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 Generation and Evaluation of an African Swine Fever Virus Mutant with Deletion of the CD2v and UK Genes

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 763
Author(s):  
Teshale Teklue ◽  
Tao Wang ◽  
Yuzi Luo ◽  
Rongliang Hu ◽  
Yuan Sun ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Virus Genome ◽  
Fever Virus ◽  
Effective Vaccine ◽  
Post Inoculation ◽  
Virus Mutant ◽  
And Control

African swine fever (ASF) is a highly contagious and often lethal disease caused by African swine fever virus (ASFV). ASF emerged in China in August 2018 and has since rapidly spread into many areas of the country. The disease has caused a significant impact on China’s pig and related industries. A safe and effective vaccine is needed to prevent and control the disease. Several gene-deleted ASFVs have been reported; however, none of them is safe enough and commercially available. In this study, we report the generation of a double gene-deleted ASFV mutant, ASFV-SY18-∆CD2v/UK, from a highly virulent field strain ASFV-SY18 isolated in China. The results showed that ASFV-SY18-∆CD2v/UK lost hemadsorption properties, and the simultaneous deletion of the two genes did not significantly affect the in vitro replication of the virus in primary porcine alveolar macrophages. Furthermore, ASFV-SY18-∆CD2v/UK was attenuated in pigs. All the ASFV-SY18-∆CD2v/UK-inoculated pigs remained healthy, and none of them developed ASF-associated clinical signs. Additionally, the ASFV-SY18-∆CD2v/UK-infected pigs developed ASFV-specific antibodies, and no virus genome was detected in blood and nasal discharges at 21 and 28 days post-inoculation. More importantly, we found that all the pigs inoculated with 104 TCID50 of ASFV-SY18-∆CD2v/UK were protected against the challenge with the parental ASFV-SY18. However, low-level ASFV DNA was detected in blood, nasal swabs, and lymphoid tissue after the challenge. The results demonstrate that ASFV-SY18-∆CD2v/UK is safe and able to elicit protective immune response in pigs and can be a potential vaccine candidate to control ASF.

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 Guidelines for oral fluid-based surveillance of viral pathogens in swine

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Alexandra Henao-Diaz ◽  
Luis Giménez-Lirola ◽  
David H. Baum ◽  
Jeffrey Zimmerman
Keyword(s):  
Oral Fluid ◽  
Health Management ◽  
African Swine Fever Virus ◽  
Animal Health ◽  
Fluid Collection ◽  
African Swine Fever ◽  
Swine Production ◽  
Viral Pathogens ◽  
Initial Report ◽  
Collateral Effect

Abstract Recent decades have seen both rapid growth and extensive consolidation in swine production. As a collateral effect, these changes have exacerbated the circulation of viruses and challenged our ability to prevent, control, and/or eliminate impactful swine diseases. Recent pandemic events in human and animal health, e.g., SARS-CoV-2 and African swine fever virus, highlight the fact that clinical observations are too slow and inaccurate to form the basis for effective health management decisions: systematic processes that provide timely, reliable data are required. Oral fluid-based surveillance reflects the adaptation of conventional testing methods to an alternative diagnostic specimen. The routine use of oral fluids in commercial farms for PRRSV and PCV2 surveillance was first proposed in 2008 as an efficient and practical improvement on individual pig sampling. Subsequent research expanded on this initial report to include the detection of ≥23 swine viral pathogens and the implementation of oral fluid-based surveillance in large swine populations (> 12,000 pigs). Herein we compile the current information regarding oral fluid collection methods, testing, and surveillance applications in swine production.

scholarly journals Live Attenuated African Swine Fever Viruses as Ideal Tools to Dissect the Mechanisms Involved in Cross-Protection

Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1474
Author(s):  
Elisabeth Lopez ◽  
Juanita van Heerden ◽  
Laia Bosch-Camós ◽  
Francesc Accensi ◽  
Maria Jesus Navas ◽  
...  
Keyword(s):  
Vaccine Development ◽  
African Swine Fever Virus ◽  
Virulent Strain ◽  
Sequence Similarity ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Cross Protection ◽  
Sub Saharan Africa ◽  
Genotype I ◽  
Genotype Ii

