Search Results (1,065)

Background/Objectives: Current prophylactic human papillomavirus (HPV) vaccines rely on major capsid proteins (L1). Although highly immunogenic, L1-based immunity is clade-restricted owing to the hypervariability of HPV strains across different geographic regions. This restricts cross-protection against diverse, localized, and non-vaccine viral strains circulating in specific areas, leaving these populations vulnerable to regional genotypes. Methods: We aimed to design a cross-protective vaccine tailored to local viral diversity through evolutionary and immunoinformatic analyses of circulating HPV strains in Thailand. Both major (L1) and minor (L2) capsid proteins were analyzed to evaluate selective evolutionary pressures, structural sequence conservation, and cross-strain promiscuity of predicted B- and T-cell epitopes using the IEDB database. The predicted immunogenic profile of the combined L1/L2 proteins was further assessed using in silico immune response simulations. Results: Evolutionary analysis confirmed that although the L1 protein is under strict purifying selection, it exhibits high regional interclade variability. L1-only epitopes demonstrated restricted cross-strain conservation, creating structural blind spots against divergent regional variants. The minor capsid protein (L2) harbored highly conserved dual-action core peptides that are evolutionarily conserved across multiple HPV type. Incorporation of conserved L2 regions alongside L1 sequences may broaden the predicted epitope coverage and help address limitations associated with L1 variability. The proposed multi-targeted L1/L2 construct therefore represents a computational framework for the development of candidate cross-reactive HPV vaccines relevant to circulating Thai genotypes. However, experimental validation remains necessary to determine immunogenicity, cross-neutralization potential, and protective efficacy. Conclusion: Our findings highlight these conserved HPV epitopes as potential targets for future development of next-generation cross-subtype prophylactic vaccines with broader population coverage. Full article

Norovirus is the leading cause of acute infectious gastroenteritis in the world and accounts for a significant proportion of outbreaks at the food-borne and person-to-person levels. Due to their low infectious dose, persistence in the environment, and broad genetic diversity, they can quickly spread and reappear in even the most diverse populations. This review integrates current knowledge on the epidemiology of noroviruses, genomic organization, structural biology, virus–host interactions, and replication mechanisms, with a focus on factors that determine virus evolution and strain dominance. Literature has been systematically searched in the PubMed and Scopus databases to incorporate recent experimental and epidemiological findings. Analysis of global surveillance data indicates ongoing genetic diversification of circulating strains, with periodic replacement of major variants, particularly the GII.4 lineage. Variability of the capsid and recognition of histo-blood Group Antigens strongly affects the host’s susceptibility, viral attachment and immune escape. The capsid consists of most of the viral protein complexes. The structural proteins VP1 and VP2 are responsible for determining the contours of the capsid and antigenic specificity. Non-structural proteins are responsible for coordinating the genome replication and the modification of host cell pathways to favor the production of the virus. Eliminating these gaps by means of integrated genomic surveillance and functional studies will provide insight into the evolution of norovirus and help to develop broadly effective vaccines and antiviral strategies. Full article

Macrosteles fascifrons, a representative aster leafhopper frequently detected in rice-growing environments, is an economically significant insect that inhabits rice fields and plays a role in the ecology of crop pests and disease transmission. To expand the understanding of viral diversity associated with the aster leafhopper, we analyzed its virome using deep transcriptome sequencing. In addition to several previously reported viruses, we identified two previously unreported RNA viruses, tentatively designated as Macrosteles fascifrons hepe-like virus 1 (MfHV1) and Macrosteles fascifrons rhabdovirus 1 (MfRV1). The complete genome sequences of both genomes were obtained using overlapping RT-PCR and rapid amplification of cDNA ends. Excluding the poly(A) tail, the genome of MfHV1 is 6688 nucleotides in length and exhibits a genomic organization characteristic of the family Hepeviridae, comprising three major open reading frames (ORFs) that encode a putative nonstructural polyprotein, a capsid protein, and a small accessory protein. The ORF encoding the capsid protein partially overlaps with the ORF encoding the small accessory protein, a genomic feature commonly observed in hepe-like viruses. The genome of MfRV1 is 14,984 nucleotides in length and displays the canonical genomic organization of the family Rhabdoviridae. An additional accessory ORF was identified between the putative M and G genes. Phylogenetic analysis based on polyprotein sequences placed MfHV1 within the Hepeviridae, most closely related to insect-associated hepe-like viruses, whereas MfRV1 clustered within the subfamily Deltarhabdovirinae. According to ICTV guidelines, virus classification is based on a combination of sequence divergence, phylogenetic relationships, and genome organization. MfHV1 and MfRV1 share low amino acid sequence identities with known viruses (maximum 36.07% for the MfHV1 polyprotein and 47.7% for the MfRV1 RNA-dependent RNA polymerase). Based on sequence divergence, genome organization, and phylogenetic placement, these viruses are classified as putative novel members of their respective families. This study expands the diversity of virus-associated sequences detected in M. fascifrons and provides additional genomic resources for understanding insect-associated RNA viruses. Full article

