Tissue Tropism Research Articles

Tissue and cellular tropism of Eptesicus fuscus gammaherpesvirus in big brown bats, potential role of pulmonary intravascular macrophages.

Gammaherpesviruses (γHVs) are recognized as important pathogens in humans but their relationship with other animal hosts, especially wildlife species, is less well characterized. Our objectives were to examine natural Eptesicus fuscus gammaherpesvirus (EfHV) infections in their host, the big brown bat (Eptesicus fuscus), and determine whether infection is associated with disease. In tissue samples from 132 individual big brown bats, EfHV DNA was detected by polymerase chain reaction in 41 bats. Tissues from 59 of these cases, including 17 from bats with detectable EfHV genomes, were analyzed. An EfHV isolate was obtained from one of the cases, and electron micrographs and whole genome sequencing were used to confirm that this was a unique isolate of EfHV. Although several bats exhibited various lesions, we did not establish EfHV infection as a cause. Latent infection, defined as RNAScope probe binding to viral latency-associated nuclear antigen in the absence of viral envelope glycoprotein probe binding, was found within cells of the lymphoid tissues. These cells also had colocalization of the B-cell probe targeting CD20 mRNA. Probe binding for both latency-associated nuclear antigen and a viral glycoprotein was observed in individual cells dispersed throughout the alveolar capillaries of the lung, which had characteristics of pulmonary intravascular macrophages. Cells with a similar distribution in bat lungs expressed major histocompatibility class II, a marker for antigen presenting cells, and the existence of pulmonary intravascular macrophages in bats was confirmed with transmission electron microscopy. The importance of this cell type in γHVs infections warrants further investigation.

Clinical significance of small extracellular vesicles in cholangiocarcinoma

Cholangiocarcinoma is an aggressive and heterogeneous malignancy originating from the bile duct epithelium. It is associated with poor prognosis and high mortality. The global incidence of cholangiocarcinoma is rising, and there is an urgent need for effective early diagnosis and treatment strategies to reduce the burden of this devastating tumor. Small extracellular vesicles, including exosomes and microparticles, are nanoscale vesicles formed by membranes that are released both normally and pathologically from cells, mediating the intercellular transfer of substances and information. Recent studies have demonstrated the involvement of small extracellular vesicles in numerous biological processes, as well as the proliferation, invasion, and metastasis of tumor cells. The present review summarizes the tumorigenic roles of small extracellular vesicles in the cholangiocarcinoma microenvironment. Owing to their unique composition, accessibility, and stability in biological fluids, small extracellular vesicles have emerged as ideal biomarkers for use in liquid biopsies for diagnosing and outcome prediction of cholangiocarcinoma. Specific tissue tropism, theoretical biocompatibility, low clearance, and strong biological barrier penetration of small extracellular vesicles make them suitable drug carriers for cancer therapy. Furthermore, the potential value of small extracellular vesicle-based therapies for cholangiocarcinoma is also reviewed.

Cardiac SARS-CoV-2 Infection, Involvement of Cytokines in Postmortem Immunohistochemical Study

In the context of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, significant attention was given to pulmonary manifestations. However, cardiac involvement is increasingly recognized as a critical factor influencing the prognosis, leading to myocardial damage, heart failure, acute coronary syndromes, potentially lethal arrhythmic events, and sudden cardiac death. Despite these findings, there is a lack of studies detailing the necroscopic, macroscopic, and microscopic cardiac changes associated with SARS-CoV-2. This study aimed to investigate the presence of SARS-CoV-2 viral proteins in cardiac tissue using immunohistochemical techniques to assess viral tropism. The analysis of cardiac tissue samples from deceased subjects, in different stages of conservation, confirmed to be positive for SARS-CoV-2 via reverse transcriptase-polymerase chain reaction (RT-PCR), showed immunopositivity for the SARS-CoV-2-NP viral antigen in 33% of cases. Notably, the presence of leukocyte infiltrates sufficient for diagnosing lymphocytic myocarditis was not observed. The central proinflammatory cytokines involved in the pathogenetic mechanism of coronavirus disease 19 (COVID-19) were researched using the immunohistochemical method. A significant increase in cytokine expression was detected, indicating myocardial involvement and dysfunction during SARS-CoV-2 infection. These findings suggest that the immunohistochemical detection of SARS-CoV-2 viral antigens and inflammatory cytokine expression in cardiac tissue could be crucial for a proper forensic assessment of the cause of death, even in sudden cardiac death.

