Viruses

Research

17 pages, 2470 KiB

Open AccessArticle

Complete Genome Sequencing and Comparative Phylogenomics of Nine African Swine Fever Virus (ASFV) Isolates of the Virulent East African p72 Genotype IX without Viral Sequence Enrichment

by Jean-Baka Domelevo Entfellner, Edward Abworo Okoth, Cynthia Kavulani Onzere, Chris Upton, Emma Peter Njau, Dirk Höper, Sonal P. Henson, Samuel O. Oyola, Edwina Bochere, Eunice M. Machuka and Richard P. Bishop

Viruses 2024, 16(9), 1466; https://doi.org/10.3390/v16091466 - 14 Sep 2024

Abstract

African swine fever virus (ASFV) is endemic to African wild pigs (Phacochoerus and Potamochoerus), in which viral infection is asymptomatic, and Ornithodoros soft ticks. However, ASFV causes a lethal disease in Eurasian domestic pigs (Sus scrofa). While Sub-Saharan Africa [...] Read more.

African swine fever virus (ASFV) is endemic to African wild pigs (Phacochoerus and Potamochoerus), in which viral infection is asymptomatic, and Ornithodoros soft ticks. However, ASFV causes a lethal disease in Eurasian domestic pigs (Sus scrofa). While Sub-Saharan Africa is believed to be the original home of ASFV, publicly available whole-genome ASFV sequences show a strong bias towards p72 Genotypes I and II, which are responsible for domestic pig pandemics outside Africa. To reduce this bias, we hereby describe nine novel East African complete genomes in p72 Genotype IX and present the phylogenetic analysis of all 16 available Genotype IX genomes compared with other ASFV p72 clades. We also document genome-level differences between one specific novel Genotype IX genome sequence (KE/2013/Busia.3) and a wild boar cell-passaged derivative. The Genotype IX genomes clustered with the five available Genotype X genomes. By contrast, Genotype IX and X genomes were strongly phylogenetically differentiated from all other ASFV genomes. The p72 gene region, on which the p72-based virus detection primers are derived, contains consistent SNPs in Genotype IX, potentially resulting in reduced sensitivity of detection. In addition to the abovementioned cell-adapted variant, eight novel ASFV Genotype IX genomes were determined: five from viruses passaged once in primary porcine peripheral blood monocytes and three generated from DNA isolated directly from field-sampled kidney tissues. Based on this methodological simplification, genome sequencing of ASFV field isolates should become increasingly routine and result in a rapid expansion of knowledge pertaining to the diversity of African ASFV at the whole-genome level. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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13 pages, 4065 KiB

Open AccessArticle

Multiplex PCR Approach for Rapid African Swine Fever Virus Genotyping

by Matthias Licheri, Manon Flore Licheri, Kemal Mehinagic, Emilia Radulovic, Nicolas Ruggli and Ronald Dijkman

Viruses 2024, 16(9), 1460; https://doi.org/10.3390/v16091460 - 13 Sep 2024

Abstract

African swine fever virus (ASFV) has been spreading through Europe, Asia, and the Caribbean after its introduction in Georgia in 2007 and, due to its particularly high mortality rate, poses a continuous threat to the pig industry. The golden standard to trace back [...] Read more.

African swine fever virus (ASFV) has been spreading through Europe, Asia, and the Caribbean after its introduction in Georgia in 2007 and, due to its particularly high mortality rate, poses a continuous threat to the pig industry. The golden standard to trace back the ASFV is whole genome sequencing, but it is a cost and time-intensive methodology. A more efficient way of tracing the virus is to amplify only specific genomic regions relevant for genotyping. This is mainly accomplished by amplifying single amplicons by PCR followed by Sanger sequencing. To reduce costs and processivity time, we evaluated a multiplex PCR based on the four primer sets routinely used for ASFV genotyping (B646L, E183L, B602L, and intergenic I73R-I329L), which was followed by Nanopore ligation-based amplicon sequencing. We show that with this protocol, we can genotype ASFV DNA originating from different biological matrices and correctly classify multiple genotypes and strains using a single PCR reaction. Further optimization of this method can be accomplished by adding or swapping the primer sets used for amplification based on the needs of a specific country or region, making it a versatile tool that can speed up the processing time and lower the costs of genotyping during ASFV outbreaks. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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18 pages, 2533 KiB

