Reversible, tunable epigenetic silencing of TCF1 generates flexibility in the T cell memory decision

The immune system encodes information about the severity of a pathogenic threat in the quantity and type of memory cells it forms. This encoding emerges from lymphocyte decisions to maintain or lose self-renewal and memory potential during a challenge. By tracking CD8+ T cells at the single-cell and clonal lineage level using time-resolved transcriptomics, quantitative live imaging, and an acute infection model, we find that T cells will maintain or lose memory potential early after antigen recognition. However, following pathogen clearance, T cells may regain memory potential if initially lost. Mechanistically, this flexibility is implemented by a stochastic cis-epigenetic switch that tunably and reversibly silences the memory regulator, TCF1, in response to stimulation. Mathematical modeling shows how this flexibility allows memory T cell numbers to scale robustly with pathogen virulence and immune response magnitudes. We propose that flexibility and stochasticity in cellular decisions ensure optimal immune responses against diverse threats.

Comparative analysis of antibiotic susceptibility patterns and clinical features of mucoid and non-mucoid Pseudomonas aeruginosa infections: a retrospective study

Background

Pseudomonas aeruginosa (PA) is a prevalent opportunistic pathogen that has close associations with both acute and chronic infections. However, there exists an insufficiency of accurate and comprehensive data pertaining to the antimicrobial susceptibility patterns and clinical characteristics of both mucoid and non-mucoid strains of PA (mPA and non-mPA, respectively).

Methods

From January 1, 2021 to December 31, 2022, a thorough retrospective study was carried out to examine and compare the antibiotic susceptibility test outcomes and clinical characteristics of hospitalized patients with mPA and non-mPA infections.

Results

This study investigated a cohort of 111 patients who were diagnosed with mPA infections, as well as 792 patients diagnosed with non-mPA infections. Significant demographic disparities, including gender (p < 0.001), age (p < 0.001), length of hospital stay (p < 0.001), diabetes (p = 0.043), and hypertension (p < 0.001), are evident between the mPA and non-mPA groups. The mPA group commonly necessitates hospitalization for respiratory system diseases, whereas the non-mPA group is associated with concomitant cardiovascular and cerebrovascular diseases. The mPA group demonstrates lower utilization rates of medical devices, such as Foley catheter (p < 0.001), nasogastric tube (p < 0.001), mechanical ventilation (p < 0.001), tracheostomy (p < 0.001), arterial and venous catheterization (p < 0.001), and exhibits superior organ function status, including lower incidences of hypoalbuminemia (p < 0.001), septic shock (p < 0.001), liver dysfunction (p < 0.001), renal failure (p < 0.001), and respiratory failure (p < 0.001). The non-mPA group is more vulnerable to infection with two or more bacterial pathogens compared to the mPA group, with the non-mPA group frequently resulting in Enterobacteriaceae infections and the mPA group being associated with fungal infections. Variations in antibiotic sensitivity are noted for Amikacin (p < 0.001), Ciprofloxacin (p < 0.001), Cefepime (p = 0.003), and Levofloxacin (p < 0.001) in antibiotic susceptibility testing, with resistance patterns closely tied to specific antibiotic usage.

Conclusion

There are significant demographic characteristics, clinical manifestations and antibiotic susceptibility between mPA and non-mPA infections. It is crucial to emphasize these characteristics due to their significant role in preventing and treating PA infections.

Higher diagnostic value of metagenomic next-generation sequencing in acute infection than chronic infection: a multicenter retrospective study

Background

The aim of this study is to compare the diagnostic value of metagenomic next-generation sequencing (mNGS) vs. conventional culture methods (CM) in chronic infection and acute infection.

Methods

We retrospectively analyzed the bronchoalveolar lavage fluid (BALF) of 88 patients with acute infection and 105 patients with chronic infection admitted to three hospitals from 2017 to 2022.

Results

The results showed that the sensitivity and specificity of mNGS were higher than those of CM. The number of patients who changed the antibiotic treatment in the mNGS positive group was larger than that of patients in the mNGS negative group in both the acute infection group (60.5 vs. 28.0%, P = 0.0022) and chronic infection group (46.2 vs. 22.6%, P = 0.01112). High levels of temperature (OR: 2.02, 95% CI: 1.18-3.70, P: 0.015), C-reactive protein (CRP) (OR: 15, 95% CI: 2.74-280.69, P: 0.011), neutrophil count (OR: 3.09, 95% CI: 1.19-8.43, P: 0.023), and low levels of lymphocyte count (OR: 3.43, 95% CI:1.26-10.21, P: 0.020) may lead to positive mNGS results in the acute infection group while no significant factor was identified to predict positive results in the chronic infection group.

Conclusion

mNGS could provide useful guidance on antibiotic strategies in infectious diseases and may be more valuable for the diagnosis and treatment of acute infection vs. chronic infection.

Epigenetic Control of Innate Immunity: Consequences of Acute Respiratory Virus Infection

Infections caused by acute respiratory viruses induce a systemic innate immune response, which can be measured by the increased levels of expression of inflammatory genes in immune cells. There is growing evidence that these acute viral infections, alongside transient transcriptomic responses, induce epigenetic remodeling as part of the immune response, such as DNA methylation and histone modifications, which might persist after the infection is cleared. In this article, we first review the primary mechanisms of epigenetic remodeling in the context of innate immunity and inflammation, which are crucial for the regulation of the immune response to viral infections. Next, we delve into the existing knowledge concerning the impact of respiratory virus infections on the epigenome, focusing on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Influenza A Virus (IAV), and Respiratory Syncytial Virus (RSV). Finally, we offer perspectives on the potential consequences of virus-induced epigenetic remodeling and open questions in the field that are currently under investigation.

Exploring Viral Metagenomics in Pediatric Patients with Acute Respiratory Infections: Unveiling Pathogens beyond SARS-CoV-2

The emergence of SARS-CoV-2 and the subsequent pandemic have prompted extensive diagnostic and clinical efforts to mitigate viral spread. However, these strategies have largely overlooked the presence of other respiratory viruses. Acute respiratory diseases in pediatric patients can be caused by a diverse range of viral agents, and metagenomics represents a powerful tool for their characterization. This study aimed to investigate the viral abundance in pediatric patients with acute respiratory symptoms who tested negative for SARS-CoV-2 during the Omicron pandemic wave. To achieve this, viral metagenomics and next-generation sequencing were employed on 96 nasopharyngeal swab samples, which were organized into 12 pools, with each pool consisting of eight individual samples. Metagenomic analysis revealed that the most prevalent viruses associated with acute disease in pediatric patients were respiratory syncytial virus (detected in all pools) and enteroviruses, which are known to cause significant morbidity and mortality in children. Additionally, clinically significant viruses such as mumps orthorubulavirus, human metapneumovirus, influenza A, and a wide array of human herpesviruses (1, 3-7) were identified. These findings highlight the extensive potential of viral metagenomics in identifying viruses other than SARS-CoV-2 that contribute to acute infections in children. Consequently, this methodology should garner clinical attention in terms of differential diagnosis and the development of public policies to address such conditions in the global pediatric population.

Kinetics of TTV Loads in Peripheral Blood Mononuclear Cells of Early Treated Acute HIV Infections

Torquetenovirus (TTV) is the most abundant component of the human blood virome and its replication is controlled by a functioning immune system. In this study, TTV replication was evaluated in 21 people with acute HIV infection (AHI) and immune reconstitution following antiretroviral therapy (ART). PBMC-associated TTV and HIV-1 DNA, as well as plasma HIV-1 RNA, were measured by real-time PCR. CD4 and CD8 differentiation, activation, exhaustion, and senescence phenotypes were analyzed by flow cytometry. Thirteen healthy donors (HD) and twenty-eight chronically infected HIV individuals (CHI), late presenters at diagnosis, were included as control groups. TTV replication in AHI seems to be controlled by the immune system being higher than in HD and lower than in CHI. During ART, a transient increase in TTV DNA levels was associated with a significant perturbation of activation and senescence markers on CD8 T cells. TTV loads were positively correlated with the expansion of CD8 effector memory and CD57+ cells. Our results shed light on the kinetics of TTV replication in the context of HIV acute infection and confirm that the virus replication is strongly regulated by the modulation of the immune system.

Is there an association between peri-diagnostic vaccination and clinical outcomes in COVID-19 patients?

Background

Peri-diagnostic vaccination contemporaneous with SARS-CoV-2 infection might boost antiviral immunity and improve patient outcomes. We investigated, among previously unvaccinated patients, whether vaccination (with the Pfizer, Moderna, or J&J vaccines) during the week before or after a positive COVID-19 test was associated with altered 30-day patient outcomes.

Methods

Using a deidentified longitudinal EHR repository, we selected all previously unvaccinated adults who initially tested positive for SARS-CoV-2 between December 11, 2020 (the date of vaccine emergency use approval) and December 19, 2021. We assessed whether vaccination between days -7 and +7 of a positive test affected outcomes. The primary measure was progression to a more severe disease outcome within 30 days of diagnosis using the following hierarchy: hospitalization, intensive care, or death.

