Persistent Viral Infection Research Articles

Type I Interferon acts as a major barrier to the establishment of infectious bursal disease virus (IBDV) persistent infections.

Infectious bursal disease virus (IBDV), the best characterized member of the Birnaviridae family, is a highly relevant avian pathogen causing both acute and persistent infections in different avian hosts. Here, we describe the establishment of clonal, long-term, productive persistent IBDV infections in DF-1 chicken embryonic fibroblasts. Although virus yields in persistently-infected cells are exceedingly lower than those detected in acutely infected cells, the replication fitness of viruses isolated from persistently-infected cells is higher than that of the parental virus. Persistently-infected DF-1 and IBDV-cured cell lines derived from them do not respond to type I interferon (IFN). High-throughput genome sequencing revealed that this defect is due to mutations affecting the IFNα/β receptor subunit 2 (IFNAR2) gene resulting in the expression of IFNAR2 polypeptides harbouring large C-terminal deletions that abolish the signalling capacity of IFNα/β receptor complex. Ectopic expression of a recombinant chicken IFNAR2 gene efficiently rescues IFNα responsiveness. IBDV-cured cell lines derived from persistently infected cells exhibit a drastically enhanced susceptibility to establishing new persistent IBDV infections. Additionally, experiments carried out with human HeLa cells lacking the IFNAR2 gene fully recapitulate results obtained with DF-1 cells, exhibiting a highly enhanced capacity to both survive the acute IBDV infection phase and to support the establishment of persistent IBDV infections. Results presented here show that the inactivation of the JAK-STAT signalling pathway significantly reduces the apoptotic response induced by the infection, hence facilitating the establishment and maintenance of IBDV persistent infections.IMPORTANCE Members of the Birnaviridae family, including infectious bursal disease virus (IBDV), exhibit a dual behaviour, causing acute infections that are often followed by the establishment of life-long persistent asymptomatic infections. Indeed, persistently infected specimens might act as efficient virus reservoirs, hence potentially contributing to virus dissemination. Despite the key importance of this biological trait, information about mechanisms triggering IBDV persistency is negligible. Our report evidences the capacity of IBDV, a highly relevant avian pathogen, to establishing long-term, productive, persistent infections in both avian and human cell lines. Data presented here provide novel and direct evidence about the crucial role of type I IFNs on the fate of IBDV-infected cells and their contribution to controlling the establishment of IBDV persistent infections. The use of cell lines unable to respond to type I IFNs opens a promising venue to unveiling additional factors contributing to IBDV persistency.

Ефективність противірусної терапії у вторинній профілактиці ішемічного інсульту на тлі маніфестації вірусної інфекції

Recurrent stroke remains the key health issue in the world. A higher three-year recurrence rate of stroke in patients with persistence of the genome of herpes viruses, and with presence in the blood of the genome of at least 2 types of viruses was identified. These investigations demonstrate the importance of further research into the role of antiviral therapy in improving the rehabilitation and secondary prevention of stroke in patients with persistent viral infection The purpose of the study was to evaluate the effectiveness of antiviral therapy in the secondary ischemic stroke prevention on the viral infection manifestation background. Material and methods. The study included 105 patients with moderate to severe ischemic stroke with a viral manifestation confirmed by the detection of herpes virus’s DNA (HSV1, HSV2, EBV, CMV, HHV6) and Flu RNA. Patients who were additionally prescribed antiviral drugs on the background of traditional therapy were in the main group (n = 35). Patients who received only traditional, recommended by the modern stroke treatment guidelines, therapy and secondary stroke prevention measures were included in the comparison group (n = 70). Results and discussion. We found that the effectiveness of the proposed preventive treatment depended on the viral load of the patient. In the presence of three or more types of viruses, the proposed therapy provided a significantly lower ischemic stroke recurrence rate, compared to the patients who did not receive antiviral therapy 11.1% vs. 49.8%, p = 0.042. Prevention of recurrent ischemic stroke, which should have started as soon as possible after the development of the first stroke or transient ischemic attack occurrence, F. Rincon and R. L. Sacco (2008) consider the most relevant in this group of patients. Herewith, as emphasized by D. G. Hackam and J. D. Spence (2007), comprehensive prevention has reduced the risk of recurrent ischemic stroke by almost 80%, thus preventing 4 out of 5 possible disorders. However, both native and world literature still has a lack of systematic data of the problem of antiviral therapy using in patients with acute disorders of cerebral circulation, although it has been proven that infectious and inflammatory complications are an important pathogenetic factor of its unfavorable and severe outcome. M. S. Elkind et al. (2016) consider that antiviral drugs such as acyclovir may play an appropriate role in the prevention of recurrent ischemic stroke in children if their causal relation is confirmed. Conclusion. The use of acyclovir in complex rehabilitation therapy and secondary stroke prevention in patients with viral infection manifestation provided an increase in the average score of Bartel index after 1 year, p = 0.017. In the case of antiviral therapy using in the complex prevention of recurrent vascular events in patients with viral infection manifestation, the three-year recurrence rate of stroke is lower (p = 0.042)

