Pasteur Hellenic Institute

Wild birds are increasingly recognized as contributors to the circulation and environmental dissemination of zoonotic pathogens, yet data from Greece remain limited, particularly for raptors, corvids, and water birds. This study investigated selected parasitic, mycotic, and bacterial pathogens of public health relevance in free-living wild birds originating from various regions of Greece and admitted to two animal health care facilities. Between November 2023 and May 2025, cloacal swabs from 212 injured or sick birds were analyzed using quantitative PCR for Cryptococcus spp., Chlamydia psittaci, Giardia duodenalis, Cryptosporidium spp., and Mycobacterium avium. At least one pathogen was detected in 37 samples (17.5%), with Cryptococcus spp. being the most frequent agent (11.8%), followed by C. psittaci (3.8%), G. duodenalis (0.9%), and Cryptosporidium spp. (0.9%). M. avium was not detected. Pathogen occurrence varied by bird category, genus, and region, and was associated with health status. To the best of our knowledge, this study provides the first molecular evidence worldwide of G. duodenalis in Ardea spp., Cryptosporidium spp. in Asio otus, and C. psittaci in Botaurus stellaris and Plegadis falcinellus. These findings highlight wild birds as potential zoonotic reservoirs and support the implementation of One Health-oriented surveillance programs.

The interface between wild boar and domestic pigs represents is a critical hotspot for the spillover and spillback of several diseases, including brucellosis. This cross-sectional study assessed the seroprevalence of Brucella spp. and B. suis in swine at the wildlife-livestock interface in northeast Portugal, focusing on wild boar and the autochthonous Bísaro pig breed. Antibodies against Brucella spp. were detected in 25.7 % of wild boar (95/370; 95 % CI: 21.2 %-30.1 %) and 15.2 % of Bísaro pigs (35/231; 95 % CI: 10.5 %-19.8 %). Among these, 82 wild boar and 33 domestic pigs tested positive for B. suis, with molecular confirmation in three domestic pigs, marking the first molecular identification of B. suis in Bísaro pigs. Spatial analysis revealed distinct B. suis prevalence, higher in wild boar in the northwest and in domestic pigs in the southeast. A significant positive correlation between the spatial distributions suggests potential transmission at the wildlife-livestock interface. Environmental and anthropogenic factors showed moderate correlation with B. suis prevalence, suggesting a link to animals' overpopulation. Additionally, prevalence was positively associated with pig farms land elevation and negatively with dense shrublands coverage/areas, reinforcing the role of farming practices in pathogen spillover. These findings highlight the multifactorial nature of B. suis distribution, shaped by both ecological and human-driven landscape features. Given the zoonotic potential, this study underscores the urgent need for integrated One Health surveillance and control strategies to mitigate public health risks in rural communities and safeguard animal and human health at both regional and national level.

Alpha-Synuclein (αSyn) plays a central role in Parkinson's disease (PD), and the p.A53T mutation causes an early-onset familial form of PD with severe manifestations. While its effects on neurons are well studied, its consequences on astrocytes and astrocytic contribution to PD pathology are understudied. Here, we differentiated patient-derived p.A53T-αSyn induced pluripotent stem cells (iPSC) to ventral midbrain astrocytes and characterized them via comprehensive molecular, functional, and proteomic analyses. Gene-corrected and healthy iPSC-derived astrocytes served as controls. To assess the effects of p.A53T-αSyn astrocytes on dopamine neurons, we established neuron-astrocyte cocultures of iPSC-derived control and mutant cells at all combinations. Our analyses uncovered cell-intrinsic pathologies in p.A53T-αSyn astrocytes, such as calcium dyshomeostasis, and accumulation of protein aggregates including those of phosphorylated αSyn. Proteomic and mechanistic studies demonstrated perturbed protein catabolic processes, with associated disturbances in lysosomal function and mTOR signaling. These deficits reduced the endocytic clearance capacity of p.A53T-αSyn astrocytes and their ability to process exogenous αSyn cargo. p.A53T-αSyn dopamine neurons cocultured with p.A53T-αSyn astrocytes displayed Lewy-like pathologies, mirroring the histopathological hallmarks identified in postmortem PD brains and exacerbated neurodegeneration, in anatomical and functional aspects. Control astrocytes mitigated these pathologies, highlighting their neuroprotective role. Additionally, p.A53T-αSyn astrocytes induced PD-relevant pathology ιn control neurons. Our findings, validated using an isogenic pair, demonstrate a critical impact of p.A53T-αSyn in disrupting astrocytic protein quality control mechanisms and establish astrocytes as active contributors to PD neuropathology. Our two-dimensional coculture model reflects key aspects of PD pathology, offering a relevant platform for mechanistic and drug discovery studies.