Results

Among 60,031 hospitalized patients, 543 (0.91%) were initially vaccinated at the time of diagnosis and 59,488 (99.09%) remained unvaccinated during the period of interest. Among 316,337 nonhospitalized patients, 2,844 (0.90%) were initially vaccinated and 313,493 (99.1%) remained unvaccinated. In both analyses, individuals receiving vaccines were older, more often located in the northeast, more commonly insured by Medicare, and more burdened by comorbidities. Among previously unvaccinated patients, there was no association between receiving an initial vaccine dose between days -7 and +7 of diagnosis and progression to more severe disease within 30 days compared to patients who did not receive vaccines.

Conclusions

Immunization during acute SARS-CoV-2 infection does not appear associated with clinical progression during the acute infectious period.

Vemurafenib Inhibits Acute and Chronic Enterovirus Infection by Affecting Cellular Kinase Phosphatidylinositol 4-Kinase Type IIIβ

Enteroviruses are one of the most abundant viruses causing mild to serious acute infections in humans and also contributing to chronic diseases like type 1 diabetes. Presently, there are no approved antiviral drugs against enteroviruses. Here, we studied the potency of vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, as an antiviral against enteroviruses. We showed that vemurafenib prevented enterovirus translation and replication at low micromolar dosage in an RAF/MEK/ERK-independent manner. Vemurafenib was effective against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect was related to a cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevented infection efficiently in acute cell models, eradicated infection in a chronic cell model, and lowered virus amounts in pancreas and heart in an acute mouse model. Altogether, instead of acting through the RAF/MEK/ERK pathway, vemurafenib affects the cellular PI4KB and, hence, enterovirus replication, opening new possibilities to evaluate further the potential of vemurafenib as a repurposed drug in clinical care. IMPORTANCE Despite the prevalence and medical threat of enteroviruses, presently, there are no antivirals against them. Here, we show that vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, prevents enterovirus translation and replication. Vemurafenib shows efficacy against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect acts through cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevents infection efficiently in acute cell models, eradicates infection in a chronic cell model, and lowers virus amounts in pancreas and heart in an acute mouse model. Our findings open new possibilities to develop drugs against enteroviruses and give hope for repurposing vemurafenib as an antiviral drug against enteroviruses.

Clinical Profile of SARS-CoV-2 Infection: Mechanisms of the Cellular Immune Response and Immunogenetic Markers in Patients from Brazil

OBJECTIVES

The aim of this study is to evaluate some mechanisms of the immune response of people infected with SARS-CoV-2 in both acute infection and early and late convalescence phases.

METHODS

This is a cohort study of 70 cases of COVID-19, confirmed by RT-PCR, followed up to 60 days. Plasma Samples and clinical data were. Viral load, blood count, indicators inflammation were the parameters evaluated. Cellular immune response was evaluated by flow cytometry and Luminex immunoassays.

RESULTS

In the severe group, hypertension was the only reported comorbidity. Non severe patients have activated memory naive CD4+ T cells. Critically ill patients have central memory CD4+ T cell activation. Severe COVID-19 patients have both central memory and activated effector CD8+ T cells. Non-severe COVID-19 cases showed an increase in IL1β, IL-6, IL-10 and TNF and severely ill patients had higher levels of the cytokines IL-6, IL-10 and CXCL8.

CONCLUSIONS

The present work showed that different cellular responses are observed according to the COVID-19 severity in patients from Brazil an epicenter the pandemic in South America. Also, we notice that some cytokines can be used as predictive markers for the disease outcome, possibility implementation of strategies effective by health managers.

First Report on Abnormal Renal Function in Acute Hepatitis E Genotype 1 Infection

Impaired renal functions have been reported with Hepatitis E virus (HEV) infections, especially with genotypes 3 and 4. These complications were reported during the acute and chronic phases of infection. HEV genotype 1 causes acute infection, and the effect of HEV-1 infections on renal functions is not known. We examined the kidney function parameters in the serum of HEV-1 patients (AHE, n = 31) during the acute phase of infection. All of the included patients developed an acute self-limiting course of infection, without progression to fulminant hepatic failure. We compared the demographic, laboratory, and clinical data between AHE patients with normal kidney function parameters and those with abnormal renal parameters. Out of 31 AHE patients, 5 (16%) had abnormal kidney function tests (KFTs) during the acute phase of infection. Three patients had abnormal serum urea and creatinine, and two patients had either abnormal urea or creatinine. Four out of five patients had an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m². AHE patients with abnormal KFTs were older and had a lower level of albumin, but a slightly elevated alanine transaminase (ALT) compared to AHE patients with normal KFTs. There were no significant differences between the two groups in terms of age, sex, liver transaminase levels, and the viral load. Similarly, the clinical presentations were comparable in both groups. Interestingly, these KFTs in patients with abnormal renal parameters returned to normal levels at the recovery. The serum creatinine level was not correlated with patients' age or liver transaminase levels, but it was significantly negatively correlated with albumin level. In conclusion, this study is the first report that evaluated KFTs in patients during the acute phase of HEV-1 infections. Impaired KFTs in some AHE patients resolved at convalescence. KFTs and renal complications should be monitored during HEV-1 infections.

Interleukin-37 suppresses the cytotoxicity of hepatitis B virus peptides-induced CD8+ T cells in patients with acute hepatitis B

Interleukin-37 (IL-37) is a newly identified anti-inflammatory cytokine, owning immunosuppressive activity in infectious diseases. The aim of this study was to investigate the regulatory function of IL-37 on CD8+ T cells during hepatitis B virus (HBV) infection. Eighteen acute hepatitis B (AHB) patients, thirty-nine chronic hepatitis B (CHB) patients, and twenty controls were enrolled. IL-37 concentration was measured by ELISA. IL-37 receptor subunits expressions on CD8+ T cells were assessed by flow cytometry. Purified CD8+ T cells were stimulated with HBV peptides and recombinant IL-37. Perforin and granzyme B secretion was investigated by ELISPOT. Programmed death-1 (PD-1) and cytotoxic T-lymphocyte associated protein-4 (CTLA-4) mRNA expressions were semi-quantified by real-time PCR. CD8+ T cell cytotoxicity was assessed in direct contact and indirect contact coculture with HepG2.2.15 cells. Plasma IL-37 level was down-regulated and negatively correlated with aminotransferase levels in AHB patients. There were no significant differences of IL-37 receptor subunits among AHB patients, CHB patients, and controls. Exogenous IL-37 stimulation suppressed HBV peptides-induced perforin and granzyme B secretion by CD8+ T cells in AHB patients, but not in CHB patients. Exogenous IL-37 stimulation did not affect proinflammatory cytokines secretion as well as PD-1/CTLA-4 mRNA expressions in CD8+ T cells in AHB and CHB patients. Exogenous IL-37 stimulation dampened HBV peptide-induced CD8+ T cell cytotoxicity in a cell-to-cell contact manner. The current data indicated that acute HBV infection might induce down-regulation of IL-37, which might be associated with enhanced CD8+ T cell cytotoxicity and liver damage.

Cell-to-Cell Transmission of HIV-1 and HIV-2 from Infected Macrophages and Dendritic Cells to CD4+ T Lymphocytes

Macrophages (Mø) and dendritic cells (DCs) are key players in human immunodeficiency virus (HIV) infection and pathogenesis. They are essential for the spread of HIV to CD4+ T lymphocytes (TCD4+) during acute infection. In addition, they constitute a persistently infected reservoir in which viral production is maintained for long periods of time during chronic infection. Defining how HIV interacts with these cells remains a critical area of research to elucidate the pathogenic mechanisms of acute spread and sustained chronic infection and transmission. To address this issue, we analyzed a panel of phenotypically distinct HIV-1 and HIV-2 primary isolates for the efficiency with which they are transferred from infected DCs or Mø to TCD4+. Our results show that infected Mø and DCs spread the virus to TCD4+ via cell-free viral particles in addition to other alternative pathways. We demonstrate that the production of infectious viral particles is induced by the co-culture of different cell populations, indicating that the contribution of cell signaling driven by cell-to-cell contact is a trigger for viral replication. The results obtained do not correlate with the phenotypic characteristics of the HIV isolates, namely their co-receptor usage, nor do we find significant differences between HIV-1 and HIV-2 in terms of cis- or trans-infection. The data presented here may help to further elucidate the cell-to-cell spread of HIV and its importance in HIV pathogenesis. Ultimately, this knowledge is critical for new therapeutic and vaccine approaches.

HIV rapidly targets a diverse pool of CD4+ T cells to establish productive and latent infections

Upon infection, HIV disseminates throughout the human body within 1-2 weeks. However, its early cellular targets remain poorly characterized. We used a single-cell approach to retrieve the phenotype and TCR sequence of infected cells in blood and lymphoid tissue from individuals at the earliest stages of HIV infection. HIV initially targeted a few proliferating memory CD4+ T cells displaying high surface expression of CCR5. The phenotype of productively infected cells differed by Fiebig stage and between blood and lymph nodes. The TCR repertoire of productively infected cells was heavily biased, with preferential infection of previously expanded and disseminated clones, but composed almost exclusively of unique clonotypes, indicating that they were the product of independent infection events. Latent genetically intact proviruses were already archived early in infection. Hence, productive infection is initially established in a pool of phenotypically and clonotypically distinct T cells, and latently infected cells are generated simultaneously.

The first case of monkeypox virus and acute HIV infection: Should we consider monkeypox a new possible sexually transmitted infection?

