scholarly journals Differential Effect of the Deletion of African Swine Fever Virus Virulence-Associated Genes in the Induction of Attenuation of the Highly Virulent Georgia Strain

Viruses ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 599 ◽  
Author(s):  
Elizabeth Ramirez-Medina ◽  
Elizabeth Vuono ◽  
Vivian O’Donnell ◽  
Lauren G. Holinka ◽  
Ediane Silva ◽  
...  
Keyword(s):  
Protective Immunity ◽  
Gene Deletion ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Early Death ◽  
Fever Virus ◽  
Differential Behavior ◽  
Viral Genes ◽  
The Uk ◽  
Highly Virulent

African swine fever virus (ASFV) is the etiological agent of an often lethal disease of domestic pigs, African swine fever (ASF). The ASFV Georgia 2007 isolate (ASFV-G) is responsible for the current epidemic situation in Europe and Asia. Genetically modified ASFVs containing deletions of virulence-associated genes have produced attenuated phenotypes and induced protective immunity in swine. Here we describe the differential behavior of two viral genes, NL (DP71L) and UK (DP96R), both originally described as being involved in virus virulence. Deletion of either of these genes efficiently attenuated ASFV strain E70. We demonstrated that deletion of the UK gene from the ASFV-G genome did not decrease virulence when compared to the parental virus. Conversely, deletion of the NL gene produced a heterogeneous response, with early death in one of the animals and transient fever in the other animals. With this knowledge, we attempted to increase the safety profile of the previously reported experimental vaccine ASFV-GΔ9GL/ΔUK by deleting the NL gene. A triple gene-deletion virus was produced, ASFV-GΔ9GL/ΔNL/ΔUK. Although ASFV-GΔ9GL/ΔNL/ΔUK replicated in primary cell cultures of swine macrophages, it demonstrated a severe replication deficiency in pigs, failing to induce protection against challenge with parental ASFV-G.

scholarly journals Novel Swine Virulence Determinant in the Left Variable Region of the African Swine Fever Virus Genome

2002 ◽  
Vol 76 (7) ◽  
pp. 3095-3104 ◽  
Author(s):  
J. G. Neilan ◽  
L. Zsak ◽  
Z. Lu ◽  
G. F. Kutish ◽  
C. L. Afonso ◽  
...  
Keyword(s):  
Deletion Mutant ◽  
Gene Deletion ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Variable Region ◽  
Fever Virus ◽  
Marker Rescue ◽  
Virulence Determinant ◽  
Gene Deletion Mutant

ABSTRACT Previously we have shown that the African swine fever virus (ASFV) NL gene deletion mutant E70ΔNL is attenuated in pigs. Our recent observations that NL gene deletion mutants of two additional pathogenic ASFV isolates, Malawi Lil-20/1 and Pr4, remained highly virulent in swine (100% mortality) suggested that these isolates encoded an additional virulence determinant(s) that was absent from E70. To map this putative virulence determinant, in vivo marker rescue experiments were performed by inoculating swine with infection-transfection lysates containing E70 NL deletion mutant virus (E70ΔNL) and cosmid DNA clones from the Malawi NL gene deletion mutant (MalΔNL). A cosmid clone representing the left-hand 38-kb region (map units 0.05 to 0.26) of the MalΔNL genome was capable of restoring full virulence to E70ΔNL. Southern blot analysis of recovered virulent viruses confirmed that they were recombinant E70ΔNL genomes containing a 23- to 28-kb DNA fragment of the Malawi genome. These recombinants exhibited an unaltered MalΔNL disease and virulence phenotype when inoculated into swine. Additional in vivo marker rescue experiments identified a 20-kb fragment, encoding members of multigene families (MGF) 360 and 530, as being capable of fully restoring virulence to E70ΔNL. Comparative nucleotide sequence analysis of the left variable region of the E70ΔNL and Malawi Lil-20/1 genomes identified an 8-kb deletion in the E70ΔNL isolate which resulted in the deletion and/or truncation of three MGF 360 genes and four MGF 530 genes. A recombinant MalΔNL deletion mutant lacking three members of each MGF gene family was constructed and evaluated for virulence in swine. The mutant virus replicated normally in macrophage cell culture but was avirulent in swine. Together, these results indicate that a region within the left variable region of the ASFV genome containing the MGF 360 and 530 genes represents a previously unrecognized virulence determinant for domestic swine.

