scholarly journals African Swine Fever in Cameroon: A Review

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 421
Author(s):  
Ebanja Joseph Ebwanga ◽  
Stephen Mbigha Ghogomu ◽  
Jan Paeshuyse
Keyword(s):  
African Swine Fever Virus ◽  
Central Africa ◽  
African Swine Fever ◽  
Fever Virus ◽  
Economic Losses ◽  
Future Research ◽  
Genotype I ◽  
Traditional System ◽  
Pork Industry ◽  
Domestic Cycle

African swine fever (ASF) is a hemorrhagic contagious porcine disease caused by the African swine fever virus. The disease poses enormous problems to the pork industry with pig mortality ranging from 30% to 100%, depending on the virulence of the virus circulating. Cameroon, situated in Central Africa is one of the countries in which the African swine fever virus (ASFV) has been endemic since its first outbreak in 1982. The disease is a major problem to the pig industry causing huge economic losses. A clear and concise review on ASF in Cameroon relating to the entry and current genotype of the virus, epidemiology, pathogenesis and economic impact is lacking. A thorough literature search revealed: (1) The virus entered the country in 1982 and caused the death of 80% of the pigs. (2) All isolates belong to serogroup I and only Genotype I is circulating in Cameroon principally in the domestic cycle as there are neither soft ticks nor warthog in the pig production regions sampled. (3) 70% of the pig farmers are involved in the traditional system of production with local and hybrid breeds of pigs with minimal input. (4) The country is endemic to the virus with huge economic losses. (5) So far, very little research has been effected on ASFV in Cameroon. This review gives a detailed overview of the situation of African swine fever virus (ASFV) in the country along with potential avenues for future research into ASFV in Cameroon.

scholarly journals Computational Analysis of African Swine Fever Virus Protein Space for the Design of an Epitope-Based Vaccine Ensemble

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1078 ◽  
Author(s):  
Albert Ros-Lucas ◽  
Florencia Correa-Fiz ◽  
Laia Bosch-Camós ◽  
Fernando Rodriguez ◽  
Julio Alonso-Padilla
Keyword(s):  
T Cell ◽  
Vaccine Development ◽  
De Novo ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Economic Losses ◽  
Virus Protein ◽  
Hemorrhagic Disease ◽  
Starting Point

African swine fever virus is the etiological agent of African swine fever, a transmissible severe hemorrhagic disease that affects pigs, causing massive economic losses. There is neither a treatment nor a vaccine available, and the only method to control its spread is by extensive culling of pigs. So far, classical vaccine development approaches have not yielded sufficiently good results in terms of concomitant safety and efficacy. Nowadays, thanks to advances in genomic and proteomic techniques, a reverse vaccinology strategy can be explored to design alternative vaccine formulations. In this study, ASFV protein sequences were analyzed using an in-house pipeline based on publicly available immunoinformatic tools to identify epitopes of interest for a prospective vaccine ensemble. These included experimentally validated sequences from the Immune Epitope Database, as well as de novo predicted sequences. Experimentally validated and predicted epitopes were prioritized following a series of criteria that included evolutionary conservation, presence in the virulent and currently circulating variant Georgia 2007/1, and lack of identity to either the pig proteome or putative proteins from pig gut microbiota. Following this strategy, 29 B-cell, 14 CD4+ T-cell and 6 CD8+ T-cell epitopes were selected, which represent a starting point to investigating the protective capacity of ASFV epitope-based vaccines.

scholarly journals Development of a Directly Visualized Recombinase Polymerase Amplification–SYBR Green I Method for the Rapid Detection of African Swine Fever Virus

2020 ◽  
Vol 11 ◽  
Author(s):  
Shuai Zhang ◽  
Aijun Sun ◽  
Bo Wan ◽  
Yongkun Du ◽  
Yanan Wu ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Sybr Green ◽  
Fever Virus ◽  
Diagnostic Methods ◽  
Sybr Green I ◽  
Recombinase Polymerase Amplification ◽  
Economic Losses ◽  
Field Samples ◽  
Standard Plasmid