Background: Prophylactic human papillomavirus (HPV) vaccines are crucial for preventing HPV-related cancers. This study aimed to preclinically evaluate a novel recombinant 9-valent HPV vaccine produced in Escherichia coli (E. coli), which targets HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58, and is based on virus-like particles (VLPs) of the HPV major capsid protein L1. Methods: The molecular weight and purity of HPV L1 protein bands were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with Coomassie Brilliant Blue staining. The morphology and size distribution of VLPs were characterized using cryo-electron microscopy and DLS. The immunogenicity and durability of the recombinant 9-valent HPV vaccine were evaluated in BALB/c mice and Wistar rats. Mice received single or triple immunizations (2-week intervals) of two vaccine batches or Gardasil^®9 (MSD, USA) control at 1/20 human dose. Antibody responses were monitored via ELISA and pseudovirus neutralization assays over 24 weeks. Rats were administered single or triple immunizations (2-week intervals) of high- (1/10), medium- (1/20), or low-dose (1/40) vaccine or Gardasil^®9 control (1/20), with neutralizing antibodies tracked for 16 weeks. Results: Cryo-electron microscopy and DLS revealed that VLPs of each type appeared as uniformly distributed, spherical or ellipsoidal hollow intact particles with a diameter of approximately 45–65 nm. This vaccine demonstrated robust immunogenicity and long-lasting efficacy in BALB/c mice and Wistar rats, with effects comparable to those of the commercially available vaccine Gardasil^®9. Conclusions: The 9-valent HPV vaccine induces robust and persistent immune responses in mice and rats, strongly supporting further clinical trials. It is expected to be an alternative to marketed vaccines and ease the global supply shortage of 9-valent HPV vaccines. Full article

Background: Four genotypes of human bocaviruses (HBoVs) have been identified, with only HBoV1 being detected in respiratory specimens, and with HBoV2 being the predominant human bocavirus in fecal specimens, which implies different tissue tropisms for HBoV1 and HBoV2. It is vital to determine the factors that influence the tissue tropisms. Methods: The major capsid proteins VP3 of HBoV1 and HBoV2 were expressed in eukaryotic cells. Then co-immunoprecipitation (Co-IP) and liquid chromatography–tandem mass spectrometry (LC-MS/MS) (IP-MS) was employed, along with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, to screen host proteins interacting with VP3 of different genotypes. Subsequently, in vitro pull-down assays were conducted to verify the direct virus–host interaction proteins with VP3. Furthermore, molecular docking was performed to predict the interaction interfaces between viral and host proteins. Results: Through IP-MS and enrichment analyses, 50 host proteins that displayed ≥10-fold differential binding affinities between HBoV1 VP3 and HBoV2 VP3 were identified. Among these, seven were considered as high-confidence candidate interactors. Notably, SPLUNC1 and VAMP8 showed predominant expression in respiratory and intestinal tissues, respectively. Subsequent in vitro pull-down assays confirmed that SPLUNC1 specifically bound to HBoV1 VP3, whereas VAMP8 specifically interacted with HBoV2 VP3. Molecular docking analysis further revealed that the binding between SPLUNC1 with HBoV1 VP3, as well as VAMP8 with HBoV2 VP3, was stabilized by extensive hydrophobic interfaces along with specific hydrogen bonds. Conclusions: The specific interactions of host proteins SPLUNC1 with HBoV1 VP3 and VAMP8 with HBoV2 VP3, respectively, provided fundamental evidence that the distinct tissue tropisms of HBoVs may be governed by specific host factors. Full article

