Roxanne Pillay

Background and Aim: The immunological interactions between soil-transmitted helminths (STHs) and herpes simplex virus type 2 (HSV-2), particularly in the context of co-infection, are poorly understood. Next-generation sequencing (NGS) offers a powerful approach to explore these complex immune responses and uncover potential therapeutic targets. This study leveraged NGS and bioinformatic tools to investigate transcriptional changes and immunological pathways in female genital tract (FGT) tissues of BALB/c mice acutely infected with Nippostrongylus brasiliensis (Nb), HSV-2, or co-infected. Methods: Total RNA was harvested from FGT tissues of BALB/c mice infected with Nb, HSV-2, co-infected with both pathogens, and uninfected controls. Differentially expressed genes (DEGs) were identified by comparing uninfected versus infected FGT tissues in R using edgeR and limma packages. Immune-related genes were identified by intersecting DEGs in each group-wise comparison with immune function gene sets derived from the Mouse Genome Informatics (MGI) database. Functional and pathway enrichment analyses were performed with g: Profiler and protein–protein interaction networks were built using the STRING database and visualized with Cytoscape. Key hub genes and significant gene modules were identified using the Cytoscape plugins CytoHubba and MCODE, followed by further functional analysis of these modules. Results: NGS analysis revealed distinct gene expression profiles in response to single infection with Nb or HSV-2, with both showing significant differences when uninfected controls were compared to infected FGT tissues at a 5% false discovery rate. Notably, there were no significant differences in gene expression profiles between uninfected and co-infected FGT tissues. In the comparison of uninfected versus Nb-infected FGT tissues, 368 DEGs were identified, with 356 genes upregulated and 12 downregulated. Several immune-related genes, such as Ptprc, Ccl11, Ccr2, and Cx3cr1, were significantly altered. Pathway analysis of DEGs, hub genes, and significant modules indicated modulation of immune and defense responses. Notably, Nb infection induced a robust Th2-dominant immune response in the FGT, with downregulation of pro-inflammatory genes. This likely reflects helminth-driven modulation that may impair protective Th1 responses and highlights the systemic impact of Nb on the FGT immunity. In the comparison of uninfected versus HSV-2-infected FGT tissues, 140 DEGs were identified, with 121 upregulated and 19 downregulated. Immune-related genes, including Ldlr, Camk1d, Lrp8 and Epg5, were notably altered. HSV-2 infection led to early and predominant downregulation of immune genes, consistent with viral immune evasion strategies. In addition, functional analysis revealed enrichment in cell cycle and sterol biosynthesis pathways, suggesting that HSV-2 modulates host metabolism to support viral replication while influencing immune responses. In co-infection, no significant transcriptional changes were observed, potentially reflecting immune antagonism where Nb-induced Th2 responses may suppress HSV-2-driven Th1 immune responses. Conclusions: This preliminary study offers insights into the gene expression responses in the FGT to acute single and co-infection with Nb and HSV-2. Together, these findings reveal distinct transcriptomic changes in the FGT following Nb and HSV-2 infection, with co-infection potentially leading to immune antagonism and transcriptional equilibrium. This highlights the complex interplay between helminth- and virus-induced immune modulation in shaping FGT immunity. By leveraging NGS, this study highlights important immune-related pathways and serves as a foundation for further investigations into the mechanistic roles of DEGs in immunity to these pathogens, with potential implications for developing novel therapeutic strategies.

