Journal of Infectious Diseases最新文献

Background: Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains the leading cause of death from a single infectious agent worldwide. Exposure to Mtb results in diverse outcomes: bacterial clearance, latent infection, asymptomatic, or symptomatic TB. Current diagnostic tools cannot reliably distinguish these outcomes. Our previous studies identified Mtb proteins in extracellular vesicles (EVs) from TB patients' serum, suggesting their potential as biomarkers. Here, we aimed to discover Mtb proteins and peptides in serum EVs across TB stages, focusing on asymptomatic individuals.

Methods: Serum was obtained from healthy, HIV-negative South African adult volunteers enrolled in a TB risk study. Based on patients' outcomes, samples were classified as prevalent, incident (controls that progressed to TB), activated TB, or community controls. EVs were isolated using ExoQuick™, followed by protein digestion and mass spectrometry (MS) analysis. Data-independent acquisition (DIA) with five different data analysis strategies, and two data-dependent (DDA) methods were used to identify Mtb proteins.

Results: Our DIA analysis using ion-mobility and spectral libraries enriched with Mtb-MS data revealed 19 Mtb proteins. Rv2997 was significantly higher at baseline in individuals who were initially TB-negative (incident) but later became bacteriologically positive, asymptomatic-TB (activated). HspX, GroEL2, and GroES, together with a MtrB peptide were significantly different between controls and asymptomatic-TB cases. DDA approaches did not resolve additional Mtb proteins.

Conclusions: Quantitative DIA analysis discovered Mtb proteins/peptides in serum-derived EVs that were differentially abundant in individuals with early, asymptomatic TB. These findings highlight their potential as biomarkers and provide insight into host-pathogen interactions during subclinical infection.

Background: Febrile disease caused by infections of Yezo virus (YEZV), a tick-borne orthonairovirus, was first reported in Japan in 2021 and subsequently identified in China. While the recent studies suggest a broader endemic area of the emerging YEZV infections, its clinical and epidemiological characteristics remain poorly elucidated due to the limited number of reported cases.

Methods: We conducted retrospective and prospective surveillance of patients with suspected tick-borne febrile illnesses in Hokkaido, Japan, between 2013 and 2024. Serum samples were analyzed by RT-qPCR, IgM/IgG ELISA, and neutralization assay. Viral genome of isolates was sequenced and phylogenetically analyzed with publicly available YEZV genomes.

Results: A total of 22 patients with YEZV infections including 10 newly identified patients was analyzed. Most infections occurred between May and July, coinciding with the peak activity of Ixodes ticks in the study area. A case from southern Hokkaido was firstly identified. Fever, leukocytopenia, thrombocytopenia, elevated levels of liver enzymes, and ferritin were determined as common features observed in patients with YEZV infections. Viral RNA was typically detectable in the serum within 7 days after the disease onset. Serum antibodies became positive later and might persist up to at least 600 days. Phylogenetic analysis incorporating five new isolates showed the circulations of two genetic groups of YEZVs in Japan.

Conclusions: Our results revealed characteristics of YEZV infections in patients and highlighted the importance of combination of molecular and serological diagnostics. The proposed case definitions and diagnostic framework may contribute future surveillance.

Background: The global dissemination of hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) poses escalating threats to public health. Substantial controversy persists regarding its true virulence potential, highlighting the need for reliable biomarkers to enable early diagnosis and targeted therapy.

Methods: Using a mouse subcutaneous challenge model, we characterized 59 carbapenem-resistant K. pneumoniae (CRKP) isolates, identifying 37.29% (22/59) as convergent hv-CRKP. Phenotypic and genotypic characterization, integrated with genome-wide association study (GWAS) and transcriptomic analysis, was performed, and reliable biomarkers for accurate hv-CRKP detection were identified.

Results: Patients infected with hv-CRKP exhibited significantly higher sepsis incidence (P = 0.028) and increased mortality. Capsule production and hypermucoviscosity robustly discriminated hv-CRKP from CRKP. GWAS identified a significant association between an SNP in the rbtT locus and the hypervirulent phenotype, whereas virulence plasmid-associated genes showed no significant association. These findings suggest chromosomally encoded factors-independent of plasmid-borne elements-contribute critically to hypervirulence. Transcriptomics revealed rcsA-mediated capsule upregulation enhances macrophage phagocytosis resistance and bacterial survival, revealing a pivotal pathogenic mechanism. Both multivariable logistic regression and LASSO regression confirmed capsule production and rcsA expression as independent and robust diagnostic biomarkers to accurately assess virulence potential in carbapenem-resistant strains.

Conclusions: We conclude that clinical application of the term "hv-CRKP" requires prudent validation and emphasize the urgency of developing biomarkers to precisely identify truly hypervirulent CRKP strains.

Background: HIV leads to reduced telomere length (TL), a biomarker of immune ageing. We investigated relationships between HIV viral load (VL) and CD4 count with TL and its rate of attrition in children with HIV (CWH) from Zambia and Zimbabwe.