Isolation, Identification, and Pathogenicity of a Goose Astrovirus Genotype 1 Strain in Goslings in China

Goose astrovirus genotype 1 (GAstV-1) has emerged in goose farms in some provinces of China in recent years and is considered to be one of the pathogens of gout in goslings in China. However, few studies have been conducted on the dynamic distribution, tissue tropism, and pathogenesis of GAstV-1 in goslings. In 2022, an epidemiological investigation of goose astrovirus (GAstV) in goslings was conducted in seven provinces of China. During the investigation, a GAstV-1 designated as GAstV-JSXZ was identified in the kidney of an 8-day-old gosling and was successfully isolated from a goose embryo. The full genome sequence of GAstV-JSXZ was determined using the next-generation sequencing technique. The complete genome of GAstV-JSXZ was 7299-nt-long. Interestingly, the phylogenetic analysis revealed that Chinese GAstV-1 has formed two distinct subgroups based on the ORF 2 genomes, designated GAstV-1 1a and GAstV-1 1b. The GAstV-JSXZ shared the highest identity with GAstV-1 1a strain FLX and TZ03 in nucleotides (ORF1a: 98.3–98.4%; ORF1b: 92.3–99.1%; ORF2: 95.8–98.8%) and amino acid sequences (ORF1a: 99.4–99.5%; ORF1b: 98.2–98.8%; ORF2: 97.0–99.4%). To evaluate the pathogenicity of GAstV-1, 1-day-old goslings were inoculated with the virus by oral and subcutaneous injection routes, respectively. The results revealed that the virus causes extensive pathological organ damage, especially in the kidney, liver, and thymus. Virus-specific genomic RNA could be detected in the cloacal swabs and tissues of infected goslings throughout the experiment. The viral copy numbers examined in the kidney and intestine were the highest, followed by the liver and spleen. These results are likely to provide a new understanding of the pathogenicity of GAstV-1 in geese.

Single-cell RNA sequencing reveals the immune features and viral tropism in the central nervous system of mice infected with Japanese encephalitis virus

Japanese encephalitis virus (JEV) is a neurotropic pathogen that causes lethal encephalitis. The high susceptibility and massive proliferation of JEV in neurons lead to extensive neuronal damage and inflammation within the central nervous system. Despite extensive research on JEV pathogenesis, the effect of JEV on the cellular composition and viral tropism towards distinct neuronal subtypes in the brain is still not well comprehended. To address these issues, we performed single-cell RNA sequencing (scRNA-seq) on cells isolated from the JEV-highly infected regions of mouse brain. We obtained 88,000 single cells and identified 34 clusters representing 10 major cell types. The scRNA-seq results revealed an increasing amount of activated microglia cells and infiltrating immune cells, including monocytes & macrophages, T cells, and natural killer cells, which were associated with the severity of symptoms. Additionally, we observed enhanced communication between individual cells and significant ligand-receptor pairs related to tight junctions, chemokines and antigen-presenting molecules upon JEV infection, suggesting an upregulation of endothelial permeability, inflammation and antiviral response. Moreover, we identified that Baiap2-positive neurons were highly susceptible to JEV. Our findings provide valuable clues for understanding the mechanism of JEV induced neuro-damage and inflammation as well as developing therapies for Japanese encephalitis.

Advancements in γδT cell engineering: paving the way for enhanced cancer immunotherapy.

