorrhagic disease virus (EHDV) is an Orbivirus of veterinary importance which is transmitted by biting midges of the genus Culicoides (Diptera: Ceratopogonidae) to ruminants. Culicoides sonorensis Wirth & Jones, the only confirmed vector of EHDV in the USA, is rare in the southeastern states where transmission persists, suggesting that other Culicoides species transmit EHDV in this region. The present study aimed to determine which Culicoides species transmitted EHDV in Florida and Alabama, two states in the southeastern USA. Viral RNA was detected in field-collected midges using molecular methods. These data are presented alongside data on Culicoides blood meal analysis, white-tailed deer (Odocoileus virginianus) aspiration, and seasonality to demonstrate an interaction between potential vector species and EHDV hosts.

RESULTS

Out of 661 pools tested, 20 pools were positive for EHDV viral RNA, including six pools from Culicoides stellifer (Coquillett) and 14 pools from Culicoides venustus Hoffman. The overall infection rate was 0.06% for C. stellifer and 2.18% for C. venustus. No positive pools were identified for a further 17 species. Serotypes identified in Culicoides included EHDV-2, EHDV-6, and coinfections of EHDV-2 and EHDV-6 and were identified in similar proportions to serotypes in deer at 3 of 4 deer farms. Viral detections conducted in Alabama also identified one positive pool of C. venustus. Blood meal analysis revealed that both Culicoides species fed on white-tailed deer (verified through aspiration), fallow deer, and elk, species for which EHDV viremia has been documented. Seasonality data indicated that both species were present throughout the period in which viral transmission occurred to EHDV hosts in 2016 in addition to the 2017 epizootic.

CONCLUSIONS

Our finding of EHDV positive pools of field-collected C. stellifer and C. venustus and an interaction between these species and EHDV hosts satisfy two of the four criteria for vector incrimination as set by the World Health Organization. Determining the vectors of EHDV is an important step towards developing sound strategies for the control of vector Culicoides and management of EHDV in the southeastern USA.

Vector Competence of Culicoides sonorensis (Diptera: Ceratopogonidae) for Epizootic Hemorrhagic Disease Virus Serotype 2 Strains from Canada and Florida

Epizootic hemorrhagic disease virus (EHDV), an Orbivirus transmitted by Culicoides spp. vectors, is represented by seven serotypes and numerous strains worldwide. While studies comparing vector competence between serotypes exist, studies between viral strains are lacking. In this study, we examined the rates of infection, dissemination, and transmission of two strains of EHDV-2 orally fed to the known vector, Culicoides sonorensis Wirth & Jones. Culicoides sonorensis cohorts were fed an infectious blood meal containing EHDV-2 strains from either Alberta, Canada (Can-Alberta) or Florida (5.5 log₁₀ PFUe/mL) and tested for the vector’s susceptibility to infection and dissemination. In addition, transmission rates of the virus were assessed and compared using capillary tube and honey card methods. Our results show that the Florida strain had higher infection and dissemination rates than the Can-Alberta strain in spite of the Florida strain having significantly lower viral titers in C. sonorensis bodies, legs, and saliva than the Can-Alberta strain. Overall transmission rates were not significantly different between the two strains but varied significantly between the methods used. These findings suggest that the consequences of EHDV infection in C. sonorensis vary between virus strains and have huge implications in future vector competence studies involving Culicoides species and Orbiviruses.

Ecology and epidemiology of rabies in humans, domestic animals and wildlife in Namibia, 2011-2017

