Influence on Herpes simplex virus type 1 glycoprotein B on viral pathogenecity and the CD8+ T cell response

Herpes simplex virus type 1 (HSV-1) is a ubiquitous human pathogen that establishes a latent infection in sensory ganglia and upon reactivation, can cause severe ocular disease. During lytic replication, viral proteins are expressed in a temporal cascade of immediate early (α), early (β) and late (γ) genes. The γ genes are further sub-classified into γ1 genes which are expressed prior to DNA replication and γ2 genes which are absolutely dependent on DNA replication for their expression. During a latent infection of the trigeminal ganglia (TG), no infectious virus is produced and latency is associated with a persistent virus-specific CD8+ T cell infiltrate that actively block reactivation. In C57BL/6 mice, approximately 50% of these CD8+ T cells are specific to a single epitope on a γ1 protein glycoprotein B (gB498-505; gB-CD8). In the TG, gB-CD8 are retained with an activated phenotype suggesting recent exposure to antigen during abortive reactivation events. While the kinetics of gene expression during lytic infection has been appreciated for some time, little is known about antigen expression during latency and reactivation, and its influence on antigen-specific CD8+ T cells in the TG. Using gB as our model antigen, in this work we show that during reactivation, gB expression occurs much sooner than gC expression, indicating that it expressed fairly early even during reactivation. Furthermore, by delaying gB expression to after DNA replication we observed a severe impairment in viral replication in the TG and a significant diminishment in the retention and activation phenotype of gB-CD8 in latently infected TG. However delaying gB did not prevent the ability of gB-CD8 to block reactivation indicating they can act very quickly even after DNA replication. Finally we demonstrate that by mutating the gB epitope such that it does not induce a gB-CD8 response, we abrogate the gB-CD8 infiltrate in the TG. These studies all demonstrate that during an HSV-1 infection, only antigen-specific CD8+ T cells infiltrate the TG and antigen exposure during latency is responsible for their retention in the TG. This work has great implications toward designing better immunogens for therapeutic vaccines to prevent HSV-1 reactivation

Pathways to care in first-episode psychosis in low-resource settings: Implications for policy and practice.

Developing countries such as India face a major mental health care gap. Delayed or inadequate care can have a profound impact on treatment outcomes. We compared pathways to care in first episode psychosis (FEP) between North and South India to inform solutions to bridge the treatment gap. Cross-sectional observation study of 'untreated' FEP patients (n = 177) visiting a psychiatry department in two sites in India (AIIMS, New Delhi and SCARF, Chennai). We compared duration of untreated psychosis (DUP), first service encounters, illness attributions and socio-demographic factors between patients from North and South India. Correlates of DUP were explored using logistic regression analysis (DUP ≥ 6 months) and generalised linear models (DUP in weeks). Patients in North India had experienced longer DUP than patients in South India (β = 17.68, p < 0.05). The most common first encounter in North India was with a faith healer (45.7%), however, this contact was not significantly associated with longer DUP. Visiting a faith healer was the second most common first contact in South India (23.6%) and was significantly associated with longer DUP (Odds Ratio: 6.84; 95% Confidence Interval: 1.77, 26.49). Being in paid employment was significantly associated with shorter DUP across both sites. Implementing early intervention strategies in a diverse country like India requires careful attention to local population demographics; one size may not fit all. A collaborative relationship between faith healers and mental health professionals could help with educational initiatives and to provide more accessible care. [Abstract copyright: Copyright © 2023. Published by Elsevier B.V.

Interferon-Induced Ifit2/ISG54 Protects Mice from Lethal VSV Neuropathogenesis

Interferon protects mice from vesicular stomatitis virus (VSV) infection and pathogenesis; however, it is not known which of the numerous interferon-stimulated genes (ISG) mediate the antiviral effect. A prominent family of ISGs is the interferon-induced with tetratricopeptide repeats (Ifit) genes comprising three members in mice, Ifit1/ISG56, Ifit2/ISG54 and Ifit3/ISG49. Intranasal infection with a low dose of VSV is not lethal to wild-type mice and all three Ifit genes are induced in the central nervous system of the infected mice. We tested their potential contributions to the observed protection of wild-type mice from VSV pathogenesis, by taking advantage of the newly generated knockout mice lacking either Ifit2 or Ifit1. We observed that in Ifit2 knockout (Ifit2−/−) mice, intranasal VSV infection was uniformly lethal and death was preceded by neurological signs, such as ataxia and hind limb paralysis. In contrast, wild-type and Ifit1−/− mice were highly protected and survived without developing such disease. However, when VSV was injected intracranially, virus replication and survival were not significantly different between wild-type and Ifit2−/− mice. When administered intranasally, VSV entered the central nervous system through the olfactory bulbs, where it replicated equivalently in wild-type and Ifit2−/− mice and induced interferon-β. However, as the infection spread to other regions of the brain, VSV titers rose several hundred folds higher in Ifit2−/− mice as compared to wild-type mice. This was not caused by a broadened cell tropism in the brains of Ifit2−/− mice, where VSV still replicated selectively in neurons. Surprisingly, this advantage for VSV replication in the brains of Ifit2−/− mice was not observed in other organs, such as lung and liver. Pathogenesis by another neurotropic RNA virus, encephalomyocarditis virus, was not enhanced in the brains of Ifit2−/− mice. Our study provides a clear demonstration of tissue-, virus- and ISG-specific antiviral action of interferon

Influence of an immunodominant herpes simplex virus type 1 CD8+ T cell epitope on the target hierarchy and function of subdominant CD8+ T cells.

