Publications by authors named "C Batten"

127 Publications

Quantifying and modelling the acquisition and retention of lumpy skin disease virus by haematophagus insects reveals clinically but not subclinically-affected cattle are promoters of viral transmission and key targets for control of disease outbreaks.

J Virol 2021 Feb 10. Epub 2021 Feb 10.

The Pirbright Institute, Ash Road, Pirbright, Surrey, United Kingdom

Lumpy skin disease virus (LSDV) is a vector-transmitted poxvirus that causes disease in cattle. Vector species involved in LSDV transmission and their ability to acquire and transmit the virus are poorly characterised. Using a highly representative bovine experimental model of lumpy skin disease we fed four model vector species (, , and ) on LSDV-inoculated cattle in order to examine their acquisition and retention of LSDV. Subclinical disease was a more common outcome than clinical disease in the inoculated cattle. Importantly, the probability of vectors acquiring LSDV from a subclinical animal (0.006) was very low compared to acquisition from a clinical animal (0.23), meaning an insect feeding on a subclinical animal was 97% less likely to acquire LSDV than one feeding on a clinical animal. All four potential vector species studied acquired LSDV at a similar rate from the host, but and retained the virus for a longer time, up to 8 days. There was no evidence of virus replication in the vector, consistent with mechanical rather than biological transmission. The parameters obtained in this study were combined with data from studies of LSDV transmission and vector life history parameters to determine the basic reproduction number of LSDV in cattle mediated by each of the model species. This was highest for (19.1), (7.1), and (2.4), indicating these three species are potentially efficient transmitters of LSDV, which can be used to inform LSD control programmes. Lumpy skin disease virus (LSDV) causes a severe systemic disease characterised by cutaneous nodules in cattle. LSDV is a rapidly emerging pathogen, having spread since 2012 into Europe and Russia, and across Asia. The vector-borne nature of LSDV transmission is believed to have promoted this rapid geographic spread of the virus, however a lack of quantitative evidence about LSDV transmission has hampered effective control of the disease during the current epidemic. Our research shows subclinical cattle play little part in virus transmission relative to clinical cattle, and reveals a low probability of virus acquisition by insects at the pre-clinical stage. We have also calculated the reproductive number of different insect species, therefore identifying efficient transmitters of LSDV. This information is of utmost importance, as it will help to define epidemiological control measures during LSDV epidemics and of particular consequence in resource-poor regions where LSD vaccination may be less than adequate.
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http://dx.doi.org/10.1128/JVI.02239-20DOI Listing
February 2021

Osteoporosis circumscripta cranii with a pathological fracture of the skull.

Rheumatology (Oxford) 2021 Jan 25. Epub 2021 Jan 25.

Department of Rheumatology, Northwick Park Hospital, Harrow, London, UK.

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http://dx.doi.org/10.1093/rheumatology/keab013DOI Listing
January 2021

Re-emergence of BTV serotype 4 in North Macedonia, July 2020.

Transbound Emerg Dis 2020 Oct 27. Epub 2020 Oct 27.

The Pirbright Institute, Pirbright, UK.

Bluetongue virus serotype 4 (BTV-4) was confirmed in sheep in North Macedonia in July 2020. The full genome of this BTV-4 strain (MKD2020/06) was shown to be most closely related (99.74% nt identity) to the Greek GRE2014/08 and the Hungarian HUN1014 strains, indicating the re-emergence of this BTV serotype in the Balkan region since it was last reported in 2017.
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http://dx.doi.org/10.1111/tbed.13900DOI Listing
October 2020

Simultaneous Detection of Bluetongue Virus Serotypes Using xMAP Technology.

Microorganisms 2020 Oct 11;8(10). Epub 2020 Oct 11.

The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK.

Bluetongue is an economically important disease of ruminants caused by the bluetongue virus (BTV). BTV is serologically diverse, which complicates vaccination strategies. Rapid identification of the causative BTV serotypes is critical, however, real-time PCR (RT-qPCR) can be costly and time consuming to perform when the circulating serotypes are unknown. The Luminex xMAP technology is a high-throughput platform that uses fluorescent beads to detect multiple targets simultaneously. We utilized existing BTV serotyping RT-qPCR assays for BTV-1 to BTV-24 and adapted them for use with the xMAP platform. The xMAP assay specifically detected all 24 BTV serotypes when testing reference strains. In all BTV-positive samples, the sensitivity of the BTV xMAP was 87.55% whereas the sensitivity of the serotype-specific RT-qPCR was 79.85%. The BTV xMAP assay allowed for the specific detection of BTV serotypes 1-24 at a lower cost than current RT-qPCR assays. Overall, the assay provides a useful novel diagnostic tool, particularly when analyzing large sample sets. The use of the BTV xMAP assay will allow for the rapid assessment of BTV epidemiology and may inform decision-making related to control and prevention measures.
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http://dx.doi.org/10.3390/microorganisms8101564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7650804PMC
October 2020

Identification of novel testing matrices for African swine fever surveillance.

J Vet Diagn Invest 2020 Nov 23;32(6):961-963. Epub 2020 Sep 23.

The Pirbright Institute, Pirbright, Woking, Surrey, UK.