African swine fever (ASF) is a lethal disease in swine caused by etiologic African swine fever virus (ASFV). The global spread of ASFV has resulted in huge economic losses globally. In the absence of effective vaccines or drugs, pathogen surveillance has been the most important first-line intervention to prevent ASF outbreaks. Among numerous diagnostic methods, recombinase polymerase amplification (RPA)-based detection is capable of producing sensitive and specific results without relying on the use of expensive instruments. However, currently used gene-specific, probe-based RPA for ASFV detection is expensive and time-consuming. To improve the efficiency of ASFV surveillance, a novel directly visualized SYBR Green I-staining RPA (RPAS) method was developed to detect the ASFV genome. SYBR Green I was added to the amplified RPA products for direct visualization by the naked eye. The sensitivity and specificity of this method were confirmed using standard plasmid and inactivated field samples. This method was shown to be highly specific with a detection limit of 103 copies/μl of ASFV in 15 min at 35°C without any cross-reactions with other important porcine viruses selected. In summary, this method enables direct sample visualization with reproducible results for ASFV detection and hence has the potential to be used as a robust tool for ASF prevention and control.

scholarly journals Differential vector competence of Ornithodoros soft ticks for African swine fever virus: What if it involves more than just crossing organic barriers in ticks?

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Rémi Pereira De Oliveira ◽  
Evelyne Hutet ◽  
Renaud Lancelot ◽  
Frédéric Paboeuf ◽  
Maxime Duhayon ◽  
...  
Keyword(s):  
Viral Replication ◽  
Vertical Transmission ◽  
African Swine Fever Virus ◽  
Vector Competence ◽  
African Swine Fever ◽  
Realistic Model ◽  
Molecular Data ◽  
Fever Virus ◽  
Genotype I ◽  
Genotype Ii

Abstract Background Several species of soft ticks in genus Ornithodoros are known vectors and reservoirs of African swine fever virus (ASFV). However, the underlying mechanisms of vector competence for ASFV across Ornithodoros species remain to be fully understood. To that end, this study compared ASFV replication and dissemination as well as virus vertical transmission to descendants between Ornithodorosmoubata, O. erraticus, and O. verrucosus in relation to what is known about the ability of these soft tick species to transmit ASFV to pigs. To mimic the natural situation, a more realistic model was used where soft ticks were exposed to ASFV by allowing them to engorge on viremic pigs. Methods Ornithodoros moubata ticks were infected with the ASFV strains Liv13/33 (genotype I) or Georgia2007/1 (genotype II), O. erraticus with OurT88/1 (genotype I) or Georgia2007/1 (genotype II), and O. verrucosus with Ukr12/Zapo (genotype II), resulting in five different tick–virus pairs. Quantitative PCR (qPCR) assays targeting the VP72 ASFV gene was carried out over several months on crushed ticks to study viral replication kinetics. Viral titration assays were also carried out on crushed ticks 2 months post infection to confirm virus survival in soft ticks. Ticks were dissected. and DNA was individually extracted from the following organs to study ASFV dissemination: intestine, salivary glands, and reproductive organs. DNA extracts from each organ were tested by qPCR. Lastly, larval or first nymph-stage progeny emerging from hatching eggs were tested by qPCR to assess ASFV vertical transmission. Results Comparative analyses revealed higher rates of ASFV replication and dissemination in O. moubata infected with Liv13/33, while the opposite was observed for O. erraticus infected with Georgia2007/1 and for O. verrucosus with Ukr12/Zapo. Intermediate profiles were found for O. moubata infected with Georgia2007/1 and for O. erraticus with OurT88/1. Vertical transmission occurred efficiently in O. moubata infected with Liv13/33, and at very low rates in O. erraticus infected with OurT88/1. Conclusions This study provides molecular data indicating that viral replication and dissemination in Ornithodoros ticks are major mechanisms underlying ASFV horizontal and vertical transmission. However, our results indicate that other determinants beyond viral replication also influence ASFV vector competence. Further research is required to fully understand this process in soft ticks.

