Deletion of virulence associated genes from attenuated African swine fever virus isolate OUR T88/3 decreases its ability to protect against challenge with virulent virus

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.

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The African swine fever virus isolate Belgium 2018/1 shows high virulence in European wild boar

Transboundary and Emerging Diseases ◽

10.1111/tbed.13503 ◽

2020 ◽

Vol 67 (4) ◽

pp. 1654-1659 ◽

Cited By ~ 8

Author(s):

Jutta Pikalo ◽

Marie‐Eve Schoder ◽

Julia Sehl ◽

Angele Breithaupt ◽

Maryléne Tignon ◽

...

Keyword(s):

Wild Boar ◽

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

European Wild Boar ◽

High Virulence

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African Swine Fever Virus Isolate, Georgia, 2007

Emerging Infectious Diseases ◽

10.3201/eid1412.080591 ◽

2008 ◽

Vol 14 (12) ◽

pp. 1870-1874 ◽

Cited By ~ 195

Author(s):

Rebecca J. Rowlands ◽

Vincent Michaud ◽

Livio Heath ◽

Geoff Hutchings ◽

Chris Oura ◽

...

Keyword(s):

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus

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Deletion of the African Swine Fever Virus Gene DP148R Does Not Reduce Virus Replication in Culture but Reduces Virus Virulence in Pigs and Induces High Levels of Protection against Challenge

Journal of Virology ◽

10.1128/jvi.01428-17 ◽

2017 ◽

Vol 91 (24) ◽

Cited By ~ 31

Author(s):

Ana L. Reis ◽

Lynnette C. Goatley ◽

Tamara Jabbar ◽

Pedro J. Sanchez-Cordon ◽

Christopher L. Netherton ◽

...

Keyword(s):

Virus Replication ◽

Infectious Virus ◽

African Swine Fever Virus ◽

Clinical Signs ◽

African Swine Fever ◽

Virus Genome ◽

Fever Virus ◽

Virulent Virus ◽

Ifn Γ ◽

Reduce Virus Replication

ABSTRACT Many of the approximately 165 proteins encoded by the African swine fever virus (ASFV) genome do not have significant similarity to known proteins and have not been studied experimentally. One such protein is DP148R. We showed that the DP148R gene is transcribed at early times postinfection. Deletion of this gene did not reduce virus replication in macrophages, showing that it is not essential for replication in these cells. However, deletion of this gene from a virulent isolate, Benin 97/1, producing the BeninΔDP148R virus, dramatically reduced the virulence of the virus in vivo. All pigs infected with the BeninΔDP148R virus survived infection, showing only transient mild clinical signs soon after immunization. Following challenge with the parental virulent virus, all pigs immunized by the intramuscular route (11/11) and all except one immunized by the intranasal route (5/6) survived. Mild or no clinical signs were observed after challenge. As expected, control nonimmune pigs developed signs of acute African swine fever (ASF). The virus genome and infectious virus were observed soon after immunization, coincident with the onset of clinical signs (∼106 genome copies or 50% tissue culture infective doses/ml). The levels of the virus genome declined over an extended period up to 60 days postimmunization. In contrast, infectious virus was no longer detectable by days 30 to 35. Gamma interferon (IFN-γ) was detected in serum between days 4 and 7 postimmunization, and IFN-γ-producing cells were detected in all pigs analyzed following stimulation of immune lymphocytes with whole virus. ASFV-specific antibodies were first detected from day 10 postimmunization. IMPORTANCE African swine fever (ASF) is endemic in Africa, parts of the Trans Caucasus, the Russian Federation, and several European countries. The lack of a vaccine hinders control. Many of the ASF virus genes lack similarity to known genes and have not been characterized. We have shown that one of these, DP148R, is transcribed early during virus replication in cells and can be deleted from the virus genome without reducing virus replication. The virus with the gene deletion, BeninΔDP148R, caused mild clinical signs in pigs and induced high levels of protection against challenge with the parental virulent virus. Therefore, deletion of this gene can provide a target for the rational development of vaccines.

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Genetically edited pigs lacking CD163 show no resistance following infection with the African swine fever virus isolate, Georgia 2007/1

Virology ◽

10.1016/j.virol.2016.11.012 ◽

2017 ◽

Vol 501 ◽

pp. 102-106 ◽

Cited By ~ 28

Author(s):

Luca Popescu ◽

Natasha N. Gaudreault ◽

Kristen M. Whitworth ◽

Maria V. Murgia ◽

Jerome C. Nietfeld ◽

...

Keyword(s):

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus

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Blood Counts, Biochemical Parameters, Inflammatory, and Immune Responses in Pigs Infected Experimentally with the African Swine Fever Virus Isolate Pol18_28298_O111

Viruses ◽

10.3390/v13030521 ◽

2021 ◽

Vol 13 (3) ◽

pp. 521

Author(s):

Marek Walczak ◽

Magdalena Wasiak ◽

Katarzyna Dudek ◽

Anna Kycko ◽

Ewelina Szacawa ◽

...

