Pathogens and Immunity最新文献

Background: Human herpesvirus-8 (HHV-8), or Kaposi sarcoma (KS)-associated herpesvirus (KSHV), causes severe disease in people with profound immunosuppression. Yet, diagnosing KS can be challenging given the diverse manifestations and current limited usual care diagnostic methods (UC; polymerase chain reaction, histopathology).

Methods: Pathogen-agnostic plasma microbial cell-free DNA sequencing was applied to banked samples from 116 outpatients included in 2 previous prospective studies of patients with antiretroviral treatment-naïve, advanced HIV (CD4 count ≤100 cells/μL). We then reviewed clinical and laboratory data for any people who tested positive for HHV-8 by mcfDNA sequencing or UC at baseline.

Results: HHV-8 was detected in 21 (18%) outpatients with advanced HIV by any method, with males comprising the majority (86%) and one-third originally from non-US countries (including Africa, Central America, and the Caribbean). Adding mcfDNA sequencing to UC proportionally increased HHV-8 detection by 38%, while also identifying in 18 (86%) people other microbes of potential interest, including common herpesviruses, Mycobacterium tuberculosis, and Pneumocystis jirovecii.

Conclusions: Plasma mcfDNA sequencing may improve UC in detection of HHV-8 infection, especially in immunocompromised outpatients, in whom early detection may facilitate appropriate management to prevent severe KS disease. The potential added benefit of the detection of other pathogens by mcfDNA sequencing may be particularly relevant for this population.

Rationale: Treatment monitoring of tuberculosis patients is complicated by a slow growth rate of Mycobacterium tuberculosis. Recently, host RNA signatures have been used to monitor the response to tuberculosis treatment.

Objective: Identifying and validating a whole blood-based RNA signature model to predict microbiological treatment responses in patients on tuberculosis therapy.

Methods: Using a multi-step machine learning algorithm to identify an RNA-based algorithm to predict the remaining time to culture conversion at flexible time points during anti-tuberculosis therapy.

Results: The identification cohort included 149 patients split into a training and a test cohort, to develop a multistep algorithm consisting of 27 genes (TB27) for predicting the remaining time to culture conversion (TCC) at any given time. In the test dataset, predicted TCC and observed TCC achieved a correlation coefficient of r=0.98. An external validation cohort of 34 patients shows a correlation between predicted and observed days to TCC also of r=0.98.

Conclusion: We identified and validated a whole blood-based RNA signature (TB27) that demonstrates an excellent agreement between predicted and observed times to M. tuberculosis culture conversion during tuberculosis therapy. TB27 is a potential useful biomarker for anti-tuberculosis drug development and for prediction of treatment responses in clinical practice.

Klebsiella pneumoniae (Kp) is a Gram-negative pathogen responsible for both hospital- and community-acquired infections. Kp is classified into 2 distinct pathotypes: classical K. pneumoniae (cKp) and hypervirulent K. pneumoniae (hvKp). First described in Taiwan in 1986, hvKp are highly pathogenic and characterized by unique phenotypic and genotypic traits. The hypermucoviscous (hmv) phenotype, generally marked by overproduction of the capsule, is often associated with hvKp, although recent studies show that some cKp strains may also have this characteristic. Furthermore, hvKp can cause severe community-acquired infections in healthy people and have been associated with metastatic infections such as liver abscess, meningitis, and endophthalmitis. HvKp are increasingly being reported in hospital-acquired settings, complicating treatment strategies. In particular, while hvKp have historically been antibiotic-susceptible, multidrug-resistant (MDR) strains have emerged and pose a significant public health threat. The combination of high virulence and limited antibiotic options demands further research into virulence mechanisms and rapid identification methods. This review discusses the epidemiology of hvKp and their virulence factors, highlighting the importance of phenotypic and non-phenotypic tests, including next-generation molecular diagnostics, for the early detection of hvKp.