Rabies is a fatal zoonotic disease that causes a heavy burden on societies. Namibia, a country in southern Africa, is aiming at controlling the disease in its main reservoir, the domestic dog. To facilitate the implementation comprehensive information on the ecology and epidemiology of the disease and surveillance is of utmost importance. The study presented assesses the baseline data for both human and animal rabies surveillance in Namibia in recent times and establishes correlations with ecological and socio-economic data in order to provide an up-to-date picture on the epidemiology of rabies in Namibia. For instance, it was important to identify the main drivers in the epidemiology, and whether the control strategy by mass vaccination of dogs is undermined by cycles of rabies in wildlife. Rabies in humans was reported mainly from the Northern Communal Areas (NCAs), with a total of 113 cases from 2011 to 2017, representing an incidence of between 1.0 and 2.4 annual human rabies deaths per 100,000 inhabitants. Kavango, the region with the highest human rabies incidence was also the region with the lowest animal rabies surveillance intensity. Generally, the vast majority (77%) of dog samples originated from communal farm land, followed by urban areas (17%), while only a small fraction (3%) was submitted from freehold farm areas. In contrast, kudu and eland submissions were almost exclusively from freehold farmland (76%) and urban areas (19%), whereas the submission of cattle samples was evenly distributed among freehold farms (46%) and communal farm land (46%). The likelihood of sample submission decreased exponentially with distance to one of the two laboratories. Overall, 67% (N = 1,907) of all samples submitted tested rabies-positive, with the highest positivity rate observed in kudus (89%) and jackals (87%). The transmission cycle of rabies in dogs appears restricted to the northern communal areas of Namibia, whilst rabies in wildlife species is predominately reported from farmland in central Namibia, mostly affecting kudu (Tragelaphus strepsiceros) and livestock with a likely reservoir in wildlife canids such as jackals or bat-eared foxes. The analysis confirms the presence of two independent transmission cycles in Namibia with little geographic overlap, thus allowing for a sustainable control of rabies in dogs in the NCAs.

Characterization of mule deerpox virus in Florida white-tailed deer fawns expands the known host and geographic range of this emerging pathogen

Infections caused by mule deerpox virus (MDPV) have been sporadically reported in North American cervids. White-tailed deer (Odocoileus virginianus) fawns from a farm located in South Central Florida presented with ulcerative and crusting lesions on the coronary band as well as the mucocutaneous tissues of the head. Evaluation of the crusted skin lesions was undertaken using microscopic pathology and molecular techniques. A crusted skin sample was processed for virus isolation in four mammalian cell lines. The resulting isolate was characterized by negative staining electron microscopy and deep sequencing. Histopathologic evaluation of the skin lesions from the fawns revealed a hyperplastic and proliferative epidermis with ballooning degeneration of epidermal and follicular keratinocytes with intracytoplasmic eosinophilic inclusions. Electron microscopy of cell culture supernatant demonstrated numerous large brick-shaped particles typical of most poxviruses. Polymerase chain reaction assays followed by Sanger sequencing revealed a poxvirus gene sequence nearly identical to that of previous strains of MDPV. The full genome was recovered by deep sequencing and genetic analyses supported the Florida white-tailed deer isolate (MDPV-F) as a strain of MDPV. Herein, we report the first genome sequence of MDPV from a farmed white-tailed deer fawn in the South Central Florida, expanding the number of locations and geographic range in which MDPV has been identified.

Presence of two different bovine hepacivirus clusters in Germany

During the last years, genetic information of hepaciviruses (family Flaviviridae), whose type species is the human hepatitis C virus, was detected in a wide range of primates and non-primate vertebrates. Here, samples collected from 263 German cattle kept in 22 different holdings were analysed for the presence of hepacivirus N (syn. bovine hepacivirus; BovHepV). One hundred eighty-six cattle that suffered from unspecific clinical signs such as fever and a reduced milk yield as well as 77 apparently healthy animals were included. A total of 39 cattle (14.8%) tested positive for BovHepV by real-time RT-PCR, but a correlation between clinical signs and virus infection could not be found. From 31 of the virus-positive samples, sequences of the NS3 coding region were generated and from two samples, viral sequences of the complete coding region were produced and compared to further European and African BovHepV sequences. Based on the NS3 genomic region, two distinct German BovHepV clusters were identified which differed between each other up to 20% at the nucleotide level, the diversity within the individual clusters reached up to 10%. Based on the full-length sequences, the newly detected virus variants group together with further German and African viruses in a sister relationship to other hepaciviruses from primates and further mammalians, but form distinct clusters within the BovHepV branch. In conclusion, highly diverse hepaciviruses were detected in German cattle further expanding the known phylogenetic diversity of the genus Hepacivirus.

