Outcome Of Chronic Infection Research Articles

Trypanosoma cruzi-specific CD8+ T cells and other immunological hallmarks in chronic Chagas cardiomyopathy: Two decades of research.

Trypanosoma cruzi, the causal agent of Chagas disease, has coexisted with humans for thousands of years. Therefore, the parasite has developed several mechanisms of antigenic variability that has allowed it to live inside the cells and evade the host immune response. SinceT. cruzidisplays an intracellular cycle-stage, our research team focused on providing insights into the CD8+T cells immune response in chronic Chagas cardiomyopathy. We began our work in the 2000s studying parasite antigens that induce natural immune responses such as the KMP11 protein and TcTLE, its N-terminal derived peptide. Different approaches allowed us to reveal TcTLE peptide as a promiscuous CD8+ T cell epitope, able of inducing multifunctional cellular immune responses and eliciting a humoral response capable of decreasing parasite movement and infective capacity. Next, we demonstrated that as the disease progresses, total CD8+T cells display a dysfunctional state characterized by a prolonged hyper-activation state along with an increase of inhibitory receptors (2B4, CD160, PD-1, TIM-3, CTLA-4) expression, an increase of specific terminal effector T cells (TTE), a decrease of proliferative capacity, a decrease of stem cell memory (TSCM) frequency, and a decrease of CD28 and CD3ζexpression. Thus, parasite-specific CD8+ T cells undergo clonal exhaustion, distinguished by an increase in late-differentiated cells, a mono-functional response, and enhanced expression of inhibitory receptors. Finally, it was found that anti-parasitic treatment induces an improved CD8+T cell response in asymptomatic individuals, and a mouse animal model led us to establish a correlation between the quality of the CD8+ T cell responses and the outcome of chronic infection. In the future, using OMICs strategies, the identification of the specific cellular signals involved in disease progression will provide an invaluable resource for discovering new biomarkers of progression or new vaccine and immunotherapy strategies. Also, the inclusion of the TcTLE peptide in the rational design of epitope-based vaccines, the development of immunotherapy strategies using TSCMor the blocking of inhibitory receptors, and the use of the CD8+T cell response quality to follow treatments, immunotherapies or vaccines, all are alternatives than could be explored in the fight against Chagas disease.

Peculiarities of the Expression of Immunohistochemical Marker HCV nS3 in the Autopsy Brain of the Patients Died in the Outcome of Chronic Infection, Caused by Hepatitis C Virus

Background . Brain lesion is one of the most common extrahepatic manifestations of chronic HCV infection. To date, its main clinical and neurometabolic features have been established. However, the morphological picture of HCV-associated cerebral changes and peculiarities of viral molecular markers expression in brain matter remain poorly understood. This significantly limits the possibilities of pathological diagnosis of this disease. Aims . To study the morphological picture of brain lesion during chronic HCV infection and to determine the peculiarities of immunohistochemical (IHC) expression of the HCV NS3 antigen in brain matter. Materials and methods . The study was performed on autopsy brain of 40 patients who died in the outcome of HCV infection and 15 patients died without signs of mental pathology. Complex of pathomorphological and ICH methods was used. Results . It was demonstrated that morphological picture of brain lesion in chronic HCV infection is represented by nonspecific dystrophic, inflammatory and proliferative changes, the severity of which varies significantly depending on the brain departments (p < 0.001). Expression of the NS3 marker is found in all studied brain regions and shows the highest intensity in white matter of cerebral hemispheres and in brain stem (p < 0.05). The ICH reaction of NS3 is manifested in microglia cells, vascular endothelium, inflammatory infiltrate cells and in periventricular ependyma cells. Using correlation analysis method it was found that NS3 expression formed the strongest correlations with such categories as CD68 expression, microgliosis, and axonal degeneration. This allows considering they are the main factors by which HCV realizes its deleterious effect on the brain. Conclusion . Characteristic morphological changes of the brain in chronic HCV infection were studied. The features of ICH expression of the NS3 in various parts of the brain are established. The results can be used to improve pathological diagnosis of brain lesion in chronic HCV infection.

Modeling Diversity: Do Homogeneous Laboratory Strains Limit Discovery?

The outcome of chronic infections is highly variable. The heterogeneous disease outcomes in natural populations differ from genetically homogeneous infection models. Here, we use tuberculosis as a 'case study' to contrast the genetic landscape in natural populations with standard infection models, discussing new strategies to bridge this gap.

HLA-A is a Predictor of Hepatitis B e Antigen Status in HIV-Positive African Adults.

Outcomes of chronic infection with hepatitis B virus (HBV) are varied, with increased morbidity reported in the context of human immunodeficiency virus (HIV) coinfection. The factors driving different outcomes are not well understood, but there is increasing interest in an HLA class I effect. We therefore studied the influence of HLA class I on HBV in an African HIV-positive cohort. We demonstrated that virologic markers of HBV disease activity (hepatitis B e antigen status or HBV DNA level) are associated with HLA-A genotype. This finding supports the role of the CD8+ T-cell response in HBV control, and potentially informs future therapeutic T-cell vaccine strategies.

Serological assay and genotyping of hepatitis C virus in infected patients in zanjan province.

Background:Hepatitis C Virus (HCV), a public health problem, is an enveloped, single-stranded RNA virus and a member of the Hepacivirus genus of the Flaviviridae family. Liver cancer, cirrhosis, and end-stage liver are the outcomes of chronic infection with HCV. HCV isolates show significant heterogeneity in genetics around the world. Therefore, determining HCV genotypes is a vital step in determining prognosis and planning therapeutic strategies.Objectives:As distribution of HCV genotypes is different in various geographical regions and HCV genotyping of patients has not been investigated in Zanjan City, this study was designed for the first time, to determine HCV genotypes in the region and to promote the impact of the treatment.Materials and Methods:Serum samples of 136 patients were collected and analyzed for anti-HCV antibodies using ELISA (The enzyme-linked immunosorbent assay) method. Then, positive samples were exposed to RT-PCR, which was performed under standard condition. Afterwards, they investigated for genotyping using allele-specific PCR (AS-PCR), and HCV genotype 2.0 line probe assay (LiPA).Results:Samples indicated 216 bp bands on 2% agarose gel. Analyses of the results demonstrated that the most dominant subtype was 3a with frequency of 38.26% in Zanjan Province followed by subtypes of 1b, 1a, 2, and 4 with frequencies of 25.73%, 22.05%, 5.14%, and 4.41%, respectively. The frequency of unknown HCV genotypes was 4.41%.Conclusions:According to the results, it was found that HCV high prevalent genotype in Zanjan is subtype 3a. Analysis of the results provides identification of certain HCV genotypes, and these valuable findings could affect the type and duration of the treatment.

Pathogenic features associated with increased virulence upon Simian immunodeficiency virus cross-species transmission from natural hosts.

While simian immunodeficiency viruses (SIVs) are generally nonpathogenic in their natural hosts, dramatic increases in pathogenicity may occur upon cross-species transmission to new hosts. Deciphering the drivers of these increases in virulence is of major interest for understanding the emergence of new human immunodeficiency viruses (HIVs). We transmitted SIVsab from the sabaeus species of African green monkeys (AGMs) to pigtailed macaques (PTMs). High acute viral replication occurred in all SIVsab-infected PTMs, yet the outcome of chronic infection was highly variable, ranging from rapid progression to controlled infection, which was independent of the dynamics of acute viral replication, CD4(+) T cell depletion, or preinfection levels of microbial translocation. Infection of seven PTMs with plasma collected at necropsy from a rapid-progressor PTM was consistently highly pathogenic, with high acute and chronic viral replication, massive depletion of memory CD4(+) T cells, and disease progression in all PTMs. The plasma inoculum used for the serial passage did not contain adventitious bacterial or viral contaminants. Single-genome amplification showed that this inoculum was significantly more homogenous than the inoculum directly derived from AGMs, pointing to a strain selection in PTMs. In spite of similar peak plasma viral loads between the monkeys in the two passages, immune activation/inflammation levels dramatically increased in PTMs infected with the passaged virus. These results suggest that strain selection and a massive cytokine storm are major factors behind increased pathogenicity of SIV upon serial passage and adaptation of SIVs to new hosts following cross-species transmission. We report here that upon cross-species transmission and serial passage of SIVsab from its natural host, the sabaeus African green monkey (AGM), to a new host, the pigtailed macaque (PTM), viral adaptation and increased pathogenicity involve strain selection and a massive cytokine storm. These results permit the design of strategies aimed at preventing cross-species transmission from natural hosts of SIVs to humans in areas of endemicity. Furthermore, our study describes a new animal model for SIV infection. As the outcomes of SIVsab infection in PTMs, African green monkeys, and rhesus macaques are different, the use of these systems enables comparative studies between pathogenic, nonpathogenic, and elite-controlled infections, to gain insight into the mechanisms of SIV immunodeficiency and comorbidities.