Comprising only 1-10% of the circulating T cell population, γδT cells play a pivotal role in cancer immunotherapy due to their unique amalgamation of innate and adaptive immune features. These cells can secrete cytokines, including interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), and can directly eliminate tumor cells through mechanisms like Fas/FasL and antibody-dependent cell-mediated cytotoxicity (ADCC). Unlike conventional αβT cells, γδT cells can target a wide variety of cancer cells independently of major histocompatibility complex (MHC) presentation and function as antigen-presenting cells (APCs). Their ability of recognizing antigens in a non-MHC restricted manner makes them an ideal candidate for allogeneic immunotherapy. Additionally, γδT cells exhibit specific tissue tropism, and rapid responsiveness upon reaching cellular targets, indicating a high level of cellular precision and adaptability. Despite these capabilities, the therapeutic potential of γδT cells has been hindered by some limitations, including their restricted abundance, unsatisfactory expansion, limited persistence, and complex biology and plasticity. To address these issues, gene-engineering strategies like the use of chimeric antigen receptor (CAR) T therapy, T cell receptor (TCR) gene transfer, and the combination with γδT cell engagers are being explored. This review will outline the progress in various engineering strategies, discuss their implications and challenges that lie ahead, and the future directions for engineered γδT cells in both monotherapy and combination immunotherapy.

Generation of a humanized mAce2 and a conditional hACE2 mouse models permissive to SARS-COV-2 infection.

The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) remains a public health concern and a subject of active research effort. Development of pre-clinical animal models is critical to study viral-host interaction, tissue tropism, disease mechanisms, therapeutic approaches, and long-term sequelae of infection. Here, we report two mouse models for studying SARS-CoV-2: A knock-in mAce2F83Y,H353K mouse that expresses a mouse-human hybrid form of the angiotensin-converting enzyme 2 (ACE2) receptor under the endogenous mouse Ace2 promoter, and a Rosa26 conditional knock-in mouse carrying the human ACE2 allele (Rosa26hACE2). Although the mAce2F83Y,H353K mice were susceptible to intranasal inoculation with SARS-CoV-2, they did not show gross phenotypic abnormalities. Next, we generated a Rosa26hACE2;CMV-Cre mouse line that ubiquitously expresses the human ACE2 receptor. By day 3 post infection with SARS-CoV-2, Rosa26hACE2;CMV-Cre mice showed significant weight loss, a variable degree of alveolar wall thickening and reduced survival rates. Viral load measurements confirmed inoculation in lung and brain tissues of infected Rosa26hACE2;CMV-Cre mice. The phenotypic spectrum displayed by our different mouse models translates to the broad range of clinical symptoms seen in the human patients and can serve as a resource for the community to model and explore both treatment strategies and long-term consequences of SARS-CoV-2 infection.

Genomic Evolution and Recombination Dynamics of Human Adenovirus D Species: Insights from Comprehensive Bioinformatic Analysis.

Human adenoviruses (HAdVs) can infect various epithelial mucosal cells, ultimately causing different symptoms in infected organ systems. With more than 110 types classified into seven species (A-G), HAdV-D species possess the highest number of viruses and are the fastest proliferating. The emergence of new adenovirus types and increased diversity are driven by homologous recombination (HR) between viral genes, primarily in structural elements such as the penton base, hexon and fiber proteins, and the E1 and E3 regions. A comprehensive analysis of the HAdV genome provides valuable insights into the evolution of human adenoviruses and identifies genes that display high variation across the entire genome to determine recombination patterns. Hypervariable regions within genetic sequences correlate with functional characteristics, thus allowing for adaptation to new environments and hosts. Proteotyping of newly emerging and already established adenoviruses allows for prediction of the characteristics of novel viruses. HAdV-D species evolved in a direction that increased diversity through gene recombination. Bioinformatics analysis across the genome, particularly in highly variable regions, allows for the verification or re-evaluation of recombination patterns in both newly introduced and pre-existing viruses, ultimately aiding in tracing various biological traits such as virus tropism and pathogenesis. Our research does not only assist in predicting the emergence of new adenoviruses but also offers critical guidance in regard to identifying potential regulatory factors of homologous recombination hotspots.

