BACKGROUND: Co-trimoxazole is a leading global cause of severe cutaneous adverse drug reactions (SCAR) including Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/ TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Co-trimoxazole-induced SCAR are associated with HLA class I alleles including HLA-B*13:01 and HLA-B*38:02 in Southeast Asian (SEA) populations. However, the global generalizability of these associations is unknown but critical for population-appropriate risk stratification and diagnosis. OBJECTIVE: To determine HLA risk factors associated with co-trimoxazole-induced SJS/TEN and DRESS in populations from the United States and South Africa. METHODS: We performed high-resolution HLA typing on dermatologist-adjudicated co-trimoxazole-induced patients with SCAR in the United States (n = 63) and South Africa (n = 26) compared with population controls. Peptide binding and docking analyses were performed using MHCcluster2.0 and CB-Dock2. RESULTS: In a multiple logistic regression model, HLA-B*44:03 (corrected P [Pc] < .001; odds ratio [OR] = 4.08), HLA-B*38:01 (Pc < .001; OR = 5.66), and HLA-C*04:01 (Pc = .003; OR = 2.50) were independently associated with co-trimoxazole-induced SJS/TEN in the United States. HLA-B*44:03 was also associated with co-trimoxazole-induced DRESS in South Africa (Pc = .019; OR = 10.69). Distinct HLA-B variants with shared peptide binding specificities (SPBS) and HLA-C*04:01 identified 94% and 78% of cotrimoxazole-induced SJS/TEN and DRESS in the United States, respectively. The SEA risk allele HLA-B*13:01, with SPBS to HLA-B*44:03, was identified in just one of 63 US patients with SCAR. CONCLUSIONS: HLA alleles with SPBS to SEA-related risk alleles, including HLA-B*44:03 (SPBS with HLA-B*13:01) and HLA-B*38:01 (SPBS with HLA-B*38:02) but also HLA-C*04:01, predisposed to co-trimoxazole-induced SCAR in the United States and South Africa. These findings provide biological plausibility and strategies for global risk prediction and diagnosis of co-trimoxazole-induced SCAR. (c) 2025 The Authors. Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). (J Allergy Clin Immunol Pract 2025;13:3042-53)

BACKGROUND:Co-trimoxazole is a leading global cause of severe cutaneous adverse drug reactions (SCAR) including Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Co-trimoxazole-induced SCAR are associated with HLA class I alleles including HLA-B∗13:01 and HLA-B∗38:02 in Southeast Asian (SEA) populations. However, the global generalizability of these associations is unknown but critical for population-appropriate risk stratification and diagnosis. OBJECTIVE:To determine HLA risk factors associated with co-trimoxazole-induced SJS/TEN and DRESS in populations from the United States and South Africa. METHODS:We performed high-resolution HLA typing on dermatologist-adjudicated co-trimoxazole-induced patients with SCAR in the United States (n = 63) and South Africa (n = 26) compared with population controls. Peptide binding and docking analyses were performed using MHCcluster2.0 and CB-Dock2. RESULTS:In a multiple logistic regression model, HLA-B∗44:03 (corrected P [Pc] < .001; odds ratio [OR] = 4.08), HLA-B∗38:01 (Pc < .001; OR = 5.66), and HLA-C∗04:01 (Pc = .003; OR = 2.50) were independently associated with co-trimoxazole-induced SJS/TEN in the United States. HLA-B∗44:03 was also associated with co-trimoxazole-induced DRESS in South Africa (Pc = .019; OR = 10.69). Distinct HLA-B variants with shared peptide binding specificities (SPBS) and HLA-C∗04:01 identified 94% and 78% of co-trimoxazole-induced SJS/TEN and DRESS in the United States, respectively. The SEA risk allele HLA-B∗13:01, with SPBS to HLA-B∗44:03, was identified in just one of 63 US patients with SCAR. CONCLUSIONS:HLA alleles with SPBS to SEA-related risk alleles, including HLA-B∗44:03 (SPBS with HLA-B∗13:01) and HLA-B∗38:01 (SPBS with HLA-B∗38:02) but also HLA-C∗04:01, predisposed to co-trimoxazole-induced SCAR in the United States and South Africa. These findings provide biological plausibility and strategies for global risk prediction and diagnosis of co-trimoxazole-induced SCAR.

