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Nielsen SS, Alvarez J, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar C, Herskin MS, Michel V, Miranda Chueca MÁ, Padalino B, Roberts HC, Spoolder H, Ståhl K, Velarde A, Viltrop A, Winckler C, Bron J, Olesen NJ, Sindre H, Stone D, Vendramin N, Antoniou SE, Broglia A, Karagianni AE, Papanikolaou A, Bicout DJ. Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU)2016/429): Infection with salmonid alphavirus (SAV). EFSA J 2023; 21:e08327. [PMID: 37908450 PMCID: PMC10613945 DOI: 10.2903/j.efsa.2023.8327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
Infection with salmonid alphavirus (SAV) was assessed according to the criteria of the Animal Health Law (AHL), in particular the criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as laid out in Article 9 and Article 8 for listing animal species related to infection with SAV. The assessment was performed following the ad hoc method on data collection and assessment developed by AHAW Panel and already published. The outcome reported is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with an uncertain outcome. According to the assessment, it was uncertain whether infection with salmonid alphavirus can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (50-80% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that infection with salmonid alphavirus does not meet the criteria in Section 1 (Category A; 5-10% probability of meeting the criteria) and it is uncertain whether it meets the criteria in Sections 2, 3, 4 and 5 (Categories B, C, D and E; 50-90%, probability of meeting the criteria). The animal species to be listed for infection with SAV according to Article 8 criteria are provided.
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Baker WS, Negi S, Braun W, Schein CH. Producing physicochemical property consensus alphavirus protein antigens for broad spectrum vaccine design. Antiviral Res 2020; 182:104905. [PMID: 32800880 DOI: 10.1016/j.antiviral.2020.104905] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/19/2020] [Accepted: 08/01/2020] [Indexed: 12/16/2022]
Abstract
There is a pressing need for new vaccines against alphaviruses, which can cause fatal encephalitis (Venezuelan equine encephalitis virus (VEEV) and others) and severe arthralgia (e.g. Chikungunya virus, CHIKV). These positive-strand RNA viruses are diverse and evolve rapidly, meaning that the sequence of any vaccine should cover multiple strains that may be quite different from any previous isolate. Here, consensus proteins were produced to represent the common physicochemical properties (PCPs) of the epitope rich, B domain of the E2 envelope protein. PCP-consensus proteins were based on multiple strains of VEEV (VEEVcon) and CHIKV (CHIKVcon) or the conserved PCPs of 24 different alphaviruses (AllAVcon). The AllAVcon was altered to include binding sites for neutralizing antibodies of both VEEV and CHIKV strains (Mosaikcon). All four designed proteins were produced solubly in E. coli and purified. They formed the β-strand core expected from experimental structures of this region of the wild type E2 proteins as indicated by circular dichroism (CD) spectra. Furthermore, the CHIKVcon protein bound to a structure dependent, CHIKV neutralizing monoclonal antibody. The AllAVcon and Mosaikcon proteins bound to polyclonal antibodies generated during natural infection with either VEEV or CHIKV, indicating they contained epitopes of both serotypes. The Mosaikcon antigen induced antibodies in rabbit sera that recognized both the VEEVcon and CHIKVcon spike proteins. These PCP-consensus antigens are promising starting points for novel, broad-spectrum alphavirus vaccines.