scholarly journals An Isothermal Molecular Point of Care Testing for African Swine Fever Virus Using Recombinase-Aided Amplification and Lateral Flow Assay Without the Need to Extract Nucleic Acids in Blood

2021 ◽  
Vol 11 ◽  
Author(s):  
Yuhang Zhang ◽  
Qingmei Li ◽  
Junqing Guo ◽  
Dongliang Li ◽  
Li Wang ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Point Of Care ◽  
African Swine Fever ◽  
Lateral Flow ◽  
Fever Virus ◽  
Lateral Flow Assay ◽  
Economic Losses ◽  
Point Of Care Testing ◽  
Viral Dna ◽  
Blood Samples

African swine fever (ASF) is a highly contagious and usually deadly porcine infectious disease listed as a notifiable disease by the World Organization for Animal Health (OIE). It has brought huge economic losses worldwide, especially since 2018, the first outbreak in China. As there are still no effective vaccines available to date, diagnosis of ASF is essential for its surveillance and control, especially in areas far from city with limited resources and poor settings. In this study, a sensitive, specific, rapid, and simple molecular point of care testing for African swine fever virus (ASFV) B646L gene in blood samples was established, including treatment of blood samples with simple dilution and boiling for 5 min, isothermal amplification with recombinase-aided amplification (RAA) at 37°C in a water bath for 10 min, and visual readout with lateral flow assay (LFA) at room temperature for 10–15 min. Without the need to extract viral DNA in blood samples, the intact workflow from sampling to final diagnostic decision can be completed with minimal equipment requirement in 30 min. The detection limit of RAA-LFA for synthesized B646L gene-containing plasmid was 10 copies/μl, which was 10-fold more sensitive than OIE-recommended PCR and quantitative PCR. In addition, no positive readout of RAA-LFA was observed in testing classical swine fever virus, porcine reproductive and respiratory syndrome virus, porcine epidemic diarrhea virus, pseudorabies virus and porcine circovirus 2, exhibiting good specificity. Evaluation of clinical blood samples of RAA-LFA showed 100% coincident rate with OIE-recommended PCR, in testing both extracted DNAs and treated bloods. We also found that some components in blood samples greatly inhibited PCR performance, but had little effect on RAA. Inhibitory effect can be eliminated when blood was diluted at least 32–64-fold for direct PCR, while only a 2–4 fold dilution of blood was suitable for direct RAA, indicating RAA is a better choice than PCR when blood is used as detecting sample. Taken together, we established an sensitive, specific, rapid, and simple RAA-LFA for ASFV molecular detection without the need to extract viral DNA, providing a good choice for point of care testing of ASF diagnosis in the future.

scholarly journals Identification and Isolation of Two Different Subpopulations Within African Swine Fever Virus Arm/07 Stock

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 625
Author(s):  
Daniel Pérez-Núñez ◽  
Eva Castillo-Rosa ◽  
Gonzalo Vigara-Astillero ◽  
Raquel García-Belmonte ◽  
Carmina Gallardo ◽  
...  
Keyword(s):  
Vaccine Development ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Single Mutation ◽  
High Sequence Identity ◽  
Genotype I ◽  
High Coverage ◽  
Purification Method

