Emerging Microbes & Infections最新文献

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with an increasing annual incidence rate. In this case report, we presented two patients infected with the SFTS virus, suggesting a potential direct transmission route from camels to humans through blood contact. Both patients developed symptoms after engaging in the slaughtering of one sick camel, while their family members living in the same environment or co-diners remained unaffected. Subsequent detection revealed a high viral load of SFTS virus, reaching 10¹⁰ viral RNA copies/ml, in the sample obtained from the sick camel. Metagenomic sequencing did not identify any other pathogens. The SFTS virus was successfully isolated from both patient and camel samples. The complete nucleotide sequences obtained from the infected patients demonstrated a remarkable 100% similarity to those found in the camel, and genetic evolution analysis classified the virus as genotype A. Additionally, partial sequences of the SFTS virus were identified in ticks captured from the camel rearing environment, however, these sequences showed only 95.9% similarity to those found in camel and humans. Furthermore, immunoglobulin M and immunoglobulin G antibodies were detected in serum samples collected from the patient. Our findings provide evidence that camel may serve as a competent reservoir for transmitting the SFTS virus to humans. Further in vitro investigations into SFTS virus infections in large animals are warranted to understand their role in viral maintenance and transmission.

Tuberculosis (TB) remains a leading cause of mortality among individuals coinfected with HIV, characterized by progressive pulmonary inflammation. Despite TB's hallmark being focal granulomatous lung lesions, our understanding of the histopathological features and regulation of inflammation in HIV & TB coinfection remains incomplete. In this study, we aimed to elucidate these histopathological features through an immunohistochemistry analysis of HIV & TB co-infected and TB patients, revealing marked differences. Notably, HIV & TB granulomas exhibited aggregation of CD68 + macrophage (Mφ), while TB lesions predominantly featured aggregation of CD20+ B cells, highlighting distinct immune responses in coinfection. Spatial transcriptome profiling further elucidated CD68+ Mφ aggregation in HIV & TB, accompanied by activation of IL6 pathway, potentially exacerbating inflammation. Through multiplex immunostaining, we validated two granuloma types in HIV & TB versus three in TB, distinguished by cell architecture. Remarkably, in the two types of HIV & TB granulomas, CD68 + Mφ highly co-expressed IL6R/pSTAT3, contrasting TB granulomas' high IFNGRA/SOCS3 expression, indicating different signaling pathways at play. Thus, activation of IL6 pathway may intensify inflammation in HIV & TB-lungs, while SOCS3-enriched immune microenvironment suppresses IL6-induced over-inflammation in TB. These findings provide crucial insights into HIV & TB granuloma formation, shedding light on potential therapeutic targets, particularly for granulomatous pulmonary under HIV & TB co-infection. Our study emphasizes the importance of a comprehensive understanding of the immunopathogenesis of HIV & TB coinfection and suggests potential avenues for targeting IL6 signaling with SOCS3 activators or anti-IL6R agents to mitigate lung inflammation in HIV & TB coinfected individuals.

Influenza virus infection poses a continual menace to public health. Here, we developed soluble trimeric HA ectodomain vaccines by establishing interprotomer disulfide bonds in the stem region, which effectively preserve the native antigenicity of stem epitopes. The stable trimeric H1 ectodomain proteins exhibited higher thermal stabilities in comparison with unmodified HAs and showed strong binding activities towards a panel of anti-stem cross-reactive antibodies that recognize either interprotomer or intraprotomer epitopes. Negative stain transmission electron microscopy (TEM) analysis revealed the stable trimer architecture of the interprotomer disulfide-stapled WA11#5, NC99#2, and FLD#1 proteins as well as the irregular aggregation of unmodified HA molecules. Immunizations of mice with those trimeric HA ectodomain vaccines formulated with incomplete Freund's adjuvant elicited significantly more potent cross-neutralizing antibody responses and offered broader immuno-protection against lethal infections with heterologous influenza strains compared to unmodified HA proteins. Additionally, the findings of our study indicate that elevated levels of HA stem-specific antibody responses correlate with strengthened cross-protections. Our design strategy has proven effective in trimerizing HA ectodomains derived from both influenza A and B viruses, thereby providing a valuable reference for designing future influenza HA immunogens.