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Affiliation(s)
- Wendy S Baker
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Surendra Negi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Werner Braun
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Catherine H Schein
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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Aksnes I, Markussen T, Braaen S, Rimstad E. Mutation of N-glycosylation Sites in Salmonid Alphavirus (SAV) Envelope Proteins Attenuate the Virus in Cell Culture. Viruses 2020; 12:v12101071. [PMID: 32987930 PMCID: PMC7650630 DOI: 10.3390/v12101071] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/16/2022] Open
Abstract
Salmonid alphavirus (SAV) is the cause of pancreas disease and sleeping disease in farmed salmonid fish in Europe. The spread of these diseases has been difficult to control with biosecurity and current vaccination strategies, and increased understanding of the viral pathogenesis could be beneficial for the development of novel vaccine strategies. N-glycosylation of viral envelope proteins may be crucial for viral virulence and a possible target for its purposed attenuation. In this study, we mutated the N-glycosylation consensus motifs of the E1 and E2 glycoproteins of a SAV3 infectious clone using site-directed mutagenesis. Mutation of the glycosylation motif in E1 gave a complete inactivation of the virus as no viral replication could be detected in cell culture and infectious particles could not be rescued. In contrast, infectious virus particles could be recovered from the SAV3 E2 mutants (E2319Q, E2319A), but not if they were accompanied by lack of N-glycosylation in E1. Compared to the non-mutated infectious clone, the SAV3-E2319Q and SAV3-E2319A recombinant viruses produced less cytopathic effects in cell culture and lower amounts of infectious viral particles. In conclusion, the substitution in the N-linked glycosylation site in E2 attenuated SAV3 in cell culture. The findings could be useful for immunization strategies using live attenuated vaccines and testing in fish will be desirable to study the clone’s properties in vivo.
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Dennehy JJ. Evolutionary ecology of virus emergence. Ann N Y Acad Sci 2016; 1389:124-146. [PMID: 28036113 PMCID: PMC7167663 DOI: 10.1111/nyas.13304] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 10/24/2016] [Accepted: 11/09/2016] [Indexed: 12/22/2022]
Abstract
The cross-species transmission of viruses into new host populations, termed virus emergence, is a significant issue in public health, agriculture, wildlife management, and related fields. Virus emergence requires overlap between host populations, alterations in virus genetics to permit infection of new hosts, and adaptation to novel hosts such that between-host transmission is sustainable, all of which are the purview of the fields of ecology and evolution. A firm understanding of the ecology of viruses and how they evolve is required for understanding how and why viruses emerge. In this paper, I address the evolutionary mechanisms of virus emergence and how they relate to virus ecology. I argue that, while virus acquisition of the ability to infect new hosts is not difficult, limited evolutionary trajectories to sustained virus between-host transmission and the combined effects of mutational meltdown, bottlenecking, demographic stochasticity, density dependence, and genetic erosion in ecological sinks limit most emergence events to dead-end spillover infections. Despite the relative rarity of pandemic emerging viruses, the potential of viruses to search evolutionary space and find means to spread epidemically and the consequences of pandemic viruses that do emerge necessitate sustained attention to virus research, surveillance, prophylaxis, and treatment.
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Affiliation(s)
- John J Dennehy
- Biology Department, Queens College of the City University of New York, Queens, New York and The Graduate Center of the City University of New York, New York, New York
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Skjold P, Sommerset I, Frost P, Villoing S. Vaccination against pancreas disease in Atlantic salmon, Salmo salar L., reduces shedding of salmonid alphavirus. Vet Res 2016; 47:78. [PMID: 27496170 PMCID: PMC4975881 DOI: 10.1186/s13567-016-0362-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/09/2016] [Indexed: 11/28/2022] Open
Abstract
Salmon pancreas disease virus, often referred to as salmonid alphavirus (SAV), causes pancreas disease (PD) in European salmonids. SAV transmits horizontally from fish shedding virus into the water and ocean currents are believed to be a main contributor of viral spread between marine farms. Vaccination against PD is previously shown to reduce mortality and severity of clinical PD. In this study, we demonstrate that vaccination against PD significantly reduces viral shedding from infected individuals. The results suggest that PD vaccination can be an important tool to reduce the infection pressure, a known key risk for PD outbreaks at neighbouring farms.
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Affiliation(s)
- Pål Skjold
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway.