African swine fever (ASF) has become the major threat for the global swine industry. Furthermore, the epidemiological situation of African swine fever virus (ASFV) in some endemic regions of Sub-Saharan Africa is worse than ever, with multiple virus strains and genotypes currently circulating in a given area. Despite the recent advances on ASF vaccine development, there are no commercial vaccines yet, and most of the promising vaccine prototypes available today have been specifically designed to fight the genotype II strains currently circulating in Europe, Asia, and Oceania. Previous results from our laboratory have demonstrated the ability of BA71∆CD2, a recombinant LAV lacking CD2v, to confer protection against homologous (BA71) and heterologous genotype I (E75) and genotype II (Georgia2007/01) ASFV strains, both belonging to same clade (clade C). Here, we extend these results using BA71∆CD2 as a tool trying to understand ASFV cross-protection, using phylogenetically distant ASFV strains. We first observed that five out of six (83.3%) of the pigs immunized once with 106 PFU of BA71∆CD2 survived the tick-bite challenge using Ornithodoros sp. soft ticks naturally infected with RSA/11/2017 strain (genotype XIX, clade D). Second, only two out of six (33.3%) survived the challenge with Ken06.Bus (genotype IX, clade A), which is phylogenetically more distant to BA71∆CD2 than the RSA/11/2017 strain. On the other hand, homologous prime-boosting with BA71∆CD2 only improved the survival rate to 50% after Ken06.Bus challenge, all suffering mild ASF-compatible clinical signs, while 100% of the pigs immunized with BA71∆CD2 and boosted with the parental BA71 virulent strain survived the lethal challenge with Ken06.Bus, without almost no clinical signs of the disease. Our results confirm that cross-protection is a multifactorial phenomenon that not only depends on sequence similarity. We believe that understanding this complex phenomenon will be useful for designing future vaccines for ASF-endemic areas.

scholarly journals African Swine Fever Laboratory Diagnosis—Lessons Learned from Recent Animal Trials

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 177
Author(s):  
Jutta Pikalo ◽  
Paul Deutschmann ◽  
Melina Fischer ◽  
Hanna Roszyk ◽  
Martin Beer ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Laboratory Diagnosis ◽  
Lessons Learned ◽  
Hemorrhagic Disease ◽  
Passive Surveillance ◽  
Animal Trials ◽  
Fit For Purpose ◽  
The Impact

African swine fever virus (ASFV) causes a hemorrhagic disease in pigs with high socio-economic consequences. To lower the impact of disease incursions, early detection is crucial. In the context of experimental animal trials, we evaluated diagnostic workflows for a high sample throughput in active surveillance, alternative sample matrices for passive surveillance, and lateral flow devices (LFD) for rapid testing. We could demonstrate that EDTA blood is significantly better suited for early ASFV detection than serum. Tissues recommended by the respective diagnostic manuals were in general comparable in their performance, with spleen samples giving best results. Superficial lymph nodes, ear punches, and different blood swabs were also evaluated as potential alternatives. In summary, all matrices yielded positive results at the peak of clinical signs and could be fit for purpose in passive surveillance. However, weaknesses were discovered for some matrices when it comes to the early phase of infection or recovery. The antigen LFD showed variable results with best performance in the clinical phase. The antibody LFD was quite comparable with ELISA systems. Concluding, alternative approaches are feasible but have to be embedded in control strategies selecting test methods and sample materials following a “fit-for-purpose” approach.

Histopathologic lesions in conventional pigs experimentally infected with Haemophilus parasuis serovar 5

2015 ◽  
Vol 43 (02) ◽  
pp. 91-96 ◽  
Author(s):  
R.-L. Austin-Busse ◽  
A. Ladinig ◽  
G. Balka ◽  
S. Zoels ◽  
M. Ritzmann ◽  
...  
Keyword(s):  
Clinical Signs ◽  
Control Group ◽  
Post Inoculation ◽  
Haemophilus Parasuis ◽  
Tissue Samples ◽  
Group A ◽  
Pathologic Lesions ◽  
Group B ◽  
Kidney Lesions ◽  
Challenge Group

Summary Objective: In the present study various tissues of pigs were investigated for the presence of histopathologic lesions after an experimental infection with Haemophilus (H.) parasuis serovar 5. Material and methods: Conventional pigs (n = 36) were divided into a control group B (n = 9) and a challenge group A (n = 27), which was infected intratracheally. Pigs that did not die prior to study termination were euthanized on day 14 post inoculation. Postmortem samples of the lung, heart, liver, kidney, spleen, left tarsal joint capsule and brain were collected. Results: All but one pig with detectable histopathologic lesions (n = 11) showed typical macroscopic changes. Histopatho logic examination of all tissue samples identified pyelitis (n = 10), synovitis (n = 7) and meningitis (n = 7) and all those animals were euthanized prior to study termination. No histopathologic lesions were found in pigs of the control group. The correlations between pyelitis and meningitis, pyelitis and synovitis and synovitis and meningitis were significant (p < 0.001). No significant correlation could be observed between the histopathologic and the clinical examination of the joints. The investigation of samples from the joints by PCR was not significantly correlated with the observed synovitis. The clinical observation of neurologic signs was significantly correlated with meningitis (p = 0.03). A significant correlation (p < 0.001) could be detected between meningitis and the detection of H. parasuis by PCR in brain samples. Conclusions: H. parasuis constantly causes clinical signs and pathologic lesions as soon as it infects the brain while it can infect the joints without causing histopathologic lesions. Pigs with histopathologic lesions do not always show typical clinical signs. Only few studies described the finding of kidney lesions in pigs with Glässer’s disease and this is the first study to describe a pyelitis in pigs experimentally infected with H. parasuis. The observed pyelitis mainly occurred in acute cases.

