Herpes simplex virus type 2 (HSV-2) is the primary causative agent of genital herpes and represents a substantial global health concern. Although laboratory-adapted HSV-2 strains have been widely studied, the natural virological and pathogenic features of clinical isolates remain less well understood. In this study, we characterized HSV-2/KM-1, a low-passage clinical isolate (passage 6) from China, using both guinea pig and mouse models. Intravaginal inoculation resulted in acute genital lesions, viral shedding (which peaked between 2 and 5 days post-infection (DPI), and systemic symptoms. Viral DNA was detected predominantly in the sacral dorsal root ganglia (DRG), vagina, and bladder. Guinea pigs displayed Th2-biased immune responses, marked by elevated interleukin-4 (IL-4) and interleukin-10 (IL-10), while mice mounted combined Th1 [iInterferon-gamma (IFN-γ), interleukin-2 (IL-2)] and Th2 (IL-4, IL-10) responses. Histopathological examination revealed acute inflammation in genital and bladder tissues but no neural damage in the examined neural tissues (DRG), suggesting initial viral invasion and replication prior to the establishment of full latency. Overall, the clinical relevance of HSV-2/KM-1 and its applicability in both animal models, with a 50% lethal dose (LD50) of 4.1 × 104 plaque-forming units (PFU) in guinea pigs and 4.7 × 102 PFU in mice, establish its value for pathogenesis research and therapeutic evaluation.

Introduction Global human papillomavirus (HPV) prevalence among women rose significantly from 14% (2019) to 24% (2024), underscoring the need to understand transmission dynamics and public health impact. Although multi-genotype infections are increasingly documented, evidence remains limited on their combined effect on cervical lesion severity and transmission, especially in regional populations. Using clinical datasets from Xiamen, China, this study evaluates co-infection patterns through integrated statistical and dynamical models to quantify associations with histological severity and transmissibility. Methods Data were sourced from positive HPV nucleic acid tests at two hospitals in Xiamen. Genotyping employed multiplex PCR-based flow fluorescence hybridisation. Cumulative link models (CLMs) were used to assess associations between multi-genotype infections and cervical lesion severity. Concurrently, an ordinary differential equation transmission model was developed to estimate reproduction numbers, comparing transmission potential across infection types. Results Of 1 33 438 samples, 15 939 (11.9%) were HPV-positive, covering 27 genotypes. HPV 16, 52 and 58 were the most prevalent high-risk types. Co-infections involving these genotypes showed strong inter-hospital correlation in pairing patterns (Pearson’s r =0.851). Co-infection severity association was context-specific: the number of genotypes predicted severity in the screening population (eg, quadruple infections OR=1.47, 95% CI 1.23 to 1.71, p<0.01) but not in the referral population. Conversely, co-infections exhibited consistently higher relative transmissibility indices in both settings (eg, high-low-risk co-infection median model-derived R 0 : 2.57–6.82). Conclusions HPV co-infection impacts are modulated by patient population: relative transmission potential is broadly elevated, whereas histological severity effects are marked in screening cohorts but minimal in referral groups. Context-aware public health strategies—adapting co-infection screening and interventions to clinical setting—are urged for more effective and efficient disease control.

Herpes simplex virus type 2 (HSV-2), a highly prevalent pathogen responsible for genital herpes, is characterized by neurotropism and the ability to establish lifelong latent infection. N6-methyladenosine (m6A) is a widespread epitranscriptomic modification that plays a critical role in regulating RNA metabolism and gene expression. In this study, we used methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) to profile m6A modifications and transcriptomic changes in human foreskin fibroblasts (HFF-1) infected with HSV-2. We identified 9477 common m6A peaks and 15,842 differentially methylated peaks, with a predominant localization within coding sequences. Analysis of m6A modification sites on HSV-2 gene transcripts from MeRIP-seq data identified a total of 145 m6A sites across 63 viral genes. Functional enrichment analysis revealed that differentially m6A-modified genes are involved in key biological processes, including gene expression, neural signaling, and immune responses. Pathway analysis highlighted significant enrichment in the NOD-like receptor signaling pathway, Rap1 signaling, endocytosis, and adherens junction pathways. RNA-seq analysis identified 6172 differentially expressed genes, of which 3181 were upregulated and 2991 were downregulated. Integrative analysis of the two datasets revealed that genes exhibiting both altered m6A methylation and differential expression were significantly enriched in pathways including TNF signaling and the NOD-like receptor pathway. This study provides the first comprehensive landscape of m6A epitranscriptomic modifications and their association with transcriptomic reprogramming during HSV-2 infection, offering new insights into the epigenetic mechanisms of virus-host interactions.