African swine fever (ASF) is a devastating viral disease of pigs and wild boar, and it threatens global food security. We aimed to identify suitable sample matrices for use in ASF surveillance programs. Six pigs inoculated with ASFV were sampled at postmortem. Blood, bone marrow, ear biopsies, and oral, nasal, and rectal swabs were taken from all pigs. All samples were analyzed using 3 real-time PCR (rtPCR) assays and a LAMP assay. ASFV was detected at > 10 genome copies/mL in blood; bone marrow was found to provide the highest viral load. Ct values provided by the rtPCR assays were correlated, and ASFV was detected in all oral, nasal, and rectal swabs and in all ear biopsy samples irrespective of the location from which they were taken. The LAMP assay had lower sensitivity, and detected ASFV in 54 of 66 positive samples, but delivered positive results within 17 min. We identified additional sample matrices that can be considered depending on the sampling situation: bone marrow had a high probability of detection, which could be useful for decomposed carcasses. However, ear biopsies provide an appropriate, high-throughput sample matrix to detect ASFV and may be useful during surveillance programs.
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http://dx.doi.org/10.1177/1040638720954888DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645617PMC
November 2020

Risk-based surveillance for bluetongue virus in cattle on the south coast of England in 2017 and 2018.

Vet Rec 2020 Nov 11;187(11):e96. Epub 2020 Sep 11.

Entomology, The Pirbright Institute, Pirbright, Surrey, UK.

Background: Bluetongue (BT) is a viral disease of ruminants and camelids which can have a significant impact on animal health and welfare and cause severe economic loss. The UK has been officially free of bluetongue virus (BTV) since 2011. In 2015, BTV-8 re-emerged in France and since then BTV has been spreading throughout Europe. In response to this outbreak, risk-based active surveillance was carried out at the end of the vector seasons in 2017 and 2018 to assess the risk of incursion of BTV into Great Britain.

Method: Atmospheric dispersion modelling identified counties on the south coast of England at higher risk of an incursion. Blood samples were collected from cattle in five counties based on a sample size designed to detect at least one positive if the prevalence was 5 per cent or greater, with 95 per cent confidence.

Results: No virus was detected in the 478 samples collected from 32 farms at the end of the 2017 vector season or in the 646 samples collected from 43 farms at the end of the 2018 vector season, when tested by RT-qPCR.

Conclusion: The negative results from this risk-based survey provided evidence to support the continuation of the UK's official BTV-free status.
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http://dx.doi.org/10.1136/vr.106016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786256PMC
November 2020

Towards a Sampling Rationale for African Swine Fever Virus Detection in Pork Products.

Foods 2020 Aug 20;9(9). Epub 2020 Aug 20.

The Pirbright Institute, Ash Road, Pirbright GU24 0NF, UK.

African swine fever (ASF) is a highly lethal disease of pigs caused by the ASF virus (ASFV), which presents a serious threat to global food security. The movement of contaminated pork products has previously been postulated as contributing to the introduction of ASF into new areas. To evaluate the performance of ASFV detection systems in multi-component pork products, we spiked sausage meat with four different ASFV-containing materials (ASFV cell culture, pork loin, meat juice and bone marrow). DNA was extracted using two manual systems (MagMAX CORE, Qiagen) and one automated (MagMAX CORE) one, and three qPCR assays (VetMAX, King, UPL) were used. The performance of the DNA extraction systems was as follows; automated MagMAX > manual MagMAX > manual Qiagen. The commercial VetMAX qPCR assay yielded significantly lower C values ( < 0.001), showing greater sensitivity than the World Organization for Animal Health (OIE)-prescribed assays (King, UPL). Detection probability was the highest for matrices contaminated with bone marrow compared with pork loin or meat juice. An estimated minimum sample size of one 1-g sample is sufficient to detect ASFV in a homogenous pork product if bone marrow from infected pigs comprises 1 part in 10,000. We demonstrated that existing ASFV detection systems are appropriate for use in a food-testing capacity, which can provide an additional control measure for ASF.
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http://dx.doi.org/10.3390/foods9091148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554881PMC
August 2020

Humoral and circulating follicular helper T cell responses in recovered patients with COVID-19.

Nat Med 2020 09 13;26(9):1428-1434. Epub 2020 Jul 13.

Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has dramatically expedited global vaccine development efforts, most targeting the viral 'spike' glycoprotein (S). S localizes on the virion surface and mediates recognition of cellular receptor angiotensin-converting enzyme 2 (ACE2). Eliciting neutralizing antibodies that block S-ACE2 interaction, or indirectly prevent membrane fusion, constitute an attractive modality for vaccine-elicited protection. However, although prototypic S-based vaccines show promise in animal models, the immunogenic properties of S in humans are poorly resolved. In this study, we characterized humoral and circulating follicular helper T cell (cTFH) immunity against spike in recovered patients with coronavirus disease 2019 (COVID-19). We found that S-specific antibodies, memory B cells and cTFH are consistently elicited after SARS-CoV-2 infection, demarking robust humoral immunity and positively associated with plasma neutralizing activity. Comparatively low frequencies of B cells or cTFH specific for the receptor binding domain of S were elicited. Notably, the phenotype of S-specific cTFH differentiated subjects with potent neutralizing responses, providing a potential biomarker of potency for S-based vaccines entering the clinic. Overall, although patients who recovered from COVID-19 displayed multiple hallmarks of effective immune recognition of S, the wide spectrum of neutralizing activity observed suggests that vaccines might require strategies to selectively target the most potent neutralizing epitopes.
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http://dx.doi.org/10.1038/s41591-020-0995-0DOI Listing
September 2020

Outbreak of African horse sickness in Thailand, 2020.