scholarly journals EFFECTS OF MODERATELY VIRULENT AFRICAN SWINE FEVER VIRUS ON INTERLEUKIN-10 PRODUCTION

2019 ◽  
pp. 23-28 ◽  
Author(s):  
A. S. Pershin ◽  
I. V. Shevchenko ◽  
A. S. Igolkin ◽  
Ye. V. Aronova ◽  
N. N. Vlasova
Keyword(s):  
Immune Response ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Noticeable Effect ◽  
Specific Antibodies ◽  
Virulent Virus ◽  
Virus Isolates ◽  
Highly Virulent

A characteristic feature of African swine fever virus (ASFV) is the ability to escape from host immune response, affecting macrophages and replicating in them. Besides, ASFV - specific antibodies do not completely neutralize the virus. Cytokines are important factors for various viral infection pathologies. The virulence of ASFV isolates may depend on the capacity to regulate cytokine expression by macrophages. Thus, when comparing in vitro and in vivo cytokine production by macrophages, it was established that infection with low virulent virus isolates leads to an immune response with a predominance of cytokines involved in cellular immunity, such as INF-α and IL-12p40, as compared with infection with highly virulent isolates. The aim of this paper was to study the effect of African swine fever virus on the production of IL-10, a pleiotropic cytokine that inhibits synthesis of cytokines and shows a strong antiinflammatory effect. For this, 12 piglets were experimentally infected intramuscularly with a continuous cell culture-adapted ASFV isolate Vero25 at a dose of 10 HAdU per animal followed by control infection of surviving animals with the reference virus isolate Arm 07 at a dose of 1,000 HAdU per animal. Temperature measurements were taken and blood sampling to obtain serum was conducted during the experiment. IL-10 amount in blood sera was determined using Invitrogen test systems (Thermo Fisher, USA). A higher IL-10 level (15.8–173 pg/ml) was observed in blood sera of dead animals infected with a moderately virulent virus, as compared with surviving pigs (4–5 pg/ml). No correlation between the speed of appearance of specific antibodies and IL-10 serum levels has been established. No noticeable effect of the IL-10 serum level prior to infection on the survival rate of animals has been observed. Further studies are needed to establish a causal relationship, including study of the expression of various cytokines during infection with both low- and highly virulent virus isolates.

scholarly journals Subunit Vaccine Approaches for African Swine Fever Virus

Vaccines ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 56 ◽  
Author(s):  
Natasha N. Gaudreault ◽  
Juergen A. Richt
Keyword(s):  
Western Europe ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Swine Industry ◽  
Fatal Disease ◽  
The Caucasus ◽  
Caucasus Region ◽  
Highly Virulent ◽  
Genotype Ii

African swine fever virus (ASFV) is the cause of a highly fatal disease in swine, for which there is no available vaccine. The disease is highly contagious and poses a serious threat to the swine industry worldwide. Since its introduction to the Caucasus region in 2007, a highly virulent, genotype II strain of ASFV has continued to circulate and spread into Eastern Europe and Russia, and most recently into Western Europe, China, and various countries of Southeast Asia. This review summarizes various ASFV vaccine strategies that have been investigated, with focus on antigen-, DNA-, and virus vector-based vaccines. Known ASFV antigens and the determinants of protection against ASFV versus immunopathological enhancement of infection and disease are also discussed.

scholarly journals Impaired T‐cell responses in domestic pigs and wild boar upon infection with a highly virulent African swine fever virus strain

2020 ◽  
Vol 67 (6) ◽  
pp. 3016-3032 ◽  
Author(s):  
Jane Hühr ◽  
Alexander Schäfer ◽  
Theresa Schwaiger ◽  
Laura Zani ◽  
Julia Sehl ◽  
...  
Keyword(s):  
T Cell ◽  
Wild Boar ◽  
Virus Strain ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
T Cell Responses ◽  
Fever Virus ◽  
Domestic Pigs ◽  
Cell Responses ◽  
Highly Virulent

Deletion of A137R gene from the pandemic strain of African swine fever virus is attenuated and offers protection against virulent pandemic virus