Avian influenza viruses (AIVs) are the origin of multiple mammal influenza viruses. The genetic determinants of AIVs adapted to humans have been widely elucidated, however, the molecular mechanism of cross-species transmission and adaptation of AIVs to canines are still poorly understood. In this study, two H3N2 influenza viruses isolated from a live poultry market (A/environment/Guangxi/13431/2018, GX13431) and a swab sample from a canine (A/canine/Guangdong/0601/2019, GD0601) were used to investigate the possible molecular basis that determined H3N2 AIV adapting to canine. We found that GD0601 exhibited more robust polymerase activity in cells and higher pathogenicity in mice compared with its evolution ancestor H3N2 AIV GX13431. A series of reassortments of the ribonucleoprotein (RNP) complex showed that the PB2 subunit was the crucial factor that conferred high polymerase activity of GD0601, and the substitution of I714S in the PB2 subunit of GD0601 attenuated the replication and pathogenicity in mammal cells and the mouse model. Mechanistically, the reverse mutation of I714S in the PB2 polymerase subunit which was identified in AIV GX13431 reduced the nuclear import efficiency of PB2 protein and interfered with the interactions of PB2-PA/NP that affected the assembly of the viral RNP complex. Our study reveals amino acid mutation at the position of 714 in the nuclear localization signal (NLS) area in PB2 plays an important role in overcoming the barrier from poultry to mammals of the H3N2 canine influenza virus and provides clues for further study of mammalian adaptation mechanism of AIVs.

The discovery of alphacoronaviruses and betacoronaviruses in plateau pikas (Ochotona curzoniae) expanded the host range of mammalian coronavirus (CoV) to a new order - Lagomorpha. However, the diversity and evolutionary relationships of CoVs in these plateau-region-specific animal population remains uncertain. We conducted a five-year longitudinal surveillance of CoVs harboured by pikas around Qinghai Lake, China. CoVs were identified in 33 of 236 plateau pikas and 2 of 6 Gansu pikas (Ochotona cansus), with a total positivity rate of 14.5%, and exhibiting a wide spatiotemporal distribution across seven sampling sites and six time points. Through meta-transcriptomic sequencing and RT-PCR, we recovered 16 near-complete viral genome sequences. Phylogenetic analyses classified the viruses as variants of either pika alphacoronaviruses or betacoronaviruses endemic to plateau pikas from the Qinghai-Tibet Plateau region. Of particular note, the pika-associated betacoronaviruses may represent a novel subgenus within the genus Betacoronavirus. Tissue tropism, evaluated using quantitative real-time PCR, revealed the presence of CoV in the rectal and/or lung tissues, with the highest viral loads at 10^3.55 or 10^2.80 RNA copies/μL. Surface plasmon resonance (SPR) assays indicated that the newly identified betacoronavirus did not bind to human or pika Angiotensin-converting enzyme 2 (ACE2) or Dipeptidyl peptidase 4 (DPP4). The findings highlight the ongoing circulation and broadening host spectrum of CoVs among pikas, emphasizing the necessity for further investigation to evaluate their potential public health risks.

Throughout history, the influenza A virus has caused numerous devastating global pandemics. Macrophages, as pivotal innate immune cells, exhibit a wide range of immune functions characterized by distinct polarization states, reflecting their intricate heterogeneity. In this study, we employed the time-resolved single-cell sequencing technique coupled with metabolic RNA labelling to elucidate the dynamic transcriptional changes in distinct polarized states of bone marrow-derived macrophages (BMDMs) upon infection with the influenza A virus. Our approach not only captures the temporal dimension of transcriptional activity, which is lacking in conventional scRNA-seq methods, but also reveals that M2-polarized Arg1_macrophage cluster is the sole state supporting successful replication of influenza A virus. Furthermore, we identified distinct antigen presentation capabilities to CD4⁺ T and CD8⁺ T cells across diverse polarized states of macrophages. Notably, the M1 phenotype, exhibited by (BMDMs) and murine alveolar macrophages (AMs), demonstrated superior conventional and cross-presentation abilities for exogenous antigens, with a particular emphasis on cross-presentation capacity. Additionally, as CD8⁺ T cell differentiation progressed, M1 polarization exhibited an enhanced capacity for cross-presentation. All three phenotypes of BMDMs, including M1, demonstrated robust presentation to CD4⁺ regulatory T cells, while displaying limited ability to present to naive CD4⁺ T cells. These findings offer novel insights into the immunological regulatory mechanisms governing distinct polarized states of macrophages, particularly their roles in restricting the replication of influenza A virus and modulating antigen-specific T cell responses through innate immunity.

We detected highly pathogenic avian influenza A(H5N1) virus in wild rats collected from a rural area in Giza, Egypt, near poultry farms, markets, and backyard flocks. Sequence and phylogenetic analyses indicated that the virus from the rats belonged to clade 2.3.4.4b, which has been the predominant virus genotype circulating in Egypt and worldwide since 2021-2022. Active surveillance of avian influenza viruses in wild and domestic mammals is recommended to prevent further spread to mammals and humans.