No efficient vaccines exist against African swine fever virus (ASFV), which causes a serious disease in wild boars and domestic pigs that produces great industrial and ecological concerns worldwide. An extensive genetic characterization of the original ASFV stocks used to produce live attenuated vaccine (LAV) prototypes is needed for vaccine biosecurity and control. Here, we sequenced for the first time the Arm/07 stock which was obtained from an infected pig during the Armenia outbreak in 2007, using an improved viral dsDNA purification method together with high coverage analysis. There was unexpected viral heterogeneity within the stock, with two genetically distinct ASFV subpopulations. The first, represented by the Arm/07/CBM/c2 clone, displayed high sequence identity to the updated genotype II Georgia 2007/1, whereas the second (exemplified by clone Arm/07/CBM/c4) displayed a hemadsorbing phenotype and grouped within genotype I based on a central region conserved among all members of this group. Intriguingly, Arm/07/CBM/c4 contained a unique EP402R sequence, produced by a single mutation in the N-terminal region. Importantly, Arm/07/CBM/c4 showed in vitro features of attenuated strains regarding innate immune response pathway. Both Arm/07/CBM/c2 and c4 represent well-characterized viral clones, useful for different molecular and virus-host interaction studies, including virulence studies and vaccine development.

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 A Proteomic Atlas of the African Swine Fever Virus Particle

2018 ◽  
Vol 92 (23) ◽  
Author(s):  
Alí Alejo ◽  
Tania Matamoros ◽  
Milagros Guerra ◽  
Germán Andrés
Keyword(s):  
Virus Particle ◽  
Immunoelectron Microscopy ◽  
Protein Modification ◽  
Molecular Mechanisms ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Sub Saharan Africa ◽  
Future Research ◽  
Host Proteins

ABSTRACTAfrican swine fever virus (ASFV) is a large and complex DNA virus that causes a highly lethal swine disease for which there is no vaccine available. The ASFV particle, with an icosahedral multilayered structure, contains multiple polypeptides whose identity is largely unknown. Here, we analyzed by mass spectroscopy the protein composition of highly purified extracellular ASFV particles and performed immunoelectron microscopy to localize several of the detected proteins. The proteomic analysis identified 68 viral proteins, which account for 39% of the genome coding capacity. The ASFV proteome includes essentially all the previously described virion proteins and, interestingly, 44 newly identified virus-packaged polypeptides, half of which have an unknown function. A great proportion of the virion proteins are committed to the virus architecture, including two newly identified structural proteins, p5 and p8, which are derived from the core polyproteins pp220 and pp62, respectively. In addition, the virion contains a full complement of enzymes and factors involved in viral transcription, various enzymes implicated in DNA repair and protein modification, and some proteins concerned with virus entry and host defense evasion. Finally, 21 host proteins, many of them localized at the cell surface and related to the cortical actin cytoskeleton, were reproducibly detected in the ASFV particle. Immunoelectron microscopy strongly supports the suggestion that these host membrane-associated proteins are recruited during virus budding at actin-dependent membrane protrusions. Altogether, the results of this study provide a comprehensive model of the ASFV architecture that integrates both compositional and structural information.IMPORTANCEAfrican swine fever virus causes a highly contagious and lethal disease of swine that currently affects many countries of sub-Saharan Africa, the Caucasus, the Russian Federation, and Eastern Europe and has very recently spread to China. Despite extensive research, effective vaccines or antiviral strategies are still lacking, and many basic questions on the molecular mechanisms underlying the infective cycle remain. One such gap regards the composition and structure of the infectious virus particle. In the study described in this report, we identified the set of viral and host proteins that compose the virion and determined or inferred the localization of many of them. This information significantly increases our understanding of the biological and structural features of an infectious African swine fever virus particle and will help direct future research efforts.

scholarly journals Effectiveness of Chemical Compounds Used against African Swine Fever Virus in Commercial Available Disinfectants

Pathogens ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 878
Author(s):  
Małgorzata Juszkiewicz ◽  
Marek Walczak ◽  
Natalia Mazur-Panasiuk ◽  
Grzegorz Woźniakowski
Keyword(s):  
Caustic Soda ◽  
Sodium Hypochlorite ◽  
African Swine Fever Virus ◽  
Animal Health ◽  
Virus Titer ◽  
African Swine Fever ◽  
Chemical Compounds ◽  
Fever Virus ◽  
Economic Losses ◽  
Potassium Peroxymonosulfate