Clinical and morphofunctional features of the cardiovascular system in children with remheld syndrome

The article is devoted to an urgent problem of pediatrics Remheld syndrome. The aim of the present work was to study the clinical and morphofunctional features of the cardiovascular system in children with Remkhelds syndrome. 23children from 10 to 18 years old with Remkhelds syndrome were examined.Research methods.Study of blood biochemical parameters (MV-CPK, ASLO titer, C-reactive protein), identification of persistent viral infection markers, ECG, daily monitoring of ECG and blood pressure by Holter, echocardiography, ultrasound of the vessels of the head and neck, ultrasound of the thyroid gland, ultrasound organs of the gastrointestinal tract. In the anamnesis, 78,3% of children had chronic gastroduodenitis, 21,7% had gastroesophageal reflux disease, and 8,7% had a hiatal hernia. All patients complained of cardialgia, interruptions in the work of the heart, a feeling of lack of air, dizziness upon admission. The appearance of noted complaints was associated with eating.Results.A study of the state of the cardiovascular system showed the presence of sinus tachycardia in 60,9% of patients, sinus bradycardia in 34,8%, single supraventricular extrasystole in 13,0%, paroxysmal supraventricular tachycardia in 4,3%,and 4,3% autonomic sinus node dysfunction, in 13,0% congenital heart disease (patent ductus arteriosus, bicuspid aortic valve), in 8,7% mitral valve anterior prolapse, in 4,3% a patent foramen ovale, in 95,7% of children vegetative-vascular dysfunction.Conclusion.Children and adolescents with diseases of the gastrointestinal tract, when cardiac complaints appear, need an in-depth examination of the cardiovascular system.

Atypical subacute sclerosing panencephalitis presenting in a toddler with a short latency period: Evolving epidemiological trend

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive degeneration of the central nervous system (CNS) caused by a persistent defective measles virus infection. We report the case of a 2.5-year-old girl who presented with complaints of sudden onset frequent falls while walking, myoclonic jerks, and loss of speech. The electroencephalogram showed generalized slowing with irregular activity and cerebral magnetic imaging revealed T2 hyperintensities in the periventricular region in the parietal and occipital lobes. SSPE was considered and the diagnosis was confirmed with the identification of measles antibodies in cerebrospinal fluid. Our findings show that SSPE should be in mind in the differential diagnosis of meningoencephalitis even when a short latency period with measles infection.

Sphingosine kinase 2 restricts T cell immunopathology but permits viral persistence.

Chronic viral infections are often established by the exploitation of immune-regulatory mechanisms that result in nonfunctional T cell responses. Viruses that establish persistent infections remain a serious threat to human health. Sphingosine kinase 2 (SphK2) generates sphingosine 1-phosphate, which is a molecule known to regulate multiple cellular processes. However, little is known about SphK2's role during the host immune responses to viral infection. Here, we demonstrate that SphK2 functions during lymphocytic choriomeningitis virus Cl 13 (LCMV Cl 13) infection to limit T cell immune pathology, which subsequently aids in the establishment of virus-induced immunosuppression and the resultant viral persistence. The infection of Sphk2-deficient (Sphk2-/-) mice with LCMV Cl 13 led to the development of nephropathy and mortality via T cell-mediated immunopathology. Following LCMV infection, Sphk2-/- CD4+ T cells displayed increased activity and proliferation, and these cells promoted overactive LCMV Cl 13-specific CD8+ T cell responses. Notably, oral instillation of an SphK2-selective inhibitor promoted protective T cell responses and accelerated the termination of LCMV Cl 13 persistence in mice. Thus, SphK2 is indicated as an immunotherapeutic target for the control of persistent viral infections.