Role of persister cells in chronic infections: clinical relevance and perspectives on anti-persister therapies

Certain infectious diseases caused by pathogenic bacteria are typically chronic in nature. Potentially deadly examples include tuberculosis, caused by Mycobacterium tuberculosis, cystic fibrosis-associated lung infections, primarily caused by Pseudomonas aeruginosa, and candidiasis, caused by the fungal pathogen Candida albicans. A hallmark of this type of illness is the recalcitrance to treatment with antibiotics, even in the face of laboratory tests showing the causative agents to be sensitive to drugs. Recent studies have attributed this treatment failure to the presence of a small, transiently multidrug-tolerant subpopulation of cells, so-called persister cells. Here, we review our current understanding of the role that persisters play in the treatment and outcome of chronic infections. In a second part, we offer a perspective on the development of anti-persister therapies based on genes and mechanisms that have been implicated in persistence over the last decade.

FoxP3 mRNA Expression in Regulatory T Cells from Patients with Tuberculosis

We read with great interest the article by Guyot-Revol and colleagues (1) assessing the role of T regulatory cells (Tregs) in tuberculosis (TB) pathogenesis. Guyot-Revol and coworkers found that in patients with TB, percentages of CD4 CD25 T cells and levels of FoxP3 mRNA expression in peripheral blood mononuclear cells were both significantly higher in comparison with controls. To better comprehend Tregs’ mechanism of action, the authors investigated whether the increased levels of FoxP3 mRNA that they had observed were effectively caused by increased gene expression, or were simply the result of increasedCD4 CD25high frequency.FoxP3mRNAinCD4 CD25 T cells was compared between patients with TB and control subjects. As no quantitative difference was observed, the authors suggest that the greater levels of FoxP3 mRNA are simply an effect of increases in Treg frequency rather than a result of an up-regulated gene expression. The transcription factor FoxP3 is the most specific molecular marker for Tregs available to date, and its correct evaluation is crucial (2–4). In the analysis of Treg dynamics, an assessment of what happens in the frequency and level of FoxP3 mRNA expression at the single cell level is mandatory. The recent literature demonstrates a strong correlation between levels of CD25 expression and the frequency of FoxP3-positive cells in healthy donors (4), and suggests that to correctly evaluate FoxP3 expression in Tregs, mRNA should be quantified in CD4 CD25 rather than in CD4 CD25 T cells (5). We are currently performing a prospective study to evaluate Tregs in patients with TB. Analysis of CD4 CD25 percentage on CD4 T cells at TB diagnosis showed similar levels of Tregs among patients with TB and controls (median percentage: 2.1% [IQR, 1.8–6.6] vs. 1.9% [IQR, 1.5–2.2]). Unlike Guyot-Revol and coworkers, we evaluated FoxP3 mRNA expression by real-time polymerase chain reaction in CD4 CD25 T cells, purified using an EPICSALTRACell Sorter (Beckman-Coulter; purity 93.6%). A considerable increase of FoxP3 mRNA expression in patients with TB with respect to control subjects was clearly observed (median: 39.1 [IQR, 5.1–109] vs. 1.6 [IQR, 0.8–2.8]; p 0.0062). These data implicate FoxP3 gene overexpression as a probable mechanism involving Tregs in the pathogenesis of TB, and suggest a possible role of FoxP3 gene up-regulation in the outcome of chronic infections. Our results underscore the importance of using the correct methodology in evaluating Treg cell dynamics, and prove that an accurate evaluation of FoxP3 mRNA expression in Treg cells may lead to the identification of previously unknown mechanisms of Treg cell involvement in disease pathogenesis.

Current status and future prospects for a vaccine against American trypanosomiasis

The clinically relevant pathognomonic consequences of human infection by Trypanosoma cruzi are dilation and hypertrophy of the left ventricle walls and thinning of the apex. The major complications and debilitating evolutionary outcomes of chronic infection include ventricular fibrillation, thromboembolism and congestive heart failure. American trypanosomiasis (Chagas disease) poses serious public healthcare and budgetary concerns. The currently available drugs, although effective against acute infection, are highly toxic and ineffective in arresting or attenuating clinical disease symptoms in chronic patients. The development of an efficacious prophylactic vaccine faces many challenges, and progress is slow, despite several years of effort. Studies in animal models and human patients have revealed the pathogenic mechanisms during disease progression, pathology of disease and features of protective immunity. Accordingly, several antigens, antigen-delivery vehicles and adjuvants have been tested in animal models, and some efforts have been successful in controlling infection and disease. This review will summarize the accumulated knowledge about the parasite and disease, as well as pathogenesis and protective immunity. The authors will discuss the efforts to date, and the challenges faced in achieving an efficient prophylactic vaccine against human American trypanosomiasis, and present the future perspectives.