African swine fever (ASF) causes huge economic losses and is one of most dangerous diseases of pigs. The disease is known for almost 100 years, an effective vaccine or treatment is still unavailable, only proper biosecurity measures, including disinfection, are being applied, in order to prevent disease outbreaks. Eight active substances, i.e., formaldehyde, sodium hypochlorite, caustic soda, glutaraldehyde, phenol, benzalkonium chloride, potassium peroxymonosulfate and acetic acid, were tested, in order to confirm their effectiveness against African swine fever virus (ASFV). This specific selection was done based on the World Organisation for Animal Health (OIE)’s recommendation and previous disinfectant studies on surfaces. The result of our study shows that most of them inactivate the virus, in recommended concentrations. In order to reduce the cytotoxicity of the four substances, Microspin S-400 HR columns were applied, therefore making it possible to demonstrate four logarithms virus titer reduction. Sodium hypochlorite, glutaraldehyde, caustic soda and potassium peroxymonosulfate showed the best ASFV inactivation rates, achieving titer reductions over 5 logs. Despite microfiltration, the virucidal activity of formaldehyde was not assessable, due to its high cytotoxicity. Our results showed that cleaning is particularly important, because removal of the soiling provides improved effectiveness of the tested chemical compounds.

scholarly journals Role of African swine fever virus (ASFV) proteins EP153R and EP402R in reducing viral persistence in blood and virulence in pigs infected with BeninΔDP148R

2021 ◽  
Author(s):  
Vlad Petrovan ◽  
Anusyah Rathakrishnan ◽  
Muneeb Islam ◽  
Lynnette C. Goatley ◽  
Katy Moffat ◽  
...  
Keyword(s):  
Vaccine Development ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Fever Virus ◽  
Genotype I ◽  
Virus Persistence ◽  
Challenge Virus

The limited knowledge on the role of many of the approximately 170 proteins encoded by African swine fever virus restricts progress towards vaccine development. Previously, the DP148R gene was deleted from the genome of genotype I virulent Benin 97/1 isolate. This virus, BeninΔDP148R, induced transient moderate clinical signs after immunization and high levels of protection against challenge. However, the BeninΔDP148R virus and genome persisted in blood over a prolonged period. In the current study deletion of either EP402R or EP153R genes individually or in combination from BeninΔDP148R genome was shown not to reduce virus replication in macrophages in vitro. However, deletion of EP402R dramatically reduced the period of infectious virus persistence in blood in immunized pigs from 28 to 14 days and virus genome from 59 to 14 days, whilst maintaining high levels of protection against challenge. The additional deletion of EP153R (BeninΔDP148RΔEP153RΔEP402R) further attenuated the virus and no viremia or clinical signs were observed post-immunization. This was associated with decreased protection and detection of moderate levels of challenge virus in blood. Interestingly, the deletion of EP153R alone from BeninΔDP148R did not result in further virus attenuation and did not reduce the period of virus persistence in blood. These results show that EP402R and EP153R have a synergistic role in reducing clinical signs and levels of virus in blood. Importance: African swine fever virus (ASFV) causes a disease of domestic pigs and wild boar which results in death of almost all infected animals. The disease has a high economic impact, and no vaccine is available. We investigated the role of two ASFV proteins, called EP402R and EP153R, in determining the levels and length of time virus persists in blood from infected pigs. EP402R causes ASFV particles and infected cells to bind to red blood cells. Deletion of the EP402R gene dramatically reduced virus persistence in blood but did not reduce the level of virus. Deletion of the EP153R alone did not reduce the period or level of virus persistence in blood. However, deleting both EP153R and EP402R resulted in undetectable levels of virus in blood and no clinical signs showing the proteins act synergistically. Importantly the infected pigs were protected following infection with the wildtype virus that kills pigs.

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