2021 ◽  
Author(s):  
Douglas P. Gladue ◽  
Elizabeth Ramirez-Medina ◽  
Elizabeth Vuono ◽  
Ediane Silva ◽  
Ayushi Rai ◽  
...  
Keyword(s):  
East Asia ◽  
Central Europe ◽  
Vaccine Candidate ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Economic Losses ◽  
Live Attenuated Vaccine ◽  
Attenuated Vaccine ◽  
Highly Virulent

African swine fever virus (ASFV) is causing a devastating pandemic in domestic and wild swine within an extended geographical area from Central Europe to East Asia resulting in economic losses for the regional swine industry. There are no commercial vaccines, therefore disease control relies on identification and culling of infected animals. We report here that the deletion of the ASFV gene A137R from the highly virulent ASFV-Georgia2010 (ASFV-G) isolate induces a significant attenuation of virus virulence in swine. A recombinant virus lacking the A137R gene, ASFV-G-ΔA137R, was developed to assess the role of this gene in ASFV virulence in domestic swine. Animals inoculated intramuscularly with 10 2 HAD 50 of ASFV-G-ΔA137R remained clinically healthy during the 28 day observational period. All animals inoculated with ASFV-G-ΔA137R had medium to high viremia titers and developed a strong virus-specific antibody response. Importantly, all ASFV-G-ΔA137R-inoculated animals were protected when challenged with the virulent parental strain ASFV-G. No evidence of replication of challenge virus was observed in the ASFV-G-ΔA137R-inoculated animals. Therefore, ASFV-G-ΔA137R is a novel potential live attenuated vaccine candidate and one of the few experimental vaccine strains reported to induce protection against the highly virulent ASFV Georgia virus that is the cause of the current Eurasian pandemic. Importance: No commercial vaccine is available to prevent African swine fever. The ASF pandemic caused by ASFV Georgia2007 (ASFV-G) is seriously affecting pork production in a contiguous area from Central Europe to East Asia. Here we report the rational development of a potential live attenuated vaccine strain by deleting a virus-specific gene, A137R, from the genome of ASFV-G. The resulting virus presented a completely attenuated phenotype and, importantly, animals infected with this genetically modified virus were protected from developing ASF after challenge with the virulent parental virus. ASFV-G-ΔA137R confers protection even at low doses (10 2 HAD 50 ) demonstrating its potential as a vaccine candidate. Therefore, ASFV-G-ΔA137R is a novel experimental ASF vaccine protecting pigs from the epidemiologically relevant ASFV Georgia isolate.

scholarly journals African Swine Fever Virus Georgia Isolate Harboring Deletions of MGF360 and MGF505 Genes Is Attenuated in Swine and Confers Protection against Challenge with Virulent Parental Virus

2015 ◽  
Vol 89 (11) ◽  
pp. 6048-6056 ◽  
Author(s):  
Vivian O'Donnell ◽  
Lauren G. Holinka ◽  
Douglas P. Gladue ◽  
Brenton Sanford ◽  
Peter W. Krug ◽  
...  
Keyword(s):  
Multigene Family ◽  
Recombinant Virus ◽  
African Swine Fever Virus ◽  
Genetically Modified ◽  
African Swine Fever ◽  
Fever Virus ◽  
Parental Virus ◽  
First Report ◽  
Highly Virulent