SARS-CoV-2 Omicron subvariants are still emerging and spreading worldwide. These variants contain a high number of polymorphisms in the spike (S) glycoprotein that could potentially impact their pathogenicity and transmission. We have previously shown that the S:655Y and P681H mutations enhance S protein cleavage and syncytia formation. Interestingly, these polymorphisms are present in Omicron S protein. Here, we characterized the cleavage efficiency and fusogenicity of the S protein of different Omicron sublineages. Our results showed that Omicron BA.1 subvariant is efficiently cleaved but it is poorly fusogenic compared to previous SARS-CoV-2 strains. To understand the basis of this phenotype, we generated chimeric S protein using combinations of the S1 and S2 domains from WA1, Delta and Omicron BA.1 variants. We found that the S2 domain of Omicron BA.1 hindered efficient cell-cell fusion. Interestingly, this domain only contains six unique polymorphisms never detected before in ancestral SARS-CoV-2 variants. WA1^614G S proteins containing the six individuals S2 Omicron mutations were assessed for their fusogenicity and S surface expression after transfection in cells. Results showed that the S:N856K and N969K substitutions decreased syncytia formation and impacted S protein cell surface levels. However, we observed that "first-generation" Omicron sublineages that emerged subsequently, had convergently evolved to an enhanced fusogenic activity and S expression on the surface of infected cells while "second-generation" Omicron variants have highly diverged and showed lineage-specific fusogenic properties. Importantly, our findings could have potential implications in the improvement and redesign of COVID-19 vaccines.

There is limited evidence to support the association between tuberculosis (TB) and the occurrence of Takayasu arteritis (TAK). To investigate the incidence of active TB (ATB) in TAK and explore the impact of anti-rheumatic therapy on the occurrence of ATB or reactivation of Latent TB infection (LTBI) and their effect on interferon-γ release assay (IGRA) results, we conducted a prospective study based on the Chinese Registry for Systemic Vasculitis cohort. The standard incidence ratio (SIR) was calculated and stratified by age. Kaplan-Meier analysis was used to determine the effect of variables on ATB or LTBI reactivation in patients with TAK. Data from 825 patients with TAK in the registry were analysed. During a median follow-up of 5 years, 5 patients developed ATB with a crude incidence of 154 (95%CI:57-381) person-years/100,000. The SIR was 5.59 (95%CI:1.81-13.04). Glucocorticoids and conventional disease-modifying anti-rheumatic drugs (cDMARDs) did not increase the risk of ATB or LTBI reactivation (P > 0.05). However, the use of tumour necrosis factor inhibitor (TNFi) increased the risk of ATB in patients with LTBI (P < 0.001). Furthermore, the value of the IGRA assay decreased after treatment (P < 0.05). In conclusion, the incidence of TB infection is markedly increased in patients with TAK and patients with TAK are at high risk of developing ATB. Treatment with glucocorticoids and cDMARDs does not significantly increase the risk for ATB in patients with TAK. Moreover, IGRA may have limited effectiveness in monitoring ATB infection or LTBI reactivation in patients with TAK.

Crimean-Congo haemorrhagic fever orthonairovirus (CCHFV) is a tick-borne, risk group 4 pathogen that often causes a severe haemorrhagic disease in humans (CCHF) with high case fatality rates. The virus is believed to be maintained in a tick-vertebrate-tick ecological cycle involving numerous wild and domestic animal species; however the biology of CCHFV infection in these animals remains poorly understood. Here, we experimentally infect domestic sheep with CCHFV Kosovo Hoti, a clinical isolate representing high pathogenicity to humans and increasingly utilized in current research. In the absence of prominent clinical signs, the infection leads to an acute viremia and coinciding viral shedding, fever and markers for potential impairment in liver and kidney functions. A number of host responses distinguish the subclinical infection in sheep versus fatal infection in humans. These include an early reduction of neutrophil recruitment and its chemoattractant, IL-8, in the blood stream of infected sheep, whereas neutrophil infiltration and elevated IL-8 are features of fatal CCHFV infections reported in immunodeficient mice and humans. Several inflammatory cytokines that correlate with poor disease outcomes in humans and have potential to cause vascular dysfunction, a primary hallmark of severe CCHF, are down-regulated or restricted from increasing in sheep. Of particular interest, the detection of CCHFV RNA (including full-length genome) in a variety of sheep tissues long after the acute phase of infection indicates a widespread viral dissemination in the host and suggests a potentially long-term persisting impact of CCHFV infection. These findings reveal previously unrecognized aspects of CCHFV biology in animals.