The persistent global burden of herpes simplex virus type 2 (HSV-2) requires region-specific therapeutic strategies, yet the limited number of characterized clinical isolates from China has hindered accurate evaluation of local viral evolution and vaccine efficacy. To address this gap, we isolated and comprehensively characterized HSV-2/KM-1, a novel clinical strain obtained from a genital herpes patient in Kunming, China. Whole-genome sequencing showed 99.92% nucleotide identity with contemporary U.S. strains (MH790606, PP099973), which was markedly higher than its homology to China's reference strain HJ12 (128 amino acid differences). This unexpected phylogeographic similarity challenges existing models of geographically restricted HSV-2 evolution and suggests global viral gene flow facilitated by human mobility. Cell tropism analyses revealed accelerated replication in human foreskin fibroblasts (HFF-1), with early viral protein expression at 12 hpi, and high-titer production (7.0 log10 TCID50/mL) in Vero cells at a low MOI (0.001). Comparative genomics identified 27 amino acid substitutions in virulence determinants (ICP4, UL52, UL36, etc.) compared with the U.S strain (PP099973), 14 of which altered residue polarity, potentially influencing viral-host interactions, as suggested by previous studies on these proteins' roles. As a phylogenetically U.S.-linked clinical isolate from China, HSV-2/KM-1 helps to fill a gap in regional pathogen resources and provides a critical tool for assessing globally circulating strains and developing targeted interventions.

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) exhibit distinct clinical manifestations, yet the molecular basis of their serotype-specific pathogenicity remains unclear. This study presents a comparative proteomic analysis of human foreskin fibroblast (HFF-1) cells during lytic HSV-1 and HSV-2 infections to elucidate host–pathogen interactions driving differential virulence. Using data-independent acquisition mass spectrometry (DIA-MS), we identified 280 and 219 differentially expressed proteins (DEPs) in HSV-1- and HSV-2-infected cells, respectively. Key DEPs revealed serotype-specific modulation: HSV-1 upregulated antiviral effectors (ISG20, IRF7) while downregulating chemokine signaling (CXCL12, DEF8) and promoting lipid metabolism (PTDSS1). In contrast, HSV-2 upregulated inflammatory effectors (IGHV3-9, SERPINA1), enhanced NF-κB signaling (BCL3), and altered glycometabolism (GYS1, FBN1). Pathway enrichment analysis showed that HSV-1 suppressed inflammatory and antigen presentation pathways to evade immune responses, whereas HSV-2 induced stronger pro-inflammatory responses and metabolic reprogramming related to lipid and glycometabolism. Overall, these findings provide a proteomic roadmap for understanding serotype-specific pathogenesis.