Influenza remains a global health threat, infecting approximately one billion people annually and causing significant mortality, particularly among older adults. While hemagglutination inhibition (HAI) antibody titers are a standard correlate of immunity against influenza, they do not reliably predict protection in high-risk populations. Using multiomic single-cell profiling, we identified a distinct subset of adaptive-like NK cells that respond to influenza antigen, predominantly in younger females. These TNFSF10 + LGALS9 + NK cells exhibit features of adaptive NK cells but lack classical cytomegalovirus-driven markers observed in previous studies. Notably, their increased frequency correlates with high pre-existing HAI titers, suggesting a link between adaptive-like NK responses and humoral immunity. Together, our findings identify an NK subset influenced by age and sex that may contribute to influenza protection, expanding the known diversity of adaptive-like NK cells. These insights could inform future vaccine strategies, particularly for aging populations, by integrating NK responses into assessments of vaccine efficacy.

Developing an effective HIV-1 vaccine is a global health priority, but HIV-1 mutational escape from T cells poses a challenge. While escape from human leukocyte antigen class I (HLA-I)–restricted CD8 + T cells is well characterized, less is known about HLA-II–restricted T cell escape. We used computational methods to identify 149 sites across the HIV-1 clade B genome under HLA-II–associated selection. Functional assays, including activation-induced intracellular cytokine staining and enzyme-linked immunospot for interferon-γ, revealed diverse mechanisms of HIV-1 adaptation to HLA-II–associated immune pressure, ranging from loss to sustained antigen recognition. T cell receptor and RNA sequencing demonstrated variable clonotype overlap of T cell clones to recognize adapted versus non-adapted peptides, with cells targeting adapted peptides exhibiting a dysfunctional transcriptomic state. Moreover, incorporating HLA-II–associated adaptation strengthened the correlation between Gag-specific viral adaptation and poor disease outcomes. Last, we mapped viral regions prone to HLA-II–associated adaptation and found that these adaptations can increase in frequency within populations.

Early delineation of host immune responses at the moment of Mycobacterium tuberculosis (Mtb) exposure and infection is critical to identify individuals at risk of progressing to active tuberculosis (TB). We performed single-cell transcriptional profiling of over 500,000 peripheral blood mononuclear cells from 57 HIV-negative close contacts of TB cases in Brazil, including 25 individuals who developed active disease within two years (progressors) and 32 matched controls who remained disease-free (non-progressors). Cells were stimulated separately with the MTB300 peptide pool or irradiated Mtb (gRV), enabling resolution of antigen-reactive states across adaptive (CD4⁺ T-cells expressing abundant cytokines including IFNG, TNF, and IL17F) and trained-innate lineages, such as NK cells (producing GM-CSF, IFNG, CCL3, CCL4) and monocytes (GM-CSF, IL12B, IL36G). Progressors exhibited early hyper-metabolic CD4⁺ T-cell programs and proliferative NK cell signatures, whereas non-progressors preferentially upregulated complement activation and CCL3/4-driven chemokine signaling in monocytes. Notably, among progressors, gene expression profiles within antigen-reactive CD4⁺ T-cells and monocytes predicted the timing of progression to active TB. Together, these findings reveal high frequencies and functional diversity of antigen-reactive cells in Mtb-exposed individuals and nominate tractable immune correlates for the rational design of next-generation TB vaccines.

A strong genetic predictor of outcome following untreated HIV-1 infection is the carriage of specific alleles of human leukocyte antigens (HLAs) that present viral epitopes to T cells. Residual variation in outcome measures may be attributed, in part, to viral adaptation to HLA-restricted T cell responses. Variants of the endoplasmic reticulum aminopeptidases (ERAPs) influence the repertoire of T cell epitopes presented by HLA alleles as they trim pathogen-derived peptide precursors to optimal lengths for antigen presentation, along with other functions unrelated to antigen presentation. We investigated whether ERAP variants influence HLA-associated HIV-1 adaptation with demonstrable effects on overall HIV-1 disease outcome. Utilizing host and viral data of 249 West Australian individuals with HIV-1 subtype B infection, we identified a novel association between two linked ERAP2 single nucleotide polymorphisms (SNPs; rs2248374 and rs2549782) with plasma HIV RNA concentration (viral load) (P adjusted = 0.0024 for both SNPs). Greater HLA-associated HIV-1 adaptation in the HIV-1 Gag gene correlated significantly with higher viral load, lower CD4+ T cell count and proportion; P = 0.0103, P = 0.0061, P = 0.0061, respectively). When considered together, there was a significant interaction between the two ERAP2 SNPs and HLA-associated HIV-1 adaptation on viral load (P = 0.0111). In a comprehensive multivariate model, addition of ERAP2 haplotypes and HLA associated adaptation as an interaction term to known HLA and CCR5 determinants and demographic factors, increased the explanatory variance of population viral load from 17.67% to 45.1% in this dataset. These effects were not replicated in publicly available datasets with comparably sized cohorts, suggesting that any true global epistasis may be dependent on specific HLA-ERAP allelic combinations. Our data raises the possibility that ERAP2 variants may shape peptide repertoires presented to HLA class I-restricted T cells to modulate the degree of viral adaptation within individuals, in turn contributing to disease variability at the population level. Analyses of other populations and experimental studies, ideally with locally derived ERAP genotyping and HLA-specific viral adaptations are needed to elucidate this further.