Background: Antibody-dependent cell-mediated cytotoxic (ADCC) response mediated by natural killer (NK) cells correlates with decreased infection risk in studies involving simian immunodeficiency virus (SIV)/simian-human immunodeficiency virus (SHIV), and human immunodeficiency virus (HIV) vaccine candidates. Currently, the heterogeneities of the functional subset of rhesus macaque natural killer (RMNK) cells are under-characterized.

Method: We engaged the RMNK cells with ADCC-mediating anti-HIV-1 monoclonal antibodies (ADCCAbs) or anti-CD16 antibodies and used CD107a expression as the surrogate marker for RMNK cells actively involved in ADCC. CD107a⁺ and CD107a^- populations were analyzed individually using single-cell RNA sequencing.

Results: Subsets of CD107a⁺ RMNK cells produced more chemokines than the others, suggesting that these cells not only eliminate infected cells but also provide immunoregulatory signals and potentially curb HIV-1 replication. Crosslinking of Fc gamma receptor IIIa via anti-CD16 antibodies resulted in a significantly higher percentage of degranulating cells than via ADCCAbs. However, the magnitude of degranulation and chemokine production was reduced by 6- to 30-fold.

Conclusion: The quality and quantity of receptor engagement are important determinants of achieving an optimal level of the RMNK response.

Background: Optimal control of microbial infections requires mucosal-associated invariant T (MAIT) cells. People living with HIV (PWH) on antiretroviral therapy (ART) can be divided into 2 groups: immune responders (IR) who recover or retain CD4 T cell numbers, and immune non-responders (INR) who do not. Compared to IR, INR have fewer MAIT cells and increased systemic inflammation and microbial translocation, but how these factors affect MAIT cells is unknown.

Methods: MAIT cells from IR, INR, and from controls without HIV were enumerated and characterized by flow cytometry. To determine the links among MAIT cells, inflammation, and microbial translocation, the correlations of MAIT cell numbers to previously published soluble inflammatory markers and plasma microbial genetic sequences were assessed by Spearman analysis. In vitro assays were used to support our findings.

Results: MAIT cell numbers were significantly negatively correlated with levels of IL-6 and IP-10 (markers of inflammation); CD14, LPS, and FABP2 (markers of microbial translocation); and with abundance of Serratia and other Proteobacteria genetic sequences in plasma. In a separate analysis of PWH on ART receiving the IL-6 receptor antagonist tocilizumab (TCZ), we found that blocking IL-6 signaling with TCZ increased IL-7 receptor expression on MAIT cells and reduced plasma IL-7 levels, consistent with improved uptake of IL-7 in vivo.

Conclusions: Our findings suggest inflammation and microbial translocation in PWH on ART lead to a loss of MAIT cells via impaired IL-7 responsiveness, resulting in further increased microbial translocation and inflammation.

Background: First-generation anti-SARS-CoV-2 monoclonal antibodies (mAbs) used for prophylaxis or therapeutic purposes in immunocompromised patients have been withdrawn because of the emergence of resistant Omicron variants. In 2024, 2 novel mAbs, VYD222/Pemivibart and AZD3152/Sipavibart, were approved by health authorities, but their activity against contemporary JN.1 sublineages is poorly characterized.

Methods: We isolated authentic JN.1.1, KP.1.1, LB.1, and KP.3.3 viruses and evaluated their sensitivity to neutralization by these mAbs in 2 target cell lines.

Results: Compared to ancestral strains, VYD222/Pemivibart remained moderately active against JN.1 subvariants, with a strong increase of 50% Inhibitory Concentration (IC50), reaching up to 3 to 15 µg/mL for KP3.3. AZD3152/Sipavibart neutralized JN.1.1 but lost antiviral efficacy against KP.1.1, LB.1, and KP3.3.

Conclusions: Our results highlight the need for a close clinical monitoring of VYD222/Pemivibart and raise concerns about the clinical efficacy of AZD3152/Sipavibart.