Transbound Emerg Dis 2020 Jun 27. Epub 2020 Jun 27.

The Pirbright Institute, Pirbright, UK.

African horse sickness was confirmed in horses in Thailand during March 2020. The virus was determined to belong to serotype 1 and is phylogenetically closely related to isolates from South Africa. This is the first incidence of African horse sickness occurring in South East Asia and of serotype 1 outside of Africa.
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http://dx.doi.org/10.1111/tbed.13701DOI Listing
June 2020

BTV-14 Infection in Sheep Elicits Viraemia with Mild Clinical Symptoms.

Microorganisms 2020 Jun 13;8(6). Epub 2020 Jun 13.

Non-Vesicular Reference Laboratories, The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK.

In 2011, Bluetongue virus serotype 14 (BTV-14) was detected in Russia during routine surveillance, and was subsequently found in a number of European countries. The strain had high sequence similarity to a BTV-14 vaccine strain. We aimed to determine the risk of this BTV-14 strain causing disease in a UK sheep breed. Four Poll Dorset sheep were infected with a Polish isolate of BTV-14 and infection kinetics were monitored over 28 days. BTV RNA was detected in EDTA blood by 4 days post-infection (dpi) and remained detectable at 28 days post-infection (dpi). Peak viraemia occurred at 6 and 7 dpi with Ct values ranging between 24.6 and 27.3 in all infected animals. BTV antibodies were detected by 10 dpi using a commercial ELISA and neutralising antibodies were detected from 10 dpi. BTV was isolated between 6 and 12 dpi. All infected sheep developed mild clinical signs such as reddening of conjunctiva and mucosal membranes, with one sheep demonstrating more overt clinical signs. Two uninoculated control animals remained clinically healthy and did not have detectable BTV RNA or antibodies. The overall mild clinical symptoms caused by this BTV-14 in this highly susceptible sheep breed were in accordance with the asymptomatic infections observed in the affected countries.
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http://dx.doi.org/10.3390/microorganisms8060892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7355590PMC
June 2020

Diversity of Transmission Outcomes Following Co-Infection of Sheep with Strains of Bluetongue Virus Serotype 1 and 8.

Microorganisms 2020 Jun 5;8(6). Epub 2020 Jun 5.

The Pirbright Institute, Pirbright, Surrey GU24 0NF, UK.

Bluetongue virus (BTV) causes an economically important disease, bluetongue (BT), in susceptible ruminants and is transmitted primarily by species of biting midges (Diptera: Ceratopogonidae). Since 2006, northern Europe has experienced multiple incursions of BTV through a variety of routes of entry, including major outbreaks of strains of BTV serotype 8 (BTV-8) and BTV serotype 1 (BTV-1), which overlapped in distribution within southern Europe. In this paper, we examined the variation in response to coinfection with strains of BTV-1 and BTV-8 using an in vivo transmission model involving , low passage virus strains, and sheep sourced in the United Kingdom. In the study, four sheep were simultaneously infected using BTV-8 and BTV-1 intrathoracically inoculated and co-infections of all sheep with both strains were established. However, there were significant variations in both the initiation and peak levels of virus RNA detected throughout the experiment, as well as in the infection rates in the that were blood-fed on experimentally infected sheep at peak viremia. This is discussed in relation to the potential for reassortment between these strains in the field and the policy implications for detection of BTV strains.
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http://dx.doi.org/10.3390/microorganisms8060851DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356686PMC
June 2020

"Frozen evolution" of an RNA virus suggests accidental release as a potential cause of arbovirus re-emergence.

PLoS Biol 2020 04 28;18(4):e3000673. Epub 2020 Apr 28.

MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.

The mechanisms underlying virus emergence are rarely well understood, making the appearance of outbreaks largely unpredictable. Bluetongue virus serotype 8 (BTV-8), an arthropod-borne virus of ruminants, emerged in livestock in northern Europe in 2006, spreading to most European countries by 2009 and causing losses of billions of euros. Although the outbreak was successfully controlled through vaccination by early 2010, puzzlingly, a closely related BTV-8 strain re-emerged in France in 2015, triggering a second outbreak that is still ongoing. The origin of this virus and the mechanisms underlying its re-emergence are unknown. Here, we performed phylogenetic analyses of 164 whole BTV-8 genomes sampled throughout the two outbreaks. We demonstrate consistent clock-like virus evolution during both epizootics but found negligible evolutionary change between them. We estimate that the ancestor of the second outbreak dates from the height of the first outbreak in 2008. This implies that the virus had not been replicating for multiple years prior to its re-emergence in 2015. Given the absence of any known natural mechanism that could explain BTV-8 persistence over this long period without replication, we hypothesise that the second outbreak could have been initiated by accidental exposure of livestock to frozen material contaminated with virus from approximately 2008. Our work highlights new targets for pathogen surveillance programmes in livestock and illustrates the power of genomic epidemiology to identify pathways of infectious disease emergence.
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http://dx.doi.org/10.1371/journal.pbio.3000673DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188197PMC
April 2020

Full genome sequencing of archived wild type and vaccine rinderpest virus isolates prior to their destruction.

Sci Rep 2020 04 16;10(1):6563. Epub 2020 Apr 16.

The Pirbright Institute, Ash Road, Pirbright, Surrey, GU24 0NF, UK.

