Integration of metalloproteome and immunoproteome reveals a tight link of iron-related proteins with COVID-19 pathogenesis and immunity.

Increasing clinical data show that the imbalance of host metallome is closely associated with different kinds of disease, however, the intrinsic mechanisms of action of metals in immunity and pathogenesis of disease remain largely undefined. There is lack of multiplexed profiling system to integrate the metalloproteome-immunoproteome information at systemic level for exploring the roles of metals in immunity and disease pathogenesis. In this study, we build up a metal-coding assisted multiplexed proteome assay platform for serum metalloproteomic and immunoproteomic profiling. By taking COVID-19 as a showcase, we unbiasedly uncovered the most evident modulation of iron-related proteins, i.e., Ft and Tf, in serum of severe COVID-19 patients, and the value of Ft/Tf could work as a robust biomarker for COVID-19 severity stratification, which overtakes the well-established clinical risk factors (cytokines). We further uncovered a tight association of transferrin with inflammation mediator IL-10 in COVID-19 patients, which was proved to be mainly governed by the monocyte/macrophage of liver, shedding light on new pathophysiological and immune regulatory mechanisms of COVID-19 disease. We finally validated the beneficial effects of iron chelators as anti-viral agents in SARS-CoV-2-infected K18-hACE2 mice through modulation of iron dyshomeostasis and alleviating inflammation response. Our findings highlight the critical role of liver-mediated iron dysregulation in COVID-19 disease severity, providing solid evidence on the involvement of iron-related proteins in COVID-19 pathophysiology and immunity.

COVID-19 drug discovery and treatment options.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused substantial morbidity and mortality, and serious social and economic disruptions worldwide. Unvaccinated or incompletely vaccinated older individuals with underlying diseases are especially prone to severe disease. In patients with non-fatal disease, long COVID affecting multiple body systems may persist for months. Unlike SARS-CoV and Middle East respiratory syndrome coronavirus, which have either been mitigated or remained geographically restricted, SARS-CoV-2 has disseminated globally and is likely to continue circulating in humans with possible emergence of new variants that may render vaccines less effective. Thus, safe, effective and readily available COVID-19 therapeutics are urgently needed. In this Review, we summarize the major drug discovery approaches, preclinical antiviral evaluation models, representative virus-targeting and host-targeting therapeutic options, and key therapeutics currently in clinical use for COVID-19. Preparedness against future coronavirus pandemics relies not only on effective vaccines but also on broad-spectrum antivirals targeting conserved viral components or universal host targets, and new therapeutics that can precisely modulate the immune response during infection.

Post-COVID-19 Pandemic Rebound of Macrolide-Resistant Mycoplasma pneumoniae Infection: A Descriptive Study.

The rebound characteristics of respiratory infections after lifting pandemic control measures were uncertain. From January to November 2023, patients presenting at a teaching hospital were tested for common respiratory viruses and Mycoplasma pneumoniae using a combination of antigen, nucleic acid amplification, and targeted next-generation sequencing (tNGS) tests. The number and rate of positive tests per month, clinical and microbiological characteristics were analyzed. A rapid rebound of SARS-CoV-2 was followed by a slower rebound of M. pneumoniae, with an interval of 5 months between their peaks. The hospitalization rate was higher, with infections caused by respiratory viruses compared to M. pneumoniae. Though the pediatric hospitalization rate of respiratory viruses (66.1%) was higher than that of M. pneumoniae (34.0%), the 4094 cases of M. pneumoniae within 6 months posed a huge burden on healthcare services. Multivariate analysis revealed that M. pneumoniae-infected adults had more fatigue, comorbidities, and higher serum C-reactive protein, whereas children had a higher incidence of other respiratory pathogens detected by tNGS or pathogen-specific PCR, fever, and were more likely to be female. A total of 85% of M. pneumoniae-positive specimens had mutations detected at the 23rRNA gene, with 99.7% showing A2063G mutation. Days to defervescence were longer in those not treated by effective antibiotics and those requiring a change in antibiotic treatment. A delayed but significant rebound of M. pneumoniae was observed after the complete relaxation of pandemic control measures. No unusual, unexplained, or unresponsive cases of respiratory infections which warrant further investigation were identified.

Risk of acute kidney injury in critically-ill patients with COVID-19 compared with seasonal influenza: a retrospective cohort study.

