The Pirbright Institute publication directory contains details of selected publications written by our researchers.

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Background: Baicalin, the main metabolic component of Scutellaria baicalensis Georgi, has various pharmacological properties including anti-inflammatory, anti-oxidant, anti-apoptotic, anti-bactericidal and anti-viral. The purpose of this study was to investigate the anti-Marek’s disease virus (MDV) activities of baicalin in CEF cells.

Results: Here, we showed that baicalin could inhibit viral mRNA, protein levels and overall plaque formation in a time-dependent manner. We also found that baicalin could consistently inhibit MDV replication and directly affect the virus infectivity. Moreover, baicalin treatment has no effect on expression level of antiviral cytokine and inflammatory cytokines in MDV infected CEFs.

Conclusions: These results demonstrate that baicalin could be a potential drug against MDV infection.

Tan T K, Rijal P, Rahikainen R, Keeble A H, Schimanski L, Hussain S, Harvey R, Hayes J W P, Edwards J C, McLean R K, Martini V, Pedrera M, Thakur N, Conceicao C, Dietrich I, Shelton H, Ludi A, Wilsden G, Browning C, Zagrajek A K, Bialy D, Bhat S, Stevenson-Leggett P, Hollinghurst P, Tully M, Moffat K, Chiu C, Waters R, Gray A, Azhar M, Mioulet V, Newman J, Asfor A S, Burman A, Crossley S, Hammond J A, Tchilian E, Charleston B, Bailey D, Tuthill T J, Graham S P, Malinauskas T, Huo J, Tree J A, Buttigieg K R, Owens R J, Caroll M W, Daniels R S, McCauley J W, Huang K-Y A, et al (2020)

A COVID-19 vaccine candidate using SpyCatcher multimerization of the SARS-CoV-2 spike protein receptor-binding domain induces potent neutralising antibody responses

bioRxiv preprint


There is dire need for an effective and affordable vaccine against SARS-CoV-2 to tackle the ongoing pandemic. In this study, we describe a modular virus-like particle vaccine candidate displaying the SARS-CoV-2 spike glycoprotein receptor-binding domain (RBD) using SpyTag/SpyCatcher technology (RBD-SpyVLP). Low doses of RBD-SpyVLP in a prime-boost regimen induced a strong neutralising antibody response in mice and pigs that was superior to convalescent human sera. We evaluated antibody quality using ACE2 blocking and neutralisation of cell infection by pseudovirus or wild-type SARS-CoV-2. Using competition assays with a monoclonal antibody panel, we showed that RBD-SpyVLP induced a polyclonal antibody response that recognised all key epitopes on the RBD, reducing the likelihood of selecting neutralisation-escape mutants. The induction of potent and polyclonal antibody responses by RBD-SpyVLP provides strong potential to address clinical and logistic challenges of the COVID-19 pandemic. Moreover, RBD-SpyVLP is highly resilient, thermostable and can be lyophilised without losing immunogenicity, to facilitate global distribution and reduce cold-chain dependence.


Bovine Pestiviruses A and B, formerly known as bovine viral diarrhoea viruses (BVDV)-1 and 2, respectively, are important pathogens of cattle worldwide, responsible for significant economic losses. Bovine viral diarrhoea control programmes are in effect in several high-income countries but less so in low- and middle-income countries where bovine pestiviruses are not considered in disease control programmes. However, bovine pestiviruses are genetically and antigenically diverse, which affects the efficiency of the control programmes. The emergence of atypical ruminant pestiviruses (Pestivirus H or BVDV-3) from various parts of the world and the detection of Pestivirus D (border disease virus) in cattle highlights the challenge that pestiviruses continue to pose to control measures including the development of vaccines with improved crossprotective potential and enhanced diagnostics. This review examines the effect of bovine pestivirus diversity and emergence of atypical pestiviruses in disease control by vaccination and diagnosis.

