Emerging Microbes & Infections最新文献

Cardiomyopathy and stroke are major complications of Chagas disease (CD). We investigated if hypercoagulability, endothelial cell (EC) dysfunction, and blood stasis cause cardiac-cerebral fibrinogenesis in CD. C57BL/6 mice infected with Trypanosoma cruzi (Tc) were evaluated at acute (AT), indeterminate (IT), and chronic (CT) stages of CD. Mice were given anti-parasite, bicistronic immunogens (BCV or BCVR) to determine the role of Tc in fibrinogenesis. We monitored (1) platelet and coagulation cascade activation; (2) cardiac-cerebral blood vessels injury; (3) proinflammatory/prothrombotic phenotypes of microglia, macrophages, and vascular cells; and (4) fibrinogenesis. After a quiescent acute phase, plasma levels of coagulation and other factors of platelet activation/aggregation, hypercoagulability, and clotting capacity were increased in IT-CT mice. Proinflammatory and prothrombotic cytokines/chemokines in cardiac-cerebral blood vessels were also significantly increased in IT-CT mice. Loss of cardiac EC and a marked increase in their proinflammatory/cell-adhesion response were not compensated for by a pro-angiogenic/wound-healing response in cardiac-cerebral tissues of infected mice. Microglial proinflammatory activation preceded the vascular inflammation suggesting a feedback cycle of EC activation in brain of infected mice. Treatment with BCV/BCVR controlled the parasite persistence and hypercoagulability/vascular inflammation in infected mice. Importantly, BCV/BCVR treatment abolished the fibrin clots that otherwise were pronounced in heart and brain of IT-CD mice. We conclude that acute Tc infection triggered a subdued hemodynamic disorder, and the persistence of low-grade parasites contributed to a cardiovascular/cerebrovascular proinflammatory and prothrombotic response and fibrin deposition in mice. BCV/BCVR offer potential immunotherapies for reducing the recurrent clot formation and risk of stroke in CD.

H11 avian influenza viruses (AIVs) circulate globally among wild bird populations, yet their evolutionary pathways and risks for zoonotic transmission remain insufficiently characterized. In the current study, analysis of 1,179 H11 hemagglutinin (HA) sequences revealed that dispersal patterns closely follow Eurasian migratory flyways, with Xinjiang identified as a seasonal transit and amplification node. From 2,674 wild-bird samples, two viruses - K77/H11N2 and BL0/H11N3 - were isolated (2/2674, approximately 0.07%). Genomic analyses positioned both viruses within Eurasian wild-bird lineages, exhibiting broad relatedness to AIVs from South Asia, East Asia, Europe, and Antarctica. HA profiles indicated a predominant avian receptor affinity; notably, K77/H11N2 exhibited prominent α2,3 binding as well as weaker, concentration-dependent α2,6 binding, and harboured putative mammalian-adaptive markers PB2-I292V and NP-52H/313F, suggesting potential for enhanced viral fitness in mammalian cells. These markers were absent in BL0/H11N3. In vitro and in vivo analyses revealed greater HA stability, moderate replication in A549 cells, and localized lung inflammation in mice for K77/H11N2, while BL0/H11N3 demonstrated limited replication and minimal pathogenicity. Both viruses achieved systemic dissemination and direct-contact transmission among chickens, corresponding to high poultry seroprevalence rates (up to 65%). Antibodies detected in cattle (3.8%) and camels (∼2%) on farms near migratory-bird habitats provide rare evidence of natural H11 exposure in mammals. Collectively, this study presents the first comprehensive genomic and phenotypic characterization of H11 viruses detected in Xinjiang, underscoring the emergence of an H11N2 strain with limited mammalian adaptation and highlighting the need for intensified surveillance at the wildlife-poultry-livestock interface.