Background: The SARS-CoV-2 virus can bind to angiotensin-converting enzyme 2 receptors on host renal cells and may cause acute kidney injury (AKI). The comparative risks of AKI in patients severely ill with COVID-19 and influenza A have not been examined. Methods: This is a retrospective cohort study including patients with positive PCR results for SARS-CoV-2 or influenza A virus admitted to the intensive care units (ICUs) of 15 public hospitals in Hong Kong between 1st January 2013 and 30th April 2023. Patients who were already on chronic dialysis or had missing values in the confounder model were excluded. Data were retrieved from Hong Kong Hospital Authority's electronic healthcare records. The primary outcome was incident AKI during ICU stay. Secondary outcomes included acute kidney disease (AKD) and hospital mortality. All analyses were examined in multivariable regression adjusting for potential confounders (age, sex, baseline eGFR, PaO2/FiO2 ratio, baseline comorbidities, APACHE IV predicted risk of death, Charlson Comorbidity Index, emergent hospital admission, admission from elderly home, reason for ICU admission, presence of bacterial co-infections, use of medications [including vasopressors, antiviral medications, steroids and nephrotoxic antibiotics], as well as anaemia and leucocytosis). Patients were matched in a 1:1 ratio using a propensity score generated based on the full confounder model. The analyses were repeated using inverse probability weighting and in propensity-score matched cohorts. Findings: A total of 5495 ICU patients were identified. After excluding 1093 (19.9%) patients who met the exclusion criteria and 74 (1.3%) patients who had one or more missing values in the logistic regression model, a total of 4328 patients were included in the final analysis, with 2787 (64.4%) patients who tested positive for SARS-CoV-2 reverse transcription (RT)-PCR and 1541 (35.6%) patients who tested positive for influenza A virus RT-PCR. The comorbidity burden was greater in patients with COVID-19 (Charlson Comorbidity Index 3 [2-4] vs. 3 [1-4]), but the median APACHE IV predicted risk of death was significantly lower (0.19 [0.08-0.38] vs. 0.25 [0.11-0.52]). A total of 1053 (37.8%) patients with COVID-19 and 828 (53.7%) patients with influenza A developed AKI of any stage during ICU stay. In adjusted analysis, the risk of AKI was significantly lower in patients with COVID-19 compared with influenza A (adjusted odds ratio 0.51, 95% confidence interval 0.42-0.61, P < 0.0001]. The risk of stage 3 AKI and AKD were also significantly lower in patients with COVID-19. These results remained robust in multiple pre-planned sensitivity analyses including inverse probability weighting and propensity score matching. Interpretation: Our results suggest that the risk of AKI in patients severely ill with COVID-19 was lower than in patients with influenza A. The burden of concurrent organ failure complicating respiratory viral infections, such as the higher disease-attributable risk of AKI associated with influenza, should be clarified. Funding: An unrestricted philanthropic donation from Mr and Mrs Laurence Tse, The Wai Im Charitable Foundation, Chan Sui Kau Family Benefits and Charitable Foundation, So Ka Wing and Lee Sau Ying Charitable Foundation, Mr & Mrs Tam Wing Fun Edmund Renal Research Fund, the Theme-Based Research Scheme of the Research Grants Council, Hong Kong Special Administrative Region, The Government of the Hong Kong Special Administrative Region; Programme of Enhancing Laboratory Surveillance and Investigation of Emerging Infectious Diseases and Antimicrobial Resistance for the Department of Health of the Hong Kong Special Administrative Region Government; Emergency COVID-19 Project, Major Projects on Public Security, National Key Research and Development Program; Emergency Collaborative Project of Guangzhou Laboratory; the National Key Research and Development Program of China; Sanming Project of Medicine in Shenzhen China; and the High Level-Hospital Program, Health Commission of Guangdong Province, China.

PMI-controlled mannose metabolism and glycosylation determines tissue tolerance and virus fitness.