Evaluation of Targeted Next-Generation Sequencing for Detection of Bovine Pathogens in Clinical Samples

The laboratory diagnosis of infectious diseases, especially those caused by mixed infections, is challenging. Routinely, it requires submission of multiple samples to separate laboratories. Advances in next-generation sequencing (NGS) have provided the opportunity for development of a comprehensive method to identify infectious agents. This study describes the use of target-specific primers for PCR-mediated amplification with the NGS technology in which pathogen genomic regions of interest are enriched and selectively sequenced from clinical samples. In the study, 198 primers were designed to target 43 common bovine and small-ruminant bacterial, fungal, viral, and parasitic pathogens, and a bioinformatics tool was specifically constructed for the detection of targeted pathogens. The primers were confirmed to detect the intended pathogens by testing reference strains and isolates. The method was then validated using 60 clinical samples (including tissues, feces, and milk) that were also tested with other routine diagnostic techniques. The detection limits of the targeted NGS method were evaluated using 10 representative pathogens that were also tested by quantitative PCR (qPCR), and the NGS method was able to detect the organisms from samples with qPCR threshold cycle (C_T) values in the 30s. The method was successful for the detection of multiple pathogens in the clinical samples, including some additional pathogens missed by the routine techniques because the specific tests needed for the particular organisms were not performed. The results demonstrate the feasibility of the approach and indicate that it is possible to incorporate NGS as a diagnostic tool in a cost-effective manner into a veterinary diagnostic laboratory.

Dembo polymerase chain reaction technique for detection of bovine abortion, diarrhea, and respiratory disease complex infectious agents in potential vectors and reservoirs

Bovine abortion, diarrhea, and respiratory disease complexes, caused by infectious agents, result in high and significant economic losses for the cattle industry. These pathogens are likely transmitted by various vectors and reservoirs including insects, birds, and rodents. However, experimental data supporting this possibility are scarce. We collected 117 samples and screened them for 44 bovine abortive, diarrheal, and respiratory disease complex pathogens by using Dembo polymerase chain reaction (PCR), which is based on TaqMan real-time PCR. Fifty-seven samples were positive for at least one pathogen, including bovine viral diarrhea virus, bovine enterovirus, Salmonella enterica ser. Dublin, Salmonella enterica ser. Typhimurium, and Neospora caninum; some samples were positive for multiple pathogens. Bovine viral diarrhea virus and bovine enterovirus were the most frequently detected pathogens, especially in flies, suggesting an important role of flies in the transmission of these viruses. Additionally, we detected the N. caninum genome from a cockroach sample for the first time. Our data suggest that insects (particularly flies), birds, and rodents are potential vectors and reservoirs of abortion, diarrhea, and respiratory infectious agents, and that they may transmit more than one pathogen at the same time.

Natural History of Plasmodium odocoilei Malaria Infection in Farmed White-Tailed Deer

Malaria parasites of the genus Plasmodium are known to infect a variety of vertebrate hosts, including ungulates (hoofed mammals). A recent study found that up to a quarter of white-tailed deer (Odocoileus virginianus) in North America are infected with the parasite Plasmodium odocoilei. In addition to occupying an important ecological niche, white-tailed deer are popular game animals and deer farming represents a rapidly growing industry. However, the effect of P. odocoilei infection in this ecologically and economically important ungulate species is unknown. Our work is significant because (i) we identified a high prevalence of P. odocoilei in farmed deer and (ii) we found evidence for both cleared and persistent infection, as well as an association with decreased survival of young fawns.

White-tailed deer (Odocoileus virginianus), an ecologically and economically important species, are the most widely distributed large animals in North America. A recent study indicated that up to 25% of all white-tailed deer may be infected with Plasmodium odocoilei, a malaria parasite belonging to the distinct clade of ungulate-infecting Plasmodium spp. Because the clinical impact of P. odocoilei on deer health and survival is unknown, we undertook a retrospective longitudinal study of farmed Floridian O. virginianus fawns. We found that a substantial proportion (21%) of fawns acquire malaria infection during the first 8 months of life. Some animals naturally clear P. odocoilei infection, while other animals remain persistently positive. Importantly, we found that animals that acquire malaria parasites very early in life have poor survival compared to animals that remain uninfected. Our report thus provides the first evidence of a clinically significant impact of malaria infection in young deer.