Open AccessArticle

A Non-Hemadsorbing Live-Attenuated Virus Vaccine Candidate Protects Pigs against the Contemporary Pandemic Genotype II African Swine Fever Virus

by Quang Lam Truong, Lihua Wang, Tuan Anh Nguyen, Hoa Thi Nguyen, Anh Dao Le, Giap Van Nguyen, Anh Thi Vu, Phuong Thi Hoang, Trang Thi Le, Huyen Thi Nguyen, Hang Thu Thi Nguyen, Huong Lan Thi Lai, Dao Anh Tran Bui, Le My Thi Huynh, Rachel Madera, Yuzhen Li, Jamie Retallick, Franco Matias-Ferreyra, Lan Thi Nguyen and Jishu Shi

Viruses 2024, 16(8), 1326; https://doi.org/10.3390/v16081326 - 19 Aug 2024

Viewed by 872

Abstract

African swine fever (ASF) is a highly contagious and severe hemorrhagic transboundary swine viral disease with up to a 100% mortality rate, which leads to a tremendous socio-economic loss worldwide. The lack of safe and efficacious ASF vaccines is the greatest challenge in [...] Read more.

African swine fever (ASF) is a highly contagious and severe hemorrhagic transboundary swine viral disease with up to a 100% mortality rate, which leads to a tremendous socio-economic loss worldwide. The lack of safe and efficacious ASF vaccines is the greatest challenge in the prevention and control of ASF. In this study, we generated a safe and effective live-attenuated virus (LAV) vaccine candidate VNUA-ASFV-LAVL3 by serially passaging a virulent genotype II strain (VNUA-ASFV-L2) in an immortalized porcine alveolar macrophage cell line (3D4/21, 50 passages). VNUA-ASFV-LAVL3 lost its hemadsorption ability but maintained comparable growth kinetics in 3D4/21 cells to that of the parental strain. Notably, it exhibited significant attenuation of virulence in pigs across different doses (10³, 10⁴, and 10⁵ TCID₅₀). All vaccinated pigs remained healthy with no clinical signs of African swine fever virus (ASFV) infection throughout the 28-day observation period of immunization. VNUA-ASFV-LAVL3 was efficiently cleared from the blood at 14–17 days post-infection, even at the highest dose (10⁵ TCID₅₀). Importantly, the attenuation observed in vivo did not compromise the ability of VNUA-ASFV-LAVL3 to induce protective immunity. Vaccination with VNUA-ASFV-LAVL3 elicited robust humoral and cellular immune responses in pigs, achieving 100% protection against a lethal wild-type ASFV (genotype II) challenge at all tested doses (10³, 10⁴, and 10⁵ TCID₅₀). Furthermore, a single vaccination (10⁴ TCID₅₀) provided protection for up to 2 months. These findings suggest that VNUA-ASFV-LAVL3 can be utilized as a promising safe and efficacious LAV candidate against the contemporary pandemic genotype II ASFV. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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10 pages, 513 KiB

Open AccessArticle

Spleen Swabs for Sensitive and High-Throughput Detection of African Swine Fever Virus by Real-Time PCR

by Christopher Cafariello, Kalhari Goonewardene, Chungwon J. Chung and Aruna Ambagala

Viruses 2024, 16(8), 1316; https://doi.org/10.3390/v16081316 - 18 Aug 2024

Viewed by 443

Abstract

African swine fever (ASF) continues to spread in Africa, Europe, Asia and the island of Hispaniola, increasing the need to develop more streamlined and highly efficient surveillance and diagnostic capabilities. One way to achieve this is by further optimization of already established standard [...] Read more.