A magnetic separation method for isolating and characterizing the biomolecular corona of lipid nanoparticles

Lipid nanoparticle (LNP) formulations are a proven method for the delivery of nucleic acids for gene therapy as exemplified by the worldwide rollout of LNP-based RNAi therapeutics and mRNA vaccines. However, targeting specific tissues or cells is still a major challenge. After LNP administration, LNPs interact with biological fluids (i.e., blood), components of which adsorb onto the LNP surface forming a layer of biomolecules termed the "biomolecular corona (BMC)" which affects LNP stability, biodistribution, and tissue tropism. The mechanisms by which the BMC influences tissue- and cell-specific targeting remains largely unknown, due to the technical challenges in isolating LNPs and their corona from complex biological media. In this study, we present a new technique that utilizes magnetic LNPs to isolate LNP-corona complexes from unbound proteins present in human serum. First, we developed a magnetic LNP formulation, containing >40 superparamagnetic iron oxide nanoparticles (IONPs)/LNP, the resulting LNPs containing iron oxide nanoparticles (IOLNPs) displayed a similar particle size and morphology as LNPs loaded with nucleic acids. We further demonstrated the isolation of the IOLNPs and their corresponding BMC from unbound proteins using a magnetic separation (MS) system. The BMC profile of LNP from the MS system was compared to size exclusion column chromatography and further analyzed via mass spectrometry, revealing differences in protein abundances. This new approach enabled a mild and versatile isolation of LNPs and its corona, while maintaining its structural integrity. The identification of the BMC associated with an intact LNP provides further insight into LNP interactions with biological fluids.

Establishment and application of a surrogate model for human Ebola virus disease in BSL-2 laboratory

The Ebola virus (EBOV) is a member of the Orthoebolavirus genus, Filoviridae family, which causes severe hemorrhagic diseases in humans and non-human primates (NHPs), with a case fatality rate of up to 90%. The development of countermeasures against EBOV has been hindered by the lack of ideal animal models, as EBOV requires handling in biosafety level (BSL)-4 facilities. Therefore, accessible and convenient animal models are urgently needed to promote prophylactic and therapeutic approaches against EBOV. In this study, a recombinant vesicular stomatitis virus expressing Ebola virus glycoprotein (VSV-EBOV/GP) was constructed and applied as a surrogate virus, establishing a lethal infection in hamsters. Following infection with VSV-EBOV/GP, 3-week-old female Syrian hamsters exhibited disease signs such as weight loss, multi-organ failure, severe uveitis, high viral loads, and developed severe systemic diseases similar to those observed in human EBOV patients. All animals succumbed at 2∼3 days post-infection (dpi). Histopathological changes indicated that VSV-EBOV/GP targeted liver cells, suggesting that the tissue tropism of VSV-EBOV/GP was comparable to wild-type EBOV (WT EBOV). Notably, the pathogenicity of the VSV-EBOV/GP was found to be species-specific, age-related, gender-associated, and challenge route-dependent. Subsequently, equine anti-EBOV immunoglobulins and a subunit vaccine were validated using this model. Overall, this surrogate model represents a safe, effective, and economical tool for rapid preclinical evaluation of medical countermeasures against EBOV under BSL-2 conditions, which would accelerate technological advances and breakthroughs in confronting Ebola virus disease.

Assessing tropism and genetic traits of carp oedema virus isolates to enhance detection strategies.

Carp oedema virus (CEV) is a relatively understudied poxvirus. It exhibits an affinity for gill and skin epithelial cells. Investigations were conducted into selected aspects of CEV biology, with a focus on determining cell and tissue tropism of CEV, acquiring gene sequences and updating CEV tests in fish tissues. A total of 238 common carp tissue samples from nine aquaculture farms were analysed. The study evaluated the efficacy of intermediate detection of CEV by real-time PCR and in situ hybridisation. The genes encoding protein P4a were sequenced, analysed and aligned in a phylogenetic tree using a molecular evolution model. In situ hybridisation revealed the necessity to validate the Centre for Environment, Fisheries and Aquaculture Science protocols for sampling for CEV detection and to use the tissues for which the virus has the highest tropism, namely the skin and kidneys, rather than solely the gills. The level of genetic variability was determined, and it was shown that CEV mutates systematically. The creation of two distinct phylogenetic clades confirms certain strains' description as Polish isolates. Determining the localisation of CEV genetic material in organs and tissues is pivotal for shaping the World Organisation for Animal Health guidelines. The utility of molecular diagnostics has been demonstrated in the skin and kidney of carp, in addition to the gills, impelling their inclusion in diagnostic protocols. The clusters identified in the phylogenetic tree offer valuable insights for developing the current PCR primers. The prevalence of CEV infection in aquaculture, juxtaposed with its notably lower detection in wild fish, underscores the significance of mandatory molecular diagnostic testing for CEV in carp farming.