Folegatti P M, Ewer K J, Aley P K, Angus B, Becker S, Belij-Rammerstorfer S, Bellamy D, Bibi S, Bittaye M, Clutterbuck E A, Dold C, Faust S N, Finn A, Flaxman A L, Hallis B, Heath P, Jenkin D, Lazarus R, Makinson R, Minassian A M, Pollock K M, Ramasamy M, Robinson H, Snape M, Tarrant R, Voysey M, Green C, Douglas A D, Hill A V S, Lambe T, Gilbert S C, Pollard A J, on behalf of Oxford COVID Vaccine Trial Group (2020)

Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial

The Lancet 396 (10249), 467-478


BACKGROUND: The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be curtailed by vaccination. We assessed the safety, reactogenicity, and immunogenicity of a viral vectored coronavirus vaccine that expresses the spike protein of SARS-CoV-2.

METHODS: We did a phase 1/2, single-blind, randomised controlled trial in five trial sites in the UK of a chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19) expressing the SARS-CoV-2 spike protein compared with a meningococcal conjugate vaccine (MenACWY) as control. Healthy adults aged 18-55 years with no history of laboratory confirmed SARS-CoV-2 infection or of COVID-19-like symptoms were randomly assigned (1:1) to receive ChAdOx1 nCoV-19 at a dose of 5 x 10(10) viral particles or MenACWY as a single intramuscular injection. A protocol amendment in two of the five sites allowed prophylactic paracetamol to be administered before vaccination. Ten participants assigned to a non-randomised, unblinded ChAdOx1 nCoV-19 prime-boost group received a two-dose schedule, with the booster vaccine administered 28 days after the first dose. Humoral responses at baseline and following vaccination were assessed using a standardised total IgG ELISA against trimeric SARS-CoV-2 spike protein, a muliplexed immunoassay, three live SARS-CoV-2 neutralisation assays (a 50% plaque reduction neutralisation assay [PRNT50]; a microneutralisation assay [MNA50, MNA80, and MNA90]; and Marburg VN), and a pseudovirus neutralisation assay. Cellular responses were assessed using an ex-vivo interferon-gamma enzyme-linked immunospot assay. The co-primary outcomes are to assess efficacy, as measured by cases of symptomatic virologically confirmed COVID-19, and safety, as measured by the occurrence of serious adverse events. Analyses were done by group allocation in participants who received the vaccine. Safety was assessed over 28 days after vaccination. Here, we report the preliminary findings on safety, reactogenicity, and cellular and humoral immune responses. The study is ongoing, and was registered at ISRCTN, 15281137, and, NCT04324606.

FINDINGS: Between April 23 and May 21, 2020, 1077 participants were enrolled and assigned to receive either ChAdOx1 nCoV-19 (n=543) or MenACWY (n=534), ten of whom were enrolled in the non-randomised ChAdOx1 nCoV-19 prime-boost group. Local and systemic reactions were more common in the ChAdOx1 nCoV-19 group and many were reduced by use of prophylactic paracetamol, including pain, feeling feverish, chills, muscle ache, headache, and malaise (all p<0.05). There were no serious adverse events related to ChAdOx1 nCoV-19. In the ChAdOx1 nCoV-19 group, spike-specific T-cell responses peaked on day 14 (median 856 spot-forming cells per million peripheral blood mononuclear cells, IQR 493-1802; n=43). Anti-spike IgG responses rose by day 28 (median 157 ELISA units [EU], 96-317; n=127), and were boosted following a second dose (639 EU, 360-792; n=10). Neutralising antibody responses against SARS-CoV-2 were detected in 32 (91%) of 35 participants after a single dose when measured in MNA80 and in 35 (100%) participants when measured in PRNT50. After a booster dose, all participants had neutralising activity (nine of nine in MNA80 at day 42 and ten of ten in Marburg VN on day 56). Neutralising antibody responses correlated strongly with antibody levels measured by ELISA (R(2)=0.67 by Marburg VN; p<0.001).