Standard single-cell RNA-sequencing alignment pipelines exhibit a propensity for misassigning killer immunoglobulin-like receptor (KIR) transcripts, thereby giving rise to inaccuracies in quantifying KIR expression. Alves et al. elucidated that these default workflows frequently misclassify activating KIR transcripts as inhibitory KIR expression, resulting in a skewed representation of the KIR repertoire.

Cellular plasticity in cancer enables adaptation to selective pressures and stress imposed by the tumor microenvironment. This plasticity facilitates the remodeling of cancer cell phenotype and function (such as tumor stemness, metastasis, chemo/radio resistance), and the reprogramming of the surrounding tumor microenvironment to enable immune evasion. Epithelial plasticity is one form of cellular plasticity, which is intrinsically linked with epithelial–mesenchymal transition (EMT). Traditionally, EMT has been regarded as a binary state. Yet, increasing evidence suggests that EMT involves a spectrum of quasi-epithelial and quasi-mesenchymal phenotypes governed by complex interactions between cellular metabolism, transcriptome regulation, and epigenetic mechanisms. Herein, we review the complex cross-talk between the different layers of epithelial plasticity in cancer, encompassing the core layer of transcription factors, their interacting epigenetic modifiers and non-coding RNAs, and the manipulation of cancer immunogenicity in transitioning between epithelial and mesenchymal states. In examining these factors, we provide insights into promising therapeutic avenues and potential anti-cancer targets.

Introduction:A vaccine against influenza is available seasonally but is not 100% effective. A predictor of successful seroconversion in adults is an increase in activated circulating T follicular helper (cTfh) cells after vaccination. However, the impact of repeated annual vaccinations on long-term protection and seasonal vaccine efficacy remains unclear.Methods:In this study, we examined the T cell receptor (TCR) repertoire and transcriptional profile of vaccine-induced expanded cTfh cells in individuals who received sequential seasonal influenza vaccines. We measured the magnitude of cTfh and plasmablast cell activation from day 0 (d0) to d7 post-vaccination as an indicator of a vaccine response. To assess TCR diversity and T cell expansion we sorted activated and resting cTfh cells at d0 and d7 post-vaccination and performed TCR sequencing. We also single cell sorted activated and resting cTfh cells for TCR analysis and transcriptome sequencing.Results and discussion:The percent of activated cTfh cells significantly increased from d0 to d7 in each of the 2016-17 (p < 0.0001) and 2017-18 (p = 0.015) vaccine seasons with the magnitude of cTfh activation increase positively correlated with the frequency of circulating plasmablast cells in the 2016-17 (p = 0.0001) and 2017-18 (p = 0.003) seasons. At d7 post-vaccination, higher magnitudes of cTfh activation were associated with increased clonality of cTfh TCR repertoire. The TCRs from vaccine-expanded clonotypes were identified and tracked longitudinally with several TCRs found to be present in both years. The transcriptomic profile of these expanded cTfh cells at the single cell level demonstrated overrepresentation of transcripts of genes involved in the type-I interferon pathway, pathways involved in gene expression, and antigen presentation and recognition. These results identify the expansion and transcriptomic profile of vaccine-induced cTfh cells important for B cell help.