Experimental infection of domestic turkeys with lymphoproliferative disease virus of North American origin.

Lymphoproliferative disease virus (LPDV) was first documented in wild turkeys in North America in 2009. LPDV infection is often subclinical but can manifest as lymphoid proliferation or round cell neoplasia. Despite high prevalence across many sampled areas corresponding to declining populations of wild turkeys, knowledge regarding LPDV pathogenesis, risk factors for disease development, and associated impacts on population dynamics are unknown. To understand transmission, viral shedding, and tissue tropism, we inoculated 21 domestic turkeys via the oral cavity, crop, nasal cavity, subcutis, or coelomic cavity. For 12 weeks, oropharyngeal swabs, cloacal swabs, and whole blood were collected weekly. At 1 week postinoculation, 3 turkeys (3/21; 14%) had detectable LPDV proviral DNA in blood by polymerase chain reaction, and 10 developed DNAemia (50%; 10/20) by 12 weeks. LPDV proviral DNA was intermittently detected in oropharyngeal and cloacal swabs. Splenomegaly was the most consistent gross finding in DNAemic birds (8/11; 73%). Lymphoid hyperplasia in the spleen was the most significant microscopic finding (9/11; 82%). Three turkeys (3/11; 27%) developed round cell neoplasia characterized by sheets of pleomorphic, round to polygonal cells in the adrenal gland, bone marrow, skin, small intestine, and/or spleen. LPDV was detected in the spleen and bone marrow from all turkeys with DNAemia and all neoplasms. Our study establishes that infection and disease with North American LPDV from wild turkeys can be experimentally reproduced in domestic turkeys, laying the groundwork for future investigations into LPDV pathogenesis, development of diagnostic techniques, and understanding the impacts of LPDV on wild turkey populations.

Comparative pathogenicity of CA1737/04 and Mass infectious bronchitis virus genotypes in laying chickens.

Infectious bronchitis virus (IBV) is a respiratory virus causing atropism in multiple body systems of chickens. Recently, the California 1737/04 (CA1737/04) IBV strain was identified as one of the circulating IBV variants among poultry operations in North America. Here, the pathogenicity and tissue tropism of CA1737/04 IBV strain in specific-pathogen-free (SPF) hens were characterized in comparison to Massachusetts (Mass) IBV. In 30 weeks-old SPF hens, Mass or CA1737/04 IBV infections were carried out, while the third group was maintained as a control group. Following infection, we evaluated clinical signs, egg production, viral shedding, serology, necropsy examination, and histopathology during a period of 19 days. Also, certain tissue affinity parameters were investigated, which involved the localization of viral antigens and the detection of viral RNA copies in designated tissues. Our findings indicate that infection with CA1737/04 or Mass IBV strain could induce significant clinical signs, reduced egg production, and anti-IBV antibodies locally in oviduct wash and systemically in serum. Both IBV strains showed detectable levels of viral RNA copies and induced pathology in respiratory, renal, enteric, and reproductive tissues. However, the CA1737/04 IBV strain had higher pathogenicity, higher tissue tropism, and higher replication in the kidney, large intestine, and different segments of the oviduct compared to the Mass IBV strain. Both IBV strains shed viral genome from the cloacal route, however, the Mass IBV infected hens shed higher IBV genome loads via the oropharyngeal route compared to CA1737/04 IBV-infected hens. Overall, the current findings could contribute to a better understanding of CA1737/04 IBV pathogenicity in laying hens.

Structure and antigenicity of the divergent human astrovirus VA1 capsid spike.