Since May 2022, a Monkeypox virus (MPXV) outbreak has been ongoing in several non-endemic countries. MPXV is usually transmitted after intimate contact, through body fluids, close contact from active lesions or through respiratory droplets. The recent outbreak occurrent in people with multiple recent sexual intercourse suggests the sexual route as the main way of transmission. However, there is no sufficient evidence to consider MPXV as a new sexually transmitted infection (STI), even though we believe that a link between MPXV and other STIs may exist with a possible facilitating action on their spreading. Herein, we illustrate the first case described during the current outbreak of a young man with both MPXV and acute HIV infection in a non-endemic country.

Acute hepatitis C virus infection: clinical update and remaining challenges

Acute hepatitis C virus (HCV) infection is a global health concern with substantial geographical variation in the incidence rate. People who have received unsafe medical procedures, used injection drugs, and lived with human immunodeficiency virus are reported to be most susceptible to acute HCV infection. The diagnosis of acute HCV infection is particularly challenging in immunocompromised, reinfected, and superinfected patients due to difficulty in detecting anti-HCV antibody seroconversion and HCV ribonucleic acid (RNA) from a previously negative antibody response. With an excellent treatment effect on chronic HCV infection, recently, clinical trials investigating the benefit of direct-acting antivirals (DAAs) treatment for acute HCV infection have been conducted. Based on the results of cost-effectiveness analysis, DAAs should be initiated early in acute HCV infection prior to spontaneous viral clearance. Compared to the standard 8-12 week-course of DAAs for chronic HCV infection, DAAs treatment duration may be shortened to 6-8 weeks in acute HCV infection without compromising the efficacy. Standard DAA regimens provide comparable efficacy in treating HCV-reinfected patients and DAA-naïve ones. For cases contracting acute HCV infection from HCV-viremic liver transplant, a 12-week course of pangenotypic DAAs is suggested. While for cases contracting acute HCV infection from HCV-viremic non-liver solid organ transplants, a short course of prophylactic or pre-emptive DAAs is suggested. Currently, prophylactic HCV vaccines are unavailable. In addition to treatment scale-up for acute HCV infection, practice of universal precaution, harm reduction, safe sex, and vigilant surveillance after viral clearance remain critical in reducing HCV transmission.

New horizons in sepsis management in older patients

Sepsis is a frequent disease in older people, characterised by an inappropriate systemic inflammatory response following an infection, leading to life-threatening organ dysfunctions. In the very old, sepsis is often difficult to diagnose, given the frequent atypical presentation. While there is no gold standard for the diagnosis of sepsis, new definitions published in 2016, aided by clinical-biological scores, namely Sequential Organ Failure Assessment (SOFA) and quick SOFA scores, allow earlier recognition of septic states at risk of poor outcome. The management of sepsis in itself differs little in older patients compared to younger subjects. However, the key question of whether or not to admit the patient to an intensive care setting has to be anticipated, depending on the sepsis severity but also on patient's comorbidities and wishes. The earliness of acute management in older subjects with decreased immune defences and physiological reserves is an essential prognostic element. The early control of comorbidities is the main plus value of the geriatrician in the acute and post-acute management of older patients with sepsis.

Divergent Cytokine and Chemokine Responses at Early Acute Simian Immunodeficiency Virus Infection Correlated with Virus Replication and CD4 T Cell Loss in a Rhesus Macaque Model

Cytokine and chemokine levels remain one of the significant predictive factors of HIV pathogenesis and disease outcome. Understanding the impact of cytokines and chemokines during early acute infection will help to recognize critical changes during HIV pathogenesis and might assist in establishing improved HIV treatment and prevention methods. Sixty-one cytokines and chemokines were evaluated in the plasma of an SIV-infected rhesus macaque model. A substantial change in 11 cytokines/growth factors and 9 chemokines were observed during acute infection. Almost all the cytokines/chemokines were below the baseline values for an initial couple of days of infection. We detected six important cytokines/chemokines, such as IL-18, IP-10, FLT3L, MCP-1, MCP-2, and MIP-3β, that can be used as biomarkers to predict the peripheral CD4+ T cell loss and increased viral replication during the acute SIV/HIV infection. Hence, regulating IL-18, IP-10, FLT3L, MCP-1, MCP-2, and MIP-3β expression might provide an antiviral response to combat acute SIV/HIV infection.

Identification of early-induced broadly neutralizing activities against transmitted founder HIV strains

OBJECTIVES

Broadly neutralizing antibodies have been proposed as key actors for HIV vaccine development. However, they display features of highly matured antibodies, hampering their induction by vaccination. As protective broadly neutralizing antibodies should be induced rapidly after vaccination and should neutralize the early-transmitted founder (T/F) viruses, we searched whether such antibodies may be induced following HIV infection.

DESIGN

Sera were collected during acute infection (Day 0) and at viral set point (Month 6/12) and the neutralizing activity against T/F strains was investigated. Neutralizing activity in sera collected from chronic progressor was analyzed in parallel.

METHODS

We compared neutralizing activity against T/F strains with neutralizing activity against non-T/F strains using the conventional TZM-bL neutralizing assay.

RESULTS

We found neutralizing antibodies (nAbs) preferentially directed against T/F viruses in sera collected shortly after infection. This humoral response evolved by shifting to nAbs directed against non-T/F strains.

CONCLUSION

Although features associated with nAbs directed against T/F viruses need further investigations, these early-induced nAbs may display lesser maturation characteristics; therefore, this might increase their interest for future vaccine designs.

The Enhancer-Binding Protein MifR, an Essential Regulator of α-Ketoglutarate Transport, Is Required for Full Virulence of Pseudomonas aeruginosa PAO1 in a Mouse Model of Pneumonia

The opportunistic human pathogen Pseudomonas aeruginosa PAO1 has an extensive metabolism, enabling it to utilize a wide range of structurally diverse compounds to meet its nutritional and energy needs. Interestingly, the utilization of some of the more unusual compounds often associated with a eukaryotic-host environment is regulated via enhancer-binding proteins (EBPs) in P. aeruginosa. Whether the utilization of such compounds and the EBPs involved contribute to the pathogenesis of P. aeruginosa remains to be fully understood. To narrow this gap, we investigated the roles of the EBPs EatR (regulator of ethanolamine catabolism), DdaR (regulator of methylarginine catabolism), and MifR (regulator of α-ketoglutarate or α-KG transport) in the virulence of P. aeruginosa PAO1 in a pneumonia-induced septic mouse model. Deletion of genes encoding EatR and DdaR had no significant effect on the mortality of P. aeruginosa PAO1-infected mice compared to wide-type (WT) PAO1-infected mice. In contrast, infected mice with ΔmifR mutant exhibited a significant reduction (~50%) in the mortality rate compared with WT PAO1 (P < 0.05). Infected mice with ΔmifR PAO1 had lower lung injury scores, fewer inflammatory cells, decreased proinflammatory cytokines, and decreased apoptosis and cell death compared to mice infected with WT PAO1 (P < 0.05). Furthermore, molecular analysis revealed decreased NLRP3 inflammasome activation in infected mice with ΔmifR PAO1 compared to WT PAO1 (P < 0.05). These results suggested that the utilization of α-KG was a contributing factor in P. aeruginosa-mediated pneumonia and sepsis and that MifR-associated regulation may be a potential therapeutic target for P. aeruginosa infectious disease.

Monkeypox in Patient Immunized with ACAM2000 Smallpox Vaccine During 2022 Outbreak

We report a case of monkeypox in the United States in a patient who had been vaccinated with ACAM2000 smallpox vaccine 8 years earlier. Despite his vaccination status, he still contracted disease. He showed prodromal symptoms preceding development of painless penile lesions that later coalesced.

Viral Clearance and Neuroinflammation in Acute TMEV Infection Vary by Host Genetic Background

A wide range of viruses cause neurological manifestations in their hosts. Infection by neurotropic viruses as well as the resulting immune response can irreversibly disrupt the complex structural and functional architecture of the brain, depending in part on host genetic background. The interaction between host genetic background, neurological response to viral infection, and subsequent clinical manifestations remains poorly understood. In the present study, we used the genetically diverse Collaborative Cross (CC) mouse resource to better understand how differences in genetic background drive clinical signs and neuropathological manifestations of acute Theiler's murine encephalomyelitis virus (TMEV) infection. For the first time, we characterized variations of TMEV viral tropism and load based on host genetic background, and correlated viral load with microglial/macrophage activation. For five CC strains (CC002, CC023, CC027, CC057, and CC078) infected with TMEV, we compared clinical signs, lesion distribution, microglial/macrophage response, expression, and distribution of TMEV mRNA, and identified genetic loci relevant to the early acute (4 days post-infection [dpi]) and late acute (14 dpi) timepoints. We examined brain pathology to determine possible causes of strain-specific differences in clinical signs, and found that fields CA1 and CA2 of the hippocampal formation were especially targeted by TMEV across all strains. Using Iba-1 immunolabeling, we identified and characterized strain- and timepoint-specific variation in microglial/macrophage reactivity in the hippocampal formation. Because viral clearance can influence disease outcome, we used RNA in situ hybridization to quantify viral load and TMEV mRNA distribution at both timepoints. TMEV mRNA expression was broadly distributed in the hippocampal formation at 4 dpi in all strains but varied between radiating and clustered distribution depending on the CC strain. We found a positive correlation between microglial/macrophage reactivity and TMEV mRNA expression at 4 dpi. At 14 dpi, we observed a dramatic reduction in TMEV mRNA expression, and localization to the medial portion of field CA1 and field CA2. To better understand how host genetic background can influence pathological outcomes, we identified quantitative trait loci associated with frequency of lesions in a particular brain region and with microglial/macrophage reactivity. These QTL were located near several loci of interest: lysosomal trafficking regulator (Lyst) and nidogen 1 (Nid1), and transmembrane protein 106 B (Tmem106b). Together, these results provide a novel understanding about the influences of genetic variation on the acute neuropathological and immunopathological environment and viral load, which collectively lead to variable disease outcomes. Our findings reveal possible avenues for future investigation which may lead to more effective intervention strategies and treatment regimens.