Adaptation to human leukocyte antigen (HLA)-associated immune pressure represents a major driver of human immunodeficiency virus (HIV) evolution at both the individual and population level. To date, there has been limited exploration of the impact of the initial cellular immune response in driving viral adaptation, the dynamics of these changes during infection and their effect on circulating transmitting viruses at the population level. Capturing detailed virological and immunological data from acute and early HIV infection is challenging as this commonly precedes the diagnosis of HIV infection, potentially by many years. In addition, rapid initiation of antiretroviral treatment following a diagnosis is the standard of care, and central to global efforts towards HIV elimination. Yet, acute untreated infection is the critical period in which the diversity of proviral reservoirs is first established within individuals, and associated with greater risk of onward transmissions in a population. Characterizing the viral adaptations evident in the earliest phases of infection, coinciding with the initial cellular immune responses is therefore relevant to understanding which changes are of greatest impact to HIV evolution at the population level. In this study, we utilized three separate cohorts to examine the initial CD8+ T cell immune response to HIV (cross-sectional acute infection cohort), track HIV evolution in response to CD8+ T cell-mediated immunity over time (longitudinal chronic infection cohort) and translate the impact of HLA-driven HIV evolution to the population level (cross-sectional HIV sequence data spanning 30 years). Using next generation viral sequencing and enzyme-linked immunospot interferon-gamma recall responses to peptides representing HLA class I-specific HIV T cell targets, we observed that CD8+ T cell responses can select viral adaptations prior to full antibody seroconversion. Using the longitudinal cohort, we uncover that viral adaptations have the propensity to be retained over time in a non-selective immune environment, which reflects the increasing proportion of pre-adapted HIV strains within the Western Australian population over an approximate 30-year period.

Background: Genetic variations across the SARS-CoV-2 genome may influence transmissibility of the virus and the host’s anti-viral immune response, in turn affecting the frequency of variants over time. In this study, we examined the adjacent amino acid polymorphisms in the nucleocapsid (R203K/G204R) of SARS-CoV-2 that arose on the background of the spike D614G change and describe how strains harboring these changes became dominant circulating strains globally. Methods: Deep-sequencing data of SARS-CoV-2 from public databases and from clinical samples were analyzed to identify and map genetic variants and sub-genomic RNA transcripts across the genome. Results: Sequence analysis suggests that the 3 adjacent nucleotide changes that result in the K203/R204 variant have arisen by homologous recombination from the core sequence of the leader transcription-regulating sequence (TRS) rather than by stepwise mutation. The resulting sequence changes generate a novel sub-genomic RNA transcript for the C-terminal dimerization domain of nucleocapsid. Deep-sequencing data from 981 clinical samples confirmed the presence of the novel TRS-CS-dimerization domain RNA in individuals with the K203/R204 variant. Quantification of sub-genomic RNA indicates that viruses with the K203/R204 variant may also have increased expression of sub-genomic RNA from other open reading frames. Conclusions: The finding that homologous recombination from the TRS may have occurred since the introduction of SARS-CoV-2 in humans, resulting in both coding changes and novel sub-genomic RNA transcripts, suggests this as a mechanism for diversification and adaptation within its new host.

Loss of T cell immunogenicity due to mutations in virally encoded epitopes is a well-described adaptation strategy to limit host anti-viral immunity. Another described, but less understood, adaptation strategy involves the selection of mutations within epitopes that retain immune recognition, suggesting a benefit for the virus despite continued immune pressure (termed non-classical adaptation). To understand this adaptation strategy, we utilized a single cell transcriptomic approach to identify features of the HIV-specific CD8 + T cell responses targeting non-adapted (NAE) and adapted (AE) forms of epitopes containing a non-classical adaptation. T cell receptor (TCR) repertoire and transcriptome were obtained from antigen-specific CD8 + T cells of chronic (n=7) and acute (n=4) HIV-infected subjects identified by either HLA class I tetramers or upregulation of activation markers following peptide stimulation. CD8 + T cells were predominantly dual tetramer + , confirming a large proportion of cross-reactive TCR clonotypes capable of recognizing the NAE and AE form. However, single-reactive CD8 + T cells were identified in acute HIV-infected subjects only, providing the potential for the selection of T cell clones over time. The transcriptomic profile of CD8 + T cells was dependent on the autologous virus: subjects whose virus encoded the NAE form of the epitope (and who transitioned to the AE form at a later timepoint) exhibited an ‘effective’ immune response, as indicated by expression of transcripts associated with polyfunctionality, cytotoxicity and apoptosis (largely driven by the genes GZMB, IFNɣ, CCL3, CCL4 and CCL5). These data suggest that viral adaptation at a single amino acid residue can provide an alternative strategy for viral survival by modulating the transcriptome of CD8 + T cells and potentially selecting for less effective T cell clones from the acute to chronic phase.

