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Publication
Journal: PLoS ONE
May/17/2016
Abstract
Most Phytophthora hybrids characterized to date have emerged from nurseries and managed landscapes, most likely generated as a consequence of biological invasions associated with the movement of living plants and germplasm for ornamental, horticultural and agricultural purposes. Presented here is evidence for natural hybridization among a group of five closely related indigenous clade 6 Phytophthora species isolated from waterways and riparian ecosystems in Western Australia. Molecular characterization of hybrids consisted of cloning and sequencing two nuclear genes (ITS and ASF), sequencing of two further nuclear loci (BT and HSP) and of two mitochondrial loci (COI and NADH). Additionally, phenotypic traits including morphology of sporangia and optima and maxima temperatures for growth were also determined. In most cases the nuclear genes were biparentally and in all cases the mtDNA were uniparentally inherited, indicating hybrid formation through sexual crosses. Some isolates bear the molecular signature of three parents suggesting additional hybrid events, although it cannot be determined from the data if these were sequential or simultaneous. These species and their hybrids co-exist in riparian ecosystems and waterways where their ability for rapid asexual proliferation would enable them to rapidly colonize green plant litter. The apparent ease of hybridization could eventually lead to the merging of species through introgression. However, at this point in time, species integrity has been maintained and a more likely scenario is that the hybrids are not stable evolutionary lineages, but rather transient hybrid clones.
Publication
Journal: PLoS ONE
March/4/2014
Abstract
African swine fever (ASF) is a highly lethal disease of domestic pigs caused by the only known DNA arbovirus. It was first described in Kenya in 1921 and since then many isolates have been collected worldwide. However, although several phylogenetic studies have been carried out to understand the relationships between the isolates, no molecular dating analyses have been achieved so far. In this paper, comprehensive phylogenetic reconstructions were made using newly generated, publicly available sequences of hundreds of ASFV isolates from the past 70 years. Analyses focused on B646L, CP204L, and E183L genes from 356, 251, and 123 isolates, respectively. Phylogenetic analyses were achieved using maximum likelihood and Bayesian coalescence methods. A new lineage-based nomenclature is proposed to designate 35 different clusters. In addition, dating of ASFV origin was carried out from the molecular data sets. To avoid bias, diversity due to positive selection or recombination events was neutralized. The molecular clock analyses revealed that ASFV strains currently circulating have evolved over 300 years, with a time to the most recent common ancestor (TMRCA) in the early 18(th) century.
Publication
Journal: PLoS ONE
April/5/2018
Abstract
African swine fever (ASF) is a complex infectious disease of swine that constitutes devastating impacts on animal health and the world economy. Here, we investigated the evolutionary epidemiology of ASF virus (ASFV) in Eurasia and Africa using the concatenated gene sequences of the viral protein 72 and the central variable region of isolates collected between 1960 and 2015. We used Bayesian phylodynamic models to reconstruct the evolutionary history of the virus, to identify virus population demographics and to quantify dispersal patterns between host species. Results suggest that ASFV exhibited a significantly high evolutionary rate and population growth through time since its divergence in the 18th century from East Africa, with no signs of decline till recent years. This increase corresponds to the growing pig trade activities between continents during the 19th century, and may be attributed to an evolutionary drift that resulted from either continuous circulation or maintenance of the virus within Africa and Eurasia. Furthermore, results implicate wild suids as the ancestral host species (root state posterior probability = 0.87) for ASFV in the early 1700s in Africa. Moreover, results indicate the transmission cycle between wild suids and pigs is an important cycle for ASFV spread and maintenance in pig populations, while ticks are an important natural reservoir that can facilitate ASFV spread and maintenance in wild swine populations. We illustrated the prospects of phylodynamic methods in improving risk-based surveillance, support of effective animal health policies, and epidemic preparedness in countries at high risk of ASFV incursion.