Bluetongue virus (BTV), the prototype of the genus Orbivirus, infects livestock, causing high morbidity and mortality and impacting global trade. BTV is a non-enveloped, double-capsid virus, composed of seven structural proteins and a genome of 10 double-stranded RNA segments. This manuscript highlights our group’s recent findings on the molecular and structural mechanisms underlying BTV entry and assembly during replication. Viral entry is a stepwise, pH-dependent process. The outermost protein, VP2, attaches to sialic acids and senses the acidic pH of early endosomes, triggering their dissociation. Subsequently, the second outer capsid protein, VP5, undergoes major changes in late endosomes, forming a membrane-penetrating pore that releases the transcriptionally active inner core into the host cytoplasm. Core assembly also proceeds stepwise and requires the accurate packaging of 10 positive-sense RNA segments. These segments form an RNA–RNA interaction network independent of viral proteins, beginning with the smaller segments and guiding the complete genome assortment. The small capsid protein, VP6, interacts with VP3 to facilitate RNA encapsidation. While infectious cores assemble in vitro without non-structural proteins, NS2 is essential for the in vivo formation of viral inclusion bodies via liquid–liquid phase separation, concentrating viral components and promoting genome assembly. These comprehensive characterizations of BTV provide a foundation for future control strategies against related reoviruses. Full article

Infection of the large yellow croaker (Larimichthys crocea) embryo cell line YCE1 with megalocytivirus strain FD201807 leads to accumulation of capsid-deficient viral intermediates within intracellular vesicles at 48 h post-infection (a phenotype associated with non-lytic egress), which coincides with the initial peak of viral genomic copies. To characterize the host molecular response during this critical stage, we performed time-course RNA sequencing at 24, 48, 96, and 144 hpi. Integrated analysis identified 6661 differentially expressed genes (DEGs) and 1138 differential alternative splicing (DAS) events affecting 892 genes, with DAS event abundance peaking at 48 h. DAS genes in autophagy and Golgi vesicle transport pathways, both integral to animal innate immunity, were significantly enriched exclusively at this timepoint, featuring novel mutually exclusive exon (MXE) isoforms in gopc (Golgi-associated PDZ and coiled-coil motif containing) and rint1 (RAD50 interactor 1). Weighted gene co-expression network analysis (WGCNA) of DEGs identified mapk9 (mitogen-activated protein kinase 9) and map1lc3a (microtubule-associated protein 1 light chain 3 alpha) as hub genes within modules enriched for autophagy-related functions. Separate co-expression analysis of DAS genes revealed rnf5, rimoc1, and golga4 as hub genes, with gopc exhibiting only a single linkage to rnf5. These findings implied concurrent transcriptional and virus-induced host splicing regulation of vesicle-associated innate defense pathways and suggest that splicing-derived features may serve as potential candidates for diagnostics or prevention against megalocytivirus disease in L. crocea. Full article

Feline calicivirus (FCV) is a major pathogen that threatens feline health worldwide. Its global prevalence, extensive genetic variability, and limited cross-protection among strains present significant challenges for vaccine development. In this study, an infectious clone of the FCV-GDJM202201 strain was constructed using the eukaryotic expression plasmid pcDNA3.1 under the control of the cytomegalovirus (CMV) promoter. The rescued virus, rGDJM-A4822T, exhibited growth kinetics comparable to those of the parental strain in vitro. Subsequently, two recombinant viruses, rGDJM-VP1_JL and rGDJM-VP1_SH, were generated by replacing the VP1 gene in the GDJM202201 backbone with those from heterologous FCV strains. Notably, these recombinant viruses exhibited reduced viral titers compared to rGDJM-A4822T. Finally, neutralization assays revealed differential neutralizing antibody titers among the recombinant FCVs, with rGDJM-A4822T inducing higher neutralizing antibody titers and cross-neutralizing activity. Collectively, this study establishes an FCV infectious clone that can be used to rescue recombinant viruses carrying heterologous VP1 proteins and to evaluate neutralizing antibody responses. Full article