Soil-transmitted helminths (STHs) and Herpes Simplex Virus type 2 (HSV-2) are highly prevalent infections with overlapping distribution, particularly in resource-poor regions. STH/HSV-2 co-infections may impact female reproductive health. However, many aspects of STH/HSV-2 co-infections, including the role of microRNAs (miRNAs) in regulating female genital tract (FGT) immunity and their potential contribution to pathologies such as chronic inflammation, impaired mucosal defense, and reproductive tract cancers remain unclear. In this study we investigated the miRNA expression profiles in murine FGT tissues following single or co-infection with Nippostrongylus brasiliensis (Nb) and HSV-2 and explored predicted miRNA-mRNA targets and pathways. An analysis of miRNA sequencing data was conducted to determine differentially expressed (DE) miRNAs between infected FGT tissues and uninfected controls. Ingenuity Pathway Analysis was conducted to predict the immune-related target genes of the DE miRNAs and reveal enriched canonical pathways, top diseases, and biological functions. Selected representative DE miRNAs were validated using RT-qPCR. Our results showed a total of eight DE miRNAs (mmu-miR-218-5p, mmu-miR-449a-5p, mmu-miR-497a-3p, mmu-miR-144-3p, mmu-miR-33-5p, mmu-miR-451a, mmu-miR-194-5p, and mmu-miR-192-5p) in the comparison of Nb-infected versus uninfected controls; nine DE miRNAs (mmu-miR-451a, mmu-miR-449a-5p, mmu-miR-144-3p, mmu-miR-376a-3p, mmu-miR-192-5p, mmu-miR-218-5p, mmu-miR-205-3p, mmu-miR-103-3p, and mmu-miR-200b-3p) in the comparison of HSV-2-infected versus uninfected controls; and one DE miRNA (mmu-miR-199a-5p) in the comparison of Nb/HSV-2 co-infected versus uninfected controls (p-value < 0.05, |logFC| ≥ 1). Core expression analysis showed that, among other canonical pathways, the DE miRNAs and their predicted mRNA targets were involved in neutrophil degranulation, interleukin-4 and interleukin-13 signaling, natural killer cell signaling, interferon alpha/beta signaling, and ISGylation. Additionally, cancer was predicted as one of the significantly enriched diseases, particularly in the co-infected group. This is the first study to provide insights into the FGT miRNA profiles following Nb and HSV-2 single and co-infection, as well as the predicted genes and pathways they regulate, which may influence host immunity and pathology. This study highlights the role of miRNAs in regulating FGT immunity and pathology in the context of STH/HSV-2 co-infection.

Over the last two decades, the field of microRNA (miRNA) research has grown significantly. MiRNAs are a class of short, single-stranded, non-coding RNAs that regulate gene expression post-transcriptionally. Thereby, miRNAs regulate various essential biological processes including immunity. Dysregulated miRNAs are associated with various infectious and non-infectious diseases. Recently co-infection with soil-transmitted helminths (STHs) and herpes simplex virus type 2 (HSV-2) has become a focus of study. Both pathogens can profoundly influence host immunity, particularly in under-resourced and co-endemic regions. It is well known that STHs induce immunomodulatory responses that have bystander effects on unrelated conditions. Typically, STHs induce T-helper 2 (Th2) and immunomodulatory responses, which may dampen the proinflammatory T-helper 1 (Th1) immune responses triggered by HSV-2. However, the extent to which STH co-infection influences the host immune response to HSV-2 is not well understood. Moreover, little is known about how miRNAs shape the immune response to STH/HSV-2 co-infection. In this article, we explore the potential influence that STH co-infection may have on host immunity to HSV-2. Because STH and HSV-2 infections are widespread and disproportionately affect vulnerable and impoverished countries, it is important to consider how STHs may impact HSV-2 immunity. Specifically, we explore how miRNAs contribute to both helminth and HSV-2 infections and discuss how miRNAs may mediate STH/HSV-2 co-infections. Insight into miRNA-mediated immune responses may further improve our understanding of the potential impact of STH/HSV-2 co-infections.

Sub-Saharan Africa (SSA) bears a disproportionate and overlapping burden of soil-transmitted helminths (STHs) and sexually transmitted viral infections. An estimated 232 million pre-school and school-aged children in SSA are vulnerable to STH infections. Together with this, SSA has a high prevalence of herpes simplex virus type II (HSV-2), the primary cause of genital herpes. Studies have examined the immunological interactions between STHs and human immunodeficiency virus and human papillomavirus during co-infections. However, epidemiological and immunological studies on STH-HSV-2 co-infections are lacking, therefore their impact on sexual and reproductive health is not fully understood. STH-driven Th2 immune responses are known to downregulate Th1/Th17 immune responses. Therefore, during STH-HSV-2 co-infections, STH-driven immune responses may alter host immunity to HSV-2 and HSV-2 pathology. Herein, we provide an overview of the burden of STH and HSV-2 infections in SSA, and host immune responses to STH and HSV-2 infections. Further, we emphasize the relevance and urgent need for (i) focused research into the interactions between these important pathogens, and (ii) integrated approaches to improve the clinical detection and management of STH-HSV-2 co-infections in SSA.