Publication
Journal: Virus Research
November/26/2018
Abstract
African swine fever (ASF) is a devastating viral disease of domestic pigs and wild boar for which there is no vaccine available. The aetiological agent ASF virus (ASFV) has a predilection for cells of the myeloid lineage. Macrophages provide a first line defence against pathogens and are the main target of ASFV, thus several studies analysed their response to infection in terms of cytokine/chemokine expression and modulation of functionality. These studies have typically used macrophages differentiated in vitro from blood or bone marrow progenitors and few studies have focused on responses of polarized macrophages (M1, M2) or functional macrophage subsets isolated from different tissues. ASFV can also infect dendritic cells (DC), but regardless of their central role in the induction of adaptive immune responses, their role in ASFV infection was only partially analysed. Future studies on ASFV-DC interaction are needed, which should take into consideration the heterogeneity within this family, composed of different subsets whose phenotype is also organ specific. Other porcine immune cells such as γδ-T cells, NK cells and fibrocytes, can act as 'non-conventional' antigen-presenting cells (APCs). In particular, γδ-T cells from ASFV immune pigs were shown to present viral antigens to T cells, but no studies have further explored the interaction of ASFV with this cell type or other non-conventional APCs. In this review we will provide an overview of the interaction of APCs with ASFV, describing the differences between virulent and attenuated strains, and suggesting areas for possible future studies.
Publication
Journal: Vaccines
September/15/2020
Abstract
African swine fever (ASF) severely threatens the swine industry worldwide, given its spread and the absence of an available licensed vaccine, and has caused severe economic losses. Its persistence in wild boar (WB), longer than in domestic pig farms, and the knowledge gaps in ASF epidemiology hinder ASF virus (ASFV) eradication. Even in areas where disease is effectively controlled and ASFV is no longer detected, declaring eradication is difficult as seropositive WBs may still be detected. The aim of this work was to estimate the main ASF epidemiological parameters specific for the north of Sardinia, Italy. The estimated basic (R0) and effective (Re) reproduction numbers demonstrate that the ASF epidemic is declining and under control with an R0 of 1.139 (95% confidence interval (CI) = 1.123-1.153) and Re of 0.802 (95% CI = 0.612-0.992). In the last phases of an epidemic, these estimates are crucial tools for identifying the intensity of interventions required to definitively eradicate the disease. This approach is useful to understand if and when the detection of residual seropositive WB is no longer associated with any further ASFV circulation.
Keywords: Sardinia; african swine fever; basic reproduction number; disease transmission; epidemiology; force of infection; wild boar.
Publication
Journal: Polymers
May/14/2020
Abstract
Eco-efficient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coefficient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E', with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects.
Publication
Journal: Plant Foods for Human Nutrition
June/3/2014
Abstract
Avocado seed contains elevated levels of phenolic compounds and exhibits antioxidant properties. We investigated the effect of Avocado Seed Flour (ASF) on the lipid levels in mice on a hyperlipidemic diet. The concentration of phenols was determined by high-performance liquid chromatography, antioxidant activity was evaluated using the Trolox equivalent antioxidant capacity method, and dietary fiber was measured using the Association of Official Analytical Chemists (AOAC) method. The LD50 of ASF was determined using Lorke's method and hypolipidemic activity was evaluated in a hypercholesterolemic model in mice. Protocatechuic acid was the main phenolic compound found in ASF, followed by kaempferide and vanillic acid. The total phenolic content in the methanolic extract of ASF was 292.00 ± 9.81 mg gallic acid equivalents/g seed dry weight and the antioxidant activity resulted in 173.3 μmol Trolox equivalents/g DW. In addition, a high content of dietary fiber was found (34.8%). The oral LD50 for ASF was 1767 mg/kg body weight, and treatment with ASF significantly reduced the levels of total cholesterol, LDL-C, and prediction of the atherogenic index. Therefore, the antioxidant activity of phenolic compounds and dietary fiber in ASF may be responsible for the hypocholesterolemic activity of ASF in a hyperlipidemic model of mice.
