Estimation of R0 for the Spread of the First ASF Epidemic in Italy from Fresh Carcasses

After fifty years of spread in the European continent, the African swine fever (ASF) virus was detected for the first time in the north of Italy (Piedmont) in a wild boar carcass in December, 2021. During the first six months of the epidemic, the central role of wild boars in disease transmission was confirmed by more than 200 outbreaks, which occurred in two different areas declared as infected. The virus entered a domestic pig farm in the second temporal cluster identified in the center of the country (Lazio). Understanding ASF dynamics in wild boars is a prerequisite for preventing the spread, and for designing and applying effective surveillance and control plans. The aim of this work was to describe and evaluate the data collected during the first six months of the ASF epidemic in Italy, and to estimate the basic reproduction number (R₀) in order to quantify the extent of disease spread. The R₀ estimates were significantly different for the two spatio-temporal clusters of ASF in Italy, and they identified the two infected areas based on the time necessary for the number of cases to double (td) and on an exponential decay model. These results (R₀ = 1.41 in Piedmont and 1.66 in Lazio) provide quantitative knowledge on the epidemiology of ASF in Italy. These parameters could represent a fundamental tool for modeling country-specific ASF transmission and for monitoring both the spread and sampling effort needed to detect the disease early.     

A Naturally Occurring Microhomology-Mediated Deletion of Three Genes in African Swine Fever Virus Isolated from Two Sardinian Wild Boars

African swine fever virus (ASFV) is the etiological agent of a lethal disease of domestic pigs and wild boars. ASF threatens the pig industry worldwide due to the lack of a licensed vaccine or treatment. The disease has been endemic for more than 40 years in Sardinia (Italy), but an intense campaign pushed it close to eradication; virus circulation was last detected in wild boars in 2019. In this study, we present a genomic analysis of two ASFV strains isolated in Sardinia from two wild boars during the 2019 hunting season. Both isolates presented a deletion of 4342 base pairs near the 5′ end of the genome, encompassing the genes MGF 360-6L, X69R, and MGF 300-1L. The phylogenetic evidence suggests that the deletion recently originated within the Sardinia ecosystem and that it is most likely the result of a non-allelic homologous recombination driven by a microhomology present in most Sardinian ASFV genomes. These results represent a striking example of a genomic feature promoting the rapid evolution of structural variations and plasticity in the ASFV genome. They also raise interesting questions about the functions of the deleted genes and the potential link between the evolutionary timing of the deletion appearance and the eradication campaign.     

Lipid metabolism and molecular changes in normal and atherosclerotic vessels.

OBJECTIVES: a positive correlation between cholesterol esterification, acyl-CoA:cholesterol acyltransferase (ACAT), multidrug resistance (MDR1) gene expression and atherosclerotic lesions has been shown in human arteries. The objective of this study was to map the expression of MDR1, ACAT genes and the cholesteryl ester content in normal, atherosclerotic and varicose human vessels. MATERIALS: vascular segments were obtained from seven cadaveric donors, 27 patients undergoing vascular surgery for severe atherosclerotic disease and 11 patients with saphenous vein varicosities. METHODS: lipid analysis and RT-PCR of MDR1 and ACAT mRNAs were performed. RESULTS: an increase in cholesteryl ester content and in ACAT and MDR1 expression was demonstrated in relation to the age in the arteries prone to atherosclerosis; this expression was maximal in arteries from symptomatic patients. In resistant arteries and in veins cholesteryl ester accumulation was rare and light, while ACAT and MDR1 expression was not related to the age of the subjects. CONCLUSIONS: the results showed that an increase in MDR1 and ACAT expression may be responsible for the accumulation of cholesteryl esters as well as for cell growth rate acceleration in vessel sites prone to atherosclerosis.     

An update on the toxicity of Aβ in Alzheimer’s disease

Alzheimer’s disease is characterized histopathologically by deposition of insoluble forms of the peptide Aβ and the protein tau in brain. Aβ is the principal component of amyloid plaques and tau of neurofibrillary tangles. Familial cases of AD are associated with causal mutations in the gene encoding the amyloid precursor protein, APP, from which the amyloidogenic Aβ peptide is derived, and this supports a role for Aβ in disease. Aβ can promote tau pathology and at the same time its toxicity is also tau-dependent. Aβ can adopt different conformations including soluble oligomers and insoluble fibrillar species present in plaques. We discuss which of these conformations exert toxicity, highlight molecular pathways involved and discuss what has been learned by applying functional genomics.     