When rinderpest virus (RPV) was declared eradicated in 2011, the only remaining samples of this once much-feared livestock virus were those held in various laboratories. In order to allow the destruction of our institute's stocks of RPV while maintaining the ability to recover the various viruses if ever required, we have determined the full genome sequence of all our distinct samples of RPV, including 51 wild type viruses and examples of three different types of vaccine strain. Examination of the sequences of these virus isolates has shown that the African isolates form a single disparate clade, rather than two separate clades, which is more in accord with the known history of the virus in Africa. We have also identified two groups of goat-passaged viruses which have acquired an extra 6 bases in the long untranslated region between the M and F protein coding sequences, and shown that, for more than half the genomes sequenced, translation of the F protein requires translational frameshift or non-standard translation initiation. Curiously, the clade containing the lapinised vaccine viruses that were developed originally in Korea appears to be more similar to the known African viruses than to any other Asian viruses.
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http://dx.doi.org/10.1038/s41598-020-63707-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7162898PMC
April 2020

Complete Genome Sequence of a Lineage IV Peste des Petits Ruminants Virus from Turkey, 2018.

Microbiol Resour Announc 2020 Apr 9;9(15). Epub 2020 Apr 9.

The Pirbright Institute, Woking, Surrey, United Kingdom

We report the whole-genome sequence of a peste des petits ruminants virus (PPRV) from a lamb exhibiting clinical signs in Turkey in September 2018. The genome of PPRV/Turkey/Central_Anatolia/2018 shows the highest nucleotide sequence identity (97.63%) to PPRV isolated in Turkey in 2000.
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http://dx.doi.org/10.1128/MRA.01446-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380515PMC
April 2020

Characterisation of Peste Des Petits Ruminants Disease in Pastoralist Flocks in Ngorongoro District of Northern Tanzania and Bluetongue Virus Co-Infection.

Viruses 2020 03 31;12(4). Epub 2020 Mar 31.

The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK.

Peste des petits ruminants (PPR) disease was first confirmed in Tanzania in 2008 in sheep and goats in Ngorongoro District, northern Tanzania, and is now endemic in this area. This study aimed to characterise PPR disease in pastoralist small ruminant flocks in Ngorongoro District. During June 2015, 33 PPR-like disease reports were investigated in different parts of the district, using semi-structured interviews, clinical examinations, PPR virus rapid detection test (PPRV-RDT), and laboratory analysis. Ten flocks were confirmed as PPRV infected by PPRV-RDT and/or real-time reverse transcription-polymerase chain reaction (RT-qPCR), and two flocks were co-infected with bluetongue virus (BTV), confirmed by RT-qPCR. Phylogenetic analysis of six partial N gene sequences showed that the PPR viruses clustered with recent lineage III Tanzanian viruses, and grouped with Ugandan, Kenyan and Democratic Republic of Congo isolates. No PPR-like disease was reported in wildlife. There was considerable variation in clinical syndromes between flocks: some showed a full range of PPR signs, while others were predominantly respiratory, diarrhoea, or oro-nasal syndromes, which were associated with different local disease names (a term for rinderpest, -lung disease, -fever, -diarrhoea). BTV co-infection was associated with severe oro-nasal lesions. This clinical variability makes the field diagnosis of PPR challenging, highlighting the importance of access to pen-side antigen tests and multiplex assays to support improved surveillance and targeting of control activities for PPR eradication.
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http://dx.doi.org/10.3390/v12040389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232183PMC
March 2020

Complete Coding Sequence of a Novel Bluetongue Virus Isolated from a Commercial Sheeppox Vaccine.

Microbiol Resour Announc 2020 Mar 5;9(10). Epub 2020 Mar 5.

The Pirbright Institute, Pirbright, Surrey, United Kingdom.

The full genome sequences of two isolates of bluetongue virus (BTV) from a commercial sheeppox vaccine were determined. Strain SPvvvv/02 shows low sequence identity to its closest relative, strain BTV-26 KUW2010/02, indicating the probable detection of a novel BTV genotype, whereas strain SPvvvv/03 shows high sequence identity to strain BTV-28/1537/14.
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http://dx.doi.org/10.1128/MRA.01539-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7171223PMC
March 2020

Origin of Bluetongue Virus Serotype 8 Outbreak in Cyprus, September 2016.

Viruses 2020 01 14;12(1). Epub 2020 Jan 14.

Pirbright Institute, Woking, Surrey, GU24 0NF, UK.

In September 2016, clinical signs, indicative of bluetongue, were observed in sheep in Cyprus. Bluetongue virus serotype 8 (BTV-8) was detected in sheep, indicating the first incursion of this serotype into Cyprus. Following virus propagation, Nextera XT DNA libraries were sequenced on the MiSeq instrument. Full-genome sequences were obtained for five isolates CYP2016/01-05 and the percent of nucleotide sequence (% nt) identity between them ranged from 99.92% to 99.95%, which corresponded to a few (2-5) amino acid changes. Based on the complete coding sequence, the Israeli ISR2008/13 (98.42-98.45%) was recognised as the closest relative to CYP2016/01-05. However, the phylogenetic reconstruction of CYP2016/01-05 revealed that the possibility of reassortment in several segments: 4, 7, 9 and 10. Based on the available sequencing data, the incursion BTV-8 into Cyprus most likely occurred from the neighbouring countries (e.g., Israel, Lebanon, Syria, or Jordan), where multiple BTV serotypes were co-circulating rather than from Europe (e.g., France) where a single BTV-8 serotype was dominant. Supporting this hypothesis, atmospheric dispersion modelling identified wind-transport events during July-September that could have allowed the introduction of BTV-8 infected midges from Lebanon, Syria or Israel coastlines into the Larnaca region of Cyprus.
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http://dx.doi.org/10.3390/v12010096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019704PMC
January 2020

Improved PCR diagnostics using up-to-date in silico validation: An F-gene RT-qPCR assay for the detection of all four lineages of peste des petits ruminants virus.