Suraxavir marboxil (GP681) is a prodrug of a novel polymerase acidic protein inhibitor, and its metabolite GP1707D07 prevents the replication of influenza virus by selectively inhibiting the cap-dependent nucleic acid endonuclease of influenza virus. This study evaluates the safety, tolerability, and pharmacokinetics of suraxavir marboxil after a single dose and assesses the effect of a high-fat, high-calorie meal on the pharmacokinetics of suraxavir marboxil in healthy Chinese subjects. The study included two parts: single ascending-dose study (SAD) and food effect study (FE). In SAD, subjects were randomized to single-dose suraxavir marboxil (20, 40, 60, or 80 mg) or placebo. In FE, subjects (n = 16) were randomized to single-dose suraxavir marboxil 40 mg in fasting and fed states. Safety assessment and sample collection were in accordance with the protocol. Suraxavir marboxil was well tolerated in healthy Chinese subjects in both SAD and FE, and all adverse events recovered without treatment after discontinuation of suraxavir marboxil. In SAD, after administration of suraxavir marboxil in the dosage range of 20-80 mg, the time to maintain the clinically defined effective target blood concentration is about 72-136 h. In FE, a high-fat, high-calorie meal reduced Cmax by approximately 19% and AUC0-∞ by approximately 15%. Suraxavir marboxil was well tolerated in healthy Chinese subjects. Based on the safety and pharmacokinetic data, 20-80 mg single oral dosing was supported for further clinical development. Food intake may slightly reduce the rate and extent of absorption of suraxavir marboxil.The study was registered on https://classic.clinicaltrials.gov/ (registration no.: NCT04729764).

Chikungunya virus (CHIKV) infection causes joint damage and gastrointestinal clinical symptoms, including vomiting and diarrhea, particularly in elderly populations, reflecting the potential role of gut immunity in infection. However, the mechanisms by which CHIKV induces gastrointestinal diseases remain largely unexplored. This study investigated the characteristics of fecal and gut microbiota, gut metabolites, and gut immunity post-infection using multi-omics analysis. The role of gut microbiota was further validated through Oral antibiotic depletion (Abx). Importantly, a systematic comparison of age-dependent differences in gut microbiota composition and immune responses following CHIKV infection was conducted to elucidate the involvement of gut microbiota in CHIKV pathogenesis. CHIKV joint inoculation induces gastrointestinal infection and histological damage, drives fluctuations in gut microbiota, markedly increasing the abundance of Bacteroides fragilis and Prevotella sp. and upregulates conjugates of taurine and bile acids. CHIKV infection further exacerbates systemic inflammatory burden and activates intestinal interferon (IFN) signaling cascades, which supports gut repair and mucosal regeneration, but low antiviral responses to CHIKV infection compared with that of adult animals. Our results suggest that the gastrointestinal tract, along with its microbes and metabolites, modulates CHIKV infection in an age-dependent manner, providing critical insights for diagnosis, treatment, and novel therapeutic development.

Many studies have demonstrated the association between intestinal microbiota and joint diseases. The “gut-joint axis” also has potential roles in chikungunya virus (CHIKV) infection. Pro-inflammatory arthritis after CHIKV infection might disrupt host homeostasis and lead to dysbacteriosis. This study investigated the characteristics of fecal and gut microbiota, intestinal metabolites, and the changes in gene regulation of intestinal tissues after CHIKV infection using multi-omics analysis to explore the involvement of gut microbiota in the pathogenesis of CHIKV infection. CHIKV infection increases the systemic burden of inflammation in the GI system of infected animals. Moreover, infection-induced alterations in GI microbiota and metabolites may be indirectly involved in the modulation of GI and bone inflammation after CHIKV infection, including the modulation of inflammasomes and interleukin-17 inflammatory cytokine levels. Our results suggest that the GI tract and its microbes are involved in the modulation of CHIKV infection, which could serve as an indicator for the adjuvant treatment of CHIKV infection.