Risk of Unsatisfactory Functional Outcome of Stroke in Patients with Clinical Manifestation of Persistent Viral Infection

Acute cerebrovascular disorders represent up to 75–85 % of strokes inUkraine. The wide spread of herpesvirus infection in developing countries (with a prevalence of 35–40 %), as well as influenza virus, requires consideration of the viral risk factor of stroke for prognostic purposes.The objective: to study the influence of the most common types of viral infection: the family of herpesviruses and influenza virus on the neurological and one-year functional outcome of stroke and to determine the predictors of unsatisfactory recovery of patients.Materials and methods. In the period from 2016–2020, on the basis of the neurological departments ofAlexanderHospital andClinicalHospital № 4 we performed research on the presence of herpes viruses. 70 patients with ischemic stroke with moderate and severe neurological disorders were examined, in whom herpes and influenza viruses were detected in the blood (the main group) within 2 weeks before hospitalization against the background of viral manifestation. The comparison group consisted of 220 patients without clinical signs of viral manifestations were compared with the main group by stroke severity, average age and gender. The severity of neurological disorders was assessed by the NIHSS scale. Functional recovery was assessed by the Barthel index. The presence of viral infection (family of herpesviruses and influenza virus) was studied using polymerase chain reaction.Results. HSV1 DNA was detected in 43 (61.4 %) cases, HSV2 – in 30 (42.9 %), EBV4 – in 19 (27.1 %), CMV5 – in 18 (25.7 %), HNV6 – in 27 (38.6 %), Influenza RNA – in 16 (22.9 %). Only one type of virus was present in 21 (30.0 %) patients, two types of viruses were identified in 31 (44.3 %), three or more types of viruses – in 18 (25.7 %). In the presence of viral infection, the relative risk of unsatisfactory recovery of neurological functions in the main group increases 1.99 times relative to the comparison group: RR=1.99 (95 % CI: 1.60–2.48). The presence of viral infection predicted unsatisfactory recovery with a sensitivity of 74.3 %, a specificity of 62.7 % and an area under the curve ROC=0.69. There was a negative correlation between increasing the number of virus types in patients and the lack of neurological improvement: r=0.370 (p=0.002). The presence of viral infection significantly increased the risk of moderate and severe disability one year after stroke, the relative risk of disability in patients of the main group relative to patients of comparison group was: RR=1,668 (95 % CI: 1,256–2,214), and IB score according to the linear regression analysis inversely depended on the number of viruses in patients, linear R2=0.423 (correlation coefficient r=–0.660). In the presence of two types of viruses in the blood, the probability of unsatisfactory recovery increased – 1.5 times (RR=1,562; 95 % CI: 1,064–2,265), three or more viruses 2.5 times (RR=2,511; 95 % CI: 1,888–3,340). One year after stroke, there was a significant correlation between lower IB score and the presence of HSV1 in associations: r=0.323; CMV: r=0.351; EBV: r=0.430. If there are at least 2 types of viruses in the blood, in particular HSV1+CMV and HHV6+CMV, the relative risk of PI and TI increases 2.9 times.Conclusions. The presence of a viral infection significantly increases the risk of unsatisfactory regression of neurological disorders, allows to predict poor neurological recovery with a sufficiently high sensitivity and specificity. In patients with viral manifestations and detection of the virus in the blood, functional recovery one year after stroke is significantly worse than in patients without it; this applies to a lower mean score of IB and the percentage of patients with minimal limitation of function. When the number of persistent viruses increases to two or more, the relative risk of PI and TI increases one year after stroke, with the highest rate in the presence of EBV and CMV associations. If there are at least 2 types of viruses in the blood, in particular HSV1+CMV, HHV6+CMV, HSV1+EBV the relative risk of PI and TI increases 2.9 times.

Broadly active zinc finger protein-guided transcriptional activation of HIV-1

Human immunodeficiency virus type 1 (HIV-1) causes a persistent viral infection resulting in the demise of immune regulatory cells. Clearance of HIV-1 infection results in integration of proviral DNA into the genome of host cells, which provides a means for evasion and long-term persistence. A therapeutic compound that specifically targets and sustainably activates a latent HIV-1 provirus could be transformative and is the goal for the “shock-and-kill” approach to a functional cure for HIV-1. Substantial progress has been made toward the development of recombinant proteins that target specific genomic loci for gene activation, repression, or inactivation by directed mutations. However, most of these modalities are too large or too complex for efficient therapeutic application. We describe here the development and testing of a novel recombinant zinc finger protein transactivator, ZFP-362-VPR, which specifically and potently enhances proviral HIV-1 transcription both in established latency models and activity across different viral clades. Additionally, ZFP-362-VPR-activated HIV-1 reporter gene expression in a well-established primary human CD4+ T cell latency model and off-target pathways were determined by transcriptome analyses. This study provides clear proof of concept for the application of a novel, therapeutically relevant, protein transactivator to purge cellular reservoirs of HIV-1.