In this interview, Jonathan Yewdell talks with Pathogens and Immunity senior editor Neil Green-span about the evolution of viral immunology, highlighting his work and the contributions of other influential scientists. He emphasizes the importance of passion and collaboration in scientific research, illustrating the potential for groundbreaking discoveries through networking. He provides advice on navigating a scientific career, stressing the significance of strong mentorship. And he shares his perspective on transforming the scientific publishing industry and research education.

Background: The potential for promotion of intestinal colonization with healthcare-associated pathogens by new antibiotics used to treat infections due to multidrug-resistant Gram-negative bacilli is unclear.

Methods: Mice treated for 3 days with daily subcutaneous phosphate-buffered saline (control), ceftazidime/avibactam, ceftolozane/tazobactam, ceftaroline, and meropenem/vaborbactam were challenged with 10,000 colony-forming units (CFU) of vancomycin-resistant Enterococcus (VRE) resistant to each of the antibioics or carbapenemase-producing Klebsiella pneumoniae 1 day after the final treatment dose. The concentrations of VRE or K. pneumoniae in stool were measured on days 1, 3, 6, and 15 after challenge.

Results: Control mice had transient low levels of VRE or K. pneumoniae (<3 log₁₀ CFU/g) detected in stool with negative cultures on days 6 and 15 after challenge. In comparison to control mice, each of the antibiotics promoted establishment of high-density colonization with VRE (mean concentration, >8 log₁₀ CFU/g of stool on day 1 after challenge) that persisted at >4 log₁₀ CFU/g of stool through day 15 (P<0.01). In comparison to control mice, meropenem/vaborbactam and ceftaroline promoted high-density colonization with K. pneumoniae (peak concentration, >8 log₁₀ CFU/g of stool) (P<0.01), ceftolozane/tazobactam promoted colonization to a lesser degree (peak concentration, >5 log₁₀ CFU/g of stool), and ceftazidime/avibactam did not promote colonization (P>0.05).

Conclusions: Our results suggest that several beta-lactam antibiotics recently developed for treatment of infections with resistant Gram-negative bacilli have the potential to promote colonization by healthcare-associated pathogens. Additional studies are needed to examine the impact of these agents in patients.

Background: A primary barrier to curing HIV is the HIV reservoir. The leading infectious cause of death worldwide for people living with HIV is tuberculosis (TB), but we do not know how TB impacts the HIV reservoir.

Methods: Participants in identification and validation cohorts were selected from previously enrolled studies at Groupe Haïtien d'Étude du Sarcome de Kaposi et des Infections Opportunistes (GHESKIO) in Port au Prince, Haiti. Intact and non-intact proviral DNA were quantified using droplet digital PCR of peripheral blood mononuclear cell (PBMC)-derived CD4+ T cells. Kruskal-Wallis tests were used to compare medians with tobit regression for censoring.

Results: In the identification cohort, we found that people living with HIV with a history of active pulmonary TB (n=19) had higher levels of intact provirus than people living with HIV without a history of active TB (n=47) (median 762; IQR, 183-1173 vs 117; IQR, 24-279 intact provirus per million CD4, respectively; P=0.0001). This difference also was seen in the validation cohort (n=31), (median 102; IQR, 0-737 vs 0; IQR, 0-24.5 intact provirus per million CD4, P=0.03) for TB vs no-TB history groups, respectively. The frequencies of CD4+ T cells with any detectable proviral fragment was directly proportional to the levels of interleukin-1 beta (r=0.524, P= 0.0025) and interleukin-2 (r=0.622, P=0.0002).

Conclusions: People living with HIV with a history of active pulmonary TB have more HIV pro-virus in their circulating CD4+ T cells, even years after TB cure. We need to characterize which CD4+ T cells are harboring intact provirus to consider the impact of T cell-targeting HIV cure interventions for people living in TB-endemic areas.