Host survival depends on the elimination of virus and mitigation of tissue damage. Herein, we report the modulation of D-mannose flux rewires the virus-triggered immunometabolic response cascade and reduces tissue damage. Safe and inexpensive D-mannose can compete with glucose for the same transporter and hexokinase. Such competitions suppress glycolysis, reduce mitochondrial reactive-oxygen-species and succinate-mediated hypoxia-inducible factor-1α, and thus reduce virus-induced proinflammatory cytokine production. The combinatorial treatment by D-mannose and antiviral monotherapy exhibits in vivo synergy despite delayed antiviral treatment in mouse model of virus infections. Phosphomannose isomerase (PMI) knockout cells are viable, whereas addition of D-mannose to the PMI knockout cells blocks cell proliferation, indicating that PMI activity determines the beneficial effect of D-mannose. PMI inhibition suppress a panel of virus replication via affecting host and viral surface protein glycosylation. However, D-mannose does not suppress PMI activity or virus fitness. Taken together, PMI-centered therapeutic strategy clears virus infection while D-mannose treatment reprograms glycolysis for control of collateral damage.

Type-II IFN inhibits SARS-CoV-2 replication in human lung epithelial cells and ex vivo human lung tissues through indoleamine 2,3-dioxygenase-mediated pathways.

Interferons (IFNs) are critical for immune defense against pathogens. While type-I and -III IFNs have been reported to inhibit SARS-CoV-2 replication, the antiviral effect and mechanism of type-II IFN against SARS-CoV-2 remain largely unknown. Here, we evaluate the antiviral activity of type-II IFN (IFNγ) using human lung epithelial cells (Calu3) and ex vivo human lung tissues. In this study, we found that IFNγ suppresses SARS-CoV-2 replication in both Calu3 cells and ex vivo human lung tissues. Moreover, IFNγ treatment does not significantly modulate the expression of SARS-CoV-2 entry-related factors and induces a similar level of pro-inflammatory response in human lung tissues when compared with IFNß treatment. Mechanistically, we show that overexpression of indoleamine 2,3-dioxygenase 1 (IDO1), which is most profoundly induced by IFNγ, substantially restricts the replication of ancestral SARS-CoV-2 and the Alpha and Delta variants. Meanwhile, loss-of-function study reveals that IDO1 knockdown restores SARS-CoV-2 replication restricted by IFNγ in Calu3 cells. We further found that the treatment of l-tryptophan, a substrate of IDO1, partially rescues the IFNγ-mediated inhibitory effect on SARS-CoV-2 replication in both Calu3 cells and ex vivo human lung tissues. Collectively, these results suggest that type-II IFN potently inhibits SARS-CoV-2 replication through IDO1-mediated antiviral response.

Genomic and phylogenetic profiling of RNA of tick-borne arboviruses in Hainan Island, China.

Ticks act as vectors and hosts of numerous arboviruses. Examples of medically important arboviruses include the tick-borne encephalitis virus, Crimean Congo hemorrhagic fever, and severe fever with thrombocytopenia syndrome. Recently, some novel arboviruses have been identified in blood specimens of patients with unexplained fever and a history of tick bites in Inner Mongolia. Consequently, tick-borne viruses are a major focus of infectious disease research. However, the spectrum of tick-borne viruses in subtropical areas of China has yet to be sufficiently characterized. In this study, we collected 855 ticks from canine and bovine hosts in four locations in Hainan Province. The ticks were combined into 18 pools according to genus and location. Viral RNA-sequence libraries were subjected to transcriptome sequencing analysis. Molecular clues from metagenomic analyses were used to classify sequence reads into virus species, genera, or families. The diverse viral reads closely associated with mammals were assigned to 12 viral families and important tick-borne viruses, such as Jingmen, Beiji nairovirus, and Colorado tick fever. Our virome and phylogenetic analyses of the arbovirus strains provide basic data for preventing and controlling human infectious diseases caused by tick-borne viruses in the subtropical areas of China.

Divergent trajectory of replication and intrinsic pathogenicity of SARS-CoV-2 Omicron post-BA.2/5 subvariants in the upper and lower respiratory tract.