Human astrovirus (HAstV) is a known cause of viral gastroenteritis in children worldwide, but HAstV can cause also severe and systemic infections in immunocompromised patients. There are three clades of HAstV: classical, MLB, and VA/HMO. While all three clades are found in gastrointestinal samples, HAstV-VA/HMO is the main clade associated with meningitis and encephalitis in immunocompromised patients. To understand how the HAstV-VA/HMO can infect the central nervous system, we investigated its sequence-divergent capsid spike, which functions in cell attachment and may influence viral tropism. Here we report the high-resolution crystal structures of the HAstV-VA1 capsid spike from strains isolated from patients with gastrointestinal and neuronal disease. The HAstV-VA1 spike forms a dimer and shares a core beta-barrel structure with other astrovirus capsid spikes but is otherwise strikingly different, suggesting that HAstV-VA1 may utilize a different cell receptor, and an infection competition assay supports this hypothesis. Furthermore, by mapping the capsid protease cleavage site onto the structure, the maturation and assembly of the HAstV-VA1 capsid is revealed. Finally, comparison of gastrointestinal and neuronal HAstV-VA1 sequences, structures, and antigenicity suggests that neuronal HAstV-VA1 strains may have acquired immune escape mutations. Overall, our studies on the HAstV-VA1 capsid spike lay a foundation to further investigate the biology of HAstV-VA/HMO and to develop vaccines and therapeutics targeting it.

Temperature impacts SARS-CoV-2 spike fusogenicity and evolution.

SARS-CoV-2 infects both the upper and lower respiratory tracts, which are characterized by different temperatures (33°C and 37°C, respectively). In addition, fever is a common COVID-19 symptom. SARS-CoV-2 has been shown to replicate more efficiently at low temperatures, but the effect of temperature on different viral proteins remains poorly understood. Here, we investigate how temperature affects the SARS-CoV-2 spike function and evolution. We first observed that increasing temperature from 33°C to 37°C or 39°C increased spike-mediated cell-cell fusion. We then experimentally evolved a recombinant vesicular stomatitis virus expressing the SARS-CoV-2 spike at these different temperatures. We found that spike-mediated cell-cell fusion was maintained during evolution at 39°C but was lost in a high proportion of viruses that evolved at 33°C or 37°C. Consistently, sequencing of the spikes evolved at 33°C or 37°C revealed the accumulation of mutations around the furin cleavage site, a region that determines cell-cell fusion, whereas this did not occur in spikes evolved at 39°C. Finally, using site-directed mutagenesis, we found that disruption of the furin cleavage site had a temperature-dependent effect on spike-induced cell-cell fusion and viral fitness. Our results suggest that variations in body temperature may affect the activity and diversification of the SARS-CoV-2 spike.IMPORTANCEWhen it infects humans, SARS-CoV-2 is exposed to different temperatures (e.g., replication site and fever). Temperature has been shown to strongly impact SARS-CoV-2 replication, but how it affects the activity and evolution of the spike protein remains poorly understood. Here, we first show that high temperatures increase the SARS-CoV-2 spike fusogenicity. Then, we demonstrate that the evolution of the spike activity and variants depends on temperature. Finally, we show that the functional effect of specific spike mutations is temperature-dependent. Overall, our results suggest that temperature may be a factor influencing the activity and adaptation of the SARS-CoV-2 spike in vivo, which will help understanding viral tropism, pathogenesis, and evolution.

NLRP1 restricts porcine deltacoronavirus infection via IL-11 inhibiting the phosphorylation of the ERK signaling pathway.