African swine fever (ASF) continues to spread in Africa, Europe, Asia and the island of Hispaniola, increasing the need to develop more streamlined and highly efficient surveillance and diagnostic capabilities. One way to achieve this is by further optimization of already established standard operating procedures to remove bottlenecks for high-throughput screening. Real-time polymerase chain reaction (real-time PCR) is the most sensitive and specific assay available for the early detection of the ASF virus (ASFV) genome, but it requires high-quality nucleic acid extracted from the samples. Whole blood from live pigs and spleen tissue from dead pigs are the preferred samples for real-time PCR. Whole blood can be used as is in nucleic acid extractions, but spleen tissues require an additional homogenization step. In this study, we compared the homogenates and swabs prepared from 52 spleen samples collected from pigs experimentally inoculated with highly and moderately virulent ASF virus strains. The results show that not only are the spleen swabs more sensitive when executed with a low-cell-count nucleic acid extraction procedure followed by real-time PCR assays but they also increase the ability to isolate ASFV from positive spleen samples. Swabbing is a convenient, simpler and less time-consuming alternative to tissue homogenization. Hence, we recommend spleen swabs over tissue homogenates for high-throughput detection of ASFV by real-time PCR. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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10 pages, 3158 KiB

Open AccessArticle

The MGF300-2R Protein of African Swine Fever Virus Promotes IKKβ Ubiquitination by Recruiting the E3 Ubiquitin Ligase TRIM21

by Zhanhao Lu, Rui Luo, Jing Lan, Shengmei Chen, Hua-Ji Qiu, Tao Wang and Yuan Sun

Viruses 2024, 16(6), 949; https://doi.org/10.3390/v16060949 - 12 Jun 2024

Cited by 2 | Viewed by 885

Abstract

African swine fever (ASF) is an acute, hemorrhagic, highly contagious disease in pigs caused by African swine fever virus (ASFV). Our previous study identified that the ASFV MGF300-2R protein functions as a virulence factor and found that MGF300-2R degrades IKKβ via selective [...] Read more.

African swine fever (ASF) is an acute, hemorrhagic, highly contagious disease in pigs caused by African swine fever virus (ASFV). Our previous study identified that the ASFV MGF300-2R protein functions as a virulence factor and found that MGF300-2R degrades IKKβ via selective autophagy. However, the E3 ubiquitin ligase responsible for IKKβ ubiquitination during autophagic degradation still remains unknown. In order to solve this problem, we first pulled down 328 proteins interacting with MGF300-2R through immunoprecipitation-mass spectrometry. Next, we analyzed and confirmed the interaction between the E3 ubiquitin ligase TRIM21 and MGF300-2R and demonstrated the catalytic role of TRIM21 in IKKβ ubiquitination. Finally, we indicated that the degradation of IKKβ by MGF300-2R was dependent on TRIM21. In summary, our results indicate TRIM21 is the E3 ubiquitin ligase involved in the degradation of IKKβ by MGF300-2R, thereby augmenting our understanding of the functions of MGF300-2R and offering insights into the rational design of live attenuated vaccines and antiviral strategies against ASF. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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12 pages, 1547 KiB

Open AccessArticle

Disease Course of Korean African Swine Fever Virus in Domestic Pigs Exposed Intraorally, Intranasally, Intramuscularly, and by Direct Contact with Infected Pigs

by Ki-Hyun Cho, Seong-Keun Hong, Da-Young Kim, Hyun-Joo Sohn, Dae-Sung Yoo, Hae-Eun Kang and Yeon-Hee Kim

Viruses 2024, 16(3), 433; https://doi.org/10.3390/v16030433 - 11 Mar 2024

Viewed by 1163

Abstract

African swine fever (ASF) is a fatal contagious disease affecting swine. The first Korean ASF virus (ASFV) isolate (Korea/Pig/Paju1/2019) was used to compare the disease course of ASFV in pigs inoculated via the four routes. In the challenge experiment, domestic pigs were infected [...] Read more.