Chikungunya virus (CHIKV) is a neglected arthropod-borne and anthropogenic alphavirus. Over the past two decades, the CHIKV distribution has undergone significant changes worldwide, from the original tropics and subtropics regions to temperate regions, which has attracted global attention. However, the interactions between CHIKV and its host remain insufficiently understood, which dampens the need for the development of an anti-CHIKV strategy. In this study, on the basis of the optimal overexpression of non-structural protein 4 (nsP4), we explore host interactions of CHIKV nsP4 using mass spectrometry-based protein-protein interaction approaches. The results reveal that some cellular proteins that interact with nsP4 are enriched in the ubiquitin-proteasome pathway. Specifically, the scaffold protein receptor for activated C kinase 1 (RACK1) is identified as a novel host interactor and regulator of CHIKV nsP4. The inhibition of the interaction between RACK1 and nsP4 by harringtonolide results in the reduction of nsP4, which is caused by the promotion of degradation but not the inhibition of nsP4 translation. Furthermore, the decrease in nsP4 triggered by the RACK1 inhibitor can be reversed by the proteasome inhibitor MG132, suggesting that RACK1 can protect nsP4 from degradation through the ubiquitin-proteasome pathway. This study reveals a novel mechanism by which the host factor RACK1 regulates CHIKV nsP4, which could be a potential target for developing drugs against CHIKV.

Variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to emerge and evade immunity, resulting in breakthrough infections in vaccinated populations. There is an urgent need for the development of vaccines with broad protective effects. In this study, we selected hotspot mutations in the receptor-binding domain (RBD) that contribute to immune escape properties and integrated them into the original RBD protein to obtain a complex RBD protein (cRBD), and we found cRBDs have broad protective effects against SARS-CoV-2 variants. Three cRBDs were designed in our study. Compared with the BA.1 RBD protein, the cRBDs induced the production of higher levels of broader-spectrum neutralizing antibodies, suggesting stronger and broader protective efficacy. In viral challenge experiments, cRBDs were more effective than BA.1 RBD in attenuating lung pathologic injury. Among the three constructs, cRBD3 showed optimal broad-spectrum and protective effects and is a promising candidate for a broad-spectrum SARS-CoV-2 vaccine. In conclusion, immunization with cRBDs triggered immunity against a wide range of variants, including those that emerged after we had completed designing the cRBDs. This study preliminarily explores and validates the feasibility of incorporating hotspot mutations that contribute to immune evasion into the RBD to expand the activity spectrum of antigen-induced antibodies.

Background The World Health Organization noted a significant rise in global human papillomavirus (HPV) prevalence among women, from 14\% (2019) to 24\% (2024), highlighting the need to understand the transmission dynamics and public health impact. Existing research focuses on single genotype infections and statistical methods, overlooking the effects of co-infection and multi-genotype interactions. Methods Data from HPV nucleic acid tests at two Xiamen hospitals were analyzed using cumulative link models to study symptom severity related to multi-genotype infections. An ordinary differential equation model estimated the reproduction numbers for different infection types. Results Increased risk of HPV-related diseases correlates with age (odds ratio, OR for ages 41–60: 37.07; over 60: 115.7). Multi-genotype infections correlate with greater disease severity (OR for two genotypes: 1.11; three genotypes: 1.21). Co-infections, especially involving high-risk genotypes, show higher transmissibility (median R0 for two high-risk genotypes: 6.82). Conclusions The findings urge a revision of HPV prevention strategies, focusing on the varying risks across age groups and the enhanced severity and transmissibility of multi-genotype infections. Enhanced surveillance and revised vaccination programs may be crucial to address these challenges.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been detected in almost all organs of coronavirus disease-19 patients, although some organs do not express angiotensin-converting enzyme-2 (ACE2), a known receptor of SARS-CoV-2, implying the presence of alternative receptors and/or co-receptors. Here, we show that the ubiquitously distributed human transferrin receptor (TfR), which binds to diferric transferrin to traffic between membrane and endosome for the iron delivery cycle, can ACE2-independently mediate SARS-CoV-2 infection. Human, not mouse TfR, interacts with Spike protein with a high affinity (KD ~2.95 nM) to mediate SARS-CoV-2 endocytosis. TfR knock-down (TfR-deficiency is lethal) and overexpression inhibit and promote SARS-CoV-2 infection, respectively. Humanized TfR expression enables SARS-CoV-2 infection in baby hamster kidney cells and C57 mice, which are known to be insusceptible to the virus infection. Soluble TfR, Tf, designed peptides blocking TfR-Spike interaction and anti-TfR antibody show significant anti-COVID-19 effects in cell and monkey models. Collectively, this report indicates that TfR is a receptor/co-receptor of SARS-CoV-2 mediating SARS-CoV-2 entry and infectivity by likely using the TfR trafficking pathway.