Respiratory infections in calves are a serious problem, particularly as maternal antibodies wane and calves become susceptible to respiratory pathogens, such as bovine respiratory syncytial virus (bRSV) and Mycobacterium bovis (M. bovis), which are two important pathogens affecting animal production. Although there are currently vaccines available against bRSV, their protection is limited. Regarding M. bovis, no vaccines are presently commercially available. However, BCG is being tested experimentally as a vaccine against this microbe. Here, we evaluated the safety and immunogenicity of the rBCG-N-hRSV vaccine against bRSV and M. bovis in 120 Polled Hereford calves in a field study. Each group, consisting of 30 calves, received either rBCG-N-hRSV, a commercial vaccine against bRSV, WT-BCG against M. bovis, or placebo. Calves, aged 14-21 days- received a first dose (day 0), followed by a booster 14 days later. Safety was evaluated by monitoring local and systemic adverse effects and potential transmissibility of the vaccine. Altogether, immune responses against both pathogens were characterized at 0, 14, 28, and 180 days after the first vaccination. The results indicate that rBCG-N-hRSV is safe and elicits a significant increase in antigen-specific IgG2 and IgA antibodies, accompanied by proliferation of CD8⁺ and γδ TCR⁺ T cells, resulting in an antigen-specific activation profile and memory CD4⁺ T cells that remained elevated up to 180 days post-vaccination. These findings suggest that rBCG-N-hRSV elicits a specific immune response against bRSV and M. bovis under field conditions.

Understanding the mechanisms underlying the emergence and spread of high pathogenicity avian influenza virus (HPAIV) is critical for tracking its global dissemination, particularly via migratory seabirds, given their role in transmission over long distances. Scavenging seabirds, such as skuas, may act as both reservoirs and vectors, and have been linked to multiple outbreaks since 2021. Here, we report the detection of HPAIV H5N1 clade 2.3.4.4b in three Tristan skua (Stercorarius antarcticus hamiltoni) carcasses on Gough Island in the central South Atlantic Ocean. To investigate potential incursion routes, we combined genomic analyses with year-round tracking data from global location sensors. Although migratory movement patterns suggested southern Africa as the most obvious pathway, the strain detected on Gough Island was more closely related to that identified in South Georgia, indicating that infection may have occurred during the pre-laying exodus, when skuas disperse into frontal waters south of the island. No further cases have been confirmed for Gough, but more systematic monitoring is needed to understand the dynamics of virus infection. The detection of HPAIV H5N1 in skuas on Gough Island highlights the importance of continued vigilance, proactive and geographically inclusive surveillance strategies, and biosecurity measures globally, alongside efforts to reduce other pressures on globally important seabird populations to help strengthen their resilience.

Dengue, transmitted by Aedes mosquitoes, can progress to severe symptoms like hemorrhagic fever and shock syndrome. While the virus and host immune response contribute to severity, other factors, such as small extracellular vesicles (sEVs), may play a role. sEVs mediate intercellular communication by transferring cellular components; however, their role in vivo infection remains unclear. We isolated and characterized sEVs from DENV-infected C6/36 mosquito cells, finding that they interact with mammalian cells and internalize the content. Using sEVs populations (with a size between 100 and 200 nm), we demonstrated enhanced infection in in vitro and in vivo murine models, including immunocompetent and immunosuppressed mice, which developed severe dengue-like symptoms. Our study reveals that sEVs from DENV-infected mosquito cells contribute to dengue pathogenesis, inducing severe symptoms in in vivo models, highlighting their potential role in disease progression and severe outcomes.

The H1N1pdm09 influenza virus, which emerged in 2009 following a unique reassortment of swine-origin gene segments, rapidly replaced the seasonal H1N1 strain and triggered the first influenza pandemic of the twenty-first century. In Brazil, the virus initially spread through intense community transmission before establishing a pattern of seasonal circulation. However, its long-term evolutionary dynamics in the country remain insufficiently characterized. To address this gap, we conducted a coordinated national genomic surveillance effort focused on the period from 2014 onward, when Brazil began systematic whole-genome sequencing of circulating H1N1pdm09 viruses. Through collaborative sequencing across all five Brazilian macroregions, we generated 597 complete genomes collected between 2014 and 2024. Using phylodynamic approaches, we reconstructed the spatiotemporal spread of H1N1pdm09, identified major circulating lineages, and integrated epidemiological data to assess patterns of persistence and regional transmission. Our findings reveal sustained circulation and multiple independent viral introductions over the past decade, with evidence of localized lineage maintenance, particularly in the Southeast and South regions. Phylogenetic analyses also indicate repeated seeding from international sources, underscoring the continued impact of global viral movement. In addition, genome-wide comparisons revealed reassortment events involving internal segments, which may have contributed to the persistence and adaptation of dominant lineages following the COVID-19 pandemic. This study presents the most comprehensive reconstruction of H1N1pdm09 evolutionary dynamics in Brazil to date, highlighting the critical role of integrated, nationwide genomic surveillance in enhancing public health preparedness in tropical and subtropical regions.