INTERPRETATION: ChAdOx1 nCoV-19 showed an acceptable safety profile, and homologous boosting increased antibody responses. These results, together with the induction of both humoral and cellular immune responses, support large-scale evaluation of this candidate vaccine in an ongoing phase 3 programme.

FUNDING: UK Research and Innovation, Coalition for Epidemic Preparedness Innovations, National Institute for Health Research (NIHR), NIHR Oxford Biomedical Research Centre, Thames Valley and South Midland's NIHR Clinical Research Network, and the German Center for Infection Research (DZIF), Partner site Giessen-Marburg-Langen.

Flannery J, King S, Rajko-Nenow P, Popova Z, Krstevski K, Djadjovski I, Batten C (2020)

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

bioRxiv preprint


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.

Buckle K, Bueno R, McFadden A, Andel M v, Spence R, Hamill C, Roe W, Vallee E, Alcala F C, Abila R, Verin B, Purevsuren B, Sutar A, Win H H, Thiha M, Lwin K O, Khounsy S, Phonthasy S, Souriya V, Keokhamphet C, Arzt J, Ludi A, Mioulet V (2020)

Detection of foot-and-mouth disease (FMD) virus in healthy cattle and buffalo at Southeast Asian slaughterhouses

Authorea preprint


Foot-and-mouth disease virus (FMDV) is widespread throughout much of the world, including parts of South East Asia. As part of the World Organisation for Animal Health (OIE)’s South East Asia and China Foot-and-Mouth Disease Project (SEACFMD), field sampling was performed to help understand evidence of widespread virus exposure observed previously. Serum and dry mucosal swabs were collected to evaluate the presence of FMDV RNA on the nasal, oral, and dorsal nasopharyngeal mucosal surfaces of 262 healthy cattle (n=38 in Laos; n=47 in Myanmar) and buffalo (n=12 in Laos; n=2 in Myanmar) immediately following slaughter in three slaughterhouses. Swabs and serum were tested by the OIE FMD world reference laboratory using pan-serotypic real-time reverse transcription-PCR (RT-PCR) and serum was evaluated using the FMD PrioCHECK non-structural protein (NSP) ELISA. In total, 7.3% of animals had detectable FMDV RNA in one or more of the three sites including 5.3% of nasopharyngeal swabs, 2.3% of oral swabs, and 1.5% of nasal swabs. In all animals, serum was found not to contain detectable FMDV RNA, and 37.8% of animals were positive for NSP antibodies, indicating likely past exposure to FMDV. Results were comparable for Laos and Myanmar, and were similar for both cattle and buffalo. The current study demonstrates the utility of detection by swabbing the nasopharynx in the post-mortem context, in situations such as post-mortem where probang samples are not feasible. Additionally, FMDV present on the oral and nasal mucosa of clinically-healthy large ruminants in Laos and Myanmar, if viable, may potentially play a role in the epidemiology of FMD in these countries, and perhaps more widely within Southeast Asia.

Browning C F J, Di Nardo A, Henry L, Pollard T, Hendry L, Romey A, Relmy A, Eble P, Brocchi E, Grazioli S, King D P, Ludi A B (2020)

Inter-laboratory comparison of 2 ELISA kits used for foot-and-mouth disease virus nonstructural protein serology

Journal of Veterinary Diagnostic Investigation early view


Serologic assays used to detect antibodies to nonstructural proteins (NSPs) of foot-and-mouth disease virus (FMDV) are used for disease surveillance in endemic countries, and are essential to providing evidence for freedom of the disease with or without vaccination and to recover the free status of a country after an outbreak. In a 5-site inter-laboratory study, we compared the performance of 2 commercial NSP ELISA kits (ID Screen FMD NSP ELISA single day [short] and overnight protocols, ID.Vet; PrioCHECK FMDV NS antibody ELISA, Thermo Fisher Scientific). The overall concordance between the PrioCHECK and ID Screen test was 93.8% (95% CI: 92.0-95.2%) and 94.8% (95% CI: 93.1-96.1%) for the overnight and short ID Screen incubation protocols, respectively. Our results indicate that the assays (including the 2 different formats of the ID Screen test) can be used interchangeably in post-outbreak serosurveillance.