Gastrointestinal (GI) infection is evidenced with involvement in COVID-19 pathogenesis caused by SARS-CoV-2. However, the correlation between GI microbiota and the distinct pathogenicity of SARS-CoV-2 Proto and its emerging variants remains unclear. In this study, we aimed to determine if GI microbiota impacted COVID-19 pathogenesis and if the effect varied between SARS-CoV-2 Proto and its variants. We performed an integrative analysis of histopathology, microbiomics, and transcriptomics on the GI tract fragments from rhesus monkeys infected with SARS-CoV-2 proto or its variants. Based on the degree of pathological damage and microbiota profile in the GI tract, five of SARS-CoV-2 strains were classified into two distinct clusters, namely, the clusters of Alpha, Beta and Delta (ABD), and Proto and Omicron (PO). Notably, the abundance of potentially pathogenic microorganisms increased in ABD but not in the PO-infected rhesus monkeys. Specifically, the high abundance of UCG-002, UCG-005, and Treponema in ABD virus-infected animals positively correlated with interleukin, integrins, and antiviral genes. Overall, this study revealed that infection-induced alteration of GI microbiota and metabolites could increase the systemic burdens of inflammation or pathological injury in infected animals, especially in those infected with ABD viruses. Distinct GI microbiota and metabolite profiles may be responsible for the differential pathological phenotypes of PO and ABD virus-infected animals. These findings improve our understanding the roles of the GI microbiota in SARS-CoV-2 infection and provide important information for the precise prevention, control, and treatment of COVID-19.

Background: There are many types of human papillomavirus (HPV), and the related diseases have caused a serious disease burden in the world. Our research aims to explore the epidemiological characteristics of HPV and the transmissibility of different genotypes.Methods: Collect HPV testing data from Xiamen Maternal and Child Health Hospital and determine the research scope. The transmission dynamics model of HPV was established to simulate the transmission of different genotypes of HPV, and the transmissibility of different genotypes of HPV was estimated by comparing the effective reproduction number (Reff).Results: The collected HPV subjects are mainly concentrated in Xiamen, Zhangzhou and Quanzhou, and there are differences in the distribution of HPV infection among different age groups. The overall fitting effect of the model is good, and the interval range of R2 is (0.138,0.530), both of which are statistically significant. Among all HPV genotypes, 13 have Reff values exceeding 1, among which 10 are high-risk types; The top five genotypes are HPV56, 18, 58, 52 and 53, among which the top four genotypes are high-risk and HPV53 is non-high-risk, with values of 3.34 (range: 0.00-29.09), 3.20 (range: 0.00-8.70), 3.19 (range: 0.00-15.58), 3.19 (range: 0.00-12.73) and 2.99 (range: 0.00-19.50). Among genotypes with Reff value over 1, HPV52 has the longest duration (about 51 months).Conclusion: Most high-risk HPV types in the hokkien golden triangle have certain transmission risks, including non-vaccine types. The region needs further optimization in the development of HPV vaccine and the design of detection methods.Funding Information: This study was partly supported by the Bill & Melinda Gates Foundation (INV-005834) and the XMU 296 Training Program of Innovation and Enterpreneurship for Undergraduates (2021X0938).Declaration of Interests: The authors declare no conflict of interest.Ethics Approval Statement: The study was approved by the Ethics 114 Committee of Xiamen Maternal and Child Health Hospital.