J Virol Methods 2019 12 14;274:113735. Epub 2019 Sep 14.

The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom.

Peste des petits ruminants (PPR) is a globally significant disease of small ruminants caused by the peste des petits ruminants virus (PPRV) that is considered for eradication by 2030 by the United Nations Food and Agriculture Organisation (FAO). Critical to the eradication of PPR are accurate diagnostic assays. RT-qPCR assays targeting the nucleocapsid gene of PPRV have been successfully used for the diagnosis of PPR. We describe the development of an RT-qPCR assay targeting an alternative region (the fusion (F) gene) based on the most up-to-date PPRV sequence data. In silico analysis of the F-gene RT-qPCR assay performed using PCRv software indicated 98% sensitivity and 100% specificity against all PPRV sequences published in Genbank. The assay indicated the greatest in silico sensitivity in comparison to other previously published and recommended PPRV RT-qPCR assays. We evaluated the assay using strains representative of all 4 lineages in addition to samples obtained from naturally and experimentally-infected animals. The F-gene RT-qPCR assay showed 100% diagnostic specificity and demonstrated a limit of detection of 10 PPRV genome copies per μl. This RT-qPCR assay can be used in isolation or in conjunction with other assays for confirmation of PPR and should support the global efforts for eradication.
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http://dx.doi.org/10.1016/j.jviromet.2019.113735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6853160PMC
December 2019

A rapid RT-LAMP assay for the detection of all four lineages of Peste des Petits Ruminants Virus.

J Virol Methods 2019 12 9;274:113730. Epub 2019 Sep 9.

The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, UK.

Peste des petits ruminants (PPR) is a viral disease of small ruminants that is caused by the PPR virus (PPRV) and is a significant burden on subsistence farmers across the developing world. Loop-mediated isothermal amplification (LAMP) provides cost-effective, rapid, specific and sensitive detection of nucleic acid and has been demonstrated to have field application for a range of viruses. We describe the development of a novel PPRV RT-LAMP assay utilising carefully-selected primers (targeting the N-gene) allowing for the detection of all known PPRV lineages in < 20 min. The assay was evaluated in comparison with a "gold standard" real-time RT-PCR assay using more than 200 samples, comprising samples from recent PPRV outbreaks, experimentally-infected goats, well-characterised cell culture isolates and samples collected from uninfected animals. The RT-LAMP assay demonstrated 100% diagnostic specificity and greater than 97% diagnostic sensitivity in comparison with the real-time RT-PCR assay. The limit of detection was between 0.3 and 0.8 log TCID ml equating to a C value of 31.52 to 33.48. In experimentally-infected animals, the RT-LAMP could detect PPRV as early as 4 days post infection (dpi) - before clinical signs were observed at 7 dpi. The RT-LAMP assay can support the global PPR eradication campaign.
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http://dx.doi.org/10.1016/j.jviromet.2019.113730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6859475PMC
December 2019

Bluetongue virus outer-capsid protein VP2 expressed in raises neutralising antibodies and a protective immune response in IFNAR mice.

Vaccine X 2019 Aug 22;2:100026. Epub 2019 Jun 22.

School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK.

Bluetongue is a severe, economically important disease of ruminants that is widely distributed in tropical and temperate regions around the world. It is associated with major production losses, restrictions of animal movements and trade, as well as costs associated with developing and implementing effective surveillance and control measures. Mammalian hosts infected with bluetongue virus (BTV) generate a protective neutralising antibody response targeting the major BTV outer-capsid protein and serotype-specific antigen, VP2. BTV VP2 proteins that have been expressed in plants are soluble, with a native conformation displaying neutralising epitopes and can assemble with other BTV structural proteins to form virus-like particles (VLPs). His-tagged VP2 proteins of BTV serotypes 4 and 8 were transiently expressed in then purified by immobilised metal affinity chromatography (IMAC). Antisera from IFNAR mice prime/boost vaccinated with the purified proteins, were shown to contain VP2-specific antibodies by Indirect ELISA (I-ELISA), western blotting and serum neutralisation tests (SNT). Vaccinated mice, subsequently challenged with either the homologous or heterologous BTV serotype, developed viraemia by day 3 post-infection. However, no clinical signs were observed in mice challenged with the homologous serotype (either prime-boost or single-shot vaccinated), all of which survived for the duration of the study. In contrast, all of the vaccinated mice challenged with a heterologous serotype, died, showing no evidence of cross-protection or suppression of viraemia, as detected by real-time RT-qPCR or virus isolation. The induction of protective, serotype-specific neutralising antibodies in IFNAR mice, indicates potential for the use of plant-expressed BTV VP2s as subunit vaccine components, or as a basis for serotype-specific serological assays.
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http://dx.doi.org/10.1016/j.jvacx.2019.100026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6668234PMC
August 2019

Rapid Detection of Peste des Petits Ruminants Virus (PPRV) Nucleic Acid Using a Novel Low-Cost Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) Assay for Future Use in Nascent PPR Eradication Programme.