Publication
Journal: Atherosclerosis
February/28/2008
Abstract
Cholesterol ester transfer protein (CETP) plays a key role in remodeling triglyceride-rich particles and high-density lipoproteins (HDL). We investigated CETP sequence variants in response to long-term overfeeding (100 days) in 12 pairs of male monozygotic twins (mean age+/-S.D.: 21+/-2 years). Body fat mass (FM), abdominal subcutaneous (<em>ASF</em>) and visceral fat (AVF), and plasma lipoproteins were determined. The CETP variants C>T/In9 (rs289714) and G>A/Ex14 (rs5882, or I405V) were investigated by RFLP-PCR methodologies. Before overfeeding, the CETP CC/In9 (n=18) genotype was associated with lower FM compared to the C>T/In9 heterozygotes. Overfeeding induced more FM and <em>ASF</em> accretion in C>T/In9 carriers (P<or=0.05). CETP V405V homozygotes (n=8) had lower BMI, FM, and <em>ASF</em> before overfeeding than those with the I405I (n=6) or I405V (n=10) genotypes. However, V405V subjects had the largest gain in AVF with overfeeding (P=0.02). Decreases from baseline were significantly different across the I405V genotypes for HDL-C, HDL-Apo AI, HDL(2), and HDL(3) (P<or=0.05). Our data suggests that CETP sequence variation contributes to the undesirable changes in adiposity and HDL-C levels when exposed to excessive calorie consumption and may be potentially helpful to identify individuals with the metabolic syndrome who are at higher risk of cardiovascular disease.
Publication
Journal: Virus Research
July/22/2019
Abstract
African swine fever virus (ASFV) is the only known DNA arbovirus, and the ability to replicate efficiently in both insect and mammalian cells is encoded in its viral genome. Despite having a relatively low overall genomic mutation rate, ASFV demonstrates genetic diversity in certain genes and complexity in gene content in other genomic regions, indicating that ASFV may exploit multiple mechanisms for diversification and acquire new phenotype characteristics. ASFV antigenic diversity is reflected in the ability to type cross-protective viruses together into serogroups, largely based on antibody-mediated inhibition of hemadsorption. Here we review ASFV genetic signatures of ASFV type specificity, genome variability, and the hemadsorption as a means of defining virus antigenic type, and how these may be used toward defining antigenic and phenotypic diversity that is problematic for development of vaccine solutions to ASF.
Publication
Journal: Transboundary and Emerging Diseases
October/20/2020
Abstract
African swine fever (ASF) has spread across many countries in Europe since the introduction into Georgia in 2007. We report here on the first cases of ASF in wild boar detected in Germany close to the border with Poland. In addition to the constant risk of ASF virus (ASFV) spread through human activities, movements of infected wild boar also represent a route of introduction. Since ASF emerged in Western Poland in November 2019, surveillance efforts, in particular examination of wild boar found dead, were intensified in the regions of Germany bordering with Poland. The first case of ASF in wild boar in Germany was therefore detected by passive surveillance and confirmed on 10th September 2020. By 24th September 2020, 32 cases were recorded. Testing of samples from tissues of carcasses in different stages of decomposition yielded cycle threshold values from 18 to 36 in the OIE-recommended PCR which were comparable between the regional and national reference laboratory. Blood swabs yielded reliable results, indicating that the method is suitable also under outbreak conditions. Phylogenetic analysis of the ASFV whole-genome sequence generated from material of the first carcass detected in Germany, revealed that it groups with ASFV genotype II including all sequences from Eastern Europe, Asia and Belgium. However, some genetic markers including a 14 bp tandem repeat duplication in the O174L gene were confirmed that have so far been detected only in sequences from Poland (including Western Poland). Epidemiological investigations that include estimated postmortem intervals of wild boar carcasses of infected animals suggest that ASFV had been introduced into Germany in the first half of July 2020 or even earlier.
Keywords: African swine fever; Germany; epidemiology; first case; virus sequence.