Marek's disease virus (MDV) transforms CD4+ T cells and causes a deadly neoplastic disease which is associated with metabolic dysregulation leading to atherosclerosis in chickens. While MDV-infected chickens have normal serum concentrations of cholesterol, their aortic tissues were found to have elevated concentrations of free and esterified cholesterol. Here, we demonstrate that infection of chicken embryonated fibroblasts (CEFs) with the highly pathogenic MDV-RB1B increases cellular cholesterol content and upregulates the genes involved in cholesterol synthesis and cellular cholesterol homeostasis using comprehensive two-dimensional gas chromatography mass spectrometry and real-time PCR (RT-PCR), respectively. Using small pharmacological inhibitors and gene silencing, we established an association between MDV-RB1B replication and mevalonic acid, sterol and cholesterol biosynthesis and trafficking/redistribution. We propose that MDV trafficking is mediated by lysosomal associated membrane protein 1+ (LAMP-1) vesicles based on short hairpin RNA (shRNA) gene silencing and colocalization of LAMP-1, glycoprotein B (gB) of MDV and cholesterol (Filipin III) fluorescent signal intensity peaks. In conclusion, our results demonstrate that MDV hijacks cellular cholesterol biosynthesis and cholesterol trafficking to facilitate cell-to-cell spread in a LAMP-1 dependent mechanism.

IMPORTANCE MDV disrupts lipid metabolism and causes atherosclerosis in the MDV-infected chickens, however the role of cholesterol metabolism in replication and spread of MDV is unknown. The MDV-infected cells do not produce infectious cell free virus in vitro, raising the question about the mechanism involved in cell-to-cell spread of MDV. In this report, we provide evidence that MDV replication depends on de novo cholesterol biosynthesis and uptake. Interruption of cholesterol trafficking within multivesicular bodies (MVBs) by chemical inhibitors or gene silencing reduced MDV titre and cell-to-cell spread. Lastly, we demonstrated that MDV gB colocalizes with cholesterol and LAMP-1 suggesting that the viral protein trafficking is mediated through LAMP-1 positive vesicles in association with cholesterol. These results provide new insights into the cholesterol dependence of MDV replication.


The Gammacoronavirus infectious bronchitis virus (IBV) causes a highly contagious and economically important respiratory disease in poultry. In the laboratory, most IBV strains are restricted to replication in ex vivo organ cultures or in ovo and do not replicate in cell culture, making the study of their basic virology difficult. Entry of IBV into cells is facilitated by the large glycoprotein on the surface of the virion, the spike (S) protein, comprised of S1 and S2 subunits. Previous research showed that the S2' cleavage site is responsible for the extended tropism of the IBV Beaudette strain. This study aims to investigate whether protease treatment can extend the tropism of other IBV strains. Here we demonstrate that the addition of exogenous trypsin during IBV propagation in cell culture results in significantly increased viral titres. Using a panel of IBV strains, exhibiting varied tropisms, the effects of spike cleavage on entry and replication were assessed by serial passage cell culture in the presence of trypsin. Replication could be maintained over serial passages, indicating that the addition of exogenous protease is sufficient to overcome the barrier to infection. Mutations were identified in both S1 and S2 subunits following serial passage in cell culture. This work provides a proof of concept that exogenous proteases can remove the barrier to IBV replication in otherwise non-permissive cells, providing a platform for further study of elusive field strains and enabling sustainable vaccine production in vitro.

Flannery J, Ashby M, Moore R, Wells S, Rajko-Nenow P, Netherton C L, Batten C (2020)

Identification of novel testing matrices for African swine fever surveillance

Journal of Veterinary Diagnostic Investigation early view


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 > 107 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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