Contribution of Innate Lymphoid Cells in Supplementing Cytokines Produced by CD4+ T Cells During Acute and Chronic SIV Infection of the Colon

HIV/SIV (simian immunodeficiency virus) infection leads to a loss of CD4+ T helper (Th) cells in number and function that begins during the acute phase and persists through the chronic phase of infection. In particular, there is a drastic decrease of Th17 and Th22 cells in the HIV/SIV-infected gastrointestinal (GI) tract as a source of interleukin (IL)-17 and IL-22. These cytokines are vital in the immune response to extracellular pathogens and maintenance of the GI tract. However, innate lymphoid cells (ILCs) are a source of IL-17 and IL-22 during the early stages of an immune response in mucosal tissue and remain vital cytokine producers when the immune response is persistent. Here, we wanted to determine whether ILCs are a source of IL-17 and IL-22 in the SIV-infected colon and could compensate for the loss of Th17 and Th22 cells. As a control, we evaluated the frequency and number of ILCs expressing interferon-gamma (IFNγ) and tumor necrosis factor-alpha (TNFα). We determined the frequency and number of cytokine expressing ILC subsets and T cell subsets within leukocytes from the colons of uninfected as well as acute and chronic SIV-infected colons without in vitro mitogenic stimulation. In the present study, we find that: (1) the frequency of IL-22, IFNγ, and TNFα but not IL-17 producing ILCs is increased in the acutely infected colon and remains high during the chronically infected colon relative to cytokine expressing ILCs in the uninfected colon, (2) ILCs are a significant source of IL-22, IFNγ, and TNFα but not IL-17 when CD4+ T lymphocytes in the gut lose their capacity to secrete these cytokines during SIV infection, and (3) the changes in the cytokines expressed by ILCs relative to CD4+ T cells in the infected colon were not due to increases in the frequency or number of ILCs in relation to T lymphocytes found in the tissue.

T Cell-Specific STAT1 Expression Promotes Lytic Replication and Supports the Establishment of Gammaherpesvirus Latent Reservoir in Splenic B Cells

Gammaherpesviruses establish lifelong infections in most vertebrate species, including humans and rodents, and are associated with cancers, including B cell lymphomas. While type I and II interferon (IFN) systems of the host are critical for the control of acute and chronic gammaherpesvirus infection, the cell type-specific role(s) of IFN signaling during infection is poorly understood and is often masked by the profoundly altered viral pathogenesis in the hosts with global IFN deficiencies. STAT1 is a critical effector of all classical IFN responses along with its involvement in other cytokine signaling pathways. In this study, we defined the effect of T cell-specific STAT1 deficiency on the viral and host parameters of infection with murine gammaherpesvirus 68 (MHV68). MHV68 is a natural rodent pathogen that, similar to human gammaherpesviruses, manipulates and usurps B cell differentiation to establish a lifelong latent reservoir in B cells. Specifically, germinal center B cells host the majority of latent MHV68 reservoir in the lymphoid organs, particularly at the peak of viral latency. Unexpectedly, T cell-specific STAT1 expression, while limiting the overall expansion of the germinal center B cell population during chronic infection, rendered these B cells more effective at hosting the latent virus reservoir. Further, T cell-specific STAT1 expression in a wild type host limited circulating levels of IFNγ, with corresponding increases in lytic MHV68 replication and viral reactivation. Thus, our study unveils an unexpected proviral role of T cell-specific STAT1 expression during gammaherpesvirus infection of a natural intact host. IMPORTANCE Interferons (IFNs) represent a major antiviral host network vital to the control of multiple infections, including acute and chronic gammaherpesvirus infections. Ubiquitously expressed STAT1 plays a critical effector role in all classical IFN responses. This study utilized a mouse model of T cell-specific STAT1 deficiency to define cell type-intrinsic role of STAT1 during natural gammaherpesvirus infection. Unexpectedly, T cell-specific loss of STAT1 led to better control of acute and persistent gammaherpesvirus replication and decreased establishment of latent viral reservoir in B cells, revealing a surprisingly diverse proviral role of T cell-intrinsic STAT1.

Bacteriophage therapy of human restricted Salmonella Species- A study in a surrogate bacterial and animal model

Salmonella Typhi has been an important human restricted pathogen from time immemorial, and unfortunately, the indiscriminate use of antibiotics has induced the emergence of Multidrug-resistance in S. Typhi. Bacteriophage therapy may be a possible alternative in countering antimicrobial resistance. Therefore, this study was planned to assess the efficacy of bacteriophages in treating acute and chronic S. Typhimurium infection in the mouse as a surrogate model. We isolated bacteriophages against S. Typhimurium and selected three different bacteriophages for the in vivo experiments. The lethal dose of S. Typhimurium was decided for Swiss albino mice, and acute infection was developed. Further, bacteriophage therapy by daily intraperitoneal injection of phage cocktail was given for 14 days. While the chronic carrier state of S. Typhimurium in Swiss albino mice was developed by inoculating intraperitoneally sequential 10 fold increasing doses of the bacterium. On the successful establishment of carrier state, oral feeding of phage cocktail at a high count was given, which completely cured the carrier state in 7 days of feeding. These experiments confirmed that the phage cocktail could eradicate the S. Typhimurium from the mice in both types of infections, i.e., acute and chronic.

Evaluation of Molecular Test for the Discrimination of "Naked" DNA from Infectious Parvovirus B19 Particles in Serum and Bone Marrow Samples

Low levels of parvovirus B19 (B19V) DNA can be detected in the circulation and in different tissue of immunocompetent individuals for months or years, which has been linked to inflammatory diseases such as cardiomyopathy, rheumatoid arthritis, hepatitis, and vasculitis. However, the detection of B19V DNA does not necessarily imply that infectious virions are present. This study aimed to evaluate the method based on the Benzonase^® treatment for differentiation between the infectious virions from “naked” DNA in serum and bone marrow (BM) samples to be useful for the B19V routine diagnosis. In addition, we estimated the period of viremia and DNAemia in the sera and bone marrow of nonhuman primates experimentally infected with B19V. Serum samples from ten patients and from four cynomolgus monkeys experimentally infected with B19V followed up for 60 days were used. Most of the human serum samples became negative after pretreatment; however, only decreased viral DNA loads were observed in four patients, indicating that these samples still contained the infectious virus. Reduced B19V DNA levels were observed in animals since 7th dpi. At approximately 45th dpi, B19V DNA levels were below 10⁵ IU/mL after Benzonase^® pretreatment, which was not a consequence of active B19V replication. The test based on Benzonase^® pretreatment enabled the discrimination of “naked DNA” from B19V DNA encapsidated in virions. Therefore, this test can be used to clarify the role of B19V as an etiological agent associated with atypical clinical manifestations.

Mast Cell Activation Triggered by Retrovirus Promotes Acute Viral Infection

Mast cells (MCs) are strategically located at the host-environment interface and their non-allergic roles in the immune-surveillance of pathogens have recently gained more attention. However, MC-caused detrimental regulation of immune inflammations can promote viral invasion. Currently, the role of MCs in retroviral infection remains elusive. We have recently proved that human gut MCs could capture and transfer HIV-1 to CD4⁺ T cells for promoting viral spread; MC-released histamine augments HIV-1-induced functional polarization of dendritic cells to cause immunosuppression via stimulating the differentiation of regulatory T cells. In this study, we used a murine model of MuLV/Friend virus infection to address MC role in acute retroviral infection in vivo. The acute infection of MuLV/Friend virus could be established in C57BL/6 wild type mice, but viral acquisition showed low efficiency in C57BL/6-Kit ^W - ^sh/W - ^sh (Sash) mice which lack MCs. In mechanism, we found that MuLV/Friend virus triggered MC activation for degranulation; MC degranulation subsequently activated the granulocyte-like myeloid derived suppressive cells (G-MDSCs) to inhibit CD8⁺ T cells- and NK cells-mediated antiviral immune responses. The reconstruction of MCs in Sash mice promoted acute retroviral infection by regulating G-MDSCs functions and antiviral immune responses. Importantly, the administration of MC stabilizers to block cell degranulation elevated antiviral immune response and consequently suppressed retrovirus infection. This study uncovers a specific role of MCs in acute retroviral infection and elucidates the underlying immune-mechanisms. Targeting MCs may provide a novel approach for controlling acute infection by retroviruses.