Publication
Journal: Vaccines
September/23/2020
Abstract
African swine fever virus (ASFV), the cause of a devastating disease affecting domestic and wild pigs, has been present in Sardinia since 1978. In the framework of the regional ASF eradication plan, 4484 illegal pigs were culled between December 2017 and February 2020. The highest disease prevalence was observed in the municipality with the highest free-ranging pig density, and culling actions drastically reduced ASFV circulation among these animals. ASFV-antibody were detected in 36.7% of tested animals, which were apparently healthy, thus, the circulation of low-virulence ASFV isolates was hypothesized. ASFV genome was detected in 53 out of 2726 tested animals, and virus isolation was achieved in two distinct culling actions. Two ASFV haemadsorbing strains were isolated from antibody-positive apparently healthy pigs: 55234/18 and 103917/18. Typing analysis revealed that both isolates belong to p72 genotype I, B602L subgroup X; phylogenetic analysis based on whole genome sequencing data showed that they were closely related to Sardinian ASFV strains collected since 2010, especially 22653/Ca/2014. Our data suggested the absence of immune-escaped ASFV variants circulating among free-ranging pigs, indicating that other elements contributed to virus circulation among these animals. Understanding factors behind disease persistence in endemic settings might contribute to developing effective countermeasures against this disease.
Keywords: African swine fever virus; Sardinia; eradication; free-ranging pigs; genotype I; haemadsorbing; next-generation sequencing.
Publication
Journal: Frontiers in Cellular and Infection Microbiology
February/12/2019
Abstract
There are 17 human-biting ticks known in Australia. The bites of Ixodes holocyclus, Ornithodoros capensis, and Ornithodoros gurneyi can cause paralysis, inflammation, and severe local and systemic reactions in humans, respectively. Six ticks, including Amblyomma triguttatum, Bothriocroton hydrosauri, Haemaphysalis novaeguineae, Ixodes cornuatus, Ixodes holocyclus, and Ixodes tasmani may transmit Coxiella burnetii, Rickettsia australis, Rickettsia honei, or Rickettsia honei subsp. marmionii. These bacterial pathogens cause Q fever, Queensland tick typhus (QTT), Flinders Island spotted fever (FISF), and Australian spotted fever (ASF). It is also believed that babesiosis can be transmitted by ticks to humans in Australia. In addition, Argas robertsi, Haemaphysalis bancrofti, Haemaphysalis longicornis, Ixodes hirsti, Rhipicephalus australis, and Rhipicephalus sanguineus ticks may play active roles in transmission of other pathogens that already exist or could potentially be introduced into Australia. These pathogens include Anaplasma spp., Bartonella spp., Burkholderia spp., Francisella spp., Dera Ghazi Khan virus (DGKV), tick-borne encephalitis virus (TBEV), Lake Clarendon virus (LCV), Saumarez Reef virus (SREV), Upolu virus (UPOV), or Vinegar Hill virus (VINHV). It is important to regularly update clinicians' knowledge about tick-borne infections because these bacteria and arboviruses are pathogens of humans that may cause fatal illness. An increase in the incidence of tick-borne infections of human may be observed in the future due to changes in demography, climate change, and increase in travel and shipments and even migratory patterns of birds or other animals. Moreover, the geographical conditions of Australia are favorable for many exotic ticks, which may become endemic to Australia given an opportunity. There are some human pathogens, such as Rickettsia conorii and Rickettsia rickettsii that are not currently present in Australia, but can be transmitted by some human-biting ticks found in Australia, such as Rhipicephalus sanguineus, if they enter and establish in this country. Despite these threats, our knowledge of Australian ticks and tick-borne diseases is in its infancy.
Publication
Journal: Journal of Biological Chemistry
August/31/2015
Abstract
In order to identify cellular factors that regulate human papillomavirus type 16 (HPV16) gene expression, cervical cancer cells permissive for HPV16 late gene expression were identified and characterized. These cells either contained a novel spliced variant of the L1 mRNAs that bypassed the suppressed HPV16 late, 5'-splice site SD3632; produced elevated levels of RNA-binding proteins SRSF1 (ASF/SF2), SRSF9 (SRp30c), and HuR that are known to regulate HPV16 late gene expression; or were shown by a gene expression array analysis to overexpress the RALYL RNA-binding protein of the heterogeneous nuclear ribonucleoprotein C (hnRNP C) family. Overexpression of RALYL or hnRNP C1 induced HPV16 late gene expression from HPV16 subgenomic plasmids and from episomal forms of the full-length HPV16 genome. This induction was dependent on the HPV16 early untranslated region. Binding of hnRNP C1 to the HPV16 early, untranslated region activated HPV16 late 5'-splice site SD3632 and resulted in production of HPV16 L1 mRNAs. Our results suggested that hnRNP C1 controls HPV16 late gene expression.