African swine fever (ASF) is a fatal contagious disease affecting swine. The first Korean ASF virus (ASFV) isolate (Korea/Pig/Paju1/2019) was used to compare the disease course of ASFV in pigs inoculated via the four routes. In the challenge experiment, domestic pigs were infected via the intraoral (IO) and intranasal (IN) routes with a 10⁶ 50% hemadsorbing dose (HAD₅₀) and an intramuscular (IM) injection of 10³ HAD₅₀. In the direct contact (DC) group, five naïve pigs were brought into direct contact with two IM-ASFV-infected pigs. IO-, IN-, and IM-inoculated pigs showed similar disease courses, whereas DC pigs had comparable ASF syndrome after a 7-day latent period. The disease course in the DC route, one of the most common routes of infection, was not significantly different from that in the IO and IN routes. IM and DC groups differed in terms of the severity of fever and hemorrhagic lesions in the lymph nodes and spleen, indicating that the IM route, suitable for early vaccine development trials, is not appropriate for studying the ASFV infection mechanism, including early stage of infection, and IO and IN challenges with a designated dose can be alternatives in trials for assessing ASFV pathogenicity and vaccine efficacy investigations. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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22 pages, 10731 KiB

Open AccessArticle

Identification of a Potential Entry-Fusion Complex Based on Sequence Homology of African Swine Fever and Vaccinia Virus

by Jesús Urquiza, Miguel Ángel Cuesta-Geijo, Isabel García-Dorival, Óscar Fernández, Ana del Puerto, José Fernando Díaz and Covadonga Alonso

Viruses 2024, 16(3), 349; https://doi.org/10.3390/v16030349 - 23 Feb 2024

Cited by 2 | Viewed by 1555

Abstract

African swine fever virus (ASFV) belongs to the family of Asfarviridae, part of the group of nucleocytoplasmic large DNA viruses (NCLDV). Little is known about the internalization of ASFV in the host cell and the fusion membrane events that take place at [...] Read more.

African swine fever virus (ASFV) belongs to the family of Asfarviridae, part of the group of nucleocytoplasmic large DNA viruses (NCLDV). Little is known about the internalization of ASFV in the host cell and the fusion membrane events that take place at early stages of the infection. Poxviruses, also members of the NCLDV and represented by vaccinia virus (VACV), are large, enveloped, double-stranded DNA viruses. Poxviruses were considered unique in having an elaborate entry-fusion complex (EFC) composed of 11 highly conserved proteins integrated into the membrane of mature virions. Recent advances in methodological techniques have again revealed several connections between VACV EFC proteins. In this study, we explored the possibility of an analogous ASFV EFC by identifying ten candidate proteins exhibiting structural similarities with VACV EFC proteins. This could reveal key functions of these ASFV proteins, drawing attention to shared features between the two virus families, suggesting the potential existence of an ASFV entry-fusion complex. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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15 pages, 1893 KiB

Open AccessArticle

Generation of High-Quality African Swine Fever Virus Complete Genome from Field Samples by Next-Generation Sequencing

by Chuan Shi, Qinghua Wang, Yutian Liu, Shujuan Wang, Yongqiang Zhang, Chunju Liu, Yongxin Hu, Dongxia Zheng, Chengyou Sun, Fangfang Song, Xiaojing Yu, Yunling Zhao, Jingyue Bao and Zhiliang Wang

Viruses 2024, 16(2), 312; https://doi.org/10.3390/v16020312 - 18 Feb 2024

Cited by 1 | Viewed by 1463

Abstract

African swine fever (ASF) is a lethal contagious viral disease of domestic pigs and wild boars caused by the African swine fever virus (ASFV). The pandemic spread of ASF has caused severe effects on the global pig industry. Whole-genome sequencing provides crucial information [...] Read more.