BACKGROUND: Earlier Omicron subvariants including BA.1, BA.2, and BA.5 emerged in waves, with a subvariant replacing the previous one every few months. More recently, the post-BA.2/5 subvariants have acquired convergent substitutions in spike that facilitated their escape from humoral immunity and gained ACE2 binding capacity. However, the intrinsic pathogenicity and replication fitness of the evaluated post-BA.2/5 subvariants are not fully understood. METHODS: We systemically investigated the replication fitness and intrinsic pathogenicity of representative post-BA.2/5 subvariants (BL.1, BQ.1, BQ.1.1, XBB.1, CH.1.1, and XBB.1.5) in weanling (3-4 weeks), adult (8-10 weeks), and aged (10-12 months) mice. In addition, to better model Omicron replication in the human nasal epithelium, we further investigated the replication capacity of the post-BA.2/5 subvariants in human primary nasal epithelial cells. FINDINGS: We found that the evaluated post-BA.2/5 subvariants are consistently attenuated in mouse lungs but not in nasal turbinates when compared with their ancestral subvariants BA.2/5. Further investigations in primary human nasal epithelial cells revealed a gained replication fitness of XBB.1 and XBB.1.5 when compared to BA.2 and BA.5.2. INTERPRETATION: Our study revealed that the post-BA.2/5 subvariants are attenuated in lungs while increased in replication fitness in the nasal epithelium, indicating rapid adaptation of the circulating Omicron subvariants in the human populations. FUNDING: The full list of funding can be found at the Acknowledgements section.

P21-activated kinase 1 (PAK1)-mediated cytoskeleton rearrangement promotes SARS-CoV-2 entry and ACE2 autophagic degradation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has had a significant impact on healthcare systems and economies worldwide. The continuous emergence of new viral strains presents a major challenge in the development of effective antiviral agents. Strategies that possess broad-spectrum antiviral activities are desirable to control SARS-CoV-2 infection. ACE2, an angiotensin-containing enzyme that prevents the overactivation of the renin angiotensin system, is the receptor for SARS-CoV-2. ACE2 interacts with the spike protein and facilitates viral attachment and entry into host cells. Yet, SARS-CoV-2 infection also promotes ACE2 degradation. Whether restoring ACE2 surface expression has an impact on SARS-CoV-2 infection is yet to be determined. Here, we show that the ACE2-spike complex is endocytosed and degraded via autophagy in a manner that depends on clathrin-mediated endocytosis and PAK1-mediated cytoskeleton rearrangement. In contrast, free cellular spike protein is selectively cleaved into S1 and S2 subunits in a lysosomal-dependent manner. Importantly, we show that the pan-PAK inhibitor FRAX-486 restores ACE2 surface expression and suppresses infection by different SARS-CoV-2 strains. FRAX-486-treated Syrian hamsters exhibit significantly decreased lung viral load and alleviated pulmonary inflammation compared with untreated hamsters. In summary, our findings have identified novel pathways regulating viral entry, as well as therapeutic targets and candidate compounds for controlling the emerging strains of SARS-CoV-2 infection.

Metal-coding assisted serological multi-omics profiling deciphers the role of selenium in COVID-19 immunity.

Uncovering how host metal(loid)s mediate the immune response against invading pathogens is critical for better understanding the pathogenesis mechanism of infectious disease. Clinical data show that imbalance of host metal(loid)s is closely associated with the severity and mortality of COVID-19. However, it remains elusive how metal(loid)s, which are essential elements for all forms of life and closely associated with multiple diseases if dysregulated, are involved in COVID-19 pathophysiology and immunopathology. Herein, we built up a metal-coding assisted multiplexed serological metallome and immunoproteome profiling system to characterize the links of metallome with COVID-19 pathogenesis and immunity. We found distinct metallome features in COVID-19 patients compared with non-infected control subjects, which may serve as a biomarker for disease diagnosis. Moreover, we generated the first correlation network between the host metallome and immunity mediators, and unbiasedly uncovered a strong association of selenium with interleukin-10 (IL-10). Supplementation of selenium to immune cells resulted in enhanced IL-10 expression in B cells and reduced induction of proinflammatory cytokines in B and CD4+ T cells. The selenium-enhanced IL-10 production in B cells was confirmed to be attributable to the activation of ERK and Akt pathways. We further validated our cellular data in SARS-CoV-2-infected K18-hACE2 mice, and found that selenium supplementation alleviated SARS-CoV-2-induced lung damage characterized by decreased alveolar inflammatory infiltrates through restoration of virus-repressed selenoproteins to alleviate oxidative stress. Our approach can be readily extended to other diseases to understand how the host defends against invading pathogens through regulation of metallome.