Porcine circovirus type 2 (PCV2) is a pathogen of major importance in swine that is characterized by ongoing genetic evolution. To provide an updated epidemiological assessment for China, our study analyzed 1051 clinical samples collected from 27 provincial-level regions between 2023 and 2024. The overall PCV2 positivity rate was 65.18%, with detection rates showing significant seasonal variation, with higher rates in spring and summer. Genotypic analysis of 379 open reading frame 2 (ORF2) sequences identified PCV2d as the dominant genotype (78.89%), and no significant geographic clustering was observed. Coinfection with porcine reproductive and respiratory syndrome virus (PRRSV) is common, yet statistical tests have revealed an epidemiologically independent relationship between the two viruses. Notably, analysis of the capsid (Cap) protein revealed that high-frequency amino acid mutations were concentrated in immunodominant loop regions. These mutations resulted in genotype-specific substitutions within key neutralizing epitopes. This study provides the latest large-scale national baseline data on PCV2 in China for 2023–2024. It systematically analyzes the epidemiological characteristics of the dominant PCV2d genotype in the post-African Swine Fever era, the patterns of antigenic epitope mutations in the Cap protein, and their potential impact on vaccine efficacy. The study fills a gap in recent national epidemiological data on PCV2 in China and provides a basis for the targeted prevention and control of PCV2 and the updating of vaccine strains. Full article

Nucleocapsids protect viral genomes and play fundamental roles in viral assembly and infection. While many viruses adopt icosahedral or helical symmetries, negative-strand RNA viruses (NSVs) assemble their nucleocapsids with a distinct translation-based symmetry that is often considered helical because of their curvature. Our study analyzes the structural basis, assembly principles, and functional implications of the linear nucleocapsids. Structural coordinates of viruses were obtained from the Protein Data Bank (PDB) and examined using PyMOL version 1.3 to compare protein folds, RNA–protein interactions, inter-subunit contacts, and curvature properties across multiple nucleocapsids. We found that linear nucleocapsids share a similar 5H + 3H fold in their capsid proteins and encapsidate a fixed number of nucleotides per subunit, though the degree of nucleotide sequestration varies. Their architecture differs in inter-subunit interactions, determining whether empty capsids can assemble and influencing RNase sensitivity. Although these nucleocapsids may appear helical, they lack strict helical symmetry and instead display variable curvature that is modulated by environmental conditions. Relaxation of this curvature is likely required for viral RNA-dependent RNA polymerase to access the sequestered RNA genome during transcription/replication. In conclusion, linear nucleocapsids constitute a class of RNA–protein assemblies with variable curvature. The topologically conserved fold of the capsid protein enables genome protection while regulating exposure of RNA during viral RNA synthesis. Full article

Background: Hepatitis E virus (HEV) is an increasingly recognized cause of acute viral hepatitis in Thailand as the burden of hepatitis A, B, and C has declined. HEV is a positive-sense RNA virus in the family Hepeviridae with three major open reading frames encoding replication proteins (ORF1), the capsid protein (ORF2), and an accessory protein involved in viral egress (ORF3). Unlike highly endemic regions where genotypes 1 and 2 are linked to waterborne outbreaks, infections in Thailand are reported mainly as sporadic cases associated with zoonotic transmission, most commonly genotype 3. Objectives: This review summarizes the epidemiology, transmission routes, and public health implications of HEV infection in Thailand. Methods: Peer-reviewed studies on HEV seroprevalence, molecular epidemiology, and transmission in Thailand were identified through PubMed using combinations of the keywords “HEV” and “Thailand”. Two investigators independently screened titles, abstracts, and full texts. Eligible studies were synthesized qualitatively. Results: Earlier studies suggested low population exposure, but more recent evidence indicates substantial cumulative risk. A nationwide survey among blood donors reported anti-HEV IgG seroprevalence of about 30%, with geographic variation and increasing prevalence with age. Detection of HEV RNA in pigs, slaughterhouse environments, and retail pork products, together with links to raw or undercooked pork consumption, supports pigs as the principal reservoir and foodborne exposure as an important route. Transfusion-associated infection has also been documented. Conclusions: In Thailand, HEV infection is linked mainly to zoonotic and foodborne transmission involving genotype 3. Stronger surveillance, food safety measures, and risk-based blood safety policies are needed. Full article