African swine fever (ASF) is a lethal contagious viral disease of domestic pigs and wild boars caused by the African swine fever virus (ASFV). The pandemic spread of ASF has caused severe effects on the global pig industry. Whole-genome sequencing provides crucial information for virus strain characterization, epidemiology analysis and vaccine development. Here, we evaluated the performance of next-generation sequencing (NGS) in generating ASFV genome sequences from clinical samples. Thirty-four ASFV-positive field samples including spleen, lymph node, lung, liver and blood with a range of Ct values from 14.73 to 25.95 were sequenced. For different tissue samples collected from the same sick pigs, the proportion of ASFV reads obtained from the spleen samples was 3.69–9.86 times higher than other tissues. For the high-viral-load spleen samples (Ct < 20), a minimum of a 99.8% breadth of ≥10× coverage was revealed for all the samples. For the spleen samples with Ct ≥ 20, 6/12 samples had a minimum of a 99.8% breadth of ≥10× coverage. A high average depth of sequencing coverage was also achieved from the blood samples. According to our results, high-quality ASFV whole-genome sequences could be obtained from the spleen or blood samples with Ct < 20. The high-quality ASFV genome sequence generated in this study was further used for the high-resolution phylogenetic analysis of the ASFV genomes in the early stage of the ASF epidemic in China. Our study demonstrates that NGS may act as a useful tool for efficient ASFV genome characterization, providing valuable information for disease control. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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10 pages, 782 KiB

Open AccessArticle

Stability of Genotube^® Swabs for African Swine Fever Virus Detection Using Loop-Mediated Isothermal (LAMP) Laboratory Testing on Samples Stored without Refrigeration

by Dianne Phillips, Felisiano da Conceicao, Joanita Bendita da Costa Jong, Grant Rawlin and Peter Mee

Viruses 2024, 16(2), 263; https://doi.org/10.3390/v16020263 - 7 Feb 2024

Viewed by 1101

Abstract

African swine fever (ASF) is a transboundary viral disease which causes high mortality in pigs. In many low- and middle-income countries and in remote areas where diagnostic surveillance for ASF virus (ASFV) is undertaken, access to trained animal health technicians, sample collection, cold [...] Read more.

African swine fever (ASF) is a transboundary viral disease which causes high mortality in pigs. In many low- and middle-income countries and in remote areas where diagnostic surveillance for ASF virus (ASFV) is undertaken, access to trained animal health technicians, sample collection, cold chain storage and transport of samples to suitably equipped laboratories can be limiting when traditional sampling and laboratory tests are used. Previously published studies have demonstrated that alternative sampling matrices such as swabs and filter papers can be tested using PCR without refrigeration for up to a week. This study used Genotube^® swabs stored in temperate and tropical climates without refrigeration for four weeks after collection to demonstrate there was no change in test performance and results using loop-mediated isothermal amplification (LAMP) ASFV detection on a series of pig serum samples including serum spiked with a synthetic ASFV positive control, naturally acquired ASFV positive serum from Timor-Leste and negative ASFV serum samples. The use of Genotube^® swabs for ASFV detection for surveillance purposes, coupled with testing platforms such as LAMP, can provide an alternative to traditional testing methodology where resources are limited and time from collection to testing of samples is prolonged. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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12 pages, 1482 KiB

Open AccessArticle

Optimizing Vaccination Strategies against African Swine Fever Using Spatial Data from Wild Boars in Lithuania

by Vincenzo Gervasi, Marius Masiulis, Paulius Bušauskas, Silvia Bellini and Vittorio Guberti

Viruses 2024, 16(1), 153; https://doi.org/10.3390/v16010153 - 19 Jan 2024

Cited by 1 | Viewed by 1257

Abstract

African swine fever (ASF) is one of the most severe suid diseases, impacting the pig industry and wild suid populations. Once an ASF vaccine is available, identifying a sufficient density of vaccination fields will be crucial to achieve eradication success. In 2020–2023, we [...] Read more.