Antibodies targeting a quaternary site on SARS-CoV-2 spike glycoprotein prevent viral receptor engagement by conformational locking.

SARS-CoV-2 continues to evolve, with many variants evading clinically authorized antibodies. To isolate monoclonal antibodies (mAbs) with broadly neutralizing capacities against the virus, we screened serum samples from convalescing COVID-19 patients. We isolated two mAbs, 12-16 and 12-19, which neutralized all SARS-CoV-2 variants tested, including the XBB subvariants, and prevented infection in hamsters challenged with Omicron BA.1 intranasally. Structurally, both antibodies targeted a conserved quaternary epitope located at the interface between the N-terminal domain and subdomain 1, uncovering a site of vulnerability on SARS-CoV-2 spike. These antibodies prevented viral receptor engagement by locking the receptor-binding domain (RBD) of spike in the down conformation, revealing a mechanism of virus neutralization for non-RBD antibodies. Deep mutational scanning showed that SARS-CoV-2 could mutate to escape 12-19, but such mutations are rarely found in circulating viruses. Antibodies 12-16 and 12-19 hold promise as prophylactic agents for immunocompromised persons who do not respond robustly to COVID-19 vaccines.

SARS-CoV-2 hijacks neutralizing dimeric IgA for nasal infection and injury in Syrian hamsters1.

Prevention of robust severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in nasal turbinate (NT) requires in vivo evaluation of IgA neutralizing antibodies. Here, we report the efficacy of receptor binding domain (RBD)-specific monomeric B8-mIgA1 and B8-mIgA2, and dimeric B8-dIgA1, B8-dIgA2 and TH335-dIgA1 against intranasal SARS-CoV-2 challenge in Syrian hamsters. These antibodies exhibited comparable neutralization potency against authentic virus by competing with human angiotensin converting enzyme-2 (ACE2) receptor for RBD binding. While reducing viral loads in lungs significantly, prophylactic intranasal B8-dIgA unexpectedly led to high amount of infectious viruses and extended damage in NT compared to controls. Mechanistically, B8-dIgA failed to inhibit SARS-CoV-2 cell-to-cell transmission, but was hijacked by the virus through dendritic cell-mediated trans-infection of NT epithelia leading to robust nasal infection. Cryo-EM further revealed B8 as a class II antibody binding trimeric RBDs in 3-up or 2-up/1-down conformation. Neutralizing dIgA, therefore, may engage an unexpected mode of SARS-CoV-2 nasal infection and injury.

The viral fitness and intrinsic pathogenicity of dominant SARS-CoV-2 Omicron sublineages BA.1, BA.2, and BA.5.

BACKGROUND: Among the Omicron sublineages that have emerged, BA.1, BA.2, BA.5, and their related sublineages have resulted in the largest number of infections. While recent studies demonstrated that all Omicron sublineages robustly escape neutralizing antibody response, it remains unclear on whether these Omicron sublineages share any pattern of evolutionary trajectory on their replication efficiency and intrinsic pathogenicity along the respiratory tract. METHODS: We compared the virological features, replication capacity of dominant Omicron sublineages BA.1, BA.2 and BA.5 in the human nasal epithelium, and characterized their pathogenicity in K18-hACE2, A129, young C57BL/6, and aged C57BL/6 mice. FINDINGS: We found that BA.5 replicated most robustly, followed by BA.2 and BA.1, in the differentiated human nasal epithelium. Consistently, BA.5 infection resulted in higher viral gene copies, infectious viral titres and more abundant viral antigen expression in the nasal turbinates of the infected K18-hACE2 transgenic mice. In contrast, the Omicron sublineages are continuously attenuated in lungs of infected K18-hACE2 and C57BL/6 mice, leading to decreased pathogenicity. Nevertheless, lung manifestations remain severe in Omicron sublineages-infected A129 and aged C57BL/6 mice. INTERPRETATION: Our results suggested that the Omicron sublineages might be gaining intrinsic replication fitness in the upper respiratory tract, therefore highlighting the importance of global surveillance of the emergence of hyper-transmissive Omicron sublineages. On the contrary, replication and intrinsic pathogenicity of Omicron is suggested to be further attenuated in the lower respiratory tract. Effective vaccination and other precautions should be in place to prevent severe infections in the immunocompromised populations at risk. FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Broad-spectrum humanized monoclonal neutralizing antibody against SARS-CoV-2 variants, including the Omicron variant.

