Project description:African swine fever virus (ASFV) is a large DNA virus belonging to the Asfarviridae family. Despite its agricultural importance, little is known about the fundamental molecular mechanisms of this pathogen. Short-read sequencing (SRS) can produce a huge amount of high-precision sequencing reads for transcriptomic profiling, but it is inefficient for comprehensively annotating transcriptomes. Long-read sequencing (LRS) can overcome some of SRS's limitations, but it also has drawbacks, such as low-coverage and high error rate. The limitations of the two approaches can be surmounted by the combined use of these techniques. In this study, we used Illumina SRS and Oxford Nanopore Technologies LRS platforms with multiple library preparation methods (amplified and direct cDNA sequencings and native RNA sequencing) for constructing the ASFV transcriptomic atlas. This work identified many novel transcripts and transcript isoforms and annotated the precise termini of previously described RNAs. This study identified a novel species of ASFV transcripts, the replication origin-associated RNAs. Additionally, we discovered several nested genes embedded into larger canonical genes. In contrast to the current view that the ASFV transcripts are monocistronic, we detected a significant extent of polycistronism. A multifaceted meshwork of transcriptional overlaps was also discovered.
Project description:In field studies and carefully controlled artificial infections, there is host variation in response to ASF infections. To better understand the mechanisms underlying this diversity and distinguish between resilient and susceptible pigs to African Swine Fever (ASF), the differentially expressed genes (DEGs) were studied between the recovered versus non-recovered pigs before and after an infection challenge and also among non-recovered animals over time. In total, 17 Babraham pigs were sampled. Twelve animals were randomly immunized with low virulent ASFV isolate, and the others received the sham vaccine. All animals were then challenged with the virulent ASFV isolate 18 days after the immunization. Except for five animals, all showed clinical signs and dead between 4 and 6 days later. RNA sequencing was done for whole blood samples collected pre-infection, one day, and one week post-infection.
Project description:African swine fever (ASF) is currently the most threatening disease for domestic and wild pigs worldwide. Wild boar has been the main affected species in all EU countries except for Romania, where most notifications occur in domestic pigs. The spread of ASF in wild boar is challenging to control; risk factors are harder to identify and establish than in domestic pigs, which, together with an underestimation of the disease and the lack of treatment or an effective vaccine, are hindering control and eradication efforts. We distributed two online questionnaires, one for domestic pigs and one for wild boar, to experts of different background and countries in Europe, to explore risk factors in relation to ASF control connected to farming, hunting, trade, the environment, and domestic pig and wild boar populations. Overall, wild boar movements were estimated to pose the highest risk of ASF introduction and spread. The movement of pork and pork products for own consumption also ranked high. Here we explored, in addition to the assessment of risk pathways, the identification of risks of transmission at the domestic/wild boar interface, the importance of biosecurity practices and improved control efforts, and controversial opinions that require further attention.
Project description:Large DNA viruses are known to manipulate and modify host miRNAs during infection. Therefore the aim of this study was to investigate the impact of infection with the large DNA virus; African swine fever virus (ASFV) on host miRNAs. Small RNA sequencing libraries were prepared from RNA extracted from ASFV (Benin 97/1) infected primary porcine macrophages at 0, 6 and 16 hours post infection. Libraries were pooled and sequenced on 1 lane of an Illumina HiSeq, yielding sequences aligning to a total of 247 different mature Sus scrofa miRNAs. On average, 3779095 (± 1911525) miRNA reads were obtained per sample. The results revealed no widespread modification to host miRNAs, though a number of specific miRNAs were differentially expressed during ASFV infection. Notably, a small number of miRNAs (Ssc-miR-10b, Ssc-miR-144 and Ssc-miR-486) were rapidly upregulated 2-6 fold within the first hour of infection.
Project description:African swine fever virus (ASFV), like other complex DNA viruses, deploys a variety of strategies to evade the host's defence systems, such as inflammatory and immune responses and cell death. Here, we analyse the modifications in the translational machinery induced by ASFV. During ASFV infection, eIF4G and eIF4E are phosphorylated (Ser1108 and Ser209, respectively), whereas 4E-BP1 is hyperphosphorylated at early times post infection and hypophosphorylated after 18 h. Indeed, a potent increase in eIF4F assembly is observed in ASFV-infected cells, which is prevented by rapamycin treatment. Phosphorylation of eIF4E, eIF4GI and 4E-BP1 is important to enhance viral protein production, but is not essential for ASFV infection as observed in rapamycin- or CGP57380-treated cells. Nevertheless, eIF4F components are indispensable for ASFV protein synthesis and virus spread, since eIF4E or eIF4G depletion in COS-7 or Vero cells strongly prevents accumulation of viral proteins and decreases virus titre. In addition, eIF4F is not only activated but also redistributed within the viral factories at early times of infection, while eIF4G and eIF4E are surrounding these areas at late times. In fact, other components of translational machinery such as eIF2alpha, eIF3b, eIF4E, eEF2 and ribosomal P protein are enriched in areas surrounding ASFV factories. Notably, the mitochondrial network is polarized in ASFV-infected cells co-localizing with ribosomes. Thus, translation and ATP synthesis seem to be coupled and compartmentalized at the periphery of viral factories. At later times after ASFV infection, polyadenylated mRNAs disappear from the cytoplasm of Vero cells, except within the viral factories. The distribution of these pools of mRNAs is similar to the localization of viral late mRNAs. Therefore, degradation of cellular polyadenylated mRNAs and recruitment of the translation machinery to viral factories may contribute to the inhibition of host protein synthesis, facilitating ASFV protein production in infected cells.