Acute infections in kidney transplant recipients

Immunosuppressed kidney transplant recipients have a high risk of infectious complications. A variety of infections of viral, bacterial, or mycotic etiology, including opportunistic infections, occur in this group of patients, but bacterial infections are primarily responsible for the high infection-related mortality. Of the bacterial infections, urinary tract infections and pneumonia are the most common, often requiring hospitalization and temporary reduction of immunosuppressive therapy after consultation of the transplant center. In addition to symptoms due to the location of the infection, fever is often present. The differential diagnosis of fever and/or high inflammatory activity is specific to patients after kidney transplantation. In addition to infectious causes, we consider drug-related fever, a rejection episode, a relapse of systemic disease or in patients with graft failure in dialysis treatment graft intolerance syndrome (&#8220;symptomatic graft&#8221;). Saving the patients life, which often requires a significant reduction in immunosuppressive therapy, always takes precedence over preventing a rejection episode. Infection prevention is an integral part of the care of transplant patients, including the recommendation of vaccination where possible.

Serum Levels of Seven General Cytokines in Acute Brucellosis Before and After Treatment

Purpose

Human brucellosis is the most common bacterial zoonosis globally that poses a severe health threat. Despite the availability of antibiotic therapy for human brucellosis, its tendencies of chronicity and persistence may lead to severe debilitating and disabling conditions in patients. Comprehensive understanding of the immune response in brucellosis will be helpful in improving the treatment strategies. In this study, we measured serum levels of T helper cell type 1 (Th1), Th2, and Th17 cytokines in patients with acute brucellosis before and after treatment.

Patients and Methods

Overall, 30 patients with acute brucellosis from the Beijing Di Tan Hospital and 26 healthy controls were enrolled in this study. All the patients received a 6-week therapy regimen comprising ceftriaxone, doxycycline, and rifampicin. Serum samples were collected from patients with acute Brucella infection and healthy controls before and after treatment. Serum seven cytokine levels of Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4, IL-6, IL-10), and Th17 (IL-17A) were measured using cytometric bead array.

Results

In patients with acute infection, the IL-2, IFN-γ, and IL-10 levels were significantly increased compared with those in healthy controls (P < 0.001). After treatment, IL-2, IFN-γ, and IL-10 levels significantly decreased (P < 0.05) and the TNF-α level significantly increased compared with the corresponding baseline levels and those in healthy controls (P < 0.05). Furthermore, the IFN-γ, IL-4, and IL-10 levels were higher in patients after treatment than in healthy controls (P < 0.05). IL-2 and IL-6 levels exhibited a positive correlation with the C-reactive protein (CRP) level in acute brucellosis (P < 0.05).

Conclusion

Levels of most serum Th1 and Th2 cytokines were simultaneously increased in acute infection, followed by reduction in the corresponding cytokine levels and residual cytokine response during treatment. This residual immune response could represent a therapeutic opportunity that may improve the long-term clinical outcomes in patients with acute brucellosis after treatment.

Cognitive Trajectories Following Acute Infection in Older Patients With and Without Cognitive Impairment: An 1-Year Follow-Up Study

Introduction: Dementia is a known risk factor for both delirium and acute systemic infections which may also play a significant role in promoting or accelerating neurodegenerative disease. Infections are both the main causes of hospitalization of dementia patients and can be a major precipitant of delirium but currently it is not possible to predict the risk of cognitive decline in older patients exposed to acute infection. Objectives: We aimed to determine the level of cognitive change at 1-year follow up in individuals with different patterns of cognitive function (dementia, delirium, delirium superimposed on dementia) at the time of their hospitalization due to a systemic infection and to correlate these cognitive patterns with clinical status variables. Methods: We recruited 53 hospitalized geriatric patients with a systemic infection, and we collected 12-months follow up data for 34 patients. These patients were classified in four groups: no cognitive impairment (controls-C), delirium only (D), dementia only (Dem), and delirium superimposed to dementia (DD). Cognitive performance was measured by change in score on the Montreal Cognitive Assessment (MoCA) and delirium was identified using Confusion Assessment Measure (CAM). We examined performance on the MoCA in the first year after hospitalization, controlling for demographic characteristics, coexisting medical conditions, and type of infection. Results: For the 34 patients to whom follow-up data was available, delirium presence in individuals with prior dementia (DD group) was associated with a negative mean change score of 3-point (p < 0.02) at 1 year follow up, whereas dementia patients without delirium had a mean change score of 1.5-point lower at 12-months (p = 0.04), when comparing follow-up and baseline MoCA scores. Cognitively healthy patients did not significantly decrease their MoCA score at follow-up (p = 0.15). MoCA and NPI scores during hospitalization were significantly correlated with the level of cognitive decline in the four groups (r = 0.658, p < 0.01 and r = 0.439, p = 0.02, respectively). Conclusions: Premorbid dementia and delirium superimposed on dementia during hospitalization in older patients with acute infections predict cognitive decline at 1 year following admission. Taken together, our findings suggest a pathophysiological interaction between neurodegenerative changes, acute infection, and delirium.

Transmitted Drug Resistance in Antiretroviral Therapy-Naive Persons With Acute/Early/Primary HIV Infection: A Systematic Review and Meta-Analysis

Background: The widespread use of antiretroviral therapy (ART) has raised concerns about the emergence of HIV transmitted drug resistance (TDR). Acute HIV infection (AHI) was the most appropriate time to detect the spread of TDR. In this meta-analysis, our purpose was to evaluate the level of TDR in ART-naive patients with primary HIV infection (PHI)/AHI/early HIV infection (EHI) and to describe the critical drug-resistant mutations.

Methods: We systematically searched the literature between January 1, 2008, and April 30, 2021, in PubMed, Web of Science, Embase, and the Cochrane Library. To evaluate the overall prevalence of TDR, we extracted raw data and analyzed prevalence estimates using Stata SE.

Results: The data of this meta-analysis come from 12 observational studies, covering 3,558 ART-naive individuals with PHI, AHI, or EHI. The overall prevalence of HIV-TDR is 9.3% (95% CI: 6.8%–11.8%, I² = 81.1%, in 11 studies). The prevalence of resistance by drug class is the highest for the nonnucleoside reverse transcriptase inhibitors (NNRTIs) at 5.7% (95% CI: 2.9%–8.5%, I² = 96.6%, in 11 studies), followed by nucleoside reverse transcriptase inhibitors (NRTIs) at 3.4% (95% CI: 1.8%–5.0%, I² = 86.3%, in 10 studies) and protease inhibitors (PIs) at 3.3% (95% CI: 2.7%–3.9%, I² = 15.6%, in 10 studies). The prevalence of TDR to integrase inhibitors (INIs) is 0.3% (95% CI: 0.1%–0.7%, I² = 95.9%, in three studies), which is the lowest among all antiretroviral drugs.

Conclusion: The overall prevalence of TDR is at a moderate level among AHI patients who have never received ART. This emphasizes the importance of baseline drug resistance testing for public health surveillance and guiding the choice of ART. In addition, the prevalence of TDR to NNRTIs is the highest, while the TDR to INIs is the lowest. This may guide the selection of clinical antiretroviral drugs.

A Stronger Innate Immune Response During Hyperacute Human Immunodeficiency Virus Type 1 (HIV-1) Infection Is Associated With Acute Retroviral Syndrome

BACKGROUND

Acute retroviral syndrome (ARS) is associated with human immunodeficiency virus type 1 (HIV-1) subtype and disease progression, but the underlying immunopathological pathways are poorly understood. We aimed to elucidate associations between innate immune responses during hyperacute HIV-1 infection (hAHI) and ARS.

METHODS

Plasma samples obtained from volunteers (≥18.0 years) before and during hAHI, defined as HIV-1 antibody negative and RNA or p24 antigen positive, from Kenya, Rwanda, Uganda, Zambia, and Sweden were analyzed. Forty soluble innate immune markers were measured using multiplexed assays. Immune responses were differentiated into volunteers with stronger and comparatively weaker responses using principal component analysis. Presence or absence of ARS was defined based on 11 symptoms using latent class analysis. Logistic regression was used to determine associations between immune responses and ARS.

RESULTS

Of 55 volunteers, 31 (56%) had ARS. Volunteers with stronger immune responses (n = 36 [65%]) had increased odds of ARS which was independent of HIV-1 subtype, age, and risk group (adjusted odds ratio, 7.1 [95% confidence interval {CI}: 1.7-28.8], P = .003). Interferon gamma-induced protein (IP)-10 was 14-fold higher during hAHI, elevated in 7 of the 11 symptoms and independently associated with ARS. IP-10 threshold >466.0 pg/mL differentiated stronger immune responses with a sensitivity of 84.2% (95% CI: 60.4-96.6) and specificity of 100.0% (95% CI]: 90.3-100.0).

CONCLUSIONS

A stronger innate immune response during hAHI was associated with ARS. Plasma IP-10 may be a candidate biomarker of stronger innate immunity. Our findings provide further insights on innate immune responses in regulating ARS and may inform the design of vaccine candidates harnessing innate immunity.

Rapid Clinical Progression and Its Correlates Among Acute HIV Infected Men Who Have Sex With Men in China： Findings From a 5-Year Multicenter Prospective Cohort Study

Background

In the “treat all” era, there are few data on the nature of HIV clinical progression in middle-income countries. The aim of the current study was to prospectively analyze the clinical progression of HIV and its indicators among men in China with acute HIV who have sex with men.