Publication
Journal: Transboundary and Emerging Diseases
October/15/2017
Abstract
Smallholder pig production in Uganda is constrained by poor management and high disease burden, with African swine fever (ASF) being one of the most important contributors. However, data to develop appropriate evidence-based disease mitigating interventions along the pig value chain are lacking. This study aimed at determining risk factors associated with the occurrence of outbreaks of ASF in selected districts. A cross-sectional survey of 1195 pig-keeping households in three districts was carried out between April and July 2013. Households were classified into one of three value chain domains (VCDs) based on where the production was located and where most of the products were sold: rural-rural (R-R), rural-urban (R-U) and urban-urban (U-U). Findings revealed that crop farming is the most common primary activity in the R-R and R-U VCDs, while pig keeping was the most common primary activity in the U-U VCDs. Pigs are mostly kept tethered or left to roam in the R-R and R-U VCDs, while in the U-U VCDs, they are mostly confined in corrals. Nearly 20% of the farmers whose farms were hit by an ASF outbreak subsequently sold all their pigs (healthy and sick) to the market in panic. Factors that positively correlated with recent ASF outbreaks were prompt disposal of dead pigs on farms (P < 0.001, OR = 2.3), wild animals present in the village (P < 0.001, OR = 1.7) and farmers sourcing drugs from stockists (P < 0.001, OR = 1.6); while protective factors were the presence of perimeter fences (P = 0.03, OR = 0.5), attendance of farmers at secondary-school level and above (P < 0.001, OR = 0.6), routine cleaning of the pig pens (P < 0.001, OR = 0.6) and pigs being the only livestock kept by farmer (P = 0.01, OR = 0.7). Given the current situation, there is a need to raise awareness among farmers and other value chain actors of biosecurity measures and create incentives for farmers to report ASF cases.
Publication
Journal: Journal of the American Chemical Society
July/24/2005
Abstract
A metallic behavior characterizes a first complete series of 2:1 AsF6- mixed-valence chiral salts of (R)-, (S)-, and racemic (+/-)-tetrathiafulvalene methyl-oxazoline derivatives. The enhanced conductivity of the pure enantiomeric salts, when compared with that of the racemic one, is the likely consequence of the structural disorder observed in the latter.
Publication
Journal: Veterinary Microbiology
May/26/2014
Abstract
African swine fever (ASF) is a viral swine disease against which neither an effective vaccine nor a treatment is available. The antiviral effect of thirty fluoroquinolones on the infectivity of African swine fever virus (ASFV) was screened in vitro. There was a severe reduction of the cytopathic effect in ASFV-infected Vero cells when exposed to six independent fluoroquinolones, or to some of their combinations, from an early phase of infection. Moreover, after 7-day treatments, ASFV genome could not be detected by PCR, and the culture supernatants were unable to infect new cell cultures. Pulsed field gel electrophoresis (PFGE) analysis revealed a diminished viral DNA replication without identifiable genome fragmentation in cells exposed to fluoroquinolones. In parallel, altered patterns of viral protein synthesis were observed from early infection. The overall results indicate that bacterial topoisomerase inhibitors interfere with the ASFV replication cycle probably by targeting a putative ASFV-topoisomerase II, opening a new window for antiviral treatments.