Project description:African swine fever (ASF) is caused by a large and highly pathogenic DNA virus, African swine fever virus (ASFV), which provokes severe economic losses and expansion threats. Presently, no specific protection or vaccine against ASF is available, despite the high hazard that the continued occurrence of the disease in sub-Saharan Africa, the recent outbreak in the Caucasus in 2007, and the potential dissemination to neighboring countries, represents. Although virus entry is a remarkable target for the development of protection tools, knowledge of the ASFV entry mechanism is still very limited. Whereas early studies have proposed that the virus enters cells through receptor-mediated endocytosis, the specific mechanism used by ASFV remains uncertain. Here we used the ASFV virulent isolate Ba71, adapted to grow in Vero cells (Ba71V), and the virulent strain E70 to demonstrate that entry and internalization of ASFV includes most of the features of macropinocytosis. By a combination of optical and electron microscopy, we show that the virus causes cytoplasm membrane perturbation, blebbing and ruffles. We have also found that internalization of the virions depends on actin reorganization, activity of Na(+)/H(+) exchangers, and signaling events typical of the macropinocytic mechanism of endocytosis. The entry of virus into cells appears to directly stimulate dextran uptake, actin polarization and EGFR, PI3K-Akt, Pak1 and Rac1 activation. Inhibition of these key regulators of macropinocytosis, as well as treatment with the drug EIPA, results in a considerable decrease in ASFV entry and infection. In conclusion, this study identifies for the first time the whole pathway for ASFV entry, including the key cellular factors required for the uptake of the virus and the cell signaling involved.
Project description:Recently moderate-virulence classical swine fever virus (CSFV) strains have been proven capable of generating postnatal persistent infection (PI), defined by the maintenance of viremia and the inability to generate CSFV-specific immune responses in animals. These animals also showed a type I interferon blockade in the absence of clinical signs. In this study, we assessed the infection generated in 7-week-old CSFV PI wild boars after infection with the African swine fever virus (ASFV). The wild boars were divided in two groups and were infected with ASFV. Group A comprised boars who were CSFV PI in a subclinical form and Group B comprised pestivirus-free wild boars. Some relevant parameters related to CSFV replication and the immune response of CSFV PI animals were studied. Additionally, serum soluble factors such as IFN-α, TNF-α, IL-6, IL-10, IFN-γ and sCD163 were analysed before and after ASFV infection to assess their role in disease progression.After ASFV infection, only the CSFV PI wild boars showed progressive acute haemorrhagic disease; however, the survival rates following ASFV infection was similar in both experimental groups. Notwithstanding, the CSFV RNA load of CSFV PI animals remained unaltered over the study; likewise, the ASFV DNA load detected after infection was similar between groups. Interestingly, systemic type I FN-α and IL-10 levels in sera were almost undetectable in CSFV PI animals, yet detectable in Group B, while detectable levels of IFN-γ were found in both groups. Finally, the flow cytometry analysis showed an increase in myelomonocytic cells (CD172a+) and a decrease in CD4+ T cells in the PBMCs from CSFV PI animals after ASFV infection.Our results showed that the immune response plays a role in the progression of disease in CSFV subclinically infected wild boars after ASFV infection, and the immune response comprised the systemic type I interferon blockade. ASFV does not produce any interference with CSFV replication, or vice versa. ASFV infection could be a trigger factor for the disease progression in CSFV PI animals, as their survival after ASFV was similar to that of the pestivirus-free ASFV-infected group. This fact suggests a high resistance in CSFV PI animals even against a virus like ASFV; this may mean that there are relevant implications for CSF control in endemic countries. The diagnosis of ASFV and CSFV co-infection in endemic countries cannot be ruled out and need to be studied in greater depth.
Project description:The pandemic spread of African swine fever virus (ASFV) genotype II (GTII) has led to a global crisis. Since the circulating strains are almost identical, time and money have been mis-invested in whole-genome sequencing the last years. New methods, harmonised protocols for sample selection, sequencing, and bioinformatics are therefore urgently needed.
Project description:To identify the potential host protein binding to African swine fever virus MGF360-9L, the 3 × FLAG tag MGF360-9L plasmid and empty FLAG were transfected into PK-15 cells for co-immunoprecipitation and LC-MS analysis. The cell lysates were immunoprecipitated using anti-FLAG antibody. Immunoprecipitation samples of cells transfected with empty FLAG were used as negative controls to eliminate non-specific interactions. LC-MS identified the interaction between MGF360-9L and PK-15 cell proteome. The final MGF360-9L binding protein data eliminated the nonspecific interaction through empty FLAG control. The interactions that remained were analyzed by significance analysis of interactome. Finally, 268 cellular proteins interacting with MGF360-9L were identified.