Methods

From 2009–2014 a total of 400 men with acute HIV infection (AHI) were identified among 7,893 men who have sex with men via periodic pooled nucleic acid amplification testing, and they were assigned to an AHI prospective cohort in Beijing and Shenyang, China. Rapid progression was defined as two consecutive CD4⁺ T cell counts < 350/µL within 3–24 months post-infection. Kaplan−Meier and Cox-regression analyses were conducted to identify predictors of rapid progression.

Results

Among 400 men with AHI 46.5% were rapid progressors, 35.1% reached rapid progressor status by 12 months post-infection, and 63.9% reached rapid progressor status by 24 months. Rapid progression was associated with herpes simplex-2 virus coinfection (adjusted hazard ratio [aHR] 1.7, 95% confidence interval [CI] 1.2–2.3], depression (aHR 1.9, 95% CI 1.5–2.6), baseline CD4⁺ T cell count < 500/μL (aHR 3.5, 95% CI 2.4–5.1), higher baseline HIV viral load (aHR 1.6, 95% CI 1.2–2.3), acute symptoms lasting ≥ 2 weeks (aHR 1.6, 95% CI 1.1–2.2), higher body mass index (aHR 0.9, 95% CI 0.9–1.0), higher HIV viral load (aHR 1.7, 95% CI 1.4–2.1), set point viral load at 3 months (aHR 2.0, 95% CI 1.6–2.5), each 100-cell/μL decrease in CD4⁺ T cell count at 3 months (aHR 2.2, 95% CI 1.9–2.5), and baseline routine blood tests including white blood cell count < 5.32, hemoglobin ≥ 151, mean corpuscular hemoglobin ≥ 30.5, hemoglobin concentration ≥ 342, mean platelet count ≥ 342, lymphocytes ≥ 1.98, and mixed cell count ≥ 0.4 (all p < 0.05).

Conclusion

Almost half of the patients underwent rapid clinical progression within 2 years after HIV infection. A treat-all policy is necessary and should be strengthened globally. Rapid progression was correlated with herpes simplex-2 virus coinfection, depression, low CD4⁺ T cell counts, and high set point viral load in acute infection stage. Rapid progression can be identified via simple indicators such as body mass index and routine blood test parameters in low and middle-income countries.

Absence of interferon-λ 4 enhances spontaneous clearance of acute hepatitis C virus genotypes 1-3 infection

OBJECTIVES

Absence of a functional interferon-λ 4 (IFN-λ4) gene (IFNL4) predicts spontaneous resolution of acute hepatitis C virus (HCV) infections in regions with a predominance of genotype 1, whereas variants of the inosine triphosphate pyrophosphatase (ITPase) gene (ITPA) entailing reduced activity associate with increased sustained virologic response rates following some therapeutic regimens. This study aimed at investigating the impact of IFNL4 on acute HCV genotype 2 or 3 infections, and whether ITPase activity influenced outcome.

MATERIALS AND METHODS

Two hundred and seven people who injected drugs (PWID) with documented anti-HCV seroconversion, and 57 PWID with reinfection with HCV were analyzed regarding IFNL4 (rs368234815 and rs12979860) and ITPA (rs1127354 and rs7270101), and longitudinally followed regarding HCV RNA.

RESULTS

The spontaneous clearance of HCV infection in anti-HCV seronegative PWID was enhanced when IFN-λ4 was absent (44% vs. 20% for IFNL4 TT/TT_rs1368234815 and ΔG_rs1368234815 respectively, p < .001; OR 3.2) across genotypes 1-3. The proportion lacking IFN-λ4 was further increased following resolution of repeated re-exposure to HCV (74% among re-infected participants who had cleared at least two documented HCV infections). ITPA genetic variants did not independently impact on the outcome, but among males lacking IFN-λ4, reduced ITPase activity markedly augmented the likelihood of resolution (65% vs. 29% for <100% and 100% ITPase activity, p = .006).

CONCLUSIONS

Absence of IFN-λ4 entails an enhanced likelihood of spontaneous resolution both following primary acute infection and repeated re-exposure to HCV across genotypes 1-3. Among men lacking IFN-λ4, reduced ITPase activity improved outcome.

Using body temperature and variables commonly available in the EHR to predict acute infection: a proof-of-concept study showing improved pretest probability estimates for acute COVID-19 infection among discharged emergency department patients

OBJECTIVES

Obtaining body temperature is a quick and easy method to screen for acute infection such as COVID-19. Currently, the predictive value of body temperature for acute infection is inhibited by failure to account for other readily available variables that affect temperature values. In this proof-of-concept study, we sought to improve COVID-19 pretest probability estimation by incorporating covariates known to be associated with body temperature, including patient age, sex, comorbidities, month, and time of day.

METHODS

For patients discharged from an academic hospital emergency department after testing for COVID-19 in March and April of 2020, we abstracted clinical data. We reviewed physician documentation to retrospectively generate estimates of pretest probability for COVID-19. Using patients' COVID-19 PCR test results as a gold standard, we compared AUCs of logistic regression models predicting COVID-19 positivity that used: (1) body temperature alone; (2) body temperature and pretest probability; (3) body temperature, pretest probability, and body temperature-relevant covariates. Calibration plots and bootstrap validation were used to assess predictive performance for model #3.

RESULTS

Data from 117 patients were included. The models' AUCs were: (1) 0.69 (2) 0.72, and (3) 0.76, respectively. The absolute difference in AUC was 0.029 (95% CI -0.057 to 0.114, p=0.25) between model 2 and 1 and 0.038 (95% CI -0.021 to 0.097, p=0.10) between model 3 and 2.

CONCLUSIONS

By incorporating covariates known to affect body temperature, we demonstrated improved pretest probability estimates of acute COVID-19 infection. Future work should be undertaken to further develop and validate our model in a larger, multi-institutional sample.

Acute Infection of Viral Pathogens and Their Innate Immune Escape

Viral infections can cause rampant disease in human beings, ranging from mild to acute, that can often be fatal unless resolved. An acute viral infection is characterized by sudden or rapid onset of disease, which can be resolved quickly by robust innate immune responses exerted by the host or, instead, may kill the host. Immediately after viral infection, elements of innate immunity, such as physical barriers, various phagocytic cells, group of cytokines, interferons (IFNs), and IFN-stimulated genes, provide the first line of defense for viral clearance. Innate immunity not only plays a critical role in rapid viral clearance but can also lead to disease progression through immune-mediated host tissue injury. Although elements of antiviral innate immunity are armed to counter the viral invasion, viruses have evolved various strategies to escape host immune surveillance to establish successful infections. Understanding complex mechanisms underlying the interaction between viruses and host’s innate immune system would help develop rational treatment strategies for acute viral infectious diseases. In this review, we discuss the pathogenesis of acute infections caused by viral pathogens and highlight broad immune escape strategies exhibited by viruses.

Akt Phosphorylation Influences Persistent Chlamydial Infection and Chlamydia-Induced Golgi Fragmentation Without Involving Rab14

Chlamydia trachomatis is an obligate intracellular bacterium that causes multiple diseases involving the eyes, gastrointestinal tract, and genitourinary system. Previous studies have identified that in acute chlamydial infection, C. trachomatis requires Akt pathway phosphorylation and Rab14-positive vesicles to transmit essential lipids from the Golgi apparatus in survival and replication. However, the roles that Akt phosphorylation and Rab14 play in persistent chlamydial infection remain unclear. Here, we discovered that the level of Akt phosphorylation was lower in persistent chlamydial infection, and positively correlated with the effect of activating the development of Chlamydia but did not change the infectivity and 16s rRNA gene expression. Rab14 was found to exert a limited effect on persistent infection. Akt phosphorylation might regulate Chlamydia development and Chlamydia-induced Golgi fragmentation in persistent infection without involving Rab14. Our results provide a new insight regarding the potential of synergistic repressive effects of an Akt inhibitor with antibiotics in the treatment of persistent chlamydial infection induced by penicillin.

Evolution and Diversity of Immune Responses during Acute HIV Infection

Understanding the earliest immune responses following HIV infection is critical to inform future vaccines and therapeutics. Here, we review recent prospective human studies in at-risk populations that have provided insight into immune responses during acute infection, including additional relevant data from non-human primate (NHP) studies. We discuss the timing, nature, and function of the diverse immune responses induced, the onset of immune dysfunction, and the effects of early anti-retroviral therapy administration. Treatment at onset of viremia mitigates peripheral T and B cell dysfunction, limits seroconversion, and enhances cellular antiviral immunity despite persistence of infection in lymphoid tissues. We highlight pertinent areas for future investigation, and how application of high-throughput technologies, alongside targeted NHP studies, may elucidate immune response features to target in novel preventions and cures.