Objective To obtain the non-structure protein 14 (Nsp14) of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) with higher purity and enzymatic activity. Methods This study firstly analyzed the rare codons in the gene of nsp14 according to the codon usage bias of E. coli, followed by codon optimization. The optimized nucleotide fragment of nsp14 was cloned into four kinds of expressing vectors respectively. Comparative analysis of yield and solubility was performed among these expressed four fusion proteins. The best one was chosen for further optimization of expressing conditions. After the fusion protein was purified by glutathione affinity column, the fusion tag was removed by 3C protease, and then the protein was purified by glutathione affinity column and molecular sieve column for further analysis of enzymatic activity through urea polyacrylamide gel electrophoresis. Results Many rare codons were found in expression of SARS-CoV-2 nsp14 in E. coli, among which some rare codons were distributed in close range and tandem. The best recombinant plasmid for expressing the fusion protein was pGEX6P1-GST-OPTI-Nsp14, which gave an eptimal expression in 30 ℃ with high yield and solubility. After purification, a higher purity of Nsp14 with nuclease activity was obtained. Conclusions This study shows that the SARS-CoV-2 Nsp14 protein with nuclease activity is successfully prepared, which lays a foundation for the further research on the structure and function of SARS-CoV-2 Nsp14, and provides favorable conditions for screening antiviral drugs targeting at Nsp14 of SARS-CoV-2.

Relapsing fever due to Borrelia hermsii is characterized by recurrent bacteremia episodes. However, infection of B. hermsii, if not treated early, can spread to various organs including the central nervous system (CNS). CNS disease manifestations are commonly referred to as relapsing fever neuroborreliosis (RFNB). In the mouse model of B. hermsii infection, we have previously shown that the development of RFNB requires innate immune cells as well as T cells. Here, we found that prior to the onset of RFNB, an increase in the systemic proinflammatory cytokine response followed by sustained levels of IP-10 concurrent with the CNS disease phase. RNA sequencing analysis of the spinal cord tissue during the disease phase revealed an association of the interleukin (IL)-17 signaling pathway in RFNB. To test a possible role for IL-17 in RFNB, we compared B. hermsii infection in wild-type and IL-17A-/- mice. Although the onset of bacteremia and protective anti-B. hermsii antibody responses occurred similarly, the blood-brain barrier permeability, proinflammatory cytokine levels, immune cell infiltration in the spinal cord, and RFNB manifestations were significantly diminished in IL-17A-/- mice compared to wild-type mice. Treatment of B. hermsii-infected wild-type mice with anti-IL-17A antibody ameliorated the severity of spinal cord inflammation, microglial cell activation, and RFNB. These data suggest that the IL-17 signaling pathway plays a major role in the pathogenesis of RFNB, and IL-17A blockade may be a therapeutic modality for controlling neuroborreliosis.

Mathematical models have played an important role in the management of the coronavirus disease 2019 (COVID-19) pandemic. The aim of this review is to describe the use of COVID-19 mathematical models, their classification, and the advantages and disadvantages of different types of models. We conducted subject heading searches of PubMed and China National Knowledge Infrastructure with the terms "COVID-19," "Mathematical Statistical Model," "Model," "Modeling," "Agent-based Model," and "Ordinary Differential Equation Model" and classified and analyzed the scientific literature retrieved in the search. We categorized the models as data-driven or mechanism-driven. Data-driven models are mainly used for predicting epidemics, and have the advantage of rapid assessment of disease instances. However, their ability to determine transmission mechanisms is limited. Mechanism-driven models include ordinary differential equation (ODE) and agent-based models. ODE models are used to estimate transmissibility and evaluate impact of interventions. Although ODE models are good at determining pathogen transmission characteristics, they are less suitable for simulation of early epidemic stages and rely heavily on availability of first-hand field data. Agent-based models consider influences of individual differences, but they require large amounts of data and can take a long time to develop fully. Many COVID-19 mathematical modeling studies have been conducted, and these have been used for predicting trends, evaluating interventions, and calculating pathogen transmissibility. Successful infectious disease modeling requires comprehensive considerations of data, applications, and purposes.