ABSTRACTAfrican swine fever virus (ASFV) is the etiological agent of a contagious and often lethal disease of domestic pigs that has significant economic consequences for the swine industry. The control of African swine fever (ASF) has been hampered by the unavailability of vaccines. Experimental vaccines have been developed using genetically modified live attenuated ASFVs where viral genes involved in virus virulence were removed from the genome. Multigene family 360 (MGF360) and MGF505 represent a group of genes sharing partial sequence and structural identities that have been connected with ASFV host range specificity, blocking of the host innate response, and virus virulence. Here we report the construction of a recombinant virus (ASFV-G-ΔMGF) derived from the highly virulent ASFV Georgia 2007 isolate (ASFV-G) by specifically deleting six genes belonging to MGF360 or MGF505: MGF505-1R, MGF360-12L, MGF360-13L, MGF360-14L, MGF505-2R, and MGF505-3R. ASFV-G-ΔMGF replicates as efficiently in primary swine macrophage cell cultures as the parental virus.In vivo, ASFV-G-ΔMGF is completely attenuated in swine, since pigs inoculated intramuscularly (i.m.) with either 102or 10450% hemadsorbing doses (HAD50) remained healthy, without signs of the disease. Importantly, when these animals were subsequently exposed to highly virulent parental ASFV-G, no signs of the disease were observed, although a proportion of these animals harbored the challenge virus. This is the first report demonstrating the role of MGF genes acting as independent determinants of ASFV virulence. Additionally, ASFV-G-ΔMGF is the first experimental vaccine reported to induce protection in pigs challenged with highly virulent and epidemiologically relevant ASFV-G.IMPORTANCEThe main problem for controlling ASF is the lack of vaccines. Studies focusing on understanding ASFV virulence led to the production of genetically modified recombinant viruses that, while attenuated, are able to confer protection in pigs challenged with homologous viruses. Here we have produced an attenuated recombinant ASFV derived from highly virulent ASFV strain Georgia (ASFV-G) lacking only six of the multigene family 360 (MGF360) and MGF505 genes (ASFV-G-ΔMGF). It is demonstrated, by first time, that deleting specific MGF genes alone can completely attenuate a highly virulent field ASFV isolate. Recombinant virus ASFV-G-ΔMGF effectively confers protection in pigs against challenge with ASFV-G when delivered once via the intramuscular (i.m.) route. The protection against ASFV-G is highly effective by 28 days postvaccination. This is the first report of an experimental vaccine that induces solid protection against virulent ASFV-G.

scholarly journals Genomic Analysis of Highly Virulent Georgia 2007/1 Isolate of African Swine Fever Virus

2011 ◽  
Vol 17 (4) ◽  
pp. 599-605 ◽  
Author(s):  
David A.G. Chapman ◽  
Alistair C. Darby ◽  
Melissa Da Silva ◽  
Chris Upton ◽  
Alan D. Radford ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Genomic Analysis ◽  
African Swine Fever ◽  
Fever Virus ◽  
Highly Virulent

scholarly journals An African Swine Fever Virus ERV1-ALRHomologue, 9GL, Affects Virion Maturation and Viral Growth in Macrophages and Viral Virulence in Swine

2000 ◽  
Vol 74 (3) ◽  
pp. 1275-1285 ◽  
Author(s):  
T. Lewis ◽  
L. Zsak ◽  
T. G. Burrage ◽  
Z. Lu ◽  
G. F. Kutish ◽  
...  
Keyword(s):  
Time Course ◽  
Gene Deletion ◽  
African Swine Fever Virus ◽  
Lethal Dose ◽  
Protein A ◽  
African Swine Fever ◽  
Fever Virus ◽  
Growth Defect ◽  
Synthesis Inhibitor ◽  
Viral Virulence

ABSTRACT The African swine fever virus (ASFV) genome contains a gene,9GL, with similarity to yeast ERV1 andALR genes. ERV1 has been shown to function in oxidative phosphorylation and in cell growth, while ALR has hepatotrophic activity. 9GL encodes a protein of 119 amino acids and was highly conserved at both nucleotide and amino acid levels among all ASFV field isolates examined. Monospecific rabbit polyclonal antibody produced to a glutathione S-transferase–9GL fusion protein specifically immunoprecipitated a 14-kDa protein from macrophage cell cultures infected with the ASFV isolate Malawi Lil-20/1 (MAL). Time course analysis and viral DNA synthesis inhibitor experiments indicated that p14 was a late viral protein. A9GL gene deletion mutant of MAL (Δ9GL), exhibited a growth defect in macrophages of approximately 2 log10 units and had a small-plaque phenotype compared to either a revertant (9GL-R) or the parental virus. 9GL affected normal virion maturation; virions containing acentric nucleoid structures comprised 90 to 99% of all virions observed in Δ9GL-infected macrophages. The Δ9GL virus was markedly attenuated in swine. In contrast to 9GL-R infection, where mortality was 100%, all Δ9GL-infected animals survived infection. With the exception of a transient fever response in some animals, Δ9GL-infected animals remained clinically normal and exhibited significant 100- to 10,000-fold reductions in viremia titers. All pigs previously infected with Δ9GL survived infection when subsequently challenged with a lethal dose of virulent parental MAL. Thus, ASFV9GL gene deletion mutants may prove useful as live-attenuated ASF vaccines.

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