A systematic study of Tupaia as a model for human acute hepatitis B infection

The molecular features of hepatitis B virus (HBV) infection, eradication, and pathogenesis are poorly understood, partly due to the lack of an adequate animal model that faithfully reproduces the course of infection. Although Tupaia belangeri were previously recognized as HBV-susceptible animals, the course of infection in adult tupaias remains obscure. Herein, we performed a longitudinal study and demonstrated that adult tupaias were efficiently infected (90% infection rate) with 10⁸ copies of the HBV genome. HBV replicated vigorously, produced high levels of covalently closed circular DNA (cccDNA) in hepatocytes, and released hepatitis B surface antigen (HBsAg), hepatitis Be antigen (HBeAg), and HBV DNA into the serum at day 9 post-inoculation (p.i.), which then decreased on day 15 p.i. The kinetics were consistent with the expression of liver HBsAg and HBeAg, as determined with immunohistochemistry. The viral products in serum at day 9 and 15 p.i. represented de novo synthesized viral products, as treatment with a viral entry inhibitor completely abolished these products from the serum. Viral clearance and serological conversion occurred at day 21 p.i. and were accompanied by elevated alanine transaminase (ALT) levels and liver pathology, such as inflammatory infiltration and hepatocyte ballooning degeneration. Although ALT levels eventually returned to normal levels by day 42 p.i., the liver pathology persisted until at least day 120 p.i. The HBV infection process in tupaia, therefore, exhibits features similar to that of human acute HBV infection, including viral replication, viral eradication, ALT elevation, and liver pathology. Thus, adopting the tupaia model to study host-HBV interactions presents an important advance which could facilitate further investigation and understanding of human HBV infection, especially for features like cccDNA that current small-animal models cannot effectively model.

Preferential Infection of α4β7+ Memory CD4+ T Cells During Early Acute Human Immunodeficiency Virus Type 1 Infection

BACKGROUND

Establishment of persistent human immunodeficiency virus type 1 (HIV-1) reservoirs occurs early in infection, and biomarkers of infected CD4+ T cells during acute infection are poorly defined. CD4+ T cells expressing the gut homing integrin complex α4β7 are associated with HIV-1 acquisition, and are rapidly depleted from the periphery and gastrointestinal mucosa during acute HIV-1 infection.

METHODS

Integrated HIV-1 DNA was quantified in peripheral blood mononuclear cells obtained from acutely (Fiebig I-III) and chronically infected individuals by sorting memory CD4+ T-cell subsets lacking or expressing high levels of integrin β7 (β7negative and β7high, respectively). HIV-1 DNA was also assessed after 8 months of combination antiretroviral therapy (cART) initiated in Fiebig II/III individuals. Activation marker and chemokine receptor expression was determined for β7-defined subsets at acute infection and in uninfected controls.

RESULTS

In Fiebig I, memory CD4+ T cells harboring integrated HIV-1 DNA were rare in both β7high and β7negative subsets, with no significant difference in HIV-1 DNA copies. In Fiebig stages II/III and in chronically infected individuals, β7high cells were enriched in integrated and total HIV-1 DNA compared to β7negative cells. During suppressive cART, integrated HIV-1 DNA copies decreased in both β7negative and β7high subsets, which did not differ in DNA copies. In Fiebig II/III, integrated HIV-1 DNA in β7high cells was correlated with their activation.

CONCLUSIONS

β7high memory CD4+ T cells are preferential targets during early HIV-1 infection, which may be due to the increased activation of these cells.

The PD-1 Pathway Regulates Development and Function of Memory CD8+ T Cells following Respiratory Viral Infection

The PD-1 pathway regulates dysfunctional T cells in chronic infection and cancer, but the role of this pathway during acute infection remains less clear. Here, we demonstrate that PD-1 signals are needed for optimal memory. Mice deficient in the PD-1 pathway exhibit impaired CD8⁺ T cell memory following acute influenza infection, including reduced virus-specific CD8⁺ T cell numbers and compromised recall responses. PD-1 blockade during priming leads to similar differences early post-infection but without the defect in memory formation, suggesting that timing and/or duration of PD-1 blockade could be tailored to modulate host responses. Our studies reveal a role for PD-1 as an integrator of CD8⁺ T cell signals that promotes CD8⁺ T cell memory formation and suggest PD-1 continues to fine-tune CD8⁺ T cells after they migrate into non-lymphoid tissues. These findings have important implications for PD-1-based immunotherapy, in which PD-1 inhibition may influence memory responses in patients.

The Effect of Proinflammatory Cytokines on the Proliferation, Migration and Secretory Activity of Mesenchymal Stem/Stromal Cells (WJ-MSCs) under 5% O2 and 21% O2 Culture Conditions

Treatment with Mesenchymal Stem/Stromal Cells (MSCs) in clinical trials is becoming one of the most-popular and fast-developing branches of modern regenerative medicine, as it is still in an experimental phase. The cross-section of diseases to which these cells are applied is very wide, ranging from degenerative diseases, through autoimmune processes and to acute inflammatory diseases, e.g., viral infections. Indeed, now that first clinical trials applying MSCs against COVID-19 have started, important questions concern not only the therapeutic properties of MSCs, but also the changes that might occur in the cell features as a response to the "cytokine storm" present in the acute phase of an infection and capable of posing a risk to a patient. The aim of our study was thus to assess changes potentially occurring in the biology of MSCs in the active inflammatory environment, e.g., in regards to the cell cycle, cell migration and secretory capacity. The study using MSCs derived from Wharton's jelly (WJ-MSCs) was conducted under two aerobic conditions: 21% O2 vs. 5% O2, since oxygen concentration is one of the key factors in inflammation. Under both oxygen conditions cells were exposed to proinflammatory cytokines involved significantly in acute inflammation, i.e., IFNγ, TNFα and IL-1β at different concentrations. Regardless of the aerobic conditions, WJ-MSCs in the inflammatory environment do not lose features typical for mesenchymal cells, and their proliferation dynamic remains unchanged. Sudden fluctuations in proliferation, the early indicator of potential genetic disturbance, were not observed, while the cells' migration activity increased. The presence of pro-inflammatory factors was also found to increase the secretion of such anti-inflammatory cytokines as IL-4 and IL-10. It is concluded that the inflammatory milieu in vitro does not cause phenotype changes or give rise to proliferation disruption of WJ-MSCs, and nor does it inhibit the secretory properties providing for their use against acute inflammation.

Surveillance of Acute SARS-CoV-2 Infections in School Children and Point-Prevalence During a Time of High Community Transmission in Switzerland

Background: Switzerland had one of the highest incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Europe during the second wave. Schools were open as in most of Europe with specific preventive measures in place. However, the frequency and transmission of acute unrecognized, asymptomatic or oligosymptomatic infections in schools during this time of high community transmission is unknown. Thereof, our aim was to pilot a surveillance system that detects acute SARS-CoV-2 infections in schools and possible transmission within classes. Methods: Fourteen out of the randomly selected sample of the Ciao Corona cohort study participated between December 1 and 11, a time when incidence rate for SARS-CoV-2 infections was high for the canton of Zurich. We determined point-prevalence of acute SARS-CoV-2 infections of school children attending primary and secondary school. A buccal swab for polymerase chain reaction (PCR) and a rapid diagnostic test (RDT) to detect SARS-CoV-2 were taken twice 1 week apart (T1 and T2) in a cohort of children from randomly selected classes. A questionnaire assessed demographics and symptoms compatible with a SARS-CoV-2 infection during the past 5 days. Results: Out of 1,299 invited children, 641 (49%) 6- to 16-year-old children and 66 teachers from 14 schools and 67 classes participated in at least one of two testings. None of the teachers but one child had a positive PCR at T1, corresponding to a point-prevalence in children of 0.2% (95% CI 0.0-1.1%), and no positive PCR was detected at T2. The child with positive PCR at T1 was negative on the RDT at T1 and both tests were negative at T2. There were 7 (0.6%) false positive RDTs in children and 2 (1.7%) false positive RDTs in teachers at T1 or T2 among 5 schools (overall prevalence 0.7%). All 9 initially positive RDTs were negative in a new buccal sample taken 2 h to 2 days later, also confirmed by PCR. Thirty-five percent of children and 8% of teachers reported mild symptoms during the 5 days prior to testing. Conclusion: In a setting of high incidence of SARS-CoV-2 infections, unrecognized virus spread within schools was very low. Schools appear to be safe with the protective measures in place (e.g., clearly symptomatic children have to stay at home, prompt contact tracing with individual and class-level quarantine, and structured infection prevention measures in school). Specificity of the RDT was within the lower boundary of performance and needs further evaluation for its use in schools. Given the low point prevalence even in a setting of very high incidence, a targeted test, track, isolate and quarantine (TTIQ) strategy for symptomatic children and school personnel adapted to school settings is likely more suitable approach than surveillance on entire classes and schools. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04448717, ClinicalTrials.gov NCT04448717.

B cell engagement with HIV-1 founder virus envelope predicts development of broadly neutralizing antibodies

Determining which immunological mechanisms contribute to the development of broad neutralizing antibodies (bNAbs) during HIV-1 infection is a major goal to inform vaccine design. Using samples from a longitudinal HIV-1 acute infection cohort, we found key B cell determinants within the first 14-43 days of viremia that predict the development of bNAbs years later. Individuals who develop neutralization breadth had significantly higher B cell engagement with the autologous founder HIV envelope (Env) within 1 month of initial viremia. A higher frequency of founder-Env-specific naive B cells was associated with increased B cell activation and differentiation and predictive of bNAb development. These data demonstrate that the initial B cell interaction with the founder HIV Env is important for the development of broadly neutralizing antibodies and provide evidence that events within HIV acute infection lead to downstream functional outcomes.