Older adults remain highly vulnerable to severe SARS-CoV-2 outcomes despite multiple vaccinations, yet age-associated differences in immune responses to updated COVID-19 booster vaccines remain incompletely characterized. Here, we administered an XBB.1.5 trivalent recombinant protein booster (WSK-V102C) to 22 individuals (<38 years) and 20 individuals (≥73 years), all of whom had previously received 2-3 doses of inactivated COVID-19 vaccines. Neutralizing antibody responses against multiple SARS-CoV-2 variants were quantified and compared between age groups. Meanwhile, single-cell RNA sequencing was also performed on peripheral blood mononuclear cells (PBMCs) collected at baseline and 28 days post-vaccination to profile age-associated immune features following boosting. Following booster immunization, both age groups achieved significantly elevated antibody titres against all tested strains. Nevertheless, the magnitude of antibody fold increase was consistently lower in elderly individuals than in younger adults. Single-cell analyses revealed age-associated differences in post-vaccination immune organization. In elderly individuals, B-cell state transitions were characterized by transcriptional signatures consistent with memory B cell-to-plasmablast differentiation, whereas younger individuals predominantly exhibited transitions from naïve B cells. CD4+ T cells from elderly individuals displayed altered transcriptional trajectories and reduced T-cell receptor diversity relative to younger adults. In contrast, younger individuals showed coordinated B- and T-cell-associated transcriptional programmes, including enrichment of transcription factors such as KLF7, CEBPB, CEBPD, and MAFB. Collectively, our study describes age-associated differences in immune coordination and cellular response patterns following XBB.1.5 booster vaccination. Further longitudinal and functional studies will be required to clarify the mechanistic basis and clinical implications of these observations.

Tuberculosis (TB) remains a global health challenge, exacerbated by the emergence of drug-resistant Mycobacterium tuberculosis strains. Most methods for drug susceptibility testing (DST) are culture-dependent and time consuming, possibly delaying optimal TB-treatment. This study aimed to develop an extensive targeted next-generation sequencing (tNGS) approach for rapid genotypic DST directly from clinical samples. We designed a tNGS panel comprising 30 amplicons targeting 19 genomic regions associated with resistance to 20 antibiotics. This method was applied to 71 smear-positive (0-3+) pulmonary TB clinical samples collected at the Portuguese National Reference Laboratory. DNA was extracted and amplified using multiplex PCRs, followed by sequencing on Oxford Nanopore Technologies MinION platform. Sequencing data were using TB-Profiler and the tNGS results compared to phenotypic DST and whole genome sequencing (WGS) data from corresponding isolates. The tNGS demonstrated high concordance with both phenotypic and WGS-based DST across different sample types and smear positivity levels. For first-line drugs, tNGS showed 88% categorical agreement (CA) with pDST, increasing to 97% when excluding undetermined results. Compared to WGS across all analysed antibiotics, tNGS achieved 92% CA, increasing to >99% when excluding undetermined results. Validation of the tNGS panel showed 90% (1,895/2,076) of amplicons reaching >10x coverage at all analysed positions and 43 (61%) samples with all complete amplicons above this threshold. Non-specific amplification of contaminant bacterial DNA was minimal, with most mapped off-target reads being of human origin. This method enables comprehensive resistance prediction directly from clinical samples and signifies an important development in TB diagnostics and resistance monitoring.