ACS Infectious Diseases最新文献

Malaria, caused by a protozoan parasite of the genus Plasmodium, is a severe infectious disease with life-threatening consequences that has burdened mankind for centuries. Although Plasmodium falciparum (P. falciparum) malaria is more prevalent globally than Plasmodium vivax (P. vivax) malaria, India bears the largest burden of P. vivax malaria, with over 3.6 million cases accounting for ∼48% of global P. vivax malaria cases. Existing detection methods for P. vivax malaria are costly or tedious or have low accuracy. To address the need for a specific diagnostic assay for P. vivax, we generated aptamers specific to Plasmodium vivax tryptophan-rich antigen (PvTRAg). We employed them in an aptamer-linked immobilized sorbent assay (ALISA) to detect P. vivax malaria infections. The two most specific aptamers for PvTRAg, identified as Apt_14 and Apt_16, were obtained using the Systematic Evolution of Ligands by Exponential Enrichment. The dissociation constant (K_D) values of Apt_14 and Apt_16 were 1.9 and 1.2 nM, respectively, indicating high affinity to PvTRAg. The limit of detection for both aptamers was found to be 2.5 nM. During clinical validation, the sensitivity of 96% and 84% was obtained with Apt_14- and Apt_16-based ALISA with 100% specificity. The aptamers demonstrated nonsignificant cross-reactivity with other nonmalarial antigens and PvTRAg homologues along with a high level of selectivity for PvTRAg over P. falciparum antigens and various other antigens. Altogether, our findings confirm the effectiveness of DNA aptamers for the accurate diagnosis of P. vivax malaria and lay the groundwork for developing an aptamer-based diagnostic assay for malaria.

Neurosyphilis, a neurological manifestation of syphilis, is closely related to neuroinflammation. Autophagy, a fundamental cellular mechanism that mediates the degradation of intracellular components, plays a crucial role in immune regulation and inflammation. Microglia, resident immune cells in the brain, are central to these processes. However, the interplay between autophagy and neuroinflammation in the context of neurosyphilis remains poorly understood. In this research, the recombinant Treponema pallidum flagellin, FlaB3, was constructed to treat human microglia clone 3 (HMC3) cells and HMC3 cells in which TLR4 (Toll-like receptor 4) had been knocked down. We discovered that FlaB3 promotes IL-6 and IL-8 secretion through the TLR4 pathway. We also observed that FlaB3 regulates the expression of autophagy-related proteins Beclin1, LC3B, and P62 via the TLR4/PI3K/AKT/mTOR pathway, thereby inhibiting autophagy and autophagic flux in HMC3 cells. Subsequently, we discovered that the concentration of soluble amyloid β_1-42 (Aβ_1-42) was decreased in the cerebrospinal fluid of neurosyphilis patients. Immunofluorescence analysis further revealed that FlaB3 suppresses the degradation of Aβ by autophagosomes in HMC3 cells. Additionally, treatment with the autophagy activators Rapamycin and LY294002 decreased the levels of IL-6 and IL-8 secretion, indicating that autophagy modulates inflammation in HMC3 cells. In summary, our study demonstrates that FlaB3 promotes inflammation in HMC3 cells by inhibiting autophagy. This inhibition also impedes Aβ degradation, providing new insights into the pathogenesis of neurosyphilis.

Understanding bacterial physiology in real-world environments requires noninvasive approaches and is a challenging yet necessary endeavor to effectively treat infectious disease. Bacteria evolve strategies to tolerate chemical gradients associated with infections. The DIVER (Deep Imaging Via Enhanced Recovery) microscope can image autofluorescence and fluorescence lifetime throughout samples with high optical scattering, enabling the study of naturally formed chemical gradients throughout intact biofilms. Using the DIVER, a long fluorescent lifetime signal associated with reduced pyocyanin, a molecule for electron cycling in low oxygen, was detected in low-oxygen conditions at the surface of Pseudomonas aeruginosa biofilms and in the presence of fermentation metabolites from Rothia mucilaginosa, which cocolonizes infected airways with P. aeruginosa. These findings underscore the utility of the DIVER microscope and fluorescent lifetime for noninvasive studies of bacterial physiology within complex environments, which could inform on more effective strategies for managing chronic infection.