Complete genome characterization of human noroviruses allows comparison of minor alleles during acute and chronic infections

Human noroviruses (HuNoVs) circulate globally, affect all age groups and place a substantial burden upon health services. High genetic diversity leading to antigenic variation plays a significant role in HuNoV epidemiology, driving periodic global emergence of epidemic variants. Studies have suggested that immunocompromised individuals may be a reservoir for such epidemic variants, but studies investigating the diversity and emergence of HuNoV variants in immunocompetent individuals are underrepresented. To address this, we sequenced the genomes of HuNoVs present in samples collected longitudinally from one immunocompetent (acute infection) and one immunocompromised (chronic infection) patient. A broadly reactive HuNoV capture-based method was used to concentrate the virus present in these specimens prior to massively parallel sequencing to recover near complete viral genomes. Using a novel bioinformatics pipeline, we demonstrated that persistent minor alleles were present in both acute and chronic infections, and that minor allele frequencies represented a larger proportion of the population during chronic infection. In acute infection, minor alleles were more evenly spread across the genome, although present at much lower frequencies, and therefore difficult to discern from error. By contrast, in the chronic infection, more minor alleles were present in the minor structural protein. No non-synonymous minor alleles were detected in the major structural protein over the short sampling period of the HuNoV chronic infection, suggesting where immune pressure is variable or non-existent, epidemic variants could emerge over longer periods of infection by random chance.

Long-lasting Imprint in the Soluble Inflammatory Milieu despite Early Treatment of Acute Symptomatic Hepatitis C

Background

Treatment with direct-acting antivirals (DAAs) in patients with chronic hepatitis C infection leads to partial restoration of soluble inflammatory mediators (SIMs). In contrast, we hypothesized that early DAA treatment of acute hepatitis C virus (HCV) with DAAs may normalize most SIMs.

Methods

In this study, we made use of a unique cohort of acute symptomatic hepatitis C patients who cleared HCV with a 6-week course of ledipasvir/sofosbuvir. Plasma samples were used for proximity extension assay measuring 92 proteins.

Results

Profound SIM alterations were observed in acute HCV patients, with marked upregulation of interleukin (IL)-6 and CXCL-10, whereas certain mediators were downregulated (eg, monocyte chemoattractant protein-4, IL-7). During treatment and follow-up, the majority of SIMs decreased but not all normalized (eg, CDCP1, IL-18). Of note, SIMs that were downregulated before DAA treatment remained suppressed, whereas others that were initially unchanged declined to lower values during treatment and follow-up (eg, CD244).

Conclusions

Acute hepatitis C was associated with marked changes in the soluble inflammatory milieu compared with both chronic hepatitis patients and healthy controls. Whereas early DAA treatment partly normalized this altered signature, long-lasting imprints of HCV remained.

Study on Circulating Antigens in Serum of Mice With Experimental Acute Toxoplasmosis

Toxoplasma gondii is a ubiquitous apicomplexan protozoan parasite that can infect all warm-blooded animals, causing toxoplasmosis. Thus, efficient diagnosis methods for acute T. gondii infection are essential for its management. Circulating antigens (CAgs) are reliable diagnostic indicators of acute infection. In this study, we established a mouse model of acute T. gondii infection and explored new potential diagnostic factors. CAgs levels peaked 60 h after T. gondii inoculation and 31 CAgs were identified by immunoprecipitation-liquid chromatography-tandem mass spectrometry, among which RuvB-like helicase (TgRuvBL1), ribonuclease (TgRNaseH1), and ribosomal protein RPS2 (TgRPS2) were selected for prokaryotic expression. Polyclonal antibodies against these three proteins were prepared. Results from indirect enzyme-linked immunosorbent assay indicated that anti-rTgRuvBL1, anti-rTgRNase H1, and anti-rTgRPS2 mouse sera were recognized by natural excretory-secretory antigens from T. gondii tachyzoites. Moreover, immunofluorescence assays revealed that TgRuvBL1 was localized in the nucleus, while TgRNase H1 and TgRPS2 were in the apical end. Western blotting data confirmed the presence of the three proteins in the sera of the infected mice. Moreover, mice immunized with rTgRuvBL1 (10.0 ± 0.30 days), TgRNaseH1 (9.67 ± 0.14 days), or rTgRPS2 (11.5 ± 0.34 days) had slightly longer lifespan when challenged with a virulent T. gondii RH strain. Altogether, these findings indicate that these three proteins can potentially be diagnostic candidates for acute toxoplasmosis. However, they hold poor protective potential against highly virulent T. gondii infection.

Contribution of Swarming Motility to Dissemination in a Pseudomonas aeruginosa Murine Skin Abscess Infection Model

Swarming motility in Pseudomonas aeruginosa is a multicellular adaptation induced by semisolid medium with amino acids as a nitrogen source. By phenotypic screening, we differentiated swarming from other complex adaptive phenotypes, such as biofilm formation, swimming and twitching, by identifying a swarming-specific mutant in ptsP, a metabolic regulator. This swarming-deficient mutant was tested in an acute murine skin abscess infection model. Bacteria were recovered at significantly lower numbers from organs of mice infected with the ∆ptsP mutant. We also tested the synthetic peptide 1018 for activity against different motilities and efficacy in vivo. Treatment with peptide 1018 mimicked the phenotype of the ∆ptsP mutant in vitro, as swarming was inhibited at low concentrations (<2 μg/mL) but not swimming or twitching, and in vivo, as mice had a reduced bacterial load recovered from organs. Therefore, PtsP functions as a regulator of swarming, which in turn contributes to dissemination and colonization in vivo.

Quasispecies dynamics of a hepatitis E virus 4 from the feces and liver biopsy of an acute hepatitis E patient during virus clearance

The presence of a quasispecies in hepatitis E virus (HEV) infection has been documented, however, the implications of a quasispecies in HEV-host interaction are poorly understood. Here, we analyzed the whole genome sequences of a HEV 4d from the feces and liver biopsy of a patient during the icteric and convalescent phases in an acute hepatitis E infection. Viral RNAs were extracted, reversely transcribed and seven fragments encompassing the entire viral genome were amplified and cloned. By sequencing multiple colonies of each cloned viral genome amplicon with Sanger sequencing, we verified the existence of the HEV quasispecies or intra-host genetic variations within the fecal and liver biopsy samples. There were broader genetic variations in the HEV ORF1 region including the PCP, HPX, and RdRp regions during the convalescent phase whereas more genetic variations in the ORF2 P domain during the icteric phase. The quasispecies dynamics might reflect host immune pressure during viral clearance.

Patterns of Hepatitis C Virus Transmission in Human Immunodeficiency Virus (HIV)-infected and HIV-negative Men Who Have Sex With Men

BACKGROUND

Sexually transmitted acute hepatitis C virus (HCV) infections (AHIs) have been mainly described in human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). Cases in HIV-negative MSM are scarce. We describe the epidemic of AHI in HIV-infected and HIV-negative MSM in Lyon, France.

METHODS

All cases of AHI diagnosed in MSM in Lyon University Hospital from 2014 to 2017 were included. AHI incidence was determined in HIV-infected and in preexposure prophylaxis (PrEP)-using MSM. Transmission clusters were identified by construction of phylogenetic trees based on HCV NS5B (genotype 1a/4d) or NS5A (genotype 3a) Sanger sequencing.

RESULTS

From 2014 to 2017, 108 AHIs (80 first infections, 28 reinfections) were reported in 96 MSM (HIV-infected, 72; HIV-negative, 24). AHI incidence rose from 1.1/100 person-years (95 confidence interval [CI], 0.7-1.7) in 2014 to 2.4/100 person-years (95 CI, 1.1-2.6) in 2017 in HIV-infected MSM (P = .05) and from 0.3/100 person-years (95 CI, 0.06-1.0) in 2016 to 3.4/100 person-years (95 CI, 2.0-5.5) in 2017 in PrEP users (P < .001). Eleven clusters were identified. All clusters included HIV-infected MSM; 6 also included HIV-negative MSM. All clusters started with ≥1 HIV-infected MSM. Risk factor distribution varied among clusters.

CONCLUSIONS

AHI incidence increased in both HIV-infected and HIV-negative MSM. Cluster analysis suggests initial transmission from HIV-infected to HIV-negative MSM through chemsex and traumatic sexual practices, leading to mixed patterns of transmission regardless of HIV status and no overlap with the general population.

Tracking the Trajectory of Functional Humoral Immune Responses Following Acute HIV Infection

Increasing evidence points to a role for antibody-mediated effector functions in preventing and controlling HIV infection. However, less is known about how these antibody effector functions evolve following infection. Moreover, how the humoral immune response is naturally tuned to recruit the antiviral activity of the innate immune system, and the extent to which these functions aid in the control of infection, are poorly understood. Using plasma samples from 10 hyper-acute HIV-infected South African women, identified in Fiebig stage I (the FRESH cohort), systems serology was performed to evaluate the functional and biophysical properties of gp120-, gp41-, and p24- specific antibody responses during the first year of infection. Significant changes were observed in both the functional and biophysical characteristics of the humoral immune response following acute HIV infection. Antibody Fc-functionality increased over the course of infection, with increases in antibody-mediated phagocytosis, NK activation, and complement deposition occurring in an antigen-specific manner. Changes in both antibody subclass and antibody Fc-glycosylation drove the evolution of antibody effector activity, highlighting natural modifications in the humoral immune response that may enable the directed recruitment of the innate immune system to target and control HIV. Moreover, enhanced antibody functionality, particularly gp120-specific polyfunctionality, was tied to improvements in clinical course of infection, supporting a role for functional antibodies in viral control.