African swine fever (ASF) is one of the most severe suid diseases, impacting the pig industry and wild suid populations. Once an ASF vaccine is available, identifying a sufficient density of vaccination fields will be crucial to achieve eradication success. In 2020–2023, we live-trapped and monitored 27 wild boars in different areas of Lithuania, in which the wild boars were fed at artificial stations. We built a simulation study to estimate the probability of a successful ASF vaccination as a function of different eco-epidemiological factors. The average 32-day home range size across all individuals was 16.2 km² (SD = 16.9). The wild boars made frequent visits of short durations to the feeding sites rather than long visits interposed by long periods of absence. A feeding site density of 0.5/km² corresponded to an expected vaccination rate of only 20%. The vaccination probability increased to about 75% when the feeding site density was 1.0/km². Our results suggest that at least one vaccination field/km² should be used when planning an ASF vaccination campaign to ensure that everyone in the population has at least 5–10 vaccination sites available inside the home range. Similar studies should be conducted in the other ecological contexts in which ASF is present today or will be present in the future, with the objective being to estimate a context-specific relationship between wild boar movement patterns and an optimal vaccination strategy. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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14 pages, 2180 KiB

Open AccessArticle

The Long-Jumping of African Swine Fever: First Genotype II Notified in Sardinia, Italy

by Silvia Dei Giudici, Federica Loi, Sonia Ghisu, Pier Paolo Angioi, Susanna Zinellu, Mariangela Stefania Fiori, Francesca Carusillo, Diego Brundu, Giulia Franzoni, Giovanni Maria Zidda, Paolo Tolu, Ennio Bandino, Stefano Cappai and Annalisa Oggiano

Viruses 2024, 16(1), 32; https://doi.org/10.3390/v16010032 - 23 Dec 2023

Cited by 7 | Viewed by 1490

Abstract

African swine fever (ASF) is a devastating infectious disease of domestic pigs and wild boar that is spreading quickly around the world and causing huge economic losses. Although the development of effective vaccines is currently being attempted by several labs, the absence of [...] Read more.

African swine fever (ASF) is a devastating infectious disease of domestic pigs and wild boar that is spreading quickly around the world and causing huge economic losses. Although the development of effective vaccines is currently being attempted by several labs, the absence of globally recognized licensed vaccines makes disease prevention and early detection even more crucial. ASF has spread across many countries in Europe and about two years ago affected the Italian susceptible population. In Italy, the first case of ASF genotype II in wild boar dates back to January 2022, while the first outbreak in a domestic pig farm was notified in August 2023. Currently, four clusters of infection are still ongoing in northern (Piedmont-Liguria and Lombardy), central (Lazio), and southern Italy (Calabria and Campania). In early September 2023, the first case of ASFV genotype II was detected in a domestic pig farm in Sardinia, historically affected by genotype I and in the final stage of eradication. Genomic characterization of p72, p54, and I73R/I329L genome regions revealed 100% similarity to those obtained from isolates that have been circulating in mainland Italy since January 2022 and also with international strains. The outbreak was detected and confirmed due to the passive surveillance plan on domestic pig farms put in place to provide evidence on genotype I’s absence. Epidemiological investigations suggest 24 August as the most probable time of ASFV genotype II’s arrival in Sardinia, likely due to human activities. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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14 pages, 3853 KiB

Open AccessArticle

Evaluation of the Deletion of the African Swine Fever Virus Gene O174L from the Genome of the Georgia Isolate

by Elizabeth Ramirez-Medina, Lauro Velazquez-Salinas, Ayushi Rai, Nallely Espinoza, Alyssa Valladares, Ediane Silva, Leeanna Burton, Edward Spinard, Amanda Meyers, Guillermo Risatti, Sten Calvelage, Sandra Blome, Douglas P. Gladue and Manuel V. Borca

Viruses 2023, 15(10), 2134; https://doi.org/10.3390/v15102134 - 23 Oct 2023

Cited by 2 | Viewed by 1591

Abstract

African swine fever virus (ASFV) is a structurally complex, double-stranded DNA virus, which causes African swine fever (ASF), a contagious disease affecting swine. ASF is currently affecting pork production in a large geographical region, including Eurasia and the Caribbean. ASFV has a large [...] Read more.