Viruses 2019 07 31;11(8). Epub 2019 Jul 31.

The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK.

Peste des petits ruminants (PPR) is a disease of small ruminants caused by peste des petits ruminants virus (PPRV), and is endemic in Asia, the Middle East and Africa. Effective control combines the application of early warning systems, accurate laboratory diagnosis and reporting, animal movement restrictions, suitable vaccination and surveillance programs, and the coordination of all these measures by efficient veterinary services. Molecular assays, including conventional reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR (RT-qPCR) have improved the sensitivity and rapidity of diagnosing PPR. However, currently these assays are only performed within laboratory settings; therefore, the development of field diagnostics for PPR would improve the fast implementation of control policies, particularly when PPR has been targeted to be eradicated by 2030. Loop-mediated isothermal amplification (LAMP) assays are simple to use, rapid, and have sensitivity and specificity within the range of RT-qPCR; and can be performed in the field using disposable consumables and portable equipment. This study describes the development of a novel RT-LAMP assay for the detection of PPRV nucleic acid by targeting the N-protein gene. The RT-LAMP assay was evaluated using cell culture propagated PPRVs, field samples from clinically infected animals and samples from experimentally infected animals encompassing all four lineages (I-IV) of PPRV. The test displayed 100% concordance with RT-qPCR when considering an RT-qPCR cut-off value of C >40. Further, the RT-LAMP assay was evaluated using experimental and outbreak samples without prior RNA extraction making it more time and cost-effective. This assay provides a solution for a pen-side, rapid and inexpensive PPR diagnostic for use in the field in nascent PPR eradication programme.
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http://dx.doi.org/10.3390/v11080699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723471PMC
July 2019

Detection of a novel reassortant epizootic hemorrhagic disease virus serotype 6 in cattle in Trinidad, West Indies, containing nine RNA segments derived from exotic EHDV strains with an Australian origin.

Infect Genet Evol 2019 10 22;74:103931. Epub 2019 Jun 22.

Non-vesicular reference laboratory, The Pirbright Institute, Woking, Surrey GU24 0NF, UK.

Epizootic hemorrhagic disease virus (EHDV) is a Culicoides-transmitted orbivirus that infects domestic and wild ruminants in many parts of the world. Of the eight proposed serotypes, only EHDV-1, 2 and 6 have been reported to be present in the Americas. Following the identification of a virulent EHD-6 reasssortant virus in the USA in 2007 (EHDV-6 Indiana), with outer coat protein segments derived from an Australian strain of EHDV and all remaining segments derived from a locally circulating EHDV-2 strain, questions have remained about the origin of the Australian parent strain and how it may have arrived in the USA. When EHDV-6 was identified in asymptomatic cattle imported into the Caribbean island of Trinidad in 2013, full genome sequencing was carried out to further characterise the virus. The EHDV-6 Trinidad was a reassortant virus, with 8 of its 10 segments, being derived from the same exotic Australian EHDV-6 strain as the VP2 and VP5 present in the EHDV-6 Indiana strain from the USA. Analyses of the two remaining segments revealed that segment 8 showed the highest nucleotide identity (90.4%) with a USA New Jersey strain of EHDV-1, whereas segment 4 had the highest nucleotide identity (96.5%) with an Australian EHDV-2 strain. This data strongly suggests that the Trinidad EHDV-6 has an Australian origin, receiving its segment 4 from a reassortment event with an EHDV-2 also from Australia. This reassortant virus likely came to the Americas, where it received its segment 8 from a locally-circulating (as yet unknown) EHDV strain. This virus then may have gained entry into the USA, where it further reassorted with a known locally-circulating EHDV-2, the resulting strain being EHDV-6 Indiana. This study therefore identifies, for the first time, the likely minor parent virus of the EHDV-6 currently circulating in the USA.
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http://dx.doi.org/10.1016/j.meegid.2019.103931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6857627PMC
October 2019

Evidence of reduced viremia, pathogenicity and vector competence in a re-emerging European strain of bluetongue virus serotype 8 in sheep.

Transbound Emerg Dis 2019 May 22;66(3):1177-1185. Epub 2019 Feb 22.

The Pirbright Institute, Pirbright, UK.

The outbreak of bluetongue virus (BTV) serotype 8 (BTV-8) during 2006-2009 in Europe was the most costly epidemic of the virus in recorded history. In 2015, a BTV-8 strain re-emerged in France which has continued to circulate since then. To examine anecdotal reports of reduced pathogenicity and transmission efficiency, we investigated the infection kinetics of a 2007 UK BTV-8 strain alongside the re-emerging BTV-8 strain isolated from France in 2017. Two groups of eight BTV-naïve British mule sheep were inoculated with 5.75 log TCID /ml of either BTV-8 strain. BTV RNA was detected by 2 dpi in both groups with peak viraemia occurring between 5-9 dpi. A significantly greater amount of BTV RNA was detected in sheep infected with the 2007 strain (6.0-8.8 log genome copies/ml) than the re-emerging BTV-8 strain (2.9-7.9 log genome copies/ml). All infected sheep developed BTV-specific antibodies by 9 dpi. BTV was isolated from 2 dpi to 12 dpi for 2007 BTV-8-inoculated sheep and from 5 to 10 dpi for sheep inoculated with the remerging BTV-8. In Culicoides sonorensis feeding on the sheep over the period 7-12 dpi, vector competence was significantly higher for the 2007 strain than the re-emerging strain. Both the proportion of animals showing moderate (as opposed to mild or no) clinical disease (6/8 vs. 1/8) and the overall clinical scores (median 5.25 vs. 3) were significantly higher in sheep infected with the 2007 strain, compared to those infected with the re-emerging strain. However, one sheep infected with the re-emerging strain was euthanized at 16 dpi having developed severe lameness. This highlights the potential of the re-emerging BTV-8 to still cause illness in naïve ruminants with concurrent costs to the livestock industry.
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http://dx.doi.org/10.1111/tbed.13131DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6563110PMC
May 2019