IMPORTANCE Malaria parasites of the genus Plasmodium are known to infect a variety of vertebrate hosts, including ungulates (hoofed mammals). A recent study found that up to a quarter of white-tailed deer (Odocoileus virginianus) in North America are infected with the parasite Plasmodium odocoilei. In addition to occupying an important ecological niche, white-tailed deer are popular game animals and deer farming represents a rapidly growing industry. However, the effect of P. odocoilei infection in this ecologically and economically important ungulate species is unknown. Our work is significant because (i) we identified a high prevalence of P. odocoilei in farmed deer and (ii) we found evidence for both cleared and persistent infection, as well as an association with decreased survival of young fawns.

Using Patient-Specific Induced Pluripotent Stem Cells and Wild-Type Mice to Develop a Gene Augmentation-Based Strategy to Treat CLN3-Associated Retinal Degeneration

Juvenile neuronal ceroid lipofuscinosis (JNCL) is a childhood neurodegenerative disease with early-onset, severe central vision loss. Affected children develop seizures and CNS degeneration accompanied by severe motor and cognitive deficits. There is no cure for JNCL, and patients usually die during the second or third decade of life. In this study, independent lines of induced pluripotent stem cells (iPSCs) were generated from two patients with molecularly confirmed mutations in CLN3, the gene mutated in JNCL. Clinical-grade adeno-associated adenovirus serotype 2 (AAV2) carrying the full-length coding sequence of human CLN3 was generated in a U.S. Food and Drug Administration-registered cGMP facility. AAV2-CLN3 was efficacious in restoring full-length CLN3 transcript and protein in patient-specific fibroblasts and iPSC-derived retinal neurons. When injected into the subretinal space of wild-type mice, purified AAV2-CLN3 did not show any evidence of retinal toxicity. This study provides proof-of-principle for initiation of a clinical trial using AAV-mediated gene augmentation for the treatment of children with CLN3-associated retinal degeneration.

Broad-range detection of arboviruses belonging to Simbu serogroup lineage 1 and specific detection of Akabane, Aino and Peaton viruses by newly developed multiple TaqMan assays

TaqMan assays were developed for the broad-range detection of arboviruses belonging to Simbu serogroup lineage 1 in the genus Orthobunyavirus and also for the specific detection of three viruses in the lineage, Akabane, Aino and Peaton viruses (AKAV, AINOV and PEAV, respectively). A primer and probe set was designed for the broad-range detection of Simbu serogroup lineage 1 (Pan-Simbu1 set) mainly targeting AKAV, AINOV, PEAV, Sathuperi and Shamonda viruses (SATV and SHAV), and the forward and reverse primers of the Pan-Simbu1 set were also used for the specific detection of AKAV with another probe (AKAV-specific set). In addition, two more primer and probe sets were designed for AINOV- and PEAV-specific detection, respectively (AINOV- and PEAV-specific sets). All of the four primer and probe sets successfully detected targeted viruses, and thus broad-range and specific detection of all the targeted viruses can be achieved by using two multiplex assays and a single assay in a dual (two-color) assay format when another primer and probe set for a bovine β-actin control is also used. The assays had an analytical sensitivity of 10 copies/tube for AKAV, at least 100 copies/tube for AINOV, 100 copies/tube for PEAV, one copy/tube for SATV and at least 10 copies/tube for SHAV, respectively. Diagnostic sensitivity of the assays was tested with field-collected bovine samples, and the results suggested that the sensitivity was higher than that of a conventional RT-PCR. These data indicate that the newly developed TaqMan assays will be useful tools for the diagnosis and screening of field-collected samples for infections of AKAV and several other arboviruses belonging to the Simbu serogroup lineage 1.