The activating immune receptor natural killer group member D (NKG2D) and its cognate ligands represent a fundamental surveillance system of cellular distress, damage or transformation. Signaling through the NKG2D receptor-ligand axis is critical for early detection of viral infection or oncogenic transformation and the presence of functional NKG2D ligands (NKG2D-L) is associated with tumor rejection and viral clearance. Many viruses and tumors have developed mechanisms to evade NKG2D recognition via transcriptional, post-transcriptional or post-translational interference with NKG2D-L, supporting the concept that circumventing immune evasion of the NKG2D receptor-ligand axis may be an attractive therapeutic avenue for antiviral therapy or cancer immunotherapy. To date, the complexity of the NKG2D receptor-ligand axis and the lack of specificity of current NKG2D-targeting therapies has not allowed for the precise manipulation required to optimally harness NKG2D-mediated immunity. However, with the discovery of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins, novel opportunities have arisen in the realm of locus-specific gene editing and regulation. Here, we give a brief overview of the NKG2D receptor-ligand axis in humans and discuss the levels at which NKG2D-L are regulated and dysregulated during viral infection and oncogenesis. Moreover, we explore the potential for CRISPR-based technologies to provide novel therapeutic avenues to improve and maximize NKG2D-mediated immunity.

Precise clustered regularly interspaced short palindromic repeats (CRISPR)-mediated genetic and epigenetic manipulation of the immune response has become a promising immunotherapeutic approach toward combating tumorigenesis and tumor progression. CRISPR-based immunologic reprograming in cancer therapy comprises the locus-specific enhancement of host immunity, the improvement of tumor immunogenicity, and the suppression of tumor immunoevasion. To date, the ex vivo re-engineering of immune cells directed to inhibit the expression of immune checkpoints or to express synthetic immune receptors (chimeric antigen receptor therapy) has shown success in some settings, such as in the treatment of melanoma, lymphoma, liver, and lung cancer. However, advancements in nuclease-deactivated CRISPR-associated nuclease-9 (dCas9)-mediated transcriptional activation or repression and Cas13-directed gene suppression present novel avenues for the development of tumor immunotherapies. In this review, the basis for development, mechanism of action, and outcomes from recently published Cas9-based clinical trial (genetic editing) and dCas9/Cas13-based pre-clinical (epigenetic editing) data are discussed. Lastly, we review cancer immunotherapyspecific considerations and barriers surrounding use of these approaches in the clinic.

The COVID-19 pandemic is caused by the single-stranded RNA virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a virus of zoonotic origin that was first detected in Wuhan, China in December 2019. There is evidence that homologous recombination contributed to this cross-species transmission. Since that time the virus has demonstrated a high propensity for human-to-human transmission. Here we report two newly identified adjacent amino acid polymorphisms in the nucleocapsid at positions 203 and 204 (R203K/G204R) due to three adjacent nucleotide changes across the two codons (i.e. AGG GGA to AAA CGA). This new strain within the LGG clade may have arisen by a form of homologous recombination from the core sequence (CS-B) of the transcription-regulating sequences of SAS-CoV-2 itself and has rapidly increased to approximately one third of reported sequences from Europe during the month of March 2020. We note that these polymorphisms are predicted to reduce the binding of an overlying putative HLA-C*07-restricted epitope and that HLA-C*07 is prevalent in Caucasians being carried by >40% of the population. The findings suggest that homologous recombination may have occurred since its introduction into humans and be a mechanism for increased viral fitness and adaptation of SARS-CoV-2 to human populations.

Human immunodeficiency virus (HIV) can adapt to an individual's T cell immune response via genomic mutations that affect antigen recognition and impact disease outcome. These viral adaptations are specific to the host's human leucocyte antigen (HLA) alleles, as these molecules determine which peptides are presented to T cells. As HLA molecules are highly polymorphic at the population level, horizontal transmission events are most commonly between HLA-mismatched donor/recipient pairs, representing new immune selection environments for the transmitted virus. In this study, we utilised a deep sequencing approach to determine the HIV quasispecies in 26 mother-to-child transmission pairs where the potential for founder viruses to be pre-adapted is high due to the pairs being haplo-identical at HLA loci. This scenario allowed the assessment of specific HIV adaptations following transmission in either a non-selective immune environment, due to recipient HLA mismatched to original selecting HLA, or a selective immune environment, mediated by matched donor/recipient HLA. We show that the pattern of reversion or fixation of HIV adaptations following transmission provides insight into the replicative cost, and likely compensatory networks, associated with specific adaptations in vivo. Furthermore, although transmitted viruses were commonly heavily pre-adapted to the child's HLA genotype, we found evidence of de novo post-transmission adaptation, representing new epitopes targeted by the child's T cell response. High-resolution analysis of HIV adaptation is relevant when considering vaccine and cure strategies for individuals exposed to adapted viruses via transmission or reactivated from reservoirs.