Although not currently in the infectious disease spotlight, there is still a pressing need for new agents to treat tuberculosis caused by Mycobacterium tuberculosis. As there is an ever-increasing amount of clinical resistance to the current drugs, ideally new drugs would be found against novel targets to circumvent pre-existing resistance. A phenotypic growth screen identified a novel singleton, 1, as an inhibitor of M. tuberculosis growth. Mechanism-of-action studies determined that 1 targeted Pks13, an essential enzyme in cell wall biosynthesis that, as of yet, has not been targeted by agents in the clinic. The reactive nature of the pentafluorophenyl warhead meant that the molecule was inherently metabolically unstable. A medicinal chemistry optimization program is described that resulted in the identification of a compound that was reactive enough to still inhibit Pks13 and M. tuberculosis growth while being metabolically stable enough to explore in vivo.

The antimicrobial resistance (AMR) crisis has been associated with millions of deaths. Of particular concern is the threat of bioweapons, exemplified by anthrax. Introduction of novel antibiotics helps mitigate AMR, but does not address the threat of bioweapons with engineered resistance. We reasoned that teixobactin, an antibiotic with no detectable resistance, is uniquely suited to address the challenge of weaponized anthrax. Teixobactin binds to immutable targets, precursors of cell wall polymers. Here we show that teixobactin is highly efficacious in a rabbit model of inhalation anthrax. Inhaling spores of Bacillus anthracis causes overwhelming morbidity and mortality. Treating rabbits with teixobactin after the onset of disease rapidly eliminates the pathogen from blood and tissues, normalizes body temperature, and prevents tissue damage. Teixobactin assembles into an irreversible supramolecular structure on the surface of B. anthracis membrane, likely contributing to its unusually high potency against anthrax. Antibiotics evading resistance provide a rational solution to both AMR and engineered bioweapons.

Efflux, mediated by a series of multidrug efflux pumps, is a major contributor to antibiotic resistance in Gram-negative bacteria. Efflux pump inhibitors (EPIs), which can block efflux, have the potential to be used as adjuvant therapies to resensitize bacteria to existing antibiotics. In this study, 36 quinoline-based compounds were synthesized as potential EPIs targeting resistance nodulation division (RND) family pumps in the multidrug-resistant pathogen Acinetobacter baumannii. In A. baumannii strains with overexpressed AdeFGH (chloramphenicol-adapted) and AdeABC (AYE, Ab5075-UW), these compounds enhanced Hoechst dye accumulation, indicating general efflux inhibition, and potentiated chloramphenicol, which is an AdeG substrate. The research focused on two generations of quinoline compounds, with modifications at the C-7 position of first-generation compounds to improve hydrophobic interactions with the Phe loop in the AdeG efflux pump, to generate second-generation compounds. The modified quinolines showed strong pump inhibition and significant chloramphenicol potentiation, with MIC reductions of 4- to 64-fold. Notably, compounds 1.8 and 3.8 exhibited the highest inhibitory activity, while compounds 1.3 and 3.3 showed up to 64-fold potentiation, highlighting the importance of specific structural features at the C-7 position for efflux pump inhibition. The study also revealed selective inhibition of AdeFGH over AdeABC, with no potentiation observed for gentamicin, showing the specificity of these quinoline-based inhibitors. Importantly, the compounds showed no toxicity in a Galleria mellonella model at a dose level of 20 mg/kg, highlighting their suitability as potential antibiotic adjuvants for combating bacterial resistance.