The expression of p16 and galectin-3 in cervical intraepithelial neoplasia (CIN) and squamous cell carcinoma (SCC) uterine cervix

Cervical cancer is the most prevalent cancer among women in India. The main cause of cervical cancer is persistent human papilloma viral (HPV) infection. HPV inactivates the pRb tumour suppressor protein; thus p16 expression, which is controlled by a negative feedback mechanism, is relatively increased. Galectin-3 is directly and indirectly connected to cancer cell activity and contributes to oncogenesis, angiogenesis, cancer progression and metastasis. Thus, the aim of this study was to study the expression of p16 and galectin-3 in Cervical Intraepithelial Neoplasia (CIN) and Squamous Cell Carcinoma (SCC) and to correlate p16 and galectin-3 expression. On hundred and eighteen newly-diagnosed untreated cases of CIN and SCC of uterine cervix were included in the study. Expression of p16 and galectin 3 was more pronounced in invasive SCC and High-grade Intraepithelial Lesion (HSIL), as compared to Low-grade Intraepithelial Lesion (LSIL).Thus, it may be used in clinical setting to monitor cervical lesions and to predict their progression. Impact statement What is already known on this subject? p16 overexpression is a surrogate biomarker of HPV infection and useful in evaluating HPV-associated squamous and glandular neoplasia of the lower gynaecologic tract. Increased galectin‐3 expression is seen in SCC cervical, with less consistent results in CIN. What do the results of this study add? The results of our study adds to the growing literature that p16 and galectin-3 expression have direct statistically significant correlation with a degree of dysplasia and SCC cervix. Expression of p16 and galectin-3 was more pronounced in invasive SCC and high-grade intraepithelial lesion (HSIL), as compared to low-grade intraepithelial lesion (LSIL). What are the implications of these findings for clinical practice and/or further research? This correction of p16 and galectin-3 expression with degree of dysplasia and SCC cervix can be used for screening and early detection of cervical lesions and thus aid their early treatment and increased survival.

Therapeutic Exploitation of Viral Interference.

Viral interference, originally, referred to a state of temporary immunity, is a state whereby infection with a virus limits replication or production of a second infecting virus. However, replication of a second virus could also be dominant over the first virus. In fact, dominance can alternate between the two viruses. Expression of type I interferon genes is many times upregulated in infected epithelial cells. Since the interferon system can control most, if not all, virus infections in the absence of adaptive immunity, it was proposed that viral induction of a nonspecific localized temporary state of immunity may provide a strategy to control viral infections. Clinical observations also support such a theory, which gave credence to the development of superinfection therapy (SIT). SIT is an innovative therapeutic approach where a non-pathogenic virus is used to infect patients harboring a pathogenic virus. For the functional cure of persistent viral infections and for the development of broad- spectrum antivirals against emerging viruses a paradigm shift was recently proposed. Instead of the virus, the therapy should be directed at the host. Such a host-directed-therapy (HDT) strategy could be the activation of endogenous innate immune response via toll-like receptors (TLRs). Superinfection therapy is such a host-directed-therapy, which has been validated in patients infected with two completely different viruses, the hepatitis B (DNA), and hepatitis C (RNA) viruses. SIT exerts post-infection interference via the constant presence of an attenuated non-pathogenic avian double- stranded (ds) RNA viral vector which boosts the endogenous innate (IFN) response. SIT could, therefore, be developed into a biological platform for a new "one drug, multiple bugs" broad-spectrum antiviral treatment approach.

Establishment of an In Vitro Model of Persistent Chicken Anemia Virus Infection.

Persistent infection of chicken anemia virus (CAV) in chickens has been suspected to result in immunosuppression and exogenous virus contamination within vaccine production. However, no direct evidence for persistent CAV infection has thus far been obtained. In this study, we aimed to establish an in vitro model of persistent CAV infection. CAV-infected MDCC-MSB1 (MSB1) cells, a Marek’s disease virus-transformed continuous cell line, were cultured in the presence of both CAV and CAV neutralizing antibody (NA). Cell viability, expression of viral antigens, viral DNA, and recovery of CAV were examined by acridine orange/propidium iodide staining, immunofluorescence measurement, real-time PCR, and viral isolation, respectively. The results indicated that CAV was maintained and possibly replicated in CAV-infected cells cultured in the presence of NA, without affecting host cell viability. It was also shown that persistently infectious CAV induced cell death again after removing NA. The persistent infection of CAV in MSB1 cells was not related to viral gene mutation. In summary, we have herein established a novel model of persistent CAV infection in MSB1 cells cultured in the presence of NA.

T Cell Receptor Diversity and Lineage Relationship between Virus-Specific CD8 T Cell Subsets during Chronic Lymphocytic Choriomeningitis Virus Infection.

Recent studies on chronic viral infections have defined a novel programmed cell death 1-positive (PD-1+) T cell factor 1-positive (TCF1+) stem-like CD8 T cell subset that gives rise to the terminally differentiated exhausted CD8 T cells. In this study, we performed T cell receptor beta (TCRβ) sequencing of virus-specific CD8 T cells during chronic lymphocytic choriomeningitis virus (LCMV) infection to examine the TCR diversity and lineage relationship of these two functionally distinct subsets. We found that >95% of the TCR repertoire of the exhausted CD8 T cell subset was shared with the stem-like CD8 T cells. The TCR repertoires of both CD8 T cell subsets were composed mostly of a few dominant clonotypes, but there was slightly more breadth and diversity in the stem-like CD8 T cells than their exhausted counterpart (∼40 versus ∼15 GP33+ clonotypes; ∼20 versus ∼7 GP276+ clonotypes). Interestingly, the breadth of the TCR repertoire was broader during the early stages (day 8) of the chronic infection than the later stages (days 45 to 60), showing that there was a narrowing of the TCR repertoire during chronic infection (∼2-fold GP33+ and GP276+ stem-like subset; ∼10-fold GP33+ and ∼5-fold GP276+ exhausted subset). In contrast, during acute LCMV infection, the TCR repertoire was much broader in both GP33-specific effector (∼160 clonotypes) and memory CD8 T cells (∼160 clonotypes). Overall, our data demonstrate that the virus-specific CD8 T cell TCR repertoire is broad and remains stable after acute LCMV infection, but it contracts and is narrower during chronic infection. Our study also shows that the repertoire of the exhausted CD8 T cell subset is almost completely derived from the stem-like CD8 T cell subset during established chronic LCMV infection.IMPORTANCE CD8 TCR repertoires responding to chronic viral infections (HIV, hepatitis C virus [HCV], Epstein-Barr virus [EBV], and cytomegalovirus [CMV]) have limited breadth and diversity. How these repertoires change and are maintained throughout the chronic infection are unknown. We thus characterized the LCMV-specific CD8 TCR repertoires of stem-like and terminally exhausted subsets generated during chronic LCMV infections. During chronic LCMV infections, the repertoires started as diverse but became more clonal at the late time point. Further, the exhausted subset was composed of dominant clonotypes that were shared with the stem-like subset. Together, we demonstrate that the TCR repertoire contracts over time and is almost exclusively derived from the stem-like subset late during the persistent viral infection. Our data suggest that dominant clonotypes in the exhausted subset are derived from a diverse pool of stem-like clonotypes, which may be contributing to the clonality observed during chronic viral infections.

LDHB inhibition induces mitophagy and facilitates the progression of CSFV infection

ABSTRACT Cellular metabolism caters to the energy and metabolite needs of cells. Although the role of the terminal metabolic enzyme LDHB (lactate dehydrogenase B) in the glycolysis pathway has been widely studied in cancer cells, its role in viral infection is relatively unknown. In this study, we found that CSFV (classical swine fever virus) infection reduces pyruvate levels while promotes lactate release in pigs and in PK-15 cells. Moreover, using a yeast two-hybrid screening system, we identified LDHB as a novel interacting partner of CSFV non-structural protein NS3. These results were confirmed via co-immunoprecipitation, glutathione S-transferase and confocal assays. Furthermore, knockdown of LDHB via interfering RNA induced mitochondrial fission and mitophagy, as detected reduced mitochondrial mass. Upon inhibition of LDHB, expression of the mitophagy proteins TOMM20 and VDAC1 decreased and the ubiquitination of MFN2, a mitochondrial fusion mediator, was promoted. In addition, a sensitive dual fluorescence reporter (mito-mRFP-EGFP) was utilized to analyze the delivery of autophagosomes to lysosomes in LDHB inhibition cells. Furthermore, LDHB inhibition promoted NFKB signaling, which was regulated by mitophagy; meanwhile, infection with CSFV negated these NFKB anti-viral responses. Inhibition of LDHB also inhibited apoptosis, providing an environment conducive to persistent viral infection. Finally, we demonstrated that LDHB inhibition promoted CSFV growth via mitophagy, whereas its overexpression decreased CSFV replication. Our data revealed a novel mechanism through which LDHB, a metabolic enzyme, mediates CSFV infection, and provides new avenues for the development of anti-viral strategies.Abbreviations: 3-MA:3-methyladenine; CCCP:carbonyl cyanide 3-chlorophenylhydrazone; CCK-8:cell counting kit-8; CSFV:classical swine fever virus; DAPI:4′,6-diamidino-2-phenylindole; DMSO:dimethyl sulfoxide; EGFP:enhanced green fluorescent protein; FBS:fetal bovine serum; FITC:fluorescein isothiocyanate; GST:glutathione-S-transferase; HCV:hepatitis C virus; IFN:interferon; LDH:lactate dehydrogenase; MAP1LC3/LC3:microtubule associated protein 1 light chain 3; MFN2:mitofusin 2; MOI:multiplicity of infection; NFKB:nuclear factor kappa B subunit 1; NFKBIA:nuclear factor inhibitor alpha; NS3:nonstructural protein 3; NKIRAS2:NFKB inhibitor interacting Ras like 2; PRKN:parkin E3 ubiquitin protein ligase; PBS:phosphate-buffered saline; qRT-PCR:real-time quantitative reverse transcriptase polymerase chain reaction; RELA:RELA proto-oncogene, NF-kB subunit; shRNA: short hairpin RNA; siRNA: small interfering RNA; TCID50:50% tissue culture infectious doses; TEM:transmission electron microscopy; TNF:tumor necrosis factor; TOMM20:translocase of outer mitochondrial membrane 20; VDAC1:voltage dependent anion channel 1.

Diagnostic Approaches and Management of Subacute Sclerosing Panencephalitis in Children

Abstract: Subacute Sclerosing Panencephalitis (SSPE) is a progressive neurodegenerative disease that attacks the central nervous system, especially in the population of children and early adolescents, due to persistent measles virus infection. The incidence of SSPE is quite rare, and data shows that in developing countries it is still quite high compared to developed countries. Diagnosis is based on clinical, supporting examinations such as EEG, as well as increased antibodies against measles virus in serum and cerebrospinal fluid. Symptoms can include changes in behavior, myoclonus, memory problems, and persistent pyramidal or extrapyramidal movements. Management to date has not provided satisfactory results and is individualized. Most SSPE patients experience a progressive and gradual course, leading to death within 1-3 years. The challenge of SSPE in children is the approach to diagnosis and management. Until now, the approach to treating SSPE in children is still based on the pathophysiological mechanisms from several existing research studies. That why therapy guidelines for children with SSPE are still varied. This paper aims to discuss the topic of SSPE in children with a major focus on diagnostic and therapeutic approaches based on the latest scientific evidence. Keywords: Subacute Sclerosing Panencephalitis (SSPE), children, diagnosis, therapy

IL-21 from high-affinity CD4 T cells drives differentiation of brain-resident CD8 T cells during persistent viral infection.

Development of tissue-resident memory (TRM) CD8 T cells depends on CD4 T cells. In polyomavirus central nervous system infection, brain CXCR5hi PD-1hi CD4 T cells produce interleukin-21 (IL-21), and CD8 T cells lacking IL-21 receptors (IL21R-/-) fail to become bTRM IL-21+ CD4 T cells exhibit elevated T cell receptor (TCR) affinity and higher TCR density. IL21R-/- brain CD8 T cells do not express CD103, depend on vascular CD8 T cells for maintenance, are antigen recall defective, and lack TRM core signature genes. CD4 T cell-deficient and IL21R-/- brain CD8 T cells show similar deficiencies in expression of genes for oxidative metabolism, and intrathecal delivery of IL-21 to CD4 T cell-depleted mice restores expression of electron transport genes in CD8 T cells to wild-type levels. Thus, high-affinity CXCR5hi PD-1hi CD4 T cells in the brain produce IL-21, which drives CD8 bTRM differentiation in response to a persistent viral infection.

A Shared TCR Bias toward an Immunogenic EBV Epitope Dominates in HLA-B*07:02-Expressing Individuals.

EBV is one of the most common viruses found in humans and is prototypic of a persistent viral infection characterized by periods of latency. Across many HLA class I molecules, the latent-specific CD8+ T cell response is focused on epitopes derived from the EBNA-3 protein family. In the case of HLA-B*07:02 restriction, a highly frequent class I allele, the T cell response is dominated by an epitope spanning residues 379-387 of EBNA-3 (RPPIFIRRL [EBVRPP]). However, little is known about either the TCR repertoire specific for this epitope or the molecular basis for this observed immunodominance. The EBVRPP CD8+ T cell response was common among both EBV-seropositive HLA-B*07:02+ healthy and immunocompromised individuals. Similar TCRs were identified in EBVRPP-specific CD8+ T cell repertoires across multiple HLA-B7+ individuals, indicating a shared Ag-driven bias in TCR usage. In particular, TRBV4-1 and TRAV38 usage was observed in five out of six individuals studied. In this study, we report the crystal structure of a TRBV4-1+ TCR-HLA-B*07:02/EBVRPP complex, which provides a molecular basis for the observed TRBV4-1 bias. These findings enhance our understanding of the CD8+ T cell response toward a common EBV determinant in HLA-B*07:02+ individuals.