Publication
Journal: BioEssays
April/15/1997
Abstract
SR proteins are essential for the splicing of messenger RNA precursors in vitro, where they also alter splice site selection in a concentration-dependent manner. Although experiments involving overexpression or dominant mutations have confirmed that these proteins can influence RNA processing decisions in vivo, similar results with loss-of-function mutations have been lacking. Now, a system for genetic depletion of the chicken B cell line DT40 has revealed that the SR protein ASF/SF2 (alternative splicing factor/splicing factor 2) is essential for viability in these cells(1). This study opens the way for a complete functional dissection of this protein, and other SR proteins, in vivo.
Authors
Publication
Journal: Analytical Biochemistry
December/22/1992
Abstract
A solid-phase assay for the activity of CMPNeuAc:Gal beta 1-4GlcNAc-R alpha-2,6-sialyltransferase (2,6ST) has been developed. In the assay an acceptor glycoprotein is immobilized onto microtiter plate wells. The two glycoprotein acceptors used were asialofetuin (ASF), which contains oligosaccharides terminating in the sequence Gal beta 1-4GlcNAc-R, and a neoglycoprotein of bovine serum albumin containing covalently attached Gal beta 1-4GlcNAc-R units. Samples containing the donor CMPNeuAc and the 2,6ST were incubated with the immobilized acceptor to generate the product NeuAc alpha 2-6Gal beta 1-4GlcNAc-R. The product was detected by a biotin-streptavidin system using the biotinylated plant lectin Sambucus nigra agglutinin (SNA), which binds to sialic acid in alpha-2,6, but not in alpha-2,3, linkage. The biotinylated SNA bound to the product was then detected with streptavidin and biotinylated forms of either alkaline phosphatase or the recombinant bioluminescent protein aequorin. The assay was optimized with respect to the commercially available 2,6ST and shown to be dependent on the concentration of acceptor and CMPNeuAc and proportional to the 2,6ST activity in the range of 20 to 400 microU in a 1-h assay. The solid-phase assay also allows for the selective detection of 2,6ST activity in human and fetal bovine serum, where the activity was proportional in the range of 0.1 to 2 microliters of serum.
Publication
Journal: PLoS ONE
August/17/2017
Abstract
A stochastic model designed to simulate transmission dynamics of African swine fever virus (ASFV) in a free-ranging pig population under various intervention scenarios is presented. The model was used to assess the relative impact of the timing of the implementation of different control strategies on disease-related mortality. The implementation of biosecurity measures was simulated through incorporation of a decay function on the transmission rate. The model predicts that biosecurity measures implemented within 14 days of the onset of an epidemic can avert up to 74% of pig deaths due to ASF while hypothetical vaccines that confer 70% immunity when deployed prior to day 14 of the epidemic could avert 65% of pig deaths. When the two control measures are combined, the model predicts that 91% of the pigs that would have otherwise succumbed to the disease if no intervention was implemented would be saved. However, if the combined interventions are delayed (defined as implementation from>> 60 days) only 30% of ASF-related deaths would be averted. In the absence of vaccines against ASF, we recommend early implementation of enhanced biosecurity measures. Active surveillance and use of pen-side diagnostic assays, preferably linked to rapid dissemination of this data to veterinary authorities through mobile phone technology platforms are essential for rapid detection and confirmation of ASF outbreaks. This prediction, although it may seem intuitive, rationally confirms the importance of early intervention in managing ASF epidemics. The modelling approach is particularly valuable in that it determines an optimal timing for implementation of interventions in controlling ASF outbreaks.
Publication
Journal: Transboundary and Emerging Diseases
June/8/2017
Abstract
African swine fever (ASF) is a devastating viral disease of swine that is present in both pigs and wild boar in the western part of the Russian Federation and the eastern part of the European Union. It represents a significant threat for the European pig production industry as neither treatment nor vaccine is available. This study analysed the spatial and spatio-temporal distributions of ASF cases that were reported in domestic pigs and wild boar for assessing the likelihood of wild boar-to-domestic pig and farm-to-farm transmission routes in the epidemic that occurred from 2007 to 2014 in the Krasnodar and the Tver regions, two of the most affected areas of the Russian Federation. Results suggest that in both regions, the spatial proximity to an infectious farm was a strong risk factor for infection of a susceptible farm. In the Krasnodar region, the results of the statistical analysis suggest that the epidemics in wild boar and in domestic pigs were independent from each other. In contrast, there seemed to be a dependence between the two epidemics in the Tver region. But because outbreaks in domestic pigs were not statistically significantly clustered around wild boar cases, the joint spatial distribution of wild boar cases and of outbreaks in domestic pigs in the Tver region may be explained by regular spillovers from the domestic pig to the wild boar population. These findings confirm the need to maintain high biosecurity standards on pig farms and justify strict control measures targeted at domestic pig production such as culling of infected herds and local movement restrictions.