In vitro characterisation of BF227 binding to α-synuclein/Lewy bodies

Amyloid-β (Aβ) plaques are a pathological hallmark of Alzheimer's disease and a current target for positron emission tomography (PET) imaging agents. Whilst [¹¹C]-PiB is currently the most widely used PET ligand in clinic, a novel family of benzoxazole compounds have shown promise as Aβ imaging agents; particularly BF227. We characterised the in vitro binding of [¹⁸F]-BF227 toward α-synuclein to address its selectivity for Aβ pathology, to establish whether [¹⁸F]-BF227 binds to α-synuclein/Lewy bodies, in addition to Aβ plaques. In vitro [¹⁸F]-BF227 saturation studies were conducted with 200 nM α-synuclein or Aβ₁₋₄₂ fibrils or 100 μg of Alzheimer's disease, pure dementia with Lewy bodies or control brain homogenates. Non-specific binding was established with PiB (1 μM). In vitro binding studies indicated that [¹⁸F]-BF227 binds with high affinity to two binding sites on Aβ₁₋₄₂ fibrils (K_D1 = 1.31 and K_D2 = 80 nM, respectively) and to one class of binding sites on α-synuclein fibrils (K_D = 9.63nM). [¹⁸F]-BF227 bound to Aβ-containing Alzheimer's disease brain (K_D = 25 ± 0.5 nM), but failed to bind to Aβ-free dementia with Lewy bodies or age-matched control homogenates. Moreover, BF227 labelled both Aβ plaques and Lewy bodies in immunohistochemical/fluorescence analysis of human Alzheimer's disease and Parkinson's disease brain sections, respectively. This study suggests that [¹⁸F]-BF227 is not Aβ-selective. Evaluation of BF227 as a potential biomarker for Parkinson's disease is warranted.     

Correct heteroduplex formation for mutation detection analysis.

BACKGROUND: The majority of mutation detection methods for unknown mutations are polymerase chain reaction (PCR)-based methods dependent on the formation of heteroduplexes between wild-type and mutant strands of DNA. METHODS AND RESULTS: This report discusses the difficulties associated with forming heteroduplexes with a large DNA fragment and the implications for subsequent mutation detection by the chemical cleavage of mismatch technique and other methods reliant on heteroduplex formation. It was found that the size and sequence context of the fragment being investigated inhibited correct heteroduplex formation. The problem was overcome by dividing the sequence into two overlapping fragments. CONCLUSIONS: Early identification of this problem in other fragments will help with the rapid optimization of PCR-based mutation detection methods.     

Distribution of HLA alleles and haplotypes in the Maldivian population

The study of human leukocyte antigen (HLA), allele and haplotype frequencies within populations provides an important source of information for anthropological investigation, organ and hematopoietic stem-cell transplantation purposes as well as disease association studies. As of today, there are no data available in the literature on the HLA structure of the Maldivian population. Altogether 106 families were studied. We used the parents of each family (212 unrelated individuals) to analyze the frequencies of HLA class I and class II allele groups and haplotypes.     

Sheep embryonic stem‐like cells transplanted in full‐thickness cartilage defects

Articular cartilage regeneration is limited. Embryonic stem (ES) cell lines provide a source of totipotent cells for regenerating cartilage. Anatomical, biomechanical, physiological and immunological similarities between humans and sheep make this animal an optimal experimental model. This study examines the repair process of articular cartilage in sheep after transplantation of ES‐like cells isolated from inner cell masses (ICMs) derived from in vitro‐produced (IVP) vitrified embryos. Thirty‐five ES‐like colonies from 40 IVP embryos, positive for stage‐specific embryonic antigens (SSEAs), were pooled in groups of two or three, embedded in fibrin glue and transplanted into osteochondral defects in the medial femoral condyles of 14 ewes. Empty defect (ED) and cell‐free glue (G) in the controlateral stifle joint served as controls. The Y gene sequence was used to detect ES‐like cells in the repair tissue by in situ hybridization (ISH). Two ewes were euthanized at 1 month post‐operatively, three each at 2 and 6 months and four at 12 months. Repairing tissue was examined by biomechanical, macroscopic, histological, immunohistochemical (collagen type II) and ISH assays. Scores of all treatments showed no statistical significant differences among treatment groups at a given time period, although ES‐like grafts showed a tendency toward a better healing process. ISH was positive in all ES‐like specimens. This study demonstrates that ES‐like cells transplanted into cartilage defects stimulate the repair process to promote better organization and tissue bulk. However, the small number of cells applied and the short interval between surgery and euthanasia might have negatively affected the results. Copyright © 2009 John Wiley & Sons, Ltd.     

Inhibition of platelet activation by the Alzheimer's disease amyloid precursor protein

The amyloid precursor protein (APP) of Alzheimer's disease is abundantly expressed in the platelet α-granule where its role remains unclear. This study describes a novel function for APP in regulating human platelet activation. Preincubation of platelet-rich plasma with recombinant secreted APP (sAPP) isoforms dose-dependently inhibited platelet aggregation and secretion induced by ADP or adrenaline. Similarly, sAPP potently inhibited low-dose thrombin-induced activation in washed platelet suspensions, indicating that the activity does not require plasma cofactors. There were no functional differences between sAPP forms with or without the Kunitz protease inhibitor domain or derived from either α- or β-secretase cleavage. In fact, the N-terminal cysteine-rich region of APP (residues 18–194) was as effective as the entire sAPP region in the inhibition of platelet activation. The inhibitory activity of sAPP correlated with a significant reduction in the agonist-induced production of the arachidonic acid (AA) metabolites thromboxane B₂ and prostaglandin E₂. However, sAPP did not affect AA-induced platelet aggregation or secretion, indicating the enzymatic conversion of AA was not inhibited. The addition of a threshold dose of AA reversed the sAPP-inhibition of agonist-induced platelet activation. This suggests that sAPP decreases the availability of free AA, although the mechanism is not yet known. These data provide evidence that the release of sAPP upon platelet degranulation may result in negative feedback regulation during platelet activation.