Otosclerosis and Measles: Do Measles Have a Role in Otosclerosis? A Review Article

Otosclerosis is a common cause of conductive hearing loss which is an autoimmune inflammatory disorder related to abnormal bone remodeling of the human otic capsule that has complex etiopathogenesis attributed to genetics, autoimmunity, viral infection, inflammation, hormonal factor, environmental factor, and disturbed bone metabolism. It has a prevalence of 0.3%-0.4% in Caucasians, which makes up 5-9% of all hearing loss and 18-22% of all conductive hearing loss. This review article aims to study the postulated role of sustained measles virus infection in the etiopathogenesis of otosclerosis, among others. A PubMed search of the related topic identified 97,990 articles. After we applied the inclusion and exclusion criteria, it was determined that 52 articles were relevant, which included 38 observational studies, 13 review articles, and a systematic review. Among them, 33 observational studies, 13 review articles and a systematic review spotted a positive association between persistent measles virus infection and otosclerosis. On the contrary, five observational studies reported no evidence of the association. The majority of the current literature supported the presence of the measles virus component in the otosclerotic stapes samples and its role in the etiopathogenesis of otosclerosis. Measles virus infection may have the amplitude to initiate a pathological process, which in the presence of other factors like autoimmunity and genes plays a significant role in causing otosclerosis. However, other studies have failed to show the presence of the measles virus component in otosclerotic stapes. So, more studies are needed to probe the role of persistent measles virus infection in the etiopathogenesis of otosclerosis.

Клінічні та УЗДГ кореляції у хворих на ішемічний інсульт iз маніфестацією вірусної інфекції в анамнезі

The goal. The goal of the work was to study the structure of viral and non-viral infections in patients with ischemic stroke, as well as the relationship between neurological recovery and severity of cerebral atherosclerosis, depending on the type of infectious agent.Materials and methods. A total of 89 patients with ischemic acute cerebral circulation disorder and a history of clinical manifestations of a viral infection in the 3 months prior to the cerebrovascular accident were included in the study. Among the patients 44 (44.9%) were men and 54 (55.1%) were women with an average age of 62.08 ± 1.29 years (from 36 years to 92 years). 61 (81.9%) patients were diagnosed with ischemic stroke, and 28 (18.1%) patients were diagnosed with TIA.The diagnosis was confirmed by magnetic resonance imaging (MRI), and the severity of neurological status was assessed using the National Institute of Health Stroke Scale (NIHSS) on the first, 7th and 21st day. Patients' blood serum was examined for the presence of herpes viruses DNA, the RNA of influenza viruses, enteroviruses, the viruses of an acute respiratory infection (adenoviruses), as well as for the common non-viral infections: mycoplasma, ureoplasma, toxoplasma, and chlamydia. The method of polycytomerase chain reaction (PCR) for DNA and RNA viruses extraction from blood serum (6; 8) and the method of enterovirus antigens detection in a cell culture by enzyme-linked immunosorbent assay (ELISA) (21; 24; 40) were used.The degree of cerebral atherosclerosis was determined by ultrasound duplex scanning (UDS) of brachiocephalic arteries.Methods of descriptive statistics were used.Research results. The average period from the clinical manifestation of the infection to the development of stroke in patients with viral persistence was 11.8 ± 2.5 days (from 1 day to 90 days). Up to 7 days — 32 (36.0%) patients, from 7 days to 14 days inclusive — 44 (49.4%), more than 14 days — 13 (14.6%).There was a weak but definite inverse correlation between the term of the viral manifestation and the severity of the acute cerebrovascular accident (r = 0.237, p = 0.025).HSV1 (51) was detected most often in the acute period of stroke in 57% of patients, (p <0.05). The persistence of HSV2 and HHV6 was 38.2% and 32.6% respectively. A combination of two different HSV2 and HHV6 viruses was observed in 84 (89.9%) patients.The combination of HSV1 / HSV2 is most commonly observed (in 29 (32.6%) patients p <0.05). Coefficients of correlation between the presence of certain types of viruses, the number of stenoses, and the number of hemodynamically significant stenoses ranged from 0.19 with ARI to 0.33 in the case of a combination with HHV6.There was no detectable relationship between the severity of neurological deficiency on the first day after the stroke and the type of viral infection or a combination thereof, except for adV (r = 0.27, p = 0.01).The reduction in the NIHSS score on the 7th and the 21st day negatively correlated with the presence of certain viruses and their combinations, in particular herpesviruses or their associations HSV1, HSV1,2; HSV1,2-HHV6.Conclusion. The DNA of HSV1, HSV2, HHV6, HHV4, HHV5 viruses was most often found in patients with ischemic stroke and a clinical manifestation of a persistent viral infection in history (within 1-90 days before the development of symptoms),The presence of major vessels stenosis in the extracranial unit, the number of stenoses, and the presence of hemodynamically significant stenoses correlated with the presence of viral persistence of HHV6 and / or the association of HHV6 and influenza.The presence of HSV1, HSV2, HHV6 viruses and / or their associations worsens the restoration of neurological functions in the acute post-ischemic period setting.

