Search Results (870)

Influenza viruses are characterized by their high mutation rates which require continuous molecular surveillance to ensure the annual effectiveness of influenza vaccines. The current study aimed to investigate the molecular evolution and vaccine match of the 2009 pandemic (A(H1N1) pdm09) virus circulating in Riyadh, Saudi Arabia. A total of 380 nasopharyngeal aspirates (NPAs) were collected during the 2020–2023 winter seasons from patients with influenza-like illness. Influenza A virus (IAV) detection, typing, and amplification of hemagglutinin (HA) and neuraminidase (NA) genes were achieved using one-step RT-PCR. The full-length HA and NA genes of 14 selected A(H1N1) pdm09 isolates were sequenced and used for sequence and phylogenetic analysis, which also included sequences of seven A(H1N1) pdm09 isolates collected in Riyadh during the 2024–2025 season. IAV was detected in 17.11% samples; A/H3N2 (9.21%) was somewhat more prevalent than A(H1N1) pdm09 (7.89%). Children aged 0–4 years had the highest incidence rate of infection. Comparing the HA1 domain of A(H1N1) pdm09 isolates circulating in Riyadh to the current vaccine strains (A/Wisconsin/67/2022 and A/Victoria/4897/2022), a total of 24 amino acid substitutions were identified. O-linked and N-linked glycosylation sites in the HA and NA proteins of the Riyadh isolates coincided with those of the two vaccine strains. The receptor-binding domain (130-loop) of the HA1 domain showed a persistent S137P substitution in all study isolates; this mutation is not present in the current vaccination strain. This finding suggests a potential antigenic mismatch between the current vaccine and the circulating A(H1N1) pdm09 strains in Riyadh, warranting hemagglutination inhibition (HAI) assays to confirm the impact of the S137P substitution on antigenicity and immune evasion. As shown above, ongoing molecular surveillance is essential for guiding the yearly selection of vaccine candidates to increase efficacy. Full article

Infectious bronchitis virus (IBV) causes a highly contagious disease in chickens. The prevalence of GVI-1 is increasing; however, the genomic characteristics and antigenic properties of this genotype strain remain insufficiently characterized. In this study, the genome characteristics and antigenic properties of a naturally attenuated CK/CH/SC/YC_GVI-1-DK/LMB20210104 (abbreviated as YC_GVI-1) strain were systematically analyzed. YC_GVI-1 occupies a distinct phylogenetic lineage and shares a similarity of 98.2%, the highest nucleotide sequence homology, with the reference strain CK/CH/FJ/202005 (accession number: MW791835.1). This strain was likely originated through a genetic recombination event between two major parental strains, CK/CH/FJ/202005 and CK/CH/GX/HX (accession number: PP817796.1). However, its S protein harbors ten unique amino acid substitutions, compared to the same protein in the other two virulent strains in the same genotype. AlphaFold3-based structural prediction reveals that one of these substitutions, methionine 485 to valine substitution, may induce a conformational change in the adjacent phenylalanine residue at position 431, resulting in a shift in the local secondary structure from β-sheet to random coil. Characterization of its antigenicity showed that this strain induces a strong humoral immune response, with neutralizing antