scholarly journals ASFV bearing an I226R gene-deletion elicits a robust immunity in pigs to African swine fever

2021 ◽  
Author(s):  
Yanyan Zhang ◽  
Junnan Ke ◽  
Jingyuan Zhang ◽  
Jinjin Yang ◽  
Huixian Yue ◽  
...  
Keyword(s):  
Vaccine Candidate ◽  
Clinical Symptoms ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Parental Virus ◽  
Economic Losses ◽  
Egfp Expression ◽  
Post Inoculation ◽  
Swine Industry

African swine fever (ASF) is a severe hemorrhagic infectious disease in pigs caused by the African swine fever virus (ASFV), leading to devastating economic losses in the epidemic regions. Its control currently depends on thorough culling and clearance of the diseased and the surrounding suspected pigs. ASF vaccine has been extensively explored for years worldwide, especially in hog-intensive areas where it is highly desired, but it is still unavailable due to numerous reasons. Herein, we reported another ASF vaccine candidate named SY18ΔI226R bearing a deletion of the I226R gene in replacement of an eGFP expression cassette at the right end of the viral genome. This deletion results in complete loss of virulence of SY18 as the gene-deleted strain does not cause any clinical symptoms in all pigs inoculated with either a dosage of 10 4.0 TCID 50 or 10 7.0 TCID 50 . An apparent viremia with the gradual decline was monitored, while the virus shedding was only occasionally detected in oral- or anal swabs. ASFV specific antibody appeared at 9 days post-inoculation. After intramuscular challenge with its parental strain ASFV SY18 on 21 days post inoculation, all the challenged pigs survived without obvious febrile or abnormal clinical signs. No viral DNA could be detected on the dissection of any tissue when viremia disappeared. These indicated that SY18ΔI226R is safe in swine and elicits a robust immunity to the virulent ASFV infection. IMPORTANCE: Outbreaks of African swine fever have resulted in devastating losses to the swine industry worldwide, but there is currently no commercial vaccine available. Although several vaccine candidates have been reported, none has been approved for use due to several reasons, especially the ones concerning bio-safety. Here, we identified a new undescribed functional gene, I226R. When deleted from the ASFV genome, the virus completely loses its virulence in the swine. Importantly, pigs infected with this gene-deleted virus were resistant to infection by an intramuscular challenge of 10 2.5 or 10 4.0 TCID 50 of its virulent parental virus. Furthermore, rarely the nucleic acid of the gene-deleted virus and its virulent parental virus was detected from oral- or anal swabs. Viruses could not be detected in any tissues after necropsy when viremia became negative, indicating that robust immunity was achieved. Therefore, SY18ΔI226R is a novel, ideal and efficacious vaccine candidate for genotype II ASF.

scholarly journals Dynamic Variations in Infrared Skin Temperature of Weaned Pigs Experimentally Inoculated with the African Swine Fever Virus: A Pilot Study

2021 ◽  
Vol 8 (10) ◽  
pp. 223
Author(s):  
Sang-Ik Oh ◽  
Hu Suk Lee ◽  
Vuong Nghia Bui ◽  
Duy Tung Dao ◽  
Ngoc Anh Bui ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Incubation Period ◽  
Clinical Symptoms ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Viral Disease ◽  
Pilot Scale ◽  
Post Inoculation ◽  
Contact Method ◽  
Swine Industry

African swine fever (ASF) is a devastating viral disease in pigs and is therefore economically important for the swine industry. ASF is characterized by a short incubation period and immediate death, making the early identification of ASF-infected pigs essential. This pilot-scale study evaluates whether the infrared thermography (IRT) technique can be used as a diagnostic tool to detect changes in skin temperature (Tsk) during the early stages of disease development in experimentally ASF-infected pigs. Clinical symptoms and rectal temperatures (Tcore) were recorded daily, and IRT readings during the experimental ASF infection were analyzed. All infected pigs died at 5–8 days post inoculation (dpi), and the incubation period was approximately 4 dpi. The average Tcore increased from 0 dpi (38.9 ± 0.3 °C) to 7 dpi (41.0 ± 0.5 °C) and decreased by 8 dpi (39.8 ± 0 °C). The maximum Tsk of ASF-infected pigs increased from 2 (35.0 °C) to 3 dpi (38.5 °C). The mean maximum Tsk observed from three regions on the skin (ear, inguinal, and neck) significantly increased from 2 to 3 dpi. This study presents a non-contact method for the early detection of ASF in infected pigs using thermal imaging at 3 days after ASF infection.

scholarly journals ASFV-G-∆I177L as an Effective Oral Nasal Vaccine against the Eurasia Strain of Africa Swine Fever

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 765
Author(s):  
Manuel V. Borca ◽  
Elizabeth Ramirez-Medina ◽  
Ediane Silva ◽  
Elizabeth Vuono ◽  
Ayushi Rai ◽  
...  
Keyword(s):  
Western Europe ◽  
Vaccine Candidate ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Similar Efficacy ◽  
Economic Losses ◽  
Swine Industry ◽  
Nasal Vaccine ◽  
Domestic Swine ◽  
Highly Virulent

The African swine fever virus (ASFV) is currently causing a pandemic affecting wild and domestic swine from Western Europe to Asia. No commercial vaccines are available to prevent African swine fever (ASF), resulting in overwhelming economic losses to the swine industry. We recently developed a recombinant vaccine candidate, ASFVG-ΔI177L, by deleting the I177L gene from the genome of the highly virulent ASFV strain Georgia (ASFV-G). ASFV-G-ΔI177L has been proven safe and highly efficacious in challenge studies using parental ASFV-G. Here, we present data demonstrating that ASFV-G-ΔI177L can be administered by the oronasal (ON) route to achieve a similar efficacy to that of intramuscular (IM) administration. Animals receiving ON ASFV-G-ΔI177L were completely protected against virulent ASFV-G challenge. As previously described, similar results were obtained when ASFV-G-ΔI177L was given intramuscularly. Interestingly, viremias induced in animals inoculated oronasally were lower than those measured in IM-inoculated animals. ASFV-specific antibody responses, mediated by IgG1, IgG2 and IgM, do not differ in animals inoculated by the ON route from that had IM inoculations. Therefore, the ASFV-G-ΔI177L vaccine candidate can be administered oronasally, a critical attribute for potential vaccination of wild swine populations.

scholarly journals Pathogenicity of an African swine fever virus strain isolated in Vietnam and alternative diagnostic specimens for early detection of viral infection

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hu Suk Lee ◽  
Vuong Nghia Bui ◽  
Duy Tung Dao ◽  
Ngoc Anh Bui ◽  
Thanh Duy Le ◽  
...  
Keyword(s):  
Early Detection ◽  
Oral Fluid ◽  
African Swine Fever Virus ◽  
Fluid Collection ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Post Inoculation ◽  
Tissue Samples ◽  
Viral Loads ◽  
Specimen Collection

Abstract Background African swine fever (ASF), caused by the ASF virus (ASFV), was first reported in Vietnam in 2019 and spread rapidly thereafter. Better insights into ASFV characteristics and early detection by surveillance could help control its spread. However, the pathogenicity and methods for early detection of ASFV isolates from Vietnam have not been established. Therefore, we investigated the pathogenicity of ASFV and explored alternative sampling methods for early detection. Results Ten pigs were intramuscularly inoculated with an ASFV strain from Vietnam (titer, 103.5 HAD50/mL), and their temperature, clinical signs, and virus excretion patterns were recorded. In addition, herd and environmental samples were collected daily. The pigs died 5–8 days-post-inoculation (dpi), and the incubation period was 3.7 ± 0.5 dpi. ASFV genome was first detected in the blood (2.2 ± 0.8) and then in rectal (3.1 ± 0.7), nasal (3.2 ± 0.4), and oral (3.6 ± 0.7 dpi) swab samples. ASFV was detected in oral fluid samples collected using a chewed rope from 3 dpi. The liver showed the highest viral loads, and ear tissue also exhibited high viral loads among 11 tissues obtained from dead pigs. Overall, ASFV from Vietnam was classified as peracute to acute form. The rope-based oral fluid collection method could be useful for early ASFV detection and allows successful ASF surveillance in large pig farms. Furthermore, ear tissue samples might be a simple alternative specimen for diagnosing ASF infection in dead pigs. Conclusions Our data provide valuable insights into the characteristics of a typical ASFV strain isolated in Vietnam and suggest an alternative, non-invasive specimen collection strategy for early detection.

scholarly journals Deletion of the L7L-L11L Genes Attenuates ASFV and Induces Protection against Homologous Challenge

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 255
Author(s):  
Jingyuan Zhang ◽  
Yanyan Zhang ◽  
Teng Chen ◽  
Jinjin Yang ◽  
Huixian Yue ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Biological Properties ◽  
High Dose ◽  
Swine Industry ◽  
Epidemic Disease ◽  
Intramuscular Inoculation ◽  
Homologous Challenge

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a major epidemic disease endangering the swine industry. Although a number of vaccine candidates have been reported, none are commercially available yet. To explore the effect of unknown genes on the biological characteristics of ASFV and the possibility of a gene-deleted isolate as a vaccine candidate, the strain SY18ΔL7-11, with deletions of L7L–L11L genes from ASFV SY18, was constructed, and its biological properties were analyzed. The results show that deletion of genes L7L-L11L did not affect replication of the virus in vitro. Virulence of SY18△L7-11 was significantly reduced, as 11 of the 12 pigs survived for 28 days after intramuscular inoculation with a low dose (103 TCID50) or a high dose (106 TCID50) of SY18ΔL7-11. All 11 surviving pigs were completely protected against challenge with the parental ASFV SY18 on 28 days postinoculation (dpi). Transient fever and/or irregularly low levels of genomic DNA in the blood were monitored in some pigs after inoculation. No ASF clinical signs or viremia were monitored after challenge. Antibodies to ASFV were induced in all pigs from 14 to 21 days postinoculation. IFN-γ was detected in most of the inoculated pigs, which is usually inhibited in ASFV-infected pigs. Overall, the results demonstrate that SY18ΔL7-11 is a candidate for further constructing safer vaccine(s), with better joint deletions of other gene(s) related to virulence.

scholarly journals Risk of African swine fever virus introduction into the United States through smuggling of pork in air passenger luggage

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Cristina Jurado ◽  
Lina Mur ◽  
María Sol Pérez Aguirreburualde ◽  
Estefanía Cadenas-Fernández ◽  
Beatriz Martínez-López ◽  
...  
Keyword(s):  
Western Europe ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
The United States ◽  
Economic Losses ◽  
Swine Industry ◽  
Virus Surveillance ◽  
Global Epidemiology ◽  
The Us ◽  
Mean Risk

Abstract African swine fever causes substantial economic losses in the swine industry in affected countries. Traditionally confined to Africa with only occasional incursions into other regions, ASF began spreading into Caucasian countries and Eastern Europe in 2007, followed by Western Europe and Asia in 2018. Such a dramatic change in the global epidemiology of ASF has resulted in concerns that the disease may continue to spread into disease-free regions such as the US. In this study, we estimated the risk of introduction of ASF virus into the US through smuggling of pork in air passenger luggage. Results suggest that the mean risk of ASFV introduction into the US via this route has increased by 183.33% from the risk estimated before the disease had spread into Western Europe or Asia. Most of the risk (67.68%) was associated with flights originating from China and Hong Kong, followed by the Russian Federation (26.92%). Five US airports accounted for >90% of the risk. Results here will help to inform decisions related to the design of ASF virus surveillance strategies in the US.

scholarly journals Genetic characterisation of African swine fever virus from 2017 outbreaks in Zambia: Identification of p72 genotype II variants in domestic pigs

2018 ◽  
Vol 85 (1) ◽  
Author(s):  
Edgar Simulundu ◽  
Yona Sinkala ◽  
Herman M. Chambaro ◽  
Andrew Chinyemba ◽  
Frank Banda ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Variable Region ◽  
Economic Losses ◽  
African Region ◽  
Swine Industry ◽  
African Countries ◽  
Central Variable Region ◽  
Close Relationship ◽  
Haemorrhagic Disease

African swine fever (ASF) is a contagious haemorrhagic disease associated with causing heavy economic losses to the swine industry in many African countries. In 2017, Zambia experienced ASF outbreaks in Mbala District (Northern province) and for the first time in Isoka and Chinsali districts (Muchinga province). Meanwhile, another outbreak was observed in Chipata District (Eastern province). Genetic analysis of part of the B646L gene, E183L gene, CP204L gene and the central variable region of the B602L gene of ASF virus (ASFV) associated with the outbreaks in Mbala and Chipata districts was conducted. The results revealed that the ASFV detected in Mbala District was highly similar to that of the Georgia 2007/1 isolate across all the genome regions analysed. In contrast, while showing close relationship with the Georgia 2007/1 virus in the B646L gene, the ASFV detected in Chipata District showed remarkable genetic variation in the rest of the genes analysed. These results suggest that the Georgia 2007/1-like virus could be more diverse than what was previously thought, underscoring the need of continued surveillance and monitoring of ASFVs within the south-eastern African region to better understand their epidemiology and the relationships between outbreaks and their possible origin.

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 Development of a Blocking Enzyme-Linked Immunosorbent Assay for Detection of Antibodies against African Swine Fever Virus

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 760
Author(s):  
Fangfeng Yuan ◽  
Vlad Petrovan ◽  
Luis Gabriel Gimenez-Lirola ◽  
Jeffrey J. Zimmerman ◽  
Raymond R. R. Rowland ◽  
...  
Keyword(s):  
Time Course ◽  
Serological Test ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Internal Quality ◽  
Enzyme Linked Immunosorbent Assay ◽  
Post Inoculation ◽  
Swine Industry ◽  
Control Serum

The incursion of African swine fever virus (ASFV) into Eurasia presents a threat to the world’s swine industry. Highly sensitive and specific diagnostic assays are urgently needed for rapid detection during an outbreak, post-outbreak investigation, and disease surveillance. In this study, a highly specific and repeatable blocking ELISA (bELISA) was developed using a recombinant p30 protein as the antigen combined with biotinylated mAb against p30 as the detection antibody. Initial test validation included sera from 810 uninfected animals and 106 animals experimentally inoculated with ASFV or recombinant alphavirus/adenovirus expressing p30. Receiver operating characteristic (ROC) analysis of the data calculated an optimal percentage of inhibition (PI) cutoff value of 45.92%, giving a diagnostic sensitivity of 98.11% and diagnostic specificity of 99.42%. The coefficient of variation of an internal quality control serum was 6.81% for between runs, 6.71% for within run, and 6.14% for within plate. A time course study of infected pigs showed that bELISA was able to detect seroconversion as early as 7 days post-inoculation. Taken together, these results demonstrate that bELISA can be used as an alternative serological test for detecting ASFV infection.

scholarly journals Short and Long-read Sequencing Survey of the Dynamic Transcriptomes of African Swine Fever Virus and its Host

2020 ◽  
Author(s):  
Ferenc Olasz ◽  
Dóra Tombácz ◽  
Gábor Torma ◽  
Zsolt Csabai ◽  
Norbert Moldován ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Economic Losses ◽  
Swine Industry ◽  
Rna Molecules ◽  
Oxford Nanopore ◽  
Combined Use ◽  
Long Read ◽  
Low Coverage

AbstractAfrican swine fever virus (ASFV) is an important animal pathogen causing substantial economic losses in the swine industry globally. At present, little is known about the molecular biology of ASFV, including its transcriptome organization. In this study, we applied cutting-edge sequencing approaches, namely the Illumina short-read sequencing (SRS) and the Oxford Nanopore Technologies long-read sequencing (LRS) techniques, together with several library preparation chemistries to analyze the ASFV dynamic transcriptome. SRS can generate a large amount of high-precision sequencing reads, but it is inefficient for identifying long RNA molecules, transcript isoforms and overlapping transcripts. LRS can overcome these limitations, but this approach also has shortcomings, such as its high error rate and the low coverage. Amplification-based LRS techniques produce relatively high read counts but also high levels of spurious transcripts, whereas the non-amplified cDNA and direct RNA sequencing techniques are more precise but achieve lower throughput. The drawbacks of the various technologies can be circumvented by the combined use of these approaches.

scholarly journals The C962R ORF of African Swine Fever Strain Georgia Is Non-Essential and Not Required for Virulence in Swine

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 676 ◽  
Author(s):  
Elizabeth. Ramirez-Medina ◽  
Elizabeth. A. Vuono ◽  
Ayushi. Rai ◽  
Sarah. Pruitt ◽  
Ediane. Silva ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Field Isolate ◽  
Protein A ◽  
African Swine Fever ◽  
Virus Genome ◽  
Economic Losses ◽  
Virus Protein ◽  
Swine Industry ◽  
Reading Frame

African swine fever virus (ASFV) is the causative agent of the African swine fever (ASF) epizootic currently affecting pigs throughout Eurasia, causing significant economic losses in the swine industry. The virus genome encodes for more than 160 genes, of which only a few have been studied in detail. Here we describe the previously uncharacterized ASFV open reading frame (ORF) C962R, a gene encoding for a putative NTPase. RNA transcription studies using infected swine macrophages demonstrate that the C962R gene is translated as a late virus protein. A recombinant ASFV lacking the C962R gene (ASFV-G-ΔC962R) demonstrates in vivo that the C962R gene is non-essential, since ASFV-G-ΔC962R has similar replication kinetics in primary swine macrophage cell cultures when compared to parental highly virulent field isolate Georgia2007 (ASFV-G). Experimental infection of domestic pigs with ASFV-G-ΔC962R produced a clinical disease similar to that caused by the parental ASFV-G, confirming that deletion of the C962R gene from the ASFV genome does not impact virulence.

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