Introduction: Therapeutic monoclonal antibodies (mAbs) against the SARS-CoV-2 spike protein have been shown to improve the outcome of severe COVID-19 patients in clinical trials. However, novel variants with spike protein mutations can render many currently available mAbs ineffective. Methods: We produced mAbs by using hybridoma cells that generated from mice immunized with spike protein trimer and receptor binding domain (RBD). The panel of mAbs were screened for binding and neutralizing activity against different SARS-CoV-2 variants. The in vivo effectiveness of WKS13 was evaluated in a hamster model. Results: Out of 960 clones, we identified 18 mAbs that could bind spike protein. Ten of the mAbs could attach to RBD, among which five had neutralizing activity against the ancestral strain and could block the binding between the spike protein and human ACE2. One of these mAbs, WKS13, had broad neutralizing activity against all Variants of Concern (VOCs), including the Omicron variant. Both murine or humanized versions of WKS13 could reduce the lung viral load in hamsters infected with the Delta variant. Conclusions: Our data showed that broad-spectrum high potency mAbs can be produced from immunized mice, which can be used in humans after humanization of the Fc region. Our method represents a versatile and rapid strategy for generating therapeutic mAbs for upcoming novel variants.

Clinical characteristics of unvaccinated or incompletely vaccinated children with neurological manifestations due to SARS-CoV-2 Omicron infection.

Omicron generally causes milder disease than previous strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), especially in fully vaccinated individuals. However, incompletely vaccinated children may develop Omicron-related complications such as those affecting the central nervous system. To characterize the spectrum of clinical manifestations of neuro-COVID and to identify potential biomarkers associated with clinical outcomes, we recruited 15 children hospitalized for Omicron-related neurological manifestations in three hospitals in Hong Kong (9 boys and 6 girls aged 1-13 years). All were unvaccinated or incompletely vaccinated. Fourteen (93.3%) were admitted for convulsion, including benign febrile seizure (n = 7), complex febrile seizure (n = 2), seizure with fever (n = 3), and recurrent breakthrough seizure (n = 2), and the remaining nonconvulsive patient developed encephalopathic state with impaired consciousness. None of the seven children with benign febrile seizure and six of eight children with other neurological manifestations had residual deficits at 9-month follow-up. SARS-CoV-2 RNA was undetectable in the cerebrospinal fluid (CSF) specimens of seven patients who underwent lumbar puncture. Spike-and-wave/sharp waves affecting the frontal lobes were detected in four of seven (57.1%) patients who underwent electroencephalogram. Children with Omicron-related neurological manifestations had significantly higher blood levels of IL-6 (p < 0.001) and CHI3L1 (p = 0.022) than healthy controls, and higher CSF levels of IL-6 (p = 0.002) than children with non-COVID-19-related febrile illnesses. Higher CSF-to-blood ratios of IL-8 and CHI3L1 were associated with longer length of stay, whereas higher ratios of IL-6 and IL-8 were associated with higher blood tau level. The role of CSF:blood ratio of IL-6, IL-8, and CHI3L1 as prognostic markers for neuro-COVID should be further evaluated.

Environmentally Resilient Microfluidic Point-of-Care Immunoassay Enables Rapid Diagnosis of Talaromycosis.

Point-of-care tests (POCTs) are increasingly being used in field settings, particularly outdoors. The performance of current POCTs─most commonly the lateral flow immunoassay─can be adversely affected by ambient temperature and humidity. We developed a self-contained immunoassay platform─the D4 POCT─that can be conducted at the POC by integrating all reagents in a capillary-driven passive microfluidic cassette that minimizes user intervention. The assay can be imaged and analyzed on a portable fluorescence reader─the D4Scope─and provide quantitative outputs. Here, we systematically investigated the resilience of our D4 POCT to varied temperature and humidity and to physiologically diverse human whole blood samples that span a wide range of physiological hematocrit (30-65%). For all conditions, we showed that the platform maintained high sensitivity (0.05-0.41 ng/mL limits of detection). The platform also demonstrated good accuracy in reporting true analyte concentration across environmental extremes when compared to the manually operated format of the same test to detect a model analyte─ovalbumin. Additionally, we engineered an improved version of the microfluidic cassette that improved the ease-of-use of the device and shortened the time-to-result. We implemented this new cassette to create a rapid diagnostic test to detect talaromycosis infection in patients with advanced HIV disease at the POC, demonstrating comparable sensitivity and specificity to the laboratory test for the disease.