A rise of intensive Mediterranean aquaculture has been associated with vulnerability to bacterial infections, necessitating alternative approaches to conventional antibiotics. This study evaluated the antibacterial and bactericidal activity of essential oils derived from fifteen medicinal plants against four key bacterial pathogens affecting Mediterranean marine aquaculture: Aeromonas veronii biovar veronii, Aeromonas veronii biovar sobria, Vibrio harveyi, and Tenacibaculum maritimum. Essential oils were screened using disc diffusion assays, and the most effective oils—thyme, oregano, cinnamon, and absinthe—underwent further evaluation through broth microdilution methods. Results demonstrated that these four oils exhibited notable inhibitory and bactericidal effects, with thyme and oregano showing the strongest overall activity across multiple pathogens. Notably, this is among the first studies to document the in vitro efficacy of essential oils against Tenacibaculum maritimum, a major pathogen with limited treatment options. The findings support the potential use of selected essential oils as sustainable and natural antibacterial agents in fish health management, contributing to reduced reliance on antibiotics in aquaculture.

Background and ObjectivesMyasthenia gravis (MG) is a chronic antibody-mediated autoimmune neuromuscular disorder causing fluctuating muscle weakness due to autoantibodies that target the acetylcholine receptor (AChR) in the neuromuscular junction (NMJ). Despite extensive research, MG remains unpredictable and heterogeneous, underscoring the need for better insight into disease pathogenesis and clinical course. The objective of this study was to identify clinical and immunologic disease-related parameters that correlate with disease severity.MethodsThis large-scale, multicenter, cross-sectional study included prospectively recruited patients with MG and MG serum samples procured from reputable biobanks. Inclusion criteria required an MG clinical presentation and a positive anti-AChR immunoglobulin G (IgG) titer (≥0.5 nM), confirmed by 2 independent tests. Enrolled patients underwent profiling of subunit-specific anti-AChR IgG titers. Disease severity patterns and their relation to age, sex, disease onset, thymic involvement, anti-AChR titer, and anti-AChR subunit immunodominance were investigated.ResultsThe study included 513 patients with MG (50.5% female) with a median age of 64 years (range 14–98.5). Extended clinical data were available for 232 patients. Anti-AChR titers increased monotonically with disease severity (ρ = 0.31, 95% CI 0.17–0.44, p < 0.0001) and were higher in female patients (median 14.6 nM vs 7.7 nM, 95% CI for Δ 2.1–7.3 nM, p < 0.0001) in whom higher antibody titers decreased monotonically with age. Male patients' titers were predominantly alpha-immunodominant (male 23.2% vs female 16.6%, 95% CI for Δ 0%–7.6%, p = 0.031), while female patients' titers were gamma-immunodominant (female 30% vs male 24.5%, 95% CI for Δ 2%–11%, p = 0.0027). Gamma immunodominance correlated with higher anti-AChR titer (ρ = 0.25, 95% CI 0.16–0.33, p < 0.0001) and severe (Myasthenia Gravis Foundation of America IV–V) disease (44% vs 27%, 95% CI for Δ 4%–34%, p = 0.0141). Unsupervised principal component analysis disclosed 2 distinct disease endotypes: female patients with moderate to severe early-onset MG, gamma subunit immunodominance, high anti-AChR titers, and frequent thymic hyperplasia (endotype A) and the remaining patients, mostly patients with late-onset MG, alpha subunit immunodominance, and low anti-AChR titers (endotype B).DiscussionTwo distinct MG endotypes emerge based on sex, age, thymic involvement, autoantibody titer, and immunoglobulin AChR subunit immunodominance—suggesting different underlying etiologies with potential implications for sex-dependent precision medicine, women's health, and the development of new therapeutic modalities for MG.