African swine fever virus (ASFV) is a structurally complex, double-stranded DNA virus, which causes African swine fever (ASF), a contagious disease affecting swine. ASF is currently affecting pork production in a large geographical region, including Eurasia and the Caribbean. ASFV has a large genome, which harbors more than 160 genes, but most of these genes’ functions have not been experimentally characterized. One of these genes is the O174L gene which has been experimentally shown to function as a small DNA polymerase. Here, we demonstrate that the deletion of the O174L gene from the genome of the virulent strain ASFV Georgia2010 (ASFV-G) does not significantly affect virus replication in vitro or in vivo. A recombinant virus, having deleted the O174L gene, ASFV-G-∆O174L, was developed to study the effect of the O174L protein in replication in swine macrophages cultures in vitro and disease production when inoculated in pigs. The results demonstrated that ASFV-G-∆O174L has similar replication kinetics to parental ASFV-G in swine macrophage cultures. In addition, animals intramuscularly inoculated with 10² HAD₅₀ of ASFV-G-∆O174L presented a clinical form of the disease that is indistinguishable from that induced by the parental virulent strain ASFV-G. All animals developed a lethal disease, being euthanized around day 7 post-infection. Therefore, although O174L is a well-characterized DNA polymerase, its function is apparently not critical for the process of virus replication, both in vitro and in vivo, or for disease production in domestic pigs. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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12 pages, 2629 KiB

Open AccessArticle

Developing an Indirect ELISA for the Detection of African Swine Fever Virus Antibodies Using a Tag-Free p15 Protein Antigen

by Zhi Wu, Huipeng Lu, Dewei Zhu, Jun Xie, Fan Sun, Yan Xu, Hua Zhang, Zhijun Wu, Wenlong Xia and Shanyuan Zhu

Viruses 2023, 15(9), 1939; https://doi.org/10.3390/v15091939 - 16 Sep 2023

Cited by 3 | Viewed by 1421

Abstract

African swine fever (ASF) is one of the most severe diseases caused by the ASF virus (ASFV), causing massive economic losses to the global pig industry. Serological tests are important in ASF epidemiological surveillance, and more antigen targets are needed to meet market [...] Read more.

African swine fever (ASF) is one of the most severe diseases caused by the ASF virus (ASFV), causing massive economic losses to the global pig industry. Serological tests are important in ASF epidemiological surveillance, and more antigen targets are needed to meet market demand for ASFV antibody detection. In the present study, ASFV p15 protein was fusion-expressed in Escherichia coli (E. coli) with elastin-like polypeptide (ELP), and the ELP-p15 protein was purified using a simple inverse transition cycling (ITC) process. The ELP tag was cleaved off using tobacco etch virus protease (TEVp), resulting in a tag-free p15 protein. Western blot analysis demonstrated that the p15 protein reacted strongly with ASFV-positive serum. The p15 protein was used as a coating antigen in an indirect ELISA (iELISA) for detecting ASFV antibodies. The p15-iELISA method demonstrated high specificity to ASFV-positive sera, with a maximum detection dilution of 1:1600. Moreover, the method exhibited good reproducibility, with less intra-assay and inter-assay CV values than 10%. Therefore, p15-iELISA offers a novel approach for accurately detecting ASFV antibodies with significant clinical application potential. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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Review

Jump to: Research, Other

23 pages, 2241 KiB

Open AccessReview

Functional Landscape of African Swine Fever Virus–Host and Virus–Virus Protein Interactions

by Katarzyna Magdalena Dolata, Gang Pei, Christopher L. Netherton and Axel Karger

Viruses 2023, 15(8), 1634; https://doi.org/10.3390/v15081634 - 27 Jul 2023

Cited by 7 | Viewed by 2555

Abstract

Viral replication fully relies on the host cell machinery, and physical interactions between viral and host proteins mediate key steps of the viral life cycle. Therefore, identifying virus–host protein–protein interactions (PPIs) provides insights into the molecular mechanisms governing virus infection and is crucial [...] Read more.