Publication
Journal: OIE Revue Scientifique et Technique
April/10/1996
Abstract
A serological survey was conducted in July 1991 on domestic pigs in two areas of southern Malawi which were severely affected by the African swine fever (ASF) epizootic in 1989-1991. Sixty-six of the 216 owners questioned reported having witnessed ASF in their pigs. Forty-seven owners had pigs with antibodies against ASF virus, and the overall prevalence of pigs with anti-ASF virus antibodies was found to be 12.4%, in 445 pigs sampled in 35 villages. Spread of ASF was thought to occur principally through the slaughter and sale of infected animals, and due to the free-ranging of pigs. Permanent penning of pigs significantly reduced the attack rate (chi 2 = 7.59, P < 0.01, 1df) in pig pens in Thyolo, an area where permanent penning of pigs was widely practised. Feeding of kitchen scraps did not appear to have been an important means of virus spread. Ornithodoros ticks were found in only 1 of the 35 villages. Although virus was not isolated from 203 pooled sera from pigs in the Mulanje district or from collected ticks, the seroconversion of a small proportion of pigs born after the last reported date of ASF occurrence suggests that the virus had continued to circulate to a limited extent in this area.
Publication
Journal: Veterinary Immunology and Immunopathology
September/18/2008
Abstract
African swine fever virus (ASFV) induces a variety of immune responses and clinical forms in domestic pigs. As it is the only member of the Asfarviridae family, ASFV encodes many novel genes not encoded by other virus families. Among these genes, A238L may regulate the synthesis of pro-inflammatory cytokines, controlled mainly by NFkappaB and NFAT pathways. In this study, we inoculated two groups of pigs, one with the ASFV highly virulent E-70 isolate, deleted on A238L gene, and the other group with the parental E-70 isolate. No significant differences were observed in the clinical signs or pathology between both groups. However, the TNF-alpha mRNA expression was strongly enhanced in the PBMC from pigs inoculated with the virus deleted in A238L, reinforcing the role of the A238L gene in the inhibition of the NFkappaB pathway of expression of cytokines. No up-regulation of pro-inflammatory cytokines was observed in the PBMC of animals inoculated with the E-70 isolate, even though apoptosis and haemorrhages were evident and might be related to the presence of bystander monocyte-macrophages expressing these cytokines. Other studies using ASFV deleted in other genes inoculated in the natural hosts should be performed to gain further insight into the role of these genes in the pathogenesis of ASF.
Publication
Journal: Veterinary Record
May/16/1974
Publication
Journal: Viruses
September/25/2017
Abstract
African swine fever (ASF) is a devastating disease of domestic pigs. It is a socioeconomically important disease, initially described from Kenya, but subsequently reported in most Sub-Saharan countries. ASF spread to Europe, South America and the Caribbean through multiple introductions which were initially eradicated-except for Sardinia-followed by re‑introduction into Europe in 2007. In this study of ASF within the Democratic Republic of the Congo, 62 domestic pig samples, collected between 2005-2012, were examined for viral DNA and sequencing at multiple loci: C-terminus of the B646L gene (p72 protein), central hypervariable region (CVR) of the B602L gene, and the E183L gene (p54 protein). Phylogenetic analyses identified three circulating genotypes: I (64.5% of samples), IX (32.3%), and XIV (3.2%). This is the first evidence of genotypes IX and XIV within this country. Examination of the CVR revealed high levels of intra-genotypic variation, with 19 identified variants.
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