Herpes simplex virus type 2 (HSV-2) and helminth infections are among the most widespread infectious diseases in sub-Saharan Africa (SSA). Helminths are known to modulate host immune responses and consequently impact the severity and outcomes of unrelated diseases, including allergies, autoimmune conditions, and infectious diseases. In this way, helminths may modulate essential immune responses against HSV-2 during co-infection and may alter susceptibility to and pathology of HSV-2. However, the epidemiology of STH/HSV-2 co-infections is understudied, and whether helminths influence the host immune response to HSV-2 is not well understood. In this perspective piece, we briefly examine the current knowledge on helminth immune modulation of important pathogens that are endemic to SSA, arguing that it is important to explore HSV-2 and helminth co-infections to elucidate potential interactions between HSV-2 and helminths. This is particularly relevant in SSA, where both pathogens are highly prevalent.

Introduction. Intestinal helminths and microbiota share the same anatomical niche during infection and are likely to interact either directly or indirectly. Whether intestinal helminths employ bactericidal strategies that influence their microbial environment is not completely understood. Hypothesis. In the present study, the hypothesis that the adult hookworm Nippostrongylus brasiliensis produces molecules that impair bacterial growth in vitro, is tested. Aim. To investigate the in vitro bactericidal activity of Nippostrongylus brasiliensis against commensal and pathogenic bacteria. Methodology. The bactericidal effect of somatic extract and excretory-secretory products of adult Nippostrongylus brasiliensis on Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli , Salmonella enterica serovar Typhimurium, and Klebsiella pneumoniae ) bacteria was assessed using growth assays. Minimum inhibitory concentration and minimum bactericidal concentration assays were performed using excretory-secretory products released from the pathogen. Results. Broad-spectrum in vitro bactericidal activity in excretory-secretory products, but not somatic extract of adult Nippostrongylus brasiliensis was detected. The bactericidal activity of excretory-secretory products was concentration-dependent, maintained after heat treatment, and preserved after repeated freezing and thawing. Conclusion. The results of this study demonstrate that helminths such as Nippostrongylus brasiliensis release molecules via their excretory-secretory pathway that have broad-spectrum bactericidal activity. The mechanisms responsible for this bactericidal activity remain to be determined and further studies aimed at isolating and identifying active bactericidal molecules are needed.

Sub-Saharan Africa is heavily burdened with human immunodeficiency virus (HIV) and helminth infections, which are potent activators of pro-inflammatory and anti-inflammatory immune responses, respectively. Considering that helminths (such as Necator americanus, Ancylostoma duodenale, Ascaris lumbricoides, Trichuris trichiura, Schistosoma haematobium, and Schistosoma mansoni) can potentially dampen the production and expression of vital anti-viral pro-inflammatory cytokines, leading to enhanced HIV replication and severity, well-designed intervention studies are needed which will offer conclusive data on the nature of these interactions and the impact of deworming in HIV-infected patients. Such research will impact governmental health policies and deworming programmes, allowing for the implementation of integrated systems that will contribute to the overall improvement of African health systems.

Helminth infections are among the neglected tropical diseases affecting billions of people globally, predominantly in developing countries. Helminths’ effects are augmented by coincident tuberculosis disease, which infects a third of the world’s population. The role of helminth infections on the pathogenesis and pathology of active tuberculosis (T.B.) remains controversial. Parasite-induced suppression of the efficacy of Bacille Calmette-Guerin (BCG) has been widely reported in helminth-endemic areas worldwide. T.B. immune response is predominantly proinflammatory T-helper type 1 (Th1)-dependent. On the other hand, helminth infections induce an opposing anti-inflammatory Th2 and Th3 immune-regulatory response. This review summarizes the literature focusing on host immune response profiles during single-helminth, T.B. and dual infections. It also aims to necessitate investigations into the complexity of immunity in helminth/T.B. coinfected patients since the research data are limited and contradictory. Helminths overlap geographically with T.B., particularly in Sub-Saharan Africa. Each disease elicits a response which may skew the immune responses. However, these effects are helminth species-dependent, where some parasites have no impact on the immune responses to concurrent T.B. The implications for the complex immunological interactions that occur during coinfection are highlighted to inform government treatment policies and encourage the development of high-efficacy T.B. vaccines in areas where helminths are prevalent.