Herpes simplex virus type 1 (HSV-1) latency in sensory ganglia such as trigeminal ganglia (TG) is associated with a persistent immune infiltrate that includes effector memory CD8+ T cells that can influence HSV-1 reactivation. In C57BL/6 mice, HSV-1 induces a highly skewed CD8+ T cell repertoire, in which half of CD8+ T cells (gB-CD8s) recognize a single epitope on glycoprotein B (gB498-505), while the remainder (non-gB-CD8s) recognize, in varying proportions, 19 subdominant epitopes on 12 viral proteins. The gB-CD8s remain functional in TG throughout latency, while non-gB-CD8s exhibit varying degrees of functional compromise. To understand how dominance hierarchies relate to CD8+ T cell function during latency, we characterized the TG-associated CD8+ T cells following corneal infection with a recombinant HSV-1 lacking the immunodominant gB498-505 epitope (S1L). S1L induced a numerically equivalent CD8+ T cell infiltrate in the TG that was HSV-specific, but lacked specificity for gB498-505. Instead, there was a general increase of non-gB-CD8s with specific subdominant epitopes arising to codominance. In a latent S1L infection, non-gB-CD8s in the TG showed a hierarchy targeting different epitopes at latency compared to at acute times, and these cells retained an increased functionality at latency. In a latent S1L infection, these non-gB-CD8s also display an equivalent ability to block HSV reactivation in ex vivo ganglionic cultures compared to TG infected with wild type HSV-1. These data indicate that loss of the immunodominant gB498-505 epitope alters the dominance hierarchy and reduces functional compromise of CD8+ T cells specific for subdominant HSV-1 epitopes during viral latency

Situational analysis of prevailing practices in the management of first‐episode psychosis in Chennai, India

Aim This paper aims to examine how existing mental health within the city of Chennai, India manages first‐episode psychosis, to determine lacunae and barriers in providing effective early intervention and to make appropriate recommendations to improve the care of first‐episode psychosis patients. Methods Interviews were held with 15 health professionals to capture information on current practices and facilities available for the management of first‐episode psychosis. Results No specialized clinic or services were available for individuals with first‐episode psychosis in Chennai, except one. Pharmacotherapy was the main treatment modality with psychological support to patients and families. Most common drugs used were Risperidone, Olanzapine, and Haloperidol in their recommended doses. General practitioners and paediatricians, due to inadequate training in mental health, referred patients with psychosis to mental health professionals. Conclusions Equipping the existing mental health services to manage FEP and training all health professionals on psychosis will improve FEP management in Chennai

Construction of gB-null virus and of HSV-1 with gB_498-505 mutations.

<p>Line i represents the parental plasmid used for derivation of the constructs in this study, detailed previously [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006732#ppat.1006732.ref047" target="_blank">47</a>]. Line iii represents the replacement of the gB ORF with EGFP followed by the remaining part of the gB ORF from residue 509 to the end (gB ORF Back) that was developed to obtain a gB-null-EGFP virus. Line ii represents the HSV genome and the approximate coding position and direction of the gene for gB. Line iv represents the replacement gB genes and the site of the epitope mutations with respect to the SnaBI site used for derivation, as detailed in the text. AvrII and SnaBI are restriction sites used to clone the replacing region of gB.</p

Stimulation of acute TG-resident CD8⁺ T cell populations with WT, SIL, or L8A gB peptides.

<p>B6 mice received corneal infections with HSV-1 expressing WT, S1L, or L8A gB. TG were obtained at 8 dpi, dispersed into single cell suspensions, and the endogenous CD8⁺ T cells were stimulated for 6 hours with B6WT3 fibroblasts pulsed individually with WT, S1L, or L8A gB_498-505 peptides, in the presence of brefeldin A. Cells were surface stained for CD45 and CD8, followed by an intracellular stain for IFNγ. The data are represented as the mean percentage of CD8⁺ T cells that produced IFNγ +/- SEM (n = 5 mice per group). * represents significance of p<0.0001 for each group compared to gB peptide stimulation of wild-type infected control (first column) using one-way ANOVA with Dunnett’s multiple comparisons posttest.</p

gB-CD8⁺ T cell retention in the HSV-1 latently infected ganglia is dependent on antigen expression.

<p><b>(A)</b> Representation of infection models in which mice received unilateral corneal infections with WT (WT only) or S1L (S1L only) HSV-1, bilateral infections with WT on one cornea and S1L on the other cornea (dual infection); or bilateral corneal infection with S1L and flank infection with WT HSV-1. All corneal infections were with 1x10⁵ PFU/scarified cornea, and flank infections were with 1x10⁶ PFU on a scarified flank. At 8 or 30 dpi, TG and spleen suspensions were analyzed by flow cytometry for CD45, CD3, CD8, and gB-tetramer. <b>(B)</b> Total number of gB-tetramer⁺ cells/spleen. <b>(C and D)</b> Frequency of CD3⁺CD8⁺ T cells in the TG that are gB-tetramer⁺. * Statistical significance by one-way ANOVA with p<0.01.</p