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 Role of African swine fever virus (ASFV) proteins EP153R and EP402R in reducing viral persistence and virulence from attenuated BeninΔDP148R

2021 ◽  
Author(s):  
Vlad Petrovan ◽  
Anusyah Rathakrishnan ◽  
Muneeb Islam ◽  
Lynnette Goatley ◽  
Katy Moffat ◽  
...  
Keyword(s):  
Virus Replication ◽  
Vaccine Development ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
Viral Persistence ◽  
Fever Virus ◽  
Post Immunization

The limited knowledge on the role of many of the approximately 170 proteins encoded by African swine fever virus restricts progress towards vaccine development. In this study we investigated the effect of deleting combinations of different genes from a previously attenuated virus, BeninΔDP148R on: virus replication in macrophages, virus persistence and clinical signs post immunization, and induction of protection against challenge. Deletion of either EP402R or EP153R genes individually or in combination from BeninΔDP148R did not reduce virus replication in vitro. However, deletion of EP402R dramatically reduced viral persistence in vivo, 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 a slight increase in virus genome copies in blood was observed at different times post immunization when compared with BeninΔDP148R. These results show that EP402R and EP153R have a synergistic role in promoting viremia, however EP153R alone does not seem to have a major impact on virus levels in blood.

scholarly journals Pathogenesis of Velogenic Genotype VII.1.1 Newcastle Disease Virus Isolated from Chicken in Egypt via Different Inoculation Routes: Molecular, Histopathological, and Immunohistochemical Study

Animals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3567
Author(s):  
Yassmin EL-Morshidy ◽  
Walied Abdo ◽  
Ehab Kotb Elmahallawy ◽  
Ghada Allam Abd EL-Dayem ◽  
Ahmed El sawak ◽  
...  
Keyword(s):  
Newcastle Disease Virus ◽  
Disease Virus ◽  
Newcastle Disease ◽  
Time Course ◽  
Clinical Signs ◽  
Post Inoculation ◽  
Tissue Samples ◽  
Genetic Characteristics ◽  
Hemagglutination Inhibition Test ◽  
Death Time

Newcastle disease virus (NDV) remains a constant threat to the poultry industry. There is scarce information concerning the pathogenicity and genetic characteristics of the circulating velogenic Newcastle disease virus (NDV) in Egypt. In the present work, NDV was screened from tracheal swabs collected from several broiler chicken farms (N = 12) in Dakahlia Governorate, Egypt. Real-time reverse transcriptase polymerase chain reaction (RRT-PCR) was used for screening of velogenic and mesogenic NDV strains through targeting F gene fragment amplification, followed by sequencing of the resulting PCR products. The identified strain, namely, NDV-CH-EGYPT-F42-DAKAHLIA-2019, was isolated and titrated in the allantoic cavity of 10 day old specific pathogen-free (SPF) embryonated chicken eggs (ECEs), and then their virulence was determined by mean death time (MDT) and intracerebral pathogenicity index (ICPI). The pathogenicity of the identified velogenic NDV strain was also assessed in 28 day old chickens using different inoculation routes as follows: intraocular, choanal slit, intranasal routes, and a combination of both intranasal and intraocular routes. In addition, sera were collected 5 and 10 days post inoculation (pi) for the detection of NDV antibodies by hemagglutination inhibition test (HI), and tissue samples from different organs were collected for histopathological and immunohistochemical examination. A series of different clinical signs and postmortem lesions were recorded with the various routes. Interestingly, histopathology and immunohistochemistry for NDV nucleoprotein displayed widespread systemic distribution. The intensity of viral nucleoprotein immunolabeling was detected within different cells including the epithelial and endothelium lining, as well as macrophages. The onset, distribution, and severity of the observed lesions were remarkably different between various inoculation routes. Collectively, a time-course comparative pathogenesis study of NDV infection demonstrated the role of different routes in the pathogenicity of NDV. The intranasal challenge was associated with a prominent increase in NDV lesions, whereas the choanal slit route was the route least accompanied by severe NDV pathological findings. Clearly, the present findings might be helpful for implementation of proper vaccination strategies against NDV.

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