Identification and characterization of epizootic hemorrhagic disease virus serotype 6 in cattle co-infected with bluetongue virus in Trinidad, West Indies.

Vet Microbiol 2019 Feb 11;229:1-6. Epub 2018 Dec 11.

School of Veterinary Medicine, Faculty of Medical Sciences, The University of theWest Indies, St. Augustine, Trinidad, West Indies.

Epizootic hemorrhagic disease virus (EHDV) is an economically important virus that can cause severe clinical disease in deer and to a lesser extent cattle. This study set out to determine and characterize which EHDV serotypes were circulating in Trinidad. Serum and whole blood samples were collected monthly for six months from a cohort of cattle imported to Trinidad from the USA. Results revealed that all the cattle seroconverted to EHDV within six months of their arrival, with EHDV RNA being detected in the samples just prior to antibodies, as expected. Serotyping assays revealed that a single serotype (EHDV-6) was circulating in the cattle. Sequencing of the surface viral protein (VP2) of EHDV-6, followed by phylogenetic analysis, revealed that the Trinidad EHDV-6 strain was closely related to EHDV-6 viruses found in Guadeloupe (2010), Martinique (2010) and USA (2006), with 96-97.2% nucleotide identity. The Trinidad EHDV-6 VP-2 shared 97.2% identity with the Australian EHDV-6 prototype strain, classifying it within the eastern topotype clade. Bayesian coalescent analysis support Australia as the most probable source for the EHDV-6 VP2 sequences in the Americas and Caribbean region and suggests that the they diverged from the Australian prototype strain around 1966 (95% HPD 1941-1979).
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http://dx.doi.org/10.1016/j.vetmic.2018.12.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340808PMC
February 2019

Assessment of reproducibility of a VP7 Blocking ELISA diagnostic test for African horse sickness.

Transbound Emerg Dis 2019 Jan 2;66(1):83-90. Epub 2018 Aug 2.

The Pirbright Institute, Pirbright, UK.

The laboratory diagnosis of African horse sickness (AHS) is important for: (a) demonstrating freedom from infection in a population, animals or products for trade (b) assessing the efficiency of eradication policies; (c) laboratory confirmation of clinical diagnosis; (d) estimating the prevalence of AHS infection; and (e) assessing postvaccination immune status of individual animals or populations. Although serological techniques play a secondary role in the confirmation of clinical cases, their use is very important for all the other purposes due to their high throughput, ease of use and good cost-benefit ratio. The main objective of this study was to support the validation of AHS VP7 Blocking ELISA up to the Stage 3 of the World Animal Health Organization (OIE) assay validation pathway. To achieve this, a collaborative ring trial, which included all OIE Reference Laboratories and other AHS-specialist diagnostic centres, was conducted in order to assess the diagnostic performance characteristics of the VP7 Blocking ELISA. In this trial, a panel of sera of different epidemiological origin and infection status was used. Through this comprehensive evaluation we can conclude that the VP7 Blocking ELISA satisfies the OIE requirements of reproducibility. The VP7 Blocking ELISA, in its commercial version is ready to enter Stage 4 of the validation pathway (Programme Implementation). Specifically, this will require testing the diagnostic performance of the assay using contemporary serum samples collected during control campaigns in endemic countries.
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http://dx.doi.org/10.1111/tbed.12968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6378617PMC
January 2019

The European Virus Archive goes global: A growing resource for research.

Antiviral Res 2018 10 29;158:127-134. Epub 2018 Jul 29.

Unite des Virus Emergents (UVE: Aix Marseille Univ, IRD 190, INSERM 1207, IHU Méditerranée Infection), Marseille, France.

The European Virus Archive (EVA) was created in 2008 with funding from the FP7-EU Infrastructure Programme, in response to the need for a coordinated and readily accessible collection of viruses that could be made available to academia, public health organisations and industry. Within three years, it developed from a consortium of nine European laboratories to encompass associated partners in Africa, Russia, China, Turkey, Germany and Italy. In 2014, the H2020 Research and Innovation Framework Programme (INFRAS projects) provided support for the transformation of the EVA from a European to a global organization (EVAg). The EVAg now operates as a non-profit consortium, with 26 partners and 20 associated partners from 21 EU and non-EU countries. In this paper, we outline the structure, management and goals of the EVAg, to bring to the attention of researchers the wealth of products it can provide and to illustrate how end-users can gain access to these resources. Organisations or individuals who would like to be considered as contributors are invited to contact the EVAg coordinator, Jean-Louis Romette, at jean-louis.romette@univmed.fr.
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http://dx.doi.org/10.1016/j.antiviral.2018.07.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7127435PMC
October 2018

Evaluating the most appropriate pooling ratio for EDTA blood samples to detect Bluetongue virus using real-time RT-PCR.