Continuously emerging highly pathogenic coronaviruses remain a major threat to human and animal health. Porcine deltacoronavirus (PDCoV) is a newly emerging enterotropic swine coronavirus that causes large-scale outbreaks of severe diarrhea disease in piglets. Unlike other porcine coronaviruses, PDCoV has a wide range of species tissue tropism, including primary human cells, which poses a significant risk of cross-species transmission. Nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) has a key role in linking host innate immunity to microbes and the regulation of inflammatory pathways. We now report a role for NLRP1 in the control of PDCoV infection. Overexpression of NLRP1 remarkably suppressed PDCoV infection, whereas knockout of NLRP1 led to a significant increase in PDCoV replication. A mechanistic study revealed that NLRP1 suppressed PDCoV replication in cells by upregulating IL-11 expression, which in turn inhibited the phosphorylation of the ERK signaling pathway. Furthermore, the ERK phosphorylation inhibitor U0126 effectively hindered PDCoV replication in pigs. Together, our results demonstrated that NLRP1 exerted an anti-PDCoV effect by IL-11-mediated inhibition of the phosphorylation of the ERK signaling pathway, providing a novel antiviral signal axis of NLRP1-IL-11-ERK. This study expands our understanding of the regulatory network of NLRP1 in the host defense against virus infection and provides a new insight into the treatment of coronaviruses and the development of corresponding drugs.IMPORTANCECoronavirus, which mainly infects gastrointestinal and respiratory epithelial cells in vivo, poses a huge threat to both humans and animals. Although porcine deltacoronavirus (PDCoV) is known to primarily cause fatal diarrhea in piglets, reports detected in plasma samples from Haitian children emphasize the potential risk of animal-to-human spillover. Finding effective therapeutics against coronaviruses is crucial for controlling viral infection. Nucleotide-binding oligomerization-like receptor (NLR) family pyrin domain-containing 1 (NLRP1), a key regulatory factor in the innate immune system, is highly expressed in epithelial cells and associated with the pathogenesis of viruses. We demonstrate here that NLRP1 inhibits the infection of the intestinal coronavirus PDCoV through IL-11-mediated phosphorylation inhibition of the ERK signaling pathway. Furthermore, the ERK phosphorylation inhibitor can control the infection of PDCoV in pigs. Our study emphasizes the importance of NLRP1 as an immune regulatory factor and may open up new avenues for the treatment of coronavirus infection.

Aichivirus A1 replicates in human intestinal epithelium and bronchial tissue: Lung–gut axis?

The role of aichivirus A1 (AiV-A1) in acute gastroenteritis remains controversial and in vitro data illustrating its pathogenesis in suitable human models are scarce. Here, we demonstrate that AiV-A1 isolate A846/88 replicates in ApoA1- (absorptive) and Ki-67-positive (proliferative) enterocytes in stem cell-derived human small intestinal epithelium (HIE) as well as in patient biopsy samples, but not in any of the tested human cell lines. The infection did not result in tissue damage and did not trigger type I and type III interferon (IFN) signalling, whereas the control, human coxsackievirus B3 (strain Nancy), triggered both IFNs. To investigate the tissue tropism, we infected a human tracheal/bronchial epithelium model (HTBE) with AiV-A1 isolates A846/88 and kvgh99012632/2010 and, as a control, with rhinovirus A2 (RV-A2). AiV-A1 isolate kvgh99012632/2010, but not isolate A846/88, replicated in HTBE and induced type III IFN and ISGs signalling. By using various pharmacological inhibitors, we elaborated that cellular entry of AiV-A1 depends on clathrin, dynamin, and lipid rafts and is strongly reliant on endosome acidification. Viral particles co-localised with Rab5a-positive endosomes and promoted leakage of endosomal content. Our data shed light on the early events of AiV-A1 infection and reveal that different isolates exhibit distinct tissue tropism. This supports its clinical importance as a human pathogen with the potential to evolve toward broader tissue specificity.

Clinical characteristics of 4,520 paediatric patients infected with the SARS-CoV-2 omicron variant, in Xi'an, China.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has broad tissue tropism and high transmission, which are likely to perpetuate the pandemic. The study aim to analyze the clinicopathogenic characteristics in paediatric patients. In this single-centre study, we retrospectively included all confirmed cases infected by SARS-CoV-2 infection at Xi'an Children's Hospital, China, from 1 December to 31 December 2022. The demographic, clinical, laboratory, and radiological features of the patients were analysed. A total of 4,520 paediatric patients with SARS-CoV-2 omicron variant infections were included. Of these, 3,861 (85.36%) were outpatients, 659 (14.64%) were hospitalised patients, and nine patients (0.20%) died. Of the nine patients who died, five were diagnosed with acute necrotising encephalopathy (ANE). The most common symptoms were fever in 4,275 (94.59%) patients, cough in 1,320 (29.20%) patients, convulsions in 610 (13.50%) patients, vomiting in 410 (9.07%) patients, runny nose/coryza in 277 (6.13%) patients, hoarseness of voice in 273 (6.04%) patients. A blood cell analysis showed a slight elevation of monocytes (mean: 11.14 ± 0.07%). The main diagnoses for both outpatients and inpatients were respiratory infection with multisystem manifestations. A high incidence of convulsions is a typical characteristic of children infected with SARS-CoV-2. Five of the nine COVID-19 fatalities were associated with ANE. This indicates that nervous system damage in children with SARS-CoV-2 infection is more significant.