Keyword(s):

Immune Responses ◽

Biochemical Parameters ◽

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Simultaneous Increase ◽

Reactive Protein ◽

Multiple Organs ◽

Different Doses

This study aimed to indicate the influence of infection caused by genotype II African swine fever virus (ASFV)–isolate Pol18_28298_O111, currently circulating in Poland, on blood counts, biochemical parameters, as well as inflammatory and immune responses. Blood and sera collected from 21 domestic pigs infected intranasally with different doses of virulent ASFV were analysed. The infection led to variable changes in blood counts depending on the stage of the disease with a tendency towards leukopenia and thrombocytopenia. The elevated C-reactive protein (CRP) concentrations and microscopic lesions in organs confirmed the development of the inflammation process, which also resulted in an increased level of biochemical markers such as: Aspartate transaminase (AST), creatine kinase (CK), creatinine, and urea. Antibodies could be detected from 9 to 18 days post infection (dpi). Two survivors presented the highest titer of antibodies (>5 log10/mL) with a simultaneous increase in the lymphocyte T (CD3+) percentage–revealed by flow cytometry. Results confirmed a progressive inflammatory process occurring during the ASFV infection, which may lead to multiple organs failure and death of the majority of affected animals.

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Different routes and doses influence protection in pigs immunised with the naturally attenuated African swine fever virus isolate OURT88/3

Antiviral Research ◽

10.1016/j.antiviral.2016.11.021 ◽

2017 ◽

Vol 138 ◽

pp. 1-8 ◽

Cited By ~ 29

Author(s):

Pedro J. Sánchez-Cordón ◽

Dave Chapman ◽

Tamara Jabbar ◽

Ana L. Reis ◽

Lynnette Goatley ◽

...

Keyword(s):

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus

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African Swine Fever Virus Georgia 2007 with a Deletion of Virulence-Associated Gene9GL(B119L), when Administered at Low Doses, Leads to Virus Attenuation in Swine and Induces an Effective Protection against Homologous Challenge

Journal of Virology ◽

10.1128/jvi.00969-15 ◽

2015 ◽

Vol 89 (16) ◽

pp. 8556-8566 ◽

Cited By ~ 55

Author(s):

Vivian O'Donnell ◽

Lauren G. Holinka ◽

Peter W. Krug ◽

Douglas P. Gladue ◽

Jolene Carlson ◽

...

Keyword(s):

African Swine Fever Virus ◽

Genetically Modified ◽

African Swine Fever ◽

Fever Virus ◽

The Caucasus ◽

Caucasus Region ◽

Homologous Virus ◽

Virulent Virus ◽

Virulent Phenotype ◽

Highly Virulent

ABSTRACTAfrican swine fever virus (ASFV) is the etiological agent of an often lethal disease of domestic pigs. Disease control strategies have been hampered by the unavailability of vaccines against ASFV. Since its introduction in the Republic of Georgia, a highly virulent virus, ASFV Georgia 2007 (ASFV-G), has caused an epizootic that spread rapidly into Eastern European countries. Currently no vaccines are available or under development to control ASFV-G. In the past, genetically modified ASFVs harboring deletions of virulence-associated genes have proven attenuated in swine, inducing protective immunity against challenge with homologous parental viruses. Deletion of the gene9GL(open reading frame [ORF] B119L) in highly virulent ASFV Malawi-Lil-20/1 produced an attenuated phenotype even when administered to pigs at 10650% hemadsorption doses (HAD50). Here we report the construction of a genetically modified ASFV-G strain (ASFV-G-Δ9GLv) harboring a deletion of the9GL(B119L) gene. Like Malawi-Lil-20/1-Δ9GL, ASFV-G-Δ9GL showed limited replication in primary swine macrophages. However, intramuscular inoculation of swine with 104HAD50of ASFV-G-Δ9GL produced a virulent phenotype that, unlike Malawi-Lil-20/1-Δ9GL, induced a lethal disease in swine like parental ASFV-G. Interestingly, lower doses (102to 103HAD50) of ASFV-G-Δ9GL did not induce a virulent phenotype in swine and when challenged protected pigs against disease. A dose of 102HAD50of ASFV-G-Δ9GLv conferred partial protection when pigs were challenged at either 21 or 28 days postinfection (dpi). An ASFV-G-Δ9GL HAD50of 103conferred partial and complete protection at 21 and 28 dpi, respectively. The information provided here adds to our recent report on the first attempts toward experimental vaccines against ASFV-G.IMPORTANCEThe main problem for controlling ASF is the lack of vaccines. Studies on ASFV virulence lead to the production of genetically modified attenuated viruses that induce protection in pigs but only against homologous virus challenges. Here we produced a recombinant ASFV lacking virulence-associated gene9GLin an attempt to produce a vaccine against virulent ASFV-G, a highly virulent virus isolate detected in the Caucasus region in 2007 and now spreading though the Caucasus region and Eastern Europe. Deletion of9GL, unlike with other ASFV isolates, did not attenuate completely ASFV-G. However, when delivered once at low dosages, recombinant ASFV-G-Δ9GL induces protection in swine against parental ASFV-G. The protection against ASFV-G is highly effective after 28 days postvaccination, whereas at 21 days postvaccination, animals survived the lethal challenge but showed signs of ASF. Here we report the design and development of an experimental vaccine that induces protection against virulent ASFV-G.

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