| | - Ingunn Sommerset
- MSD Animal Health Norge AS, Thormøhlensgate 55, 5008, Bergen, Norway
| | - Petter Frost
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway
| | - Stephane Villoing
- MSD Animal Health Innovation AS, Thormøhlensgate 55, 5008, Bergen, Norway
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Hikke MC, Geertsema C, Wu V, Metz SW, van Lent JW, Vlak JM, Pijlman GP. Alphavirus capsid proteins self-assemble into core-like particles in insect cells: A promising platform for nanoparticle vaccine development. Biotechnol J 2015; 11:266-73. [PMID: 26287127 DOI: 10.1002/biot.201500147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/18/2015] [Accepted: 08/13/2015] [Indexed: 11/07/2022]
Abstract
The mosquito-borne chikungunya virus (CHIKV) causes arthritic diseases in humans, whereas the aquatic salmonid alphavirus (SAV) is associated with high mortality in aquaculture of salmon and trout. Using modern biotechnological approaches, promising vaccine candidates based upon highly immunogenic, enveloped virus-like particles (eVLPs) have been developed. However, the eVLP structure (core, lipid membrane, surface glycoproteins) is more complex than that of non-enveloped, protein-only VLPs, which are structurally and morphologically 'simple'. In order to develop an alternative to alphavirus eVLPs, in this paper we engineered recombinant baculovirus vectors to produce high levels of alphavirus core-like particles (CLPs) in insect cells by expression of the CHIKV and SAV capsid proteins. The CLPs localize in dense nuclear bodies within the infected cell nucleus and are purified through a rapid and scalable protocol involving cell lysis, sonication and low-speed centrifugation steps. Furthermore, an immunogenic epitope from the alphavirus E2 glycoprotein can be successfully fused to the N-terminus of the capsid protein without disrupting the CLP self-assembling properties. We propose that immunogenic epitope-tagged alphavirus CLPs produced in insect cells present a simple and perhaps more stable alternative to alphavirus eVLPs.
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Affiliation(s)
- Mia C Hikke
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Corinne Geertsema
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Vincen Wu
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Stefan W Metz
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Jan W van Lent
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Just M Vlak
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands.
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Petterson E, Guo TC, Evensen Ø, Haugland Ø, Mikalsen AB. In vitro adaptation of SAV3 in cell culture correlates with reduced in vivo replication capacity and virulence to Atlantic salmon (Salmo salar L.) parr. J Gen Virol 2015; 96:3023-3034. [PMID: 26297344 DOI: 10.1099/jgv.0.000242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Salmonid alphavirus (SAV) is the causative agent of pancreas disease affecting Atlantic salmon and rainbow trout and causes a major burden to the aquaculture industry. This study describes a Norwegian subtype SAV3 virus isolate (SAV3-H10) subjected to serial passages in Chinook salmon embryo cells (CHSE-214) followed by Asian Grouper skin cells (AGK). Two passages from CHSE and one after transfer to AGK cells were chosen for further investigation, based on variation in degree and development of cytopathic effect (CPE). After plaque purification, several in vitro studies were performed. Cell viability after infection, viral replication and ability to cause morphological changes in CHSE and AGK cells was studied for the three isolates. The AGK-transferred isolate was identified with the strongest abilities to reduce cell viability, replicate more and cause more CPE in cell culture when compared with the early and late CHSE-grown isolates. Subsequently, the isolates were tested in an experimental fish challenge, showing higher viral load and higher pathological score for the least cell-cultured isolate. Full-length sequencing of the viral genome of the three isolates revealed divergence in four amino acid positions and the AGK-grown isolate also had a 3 nt deletion in the 3'UTR. In conclusion, we show that cell culture of SAV3-H10 selects for strains inducing earlier CPE in vitro with increased viral replication. In vivo, the effect is reversed, with lower replication levels and lower pathology scores in target organs. This study outlines a path to identify potential virulence motifs of SAV3.
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Affiliation(s)
- Elin Petterson
- Norwegian University of Life Sciences, Department of Basic Science and Aquatic Medicine, PO Box 8146 Dep., 0033 Oslo, Norway
| | - Tz-Chun Guo
- Norwegian University of Life Sciences, Department of Basic Science and Aquatic Medicine, PO Box 8146 Dep., 0033 Oslo, Norway
| | - Øystein Evensen
- Norwegian University of Life Sciences, Department of Basic Science and Aquatic Medicine, PO Box 8146 Dep., 0033 Oslo, Norway
| | - Øyvind Haugland
- Norwegian University of Life Sciences, Department of Basic Science and Aquatic Medicine, PO Box 8146 Dep., 0033 Oslo, Norway
| | - Aase B Mikalsen
- Norwegian University of Life Sciences, Department of Basic Science and Aquatic Medicine, PO Box 8146 Dep., 0033 Oslo, Norway
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