Determining patterns of tissue tropism for IHHNV, GAV and YHV-7 infection in giant black tiger shrimp (Penaeus monodon) using real-time RT-qPCR

Disease management in shrimp aquaculture is heavily dependent on accurate and rapid pathogen detection and diagnosis. Understanding the presence and distribution of pathogens within various tissues of the shrimp host is critical to ensure detection efforts are targeted for optimal sensitivity and reliability. Modern advancements in molecular technologies, including nucleic acid extraction and RT-qPCR, have yielded significant improvements in pathogen detection capabilities. Despite these advancements and their widespread adoption within both research and industry applications, evidence to inform their optimised use, such as revisions to tissue-specific viral detection to support selection of appropriate target tissues, has not been established. To address these gaps, this study aimed to establish contemporary evidence of viral tissue tropism for three major shrimp pathogens. TaqMan qPCR analysis was used to determine tissue-specific loading of viral pathogens in naturally infected Penaeus monodon pleopod, gill, hepatopancreas, lymphoid organ, abdominal muscle tissue, hindgut and ventral nerve cord. The viral targets analysed included Penaeus stylirostris penstyldensovirus 1 (PstDV1), formerly named infectious hypodermal haematopoietic necrosis virus (IHHNV) and, two genotypes of the yellow head virus complex, including genotype 2 known as gill associated virus (YHV-2/ GAV), and genotype 7 (YHV-7). QPCR analyses demonstrated the highest level of genetic IHHNV detection from gill tissue, followed sequentially by hindgut, pleopod, hepatopancreas, lymphoid organ, ventral nerve cord and abdominal muscle. For the yellow head viruses (GAV and YHV-7), no significant differences in genetic viral detection were demonstrated, although a non-significant advantage was observed for lymphoid organ and hindgut tissue. Beyond establishing contemporary evidence of viral distribution to improve understanding of host-viral interactions, these findings offer supporting evidence for revisions to appropriate target tissue recommendations, within the World Organisation for Animal Health (WOAH, founded as OIE) Manual of Diagnostic Tests for Aquatic Animals, for optimised modern shrimp pathogen detection.

Two promising candidates for paratransgenesis, Elizabethkingia and Asaia, increase in both sexes of Anopheles gambiae mosquitoes after feeding

BackgroundThe male mosquito microbiome may be important for identifying ideal candidates for disease control. Among other criteria, mosquito-associated symbionts that have high localization in both male and female mosquitoes and are transmissible through both vertical and sexual routes are desirable. However, mosquito microbiome studies have mainly been female-focused. In this study, the microbiota of male and female Anopheles gambiae sensu lato (s.l.) were compared to identify shared or unique bacteria.MethodsLate larval instars of Anopheles mosquitoes were collected from the field and raised to adults. Equal numbers of males and females of 1-day-old non-sugar-fed, 4–5-day-old sugar-fed and post-blood-fed females were randomly selected for whole-body analyses of bacteria 16S rRNA.ResultsResults revealed that male and female mosquitoes generally share similar microbiota except when females were blood-fed. Compared to newly emerged unfed mosquitoes, feeding on sugar and/or blood increased variability in microbial composition (⍺-diversity), with a higher disparity among females (39% P = 0.01) than in males (29% P = 0.03). Elizabethkingia meningoseptica and Asaia siamensis were common discriminants between feeding statuses in both males and females. While E. meningoseptica was particularly associated with sugar-fed mosquitoes of both sexes and sustained after blood feeding in females, A. siamensis was also increased in sugar-fed mosquitoes but decreased significantly in blood-fed females (LDA score > 4.0, P < 0.05). Among males, A. siamensis did not differ significantly after sugar meals.ConclusionsResults indicate the opportunities for stable infection in mosquitoes should these species be used in bacteria-mediated disease control. Further studies are recommended to investigate possible host-specific tissue tropism of bacteria species which will inform selection of the most appropriate microbes for effective transmission-blocking strategies.