Viral nervous necrosis, caused by the nervous necrosis virus (NNV), is an important threat to aquaculture, causing great economic losses and a high environmental burden. European sea bass (Dicentrarchus labrax) is highly affected by NNV, and selective breeding programs for disease resistance have been established in order to achieve a sustainable aquaculture and minimize the need for vaccines, drugs and antibiotics. Resistant and susceptible European sea bass were experimentally challenged with NNV and their head kidney transcriptomes were analyzed at three time points, i.e., 3 hpi, 2 dpi and 14 dpi. Numerous differentially expressed genes (DEGs) were identified in the head kidneys of resistant and susceptible infected vs. non-infected sea bass. Gene ontology enrichment, pathway, and protein–protein interaction analyses revealed that the NNV-resistant fish control their response to viral infection more efficiently, utilizing different mechanisms compared to the susceptible fish. Resistant fish displayed higher levels of interferon-related elements, cytokines, antigen presentation, T-cell activity, apoptosis, and programmed cell death combined with a controlled inflammatory response and more active proteasome and lysosome functions. The susceptible fish appeared to have high immune responses at the early infection stages, accompanied by high expressions of inflammatory, complement and coagulation pathways. Insulin metabolism was better regulated in the resistant fish and the control of lipid metabolism was less effective in the susceptible family. The cytoskeleton- and cell adhesion-related pathways were mostly down-regulated in the susceptible fish, and the intracellular transport and motor proteins were utilized more efficiently by the resistant fish. The present study represents a thorough transcriptomic analysis of NNV infection effects on a resistant and a susceptible European sea bass head kidney. The obtained results provide valuable information on the mechanisms that offers pathogen resistance to a host, with many aspects that can be exploited to develop more efficient approaches to fighting viral diseases in aquaculture.

Polyphenolic compounds, commonly found in Greek medicinal plants, exhibit promising antiviral and antioxidant properties, making them potential candidates for therapeutic purposes. This study aims to evaluate the antiviral activity of nine selected polyphenols against Dengue virus (DENV) and Yellow Fever virus (YFV) life cycles, alongside their antioxidant capacity determined by the DPPH method and the ABTS assay, and their ability to inhibit DNA strand scission induced by peroxyl radicals. Kaempferol and caffeic acid demonstrated the most potent inhibitory effects on DENV genome replication, while coumaric acid blocked viral entry more effectively. Notably, among the nine compounds, kaempferol exhibited the strongest anti-DENV effect, especially at the level of virus-released infectivity, showing the lowest EC50 (3.55 μΜ) and the highest selectivity index (SI = 25.45). In contrast, none of the compounds showed significant antiviral activity against YFV genome replication. Concomitantly, caffeic acid and kaempferol had the highest radical scavenging activity (DPPH and ABTS assays), highlighting their dual properties. Moreover, DNA scission inhibition assays confirmed the strong antioxidant potential of all tested compounds, with caffeic acid and kaempferol achieving the highest inhibition rate of 98.98% and 97.34% respectively. These findings underscore the potential of specific polyphenols, particularly kaempferol and caffeic acid, as antiviral and antioxidant agents targeting DENV and oxidative stress-related damage.

New genes can emerge de novo from non-genic genomic regions. In budding yeast, computational predictions have shown that intergenic regions harbour a higher-than-expected propensity to encode transmembrane domains, if theoretically translated into proteins. This propensity seems to be linked to the high prevalence of predicted transmembrane domains in evolutionarily young genes. However, what accounts for this enriched propensity is not known. Here, we show that specific arrangements of polyA/T tracts, which are abundant and enriched in yeast intergenic regions, explain this observation. These tracts are known to function as nucleosome-depleted regions, which prevent or reduce nucleosome formation to enable transcription of surrounding genes. We provide evidence that these polyA/T tracts have been repeatedly coopted through de novo gene emergence for the evolution of novel small genes encoding proteins with predicted transmembrane domains. These findings support a previously proposed "transmembrane-first" model of de novo gene birth and help explain why evolutionarily young yeast genes are rich in transmembrane domains. They contribute to our understanding of the process of de novo gene evolution and show how seemingly distinct but potentially interacting levels of functionality can exist within the same genomic loci.