An efficient bacteriophage delivery system needs to be developed to overcome the challenges associated with phage instability, rapid diffusion, and loss of infectivity at the infection site. Hydrogels have been found to be potential carriers. Hydrogels have emerged as promising carriers due to their biocompatibility, tunable physicochemical properties and capacity for controlled release. However, the molecular factors that regulate phage–hydrogel interactions remain poorly understood. In this study, we employed an in silico framework combining molecular docking, molecular dynamics (MD) simulations, MM/PBSA binding energy calculations, machine learning-based adhesion prediction, and diffusion modeling to explore phage–hydrogel interactions at the molecular level. Surface-exposed bacteriophage proteins, such as capsid and tail proteins, were evaluated against eight different hydrogel polymers. Binding site analysis revealed the presence of multiple solvent-accessible pockets that can interact with the polymer. Docking studies showed favorable and stable interactions, with hyaluronic acid showing strong binding affinity to multiple phage proteins (−5.5 to −5.7 kcal/mol) and GelMA showing high affinity to the capsid gp10 protein (−5.6 kcal/mol). The integrity of the structural complexes was further confirmed by 100 ns MD simulations, stable RMSD and RMSF trajectories, compact structural conformations, and favorable MM/PBSA binding energies. Machine learning classification successfully differentiated high- and low-adhesion systems and identified hydrogen bonding and electrostatic interactions as key determinants of sustained yet reversible phage retention. Collectively, our findings suggest that the hydrogels enriched with charged and polar functional groups can facilitate stable but non-destructive phage binding, enabling controlled and sustained release. This study provides mechanistic insights into rational hydrogel design for phage delivery systems and highlights the potential of high-throughput computational strategies to accelerate the development of optimized phage therapeutics. Full article

Alphaherpesviruses, including Herpes Simplex Virus 1 (HSV-1) and Pseudorabies Virus (PrV), establish lifelong latency in the nervous system and can cause recurrent disease. While latency has classically been attributed to peripheral sensory ganglia, accumulating evidence indicates that the central nervous system (CNS) may also serve as a site of long-term viral persistence and reactivation. Here, we investigated the CNS as a viral reservoir using the attenuated mutant PrV-∆UL21/US3∆kin, which preferentially targets mesiotemporal brain regions. Following intranasal inoculation, mice were analyzed at 11–14, 21, 28, 42, 105, and 190 days post-infection (dpi). To assess the reactivation potential, a subset of animals received cyclophosphamide/dexamethasone at 170 dpi. Viral transcripts were detected by RNAscope™ in situ hybridization and RT-qPCR targeting the lytic gene UL19 encoding the major capsid protein and the latency-associated transcript (LAT). Histopathology included hematoxylin and eosin staining and immunohistochemistry for CD3, Iba1, GFAP, cleaved caspase-3 and viral glycoprotein gB. UL19 RNA signals displayed marked regional and temporal heterogeneity, with prominent detection in mesiotemporal structures. In contrast, LAT RNA levels remained low overall, with a transient peak during the acute phase. RT-qPCR confirmed high UL19 and LAT transcript levels during early infection, while LAT transcription returned to baseline levels thereafter. Histopathology showed a transition from acute necrotizing meningoencephalitis to prolonged low-grade inflammation with glial activation and focal apoptosis. Notably, UL19 RNA signals strongly correlated with T-cell infiltration, particularly at 42 dpi. Together, these findings define regional and temporal patterns of long-term PrV transcriptional activity and associated neuropathology in the murine CNS. Full article

The capsid protein pE120R of African swine fever virus (ASFV) is highly immunogenic and is thought to play an important role in viral replication, yet its molecular characteristics and functions during infection remain poorly understood. Here, we generated two monoclonal antibodies (mAbs), 1C11 and 3G7, against ASFV pE120R and characterized their specificity and utility. Epitope mapping showed that 1C11 recognized the linear epitope ¹⁰⁹KKHLFP¹¹⁴, whereas 3G7 recognized ¹¹²LFPKL¹¹⁶. These antibodies enabled analysis of pE120R expression and localization during ASFV infection, demonstrating that pE120R is expressed at a late stage and partially co-localizes with the structural protein p54 in viral factories. Together, these results provide valuable immunological tools for further investigation of pE120R in ASFV replication and pathogenesis. Full article

Members of Marseilleviridae, a family of icosahedral giant viruses, have been identified worldwide in all types of environments. The virion shows a characteristic internal membrane extrusion at the five-fold vertices of the capsid, but its structural details need to be elucidated. We now report the 4.4 Å cryo-electron microscopy structure of the melbournevirus capsid by using a block-based reconstruction approach. Results: An atomic model of the major capsid protein (MCP) shows a unique cup structure on the trimer that accommodates additional proteins. A polyalanine model of the Penton base protein shows internally extended N- and C-terminals, which indirectly connect to the internal membrane extrusion. The Marseilleviruses share the same orientational organization of the MCPs as previously reported for other giant viruses, but the unique minor capsid protein components named Scaffold may be alternatively utilized to control the dimensions of the capsid during assembly as the tape measure protein. Full article