Viral replication fully relies on the host cell machinery, and physical interactions between viral and host proteins mediate key steps of the viral life cycle. Therefore, identifying virus–host protein–protein interactions (PPIs) provides insights into the molecular mechanisms governing virus infection and is crucial for designing novel antiviral strategies. In the case of the African swine fever virus (ASFV), a large DNA virus that causes a deadly panzootic disease in pigs, the limited understanding of host and viral targets hinders the development of effective vaccines and treatments. This review summarizes the current knowledge of virus–host and virus–virus PPIs by collecting and analyzing studies of individual viral proteins. We have compiled a dataset of experimentally determined host and virus protein targets, the molecular mechanisms involved, and the biological functions of the identified virus–host and virus–virus protein interactions during infection. Ultimately, this work provides a comprehensive and systematic overview of ASFV interactome, identifies knowledge gaps, and proposes future research directions. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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Other

Jump to: Research, Review

14 pages, 4449 KiB

Open AccessBrief Report

Evaluation of the Deletion of African Swine Fever Virus E111R Gene from the Georgia Isolate in Virus Replication and Virulence in Domestic Pigs

by Elizabeth Ramirez-Medina, Lauro Velazquez-Salinas, Alyssa Valladares, Amanda Meyers, Leeanna Burton, Ediane Silva, Jason Clark, Manuel V. Borca and Douglas P. Gladue

Viruses 2024, 16(9), 1502; https://doi.org/10.3390/v16091502 - 23 Sep 2024

Abstract

African swine fever virus (ASFV) is the causative agent of an often lethal disease in domestic pigs, African swine fever (ASF). ASF is currently a pandemic disease challenging pig production in Eurasia. While the ASFV genome encodes for over 160 proteins, the function [...] Read more.

African swine fever virus (ASFV) is the causative agent of an often lethal disease in domestic pigs, African swine fever (ASF). ASF is currently a pandemic disease challenging pig production in Eurasia. While the ASFV genome encodes for over 160 proteins, the function of most of them are still not characterized. Among those ASF genes with unknown functions is the E111R gene. It has been recently reported that the deletion of the E111R gene from the genome of the virulent Chinese field isolate SY18 strain produced a reduction of virus virulence when pigs were inoculated at relatively low doses. Conversely, we report here that deletion of the ASFV gene E111R in the Georgia 2010 isolate does not alter the virulence of the parental virus in experimentally inoculated pigs. A recombinant virus lacking the E111R gene, ASFV-G-∆E111R was intramuscularly (IM) inoculated in domestic pigs at a dose of 10² HAD₅₀ of ASFV-G-∆E111R and compared with animals that received a similar dose of virulent ASFV-G. Both, animals inoculated with either the recombinant ASFV-G-∆E111R or the parental virus developed a fatal form of the disease and were euthanized around the 6th–7th day post-inoculation (dpi). Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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11 pages, 2591 KiB

Open AccessBrief Report

Insights into the Role of VPS39 and Its Interaction with CP204L and A137R in ASFV Infection

by Katarzyna Magdalena Dolata and Axel Karger

Viruses 2024, 16(9), 1478; https://doi.org/10.3390/v16091478 - 17 Sep 2024

Abstract

The African swine fever virus (ASFV) is a large and complex DNA virus that causes a highly lethal disease in swine, for which no antiviral drugs or vaccines are currently available. Studying viral–host protein–protein interactions advances our understanding of the molecular mechanisms underlying [...] Read more.

The African swine fever virus (ASFV) is a large and complex DNA virus that causes a highly lethal disease in swine, for which no antiviral drugs or vaccines are currently available. Studying viral–host protein–protein interactions advances our understanding of the molecular mechanisms underlying viral replication and pathogenesis and can facilitate the discovery of antiviral therapeutics. In this study, we employed affinity tagging and purification mass spectrometry to characterize the interactome of VPS39, an important cellular factor during the early phase of ASFV replication. The interaction network of VPS39 revealed associations with mitochondrial proteins involved in membrane contact sites formation and cellular respiration. We show that the ASFV proteins CP204L and A137R target VPS39 by interacting with its clathrin heavy-chain functional domain. Furthermore, we elaborate on the potential mechanisms by which VPS39 may contribute to ASFV replication and prioritize interactions for further investigation into mitochondrial protein function in the context of ASFV infection. Full article

(This article belongs to the Special Issue African Swine Fever Virus 4.0)

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