The hepatitis B virus and common mutants.

Most biological systems have developed complex mechanisms to maintain the stability of their genetic information. Exceptions to this include viruses that can undergo rapid and substantial genetic sequence changes and alterations. The hepatitis B virus (HBV) has evolved a unique life cycle resulting in the production of enormous viral loads during active replication without actually directly killing the infected cell. Because the virus uses reverse transcription to copy its DNA genome, mutant viral genomes are frequently found. Particular selection pressures, both endogenous (host immune clearance) and exogenous (vaccines and antivirals), readily select out these escape mutants. It is still not known which particular viral mutations or combination of mutations directly affects the clinical presentation of the liver disease, the nature of the viral persistence, or the course and outcome of chronic infection. Further studies are needed to identify the pathogenic basis for the selection of these mutants. Such research should help improve the basic understanding of this unique virus-host relationship and provide new strategies for complete control of HBV infections.

Outcomes of Chronic Infection with Hepatitis B Virus

Outcomes of Chronic Infection with Hepatitis B Virus

Hepatitis B virus infection: Precore mutants and its relation to viral genotypes and core mutations

The precore-core gene of hepatitis B virus (HBV) was directly sequenced from serum samples of 42 patients with chronic B hepatitis (19 hepatitis B e antigen [HBeAg]+ and 23 anti-HBe+). Viral genotypes were determined by comparison with 11 reference sequences and by restriction analysis. Genotype A was identified in 16 cases, genotype D in 24 cases, and other genotypes in 2 cases. Precore mutations, mainly Ml (stop at codon 28), were differently distributed among the viral genotypes: 3 cases (18.8%) with genotype A and 18 cases (75%) with genotype D. In sequences with precore mutants, the encapsidation signal was more stable (negative stabilization energy) than in sequences without precore mutants. In genotype A, the Ml mutation coexisted with a second mutation (C → T at position 1858 in codon 15), and both mutations were paired in the secondary structure of the RNA encapsidation signal, which justified the rare presence of precore mutants in this genotype. The analysis showed different distribution of mutations depending on the viral genotype; patients with genotype D were more likely to have persistent HBV infection by selection of precore mutants. Multiple amino acid substitutions were detected in the core region, mainly in two subsequences that have been previously described as epitopes (flanked by codons 11 to 27 and 74 to 83); the presence of these mutations was significantly related to the presence of precore variants which abolished the expression of HBeAg. The study of viral genotypes in chronic HBV infection may be valuable in predicting the persistence of viral replication after seroconversion to anti-HBe and suggest that the outcome of chronic infection may be affected by the HBV variability.

Hepatitis B virus infection: precore mutants and its relation to viral genotypes and core mutations.

The precore-core gene of hepatitis B virus (HBV) was directly sequenced from serum samples of 42 patients with chronic B hepatitis (19 hepatitis B e antigen [HBeAg]+ and 23 anti-HBE+). Viral genotypes were determined by comparison with 11 reference sequences and by restriction analysis. Genotype A was identified in 16 cases, genotype D in 24 cases, and other genotypes in 2 cases. Precore mutations, mainly M1 (stop at codon 28), were differently distributed among the viral genotypes: 3 cases (18.8%) with genotype A and 18 cases (75%) with genotype D. In sequences with precore mutants, the encapsidation signal was more stable (negative stabilization energy) than in sequences without precore mutants. In genotype A, the M1 mutation coexisted with a second mutation (C-->T at position 1858 in codon 15), and both mutations were paired in the secondary structure of the RNA encapsidation signal, which justified the rare presence of precore mutants in this genotype. The analysis showed different distribution of mutations depending on the viral genotype; patients with genotype D were more likely to have persistent HBV infection by selection of precore mutants. Multiple amino acid substitutions were detected in the core region, mainly in two subsequences that have been previously described as epitopes (flanked by codons 11 to 27 and 74 to 83); the presence of these mutations was significantly related to the presence of precore variants which abolished the expression of HBeAg.(ABSTRACT TRUNCATED AT 250 WORDS)