Whipple's disease presenting as weight gain and constipation in a Chinese woman.

BACKGROUND: Whipple's disease is a chronic infection due to Tropheryma whipplei, commonly reported in the Caucasian but not in the Chinese population. CASE PRESENTATION: A 52-year-old female with good past health, was diagnosed with Whipple's disease, presenting with constipation, unintentional weight gain, and fleeting polyarthralgia. Investigations prior to admission showed raised CA125 and computed tomography of the abdomen showed multiple retroperitoneal mesenteric lymphadenopathies. Extensive investigations performed on secondary causes of weight gain were unrevealing. Subsequent PET-CT scan revealed generalized lymphadenopathy involving the left deep cervical, supraclavicular, and retroperitoneal mesenteric area. Excisional biopsy of the left supraclavicular lymph node was performed, with histology showing infiltrations of Periodic acid-Schiff positive foamy macrophages. T. whipplei DNA was detected in her serum, saliva, stool, and lymph node by PCR targeting the 16S ribosomal RNA gene. She was started on intravenous ceftriaxone, and then stepped down to oral antibiotics for a total of 44 months. The recurrence of fever after 12 days of ceftriaxone raised the suspicion of Immune Reconstitution Inflammatory Syndrome (IRIS). Serial imaging showed a gradual reduction in the size of retroperitoneal lymphadenopathies. Literature review on Whipple's disease in the Chinese population identified 13 reports of detectable T. whipplei DNA in clinical specimens. The majority of the cases were pneumonia, followed by culture-negative endocarditis, encephalitis, and skin and soft tissue infection. However, most patients with pneumonia were diagnosed based on next generation sequencing alone, with the resolution of pulmonary infiltrates without adequate duration of antibiotics, suggesting the possibility of colonization instead of infection. The recommendation of long-term doxycycline suppression after treatment may be supported by the slow response of retroperitoneal lymphadenopathies to antibiotics in our patient. CONCLUSIONS: Unintentional weight gain and constipation could be atypical presentations of Whipple's disease. It is a rare disease in the Chinese population despite the advancement of molecular techniques in the diagnosis of infections. A prolonged course of antibiotics may be required due to slow clinical response as documented by serial imaging in our case. The possibility of IRIS should be considered in patients with breakthrough fever during treatment of Whipple's disease.

Intranasal infection by SARS-CoV-2 Omicron variants can induce inflammatory brain damage in newly weaned hamsters.

SUMMARY: Intranasal infection of newly-weaned Syrian hamsters by SARS-CoV-2 Omicron variants can lead to brain inflammation and neuron degeneration with detectable low level of viral load and sparse expression of viral nucleoprotein.

Human airway and nasal organoids reveal escalating replicative fitness of SARS-CoV-2 emerging variants.

The high transmissibility of SARS-CoV-2 Omicron subvariants was generally ascribed to immune escape. It remained unclear whether the emerging variants have gradually acquired replicative fitness in human respiratory epithelial cells. We sought to evaluate the replicative fitness of BA.5 and earlier variants in physiologically active respiratory organoids. BA.5 exhibited a dramatically increased replicative capacity and infectivity than B.1.1.529 and an ancestral strain wildtype (WT) in human nasal and airway organoids. BA.5 spike pseudovirus showed a significantly higher entry efficiency than that carrying WT or B.1.1.529 spike. Notably, we observed prominent syncytium formation in BA.5-infected nasal and airway organoids, albeit elusive in WT- and B.1.1.529-infected organoids. BA.5 spike-triggered syncytium formation was verified by lentiviral overexpression of spike in nasal organoids. Moreover, BA.5 replicated modestly in alveolar organoids, with a significantly lower titer than B.1.1.529 and WT. Collectively, the higher entry efficiency and fusogenic activity of BA.5 spike potentiated viral spread through syncytium formation in the human airway epithelium, leading to enhanced replicative fitness and immune evasion, whereas the attenuated replicative capacity of BA.5 in the alveolar organoids may account for its benign clinical manifestation.