Persistent Innate Immune Stimulation Results in IRF3-Mediated but Caspase-Independent Cytostasis.

Persistent virus infection continuously produces non-self nucleic acids that activate cell-intrinsic immune responses. However, the antiviral defense evolved as a transient, acute phase response and the effects of persistently ongoing stimulation onto cellular homeostasis are not well understood. To study the consequences of long-term innate immune activation, we expressed the NS5B polymerase of Hepatitis C virus (HCV), which in absence of viral genomes continuously produces immune-stimulatory RNAs. Surprisingly, within 3 weeks, NS5B expression declined and the innate immune response ceased. Proteomics and functional analyses indicated a reduced proliferation of those cells most strongly stimulated, which was independent of interferon signaling but required mitochondrial antiviral signaling protein (MAVS) and interferon regulatory factor 3 (IRF3). Depletion of MAVS or IRF3, or overexpression of the MAVS-inactivating HCV NS3/4A protease not only blocked interferon responses but also restored cell growth in NS5B expressing cells. However, pan-caspase inhibition could not rescue the NS5B-induced cytostasis. Our results underline an active counter selection of cells with prolonged innate immune activation, which likely constitutes a cellular strategy to prevent persistent virus infections.

Retinoic Acid Modulates Hyperactive T Cell Responses and Protects Vitamin A-Deficient Mice against Persistent Lymphocytic Choriomeningitis Virus Infection.

Vitamin A deficiency (VAD) is a major public health problem and is associated with increased host susceptibility to infection; however, how VAD influences viral infection remains unclear. Using a persistent lymphocytic choriomeningitis virus infection model, we showed in this study that although VAD did not alter innate type I IFN production, infected VAD mice had hyperactive, virus-specific T cell responses at both the acute and contraction stages, showing significantly decreased PD-1 but increased cytokine (IFN-γ, TNF-α, and IL-2) expression by T cells. Compared with control mice, VAD mice displayed excessive inflammation and more severe liver pathology, with increased death during persistent infection. Of note, supplements of all-trans retinoic acid (RA), one of the important metabolites of vitamin A, downregulated hyperactive T cell responses and rescued the persistently infected VAD mice. By using adoptive transfer of splenocytes, we found that the environmental vitamin A or its metabolites acted as rheostats modulating antiviral T cells. The analyses of T cell transcriptional factors and signaling pathways revealed the possible mechanisms of RA, as its supplements inhibited the abundance of NFATc1 (NFAT 1), a key regulator for T cell activation. Also, following CD3/CD28 cross-linking stimulation, RA negatively regulated the TCR-proximal signaling in T cells, via decreased phosphorylation of Zap70 and its downstream signals, including phosphorylated AKT, p38, ERK, and S6, respectively. Together, our data reveal VAD-mediated alterations in antiviral T cell responses and highlight the potential utility of RA for modulating excessive immune responses and tissue injury in infectious diseases.

Persistent SARS-CoV-2 infection and the risk for cancer

The current SARS-CoV-2 has put significant strain on healthcare services worldwide due to acute COVID-19. However, the potential long-term effects of this infection haven’t been extensively discussed.We hypothesize that SARS-CoV-2 may be able to cause persistent infection in some individuals, and should this be the case, that in a few years we may see a rise in cancer incidence due to carcinogenic effects of this coronavirus.Non-retroviral RNA viruses such as Coronaviridae have been shown to cause persistent infection in hosts. Empirical evidence of viral genomic material shedding weeks after apparent clinical and laboratorial resolution of COVID-19 may be an indirect proof for persistent viral infection. Furthermore, tropism towards certain immune-privileged territories may facilitate immune evasion by this virus.Structural homology with SARS-CoV-1 indicates that SARS-CoV-2 may be able to directly impair pRb and p53, which are key gatekeepers with tumor suppressor functions. Additionally, COVID-19 features preeminent inflammatory response with marked oxidative stress, which acts as both as initiator and promotor of carcinogenesis.Should there be a carcinogenic risk associated with SARS-CoV-2, the implications for public health are plenty, as infected patients should be closely watched during long periods of follow-up.Additional investigation to establish or exclude the possibility for persistent infection is paramount to identify and prevent possible complications in the future.