Targeting the specific RNA conformations that are crucial for SARS-CoV-2 replication is a viable antiviral approach. The SARS-CoV-2 genome contains GG repeats capable of forming unstable two-tetrad G-quadruplex (GQ) structures, which exist as a mix of conformations, including hairpin (Hp), intra-, and intermolecular GQs. RGQ-1, originating from the nucleocapsid gene's ORF, adopts a dynamic equilibrium of conformations, including intramolecular hairpin and G-quadruplex (Hp-GQ) structures, as confirmed by CD analysis. In this study, tetraphenylethene (TPE) derivatives were developed to target the Hp-GQ conformational equilibrium of RGQ-1. EMSA, fluorescence spectroscopy, and ITC assays confirmed that two TPE derivatives, TPE-MePy and TPE-Allyl Py, bind to RGQ-1. CD thermal melting experiments indicate that RGQ-1 is stabilized by 8.56 and 12.54 °C in the presence of TPE-MePy and TPE-Allyl Py, respectively. Additionally, luciferase assays demonstrated that TPE derivatives suppressed luciferase activity by 2.2-fold and 3.6-fold, respectively, shifting the HpGQ equilibrium toward the GQ conformation, as suggested by CD spectroscopy. Treatment of SARS-CoV-2-infected A549 cells with TPE derivatives reduced the levels of viral RNA, spikes, and nucleocapsid proteins. To explore their antiviral mechanism, preinfection and postinfection treatments were tested, revealing that the TPE derivatives specifically suppressed the postentry stages of viral replication without affecting viral entry. These findings highlight the therapeutic potential of TPE derivatives in inhibiting key gene expressions critical for SARS-CoV-2 replication.

One of the primary healthcare problems in the world today is tuberculosis (TB), a chronic infectious illness brought on by Mycobacterium tuberculosis (M. tuberculosis). A distinct family of PE_PGRS proteins, encoded by the M. tuberculosis genome, has attracted more attention because of their involvement in immune evasion and bacterial pathogenicity. Nevertheless, the specific functions and mechanisms of action for the majority of PE_PGRS proteins remain largely unexplored. This study focuses on the Rv2741 (PE_PGRS47) gene, which is exclusively present in pathogenic mycobacteria. To examine the function of Rv2741 in host-pathogen interactions, we created recombinant strains of Mycobacterium smegmatis (M. smegmatis) that expressed the M. tuberculosis Rv2741 gene. IL-1α was found to be a key mediator of host response modulation by Rv2741. Rv2741 downregulates the secretion of IL-1α and inhibits the MAPK signaling pathway, particularly the p38 and ERK1/2 pathways, thereby cooperatively inhibiting macrophage autophagy and apoptosis. Meanwhile, the decrease in IL-1α secretion directly leads to changes in the cytokine secretion pattern and a reduction in nitric oxide (NO) production. This multifaceted regulatory mechanism ultimately favors the survival of M. smegmatis in macrophages. This research significantly expands our understanding of Rv2741 function, revealing its crucial role as a multifunctional virulence factor in the immune evasion of M. tuberculosis.

Tuberculosis (TB) is the leading cause of death from infectious disease. Macrophages are the primary immune responders and become the primary host cells for the causative agent Mycobacterium tuberculosis. Following the uptake of M. tuberculosis, the inherent antimicrobial action of macrophages is dampened, enabling the bacterium to reside within these cells and multiply. Rising resistance of M. tuberculosis to antibiotics has led to the investigation of novel approaches for the treatment of TB. Here, we report a host-directed approach, employing biomimetic Curdlan poly(lactic-co-glycolic acid) (C-PLGA) nanoparticles (NPs), and examine autophagy induction in infected macrophages, eradication of M. tuberculosis and immune modulation in a mouse model. We demonstrate that the NPs induce autophagy in M. tuberculosis-infected macrophages. Treatment of H37Rv infected C57BL/6 mice with these NPs reduced M. tuberculosis burden in the lungs of mice and modulated cytokines and chemokines and this work demonstrates that these immunomodulatory NPs are a potential treatment approach for TB.

Acinetobacter baumannii is a hospital-associated pathogen with unique fatty acid homeostasis features. This includes a reliance on desaturases for proliferation, due to an inability to generate unsaturated fatty acids during the synthesis cycles. However, there are various unexplained gaps in A. baumannii fatty acid homeostasis, such as the desaturation of de novo synthesized fatty acids. We identified a conserved desaturase (DesC) with a rare structural feature that may have roles in coordinating fatty acids with acyl carrier protein conjugants. We showed that DesC can generate fatty acids with cis double bonds in the delta-9 position. Profiling of A. baumannii fatty acids and mRNA transcripts emphasized its significance during fatty acid synthesis. DesC was found to be most critical in mouse niches where A. baumannii relies on fatty acid synthesis. This work has contributed to our understanding of core metabolic features that are key to the disease potential of A. baumannii.