Vet Microbiol 2018 Apr 3;217:58-63. Epub 2018 Mar 3.

The Pirbright Institute, Pirbright, Woking, Surrey, United Kingdom.

The control of Bluetongue virus (BTV) presents a significant challenge to European Union (EU) member states as trade restrictions are placed on animals imported from BTV-affected countries. BTV surveillance programs are costly to maintain, thus, pooling of EDTA blood samples is used to reduce costs and increase throughput. We investigated different pooling ratios (1:2, 1:5, 1:10 and 1:20) for EDTA blood samples to detect a single BTV positive animal. A published real-time RT-PCR assay (Hofmann et al., 2008) and a commercial assay (ThermoFisher VetMax™ BTV NS3 kit) were used to analyse BTV RNA extracted from pooled EDTA blood samples. The detection rate was low for the onset of infection sample (0-2 days post infection (dpi); C 36) irrespective of the pooling ratio. Both assays could reliably detect a single BTV-positive animal at early viraemia (3-6 dpi; C 33) when pooled, however, detection rate diminished with increasing pooling ratio. A statistical model indicated that pooling samples up to 1:20, is suitable to detect a single BTV positive animal at peak viraemia (7-12 dpi) or late infection (13-30 dpi) with a probability of detection of >80% and >94% using the Hofmann et al. (2008) and VetMAX assays, respectively. Using the assays highlighted in our study, pooling at ratios of 1:20 would be technically suitable in BTV-endemic countries for surveillance purposes. As peak viraemia occurs between 7-12 days post infection, a 1:10 pooling ratio is appropriate for post-import testing when animals are sampled within a similar time frame post-import.
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http://dx.doi.org/10.1016/j.vetmic.2018.03.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5904549PMC
April 2018

Experimental infection of sheep, goats and cattle with a bluetongue virus serotype 4 field strain from Bulgaria, 2014.

Transbound Emerg Dis 2018 Apr 8;65(2):e243-e250. Epub 2017 Nov 8.

Friedrich-Loeffler-Institut, Institute of Diagnostic Virology, Greifswald-Insel Riems, Germany.

In 2014, a new bluetongue virus serotype 4 (BTV-4) strain was detected in southern Greece and spread rapidly throughout the Balkan Peninsula and adjacent countries. Within half a year, more than 7,068 outbreaks were reported in ruminants, particularly in sheep. However, the reported morbidity and case fatality rates in ruminants varied. The pathogenesis of a Bulgarian BTV-4 strain isolated from sheep during the BTV-4 epizootic was studied in different species. Therefore, four sheep, three goats and three cattle were experimentally infected with the isolate BTV-4/BUL2014/15 and monitored for clinical signs up to several weeks. Serum and whole-blood samples were collected at regular intervals and subjected to serological and virological analyses. In this context, BTV-4-specific real-time RT-PCR assays were developed. The infection kinetics were similar to those known for other traditional BTV serotypes, and only mild BT-like clinical signs were observed in goats and sheep. In cattle, no obvious clinical signs were observed, except a transient increase in body temperature. The study results contrast with the severe clinical signs reported in sheep experimentally infected with an African BTV-4 strain and with the reports of BT-like clinical signs in a considerable proportion of different ruminant species infected with BTV-4 in the Balkan region and Italy. The discrepancies between the results of these animal trials and observations of BTV-4 infection in the field may be explained by the influence of various factors on the manifestation of BT disease, such as animal breed, fitness and virus strain, as described previously.
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http://dx.doi.org/10.1111/tbed.12746DOI Listing
April 2018

Bluetongue virus infection in naïve cattle: Identification of circulating serotypes and associated Culicoides biting midge species in Trinidad.

Vet Microbiol 2017 Nov 18;211:1-5. Epub 2017 Sep 18.

School of Veterinary Medicine, Faculty of Medical Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago.

To better understand risks associated with trading cattle, it is important to know which serotypes of Bluetongue virus (BTV) are circulating within the exporting and importing country. Hence, this study was conducted to identify the circulating serotypes of BTV in Trinidad. Blood samples were collected monthly from sixty BTV- naïve imported cattle over a six month period after their arrival in the country. Virological (PCR and virus isolation) and serological (ELISA) analyses were carried out on the samples and CDC light traps were placed near the cattle enclosure to trap and identify the species of Culicoides biting midges that were present. All of the cattle seroconverted for BTV antibodies within three months of their arrival in the country and real-time reverse transcription PCR (rRT-PCR) detected BTV-RNA in the samples throughout the remainder of the study. The patterns of infection observed in the cattle indicated serial infections with multiple serotypes. A combination of BTV serotype-specific rRT-PCR on the original blood samples and virus isolation followed by serotype-specific rRT-PCR on selected samples, confirmed the presence of BTV serotypes 1, 2, 3, 5, 12 and 17. This is the first report of BTV-2 and BTV-5 in Trinidad. Light-suction traps placed in close proximity to the cattle predominantly trapped Culicoides insignis Lutz 1913 species (96%), with a further six Culicoides species making up the remaining 4% of trapped samples. The circulation of multiple BTV serotypes in Trinidad underlines the need for regular surveillance, which will contribute to the development of risk assessments for trade in livestock.
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http://dx.doi.org/10.1016/j.vetmic.2017.09.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5680695PMC
November 2017