Methods: Buffy coat was obtained at baseline and 48 weeks from children aged 11-19 years with perinatally-acquired HIV taking combination antiretroviral therapy (cART) for >6 months recruited into the VITALITY trial [Trial registration no: PACTR202009897660297]. Relative TL was measured using monochrome multiplex qPCR, standardising units for analysis. Cross-sectional analyses used multivariable linear regression adjusting for age, sex and study site; longitudinal analysis additionally adjusted for baseline TL.

Results: Among participants at baseline (N=842, mean±SD age 15.5±2.6 years, 53.2% female), 678(80.5%) had HIV VL<60 copies/mL, 66(7.8%) had 60-1000 copies/mL and 98(11.6%) had >1000 copies/mL. The CD4 count was 584±243 cells/μL. Compared to participants with VL<60 copies/mL, those with VL>1000 copies/mL had shorter TL (β[95%CI]=-0.239[-0.451, -0.026], P=0.028) whereas those with 60-1000 copies/mL did not (P=0.836). Lower CD4 cell count was associated with shorter TL (β[95%CI]=-0.038[-0.009, -0.066] per 100 CD4 cells/μL, P=0.009). In longitudinal analysis (N=783) after 336±6 days, those with HIV VL>1000 copies/mL at both timepoints had an accelerated telomere attrition rate (β[95%CI]=-0.276[-0.546, -0.005], P=0.046) compared with participants with VL<1000 copies/mL. Lower baseline CD4 count was associated with faster telomere attrition rate (β[95%CI]=-0.033[-0.008, -0.057], P=0.009).

Conclusions: HIV VL>1000 copies/mL among CWH on cART in Africa is associated with a degradation of immune age within one year, which may increase risk of co-morbidities later in life.

Background: Little is known about the specific inflammatory networks and immune parameters that drive frailty outcomes in people with HIV (PWH).

Methods: Plasma analytes and T cell phenotypes from PWH without frailty (0 Fried score, n=60) and with frailty (≥3 Fried score, n=60) were measured by Luminex assay or flow cytometry. Multiple least-squares linear regression analysis was used to determine the association of each marker with frailty in unadjusted and adjusted models. Spearman correlations were used to determine the association of plasma analytes with T cell phenotypes.

Results: We found that 19 of 75 markers measured in plasma were significantly associated with frailty, most of which are downstream of NF-κB signaling and are senescence-associated secretory phenotype (SASP) components. In frail individuals, the proportions of CD4 and CD8 T cells with a naïve phenotype were significantly reduced, and the proportions of CD4 T cells expressing TIGIT and PD-1 were significantly elevated. Of the frailty-associated analytes, we found that only osteoprotegerin and TNF levels were significantly correlated with percent naïve, TIGIT+, and PD-1+ CD4 T cells among PWH with frailty. Osteoprotegerin levels were negatively correlated with CD4/CD8 T cell ratio.

Conclusions: We found a strong association of the SASP and NF-κB related inflammation with frailty in PWH. Osteoprotegerin can inhibit osteoclast formation and prevent bone resorption. Low proportion of naïve CD4 T cells and increased TIGIT and PD-1 expression were associated with both osteroprotegerin levels and frailty, suggesting a link between inflammation, T cell activation, bone health, and frailty in PWH.

Background: Fc gamma receptor III b (FcγRIIIb), a glycosylphosphatidylinositol (GPI) linked receptor, is the most abundant neutrophil FcγR on neutrophils followed by FcγRIIa. FcγRs interact with IgG and studies have reported the association of antibody dependent neutrophil phagocytosis (ADNP) with protection against malaria, but the role of specific FcγRs is not clear.

Methods: To investigate the relative importance of FcγRIIIb and FcγRIIa as mediators of ADNP of Plasmodium falciparum infected erythrocytes (IEs), purified neutrophils from healthy donors were treated with tumor necrosis factor (TNF) to mobilize the intracellular stores of FcγRIIIb to the surface followed by enzymatic cleavage of GPI-linked FcγRIIIb with phosphatidylinositol phospholipase C (PIPLC).

Results: In TNF/PIPLC treated neutrophils, detectable FcγRIII decreased by 79% (relative gMFI = 21 ± 4.5), while FcγRIIa detection increased by 82% (relative gMFI = 182 ± 2.3), compared to untreated neutrophils (relative gMFI = 100%). When opsonised IEs were incubated with TNF/PIPLC treated neutrophils, ADNP by FcγRIIIb-depleted neutrophils increased significantly (relative phagocytosis = 585% ± 108%) compared to untreated neutrophils (relative phagocytosis = 100%, p = 0.042). Using FcγR blocking we show that compared to no-blocker (relative phagocytosis = 100%), ADNP was reduced more than five-fold by FcγRIIa blocker alone (relative phagocytosis ∼17% ± 1.5%, p<0.05) and to a similar extent by combined FcγRIIa and FcγRIII blockers (relative phagocytosis ∼24% ± 5.5%, p <0.05).

Conclusions: Our data suggest that FcγRIIa is the main phagocytic receptor that mediates ADNP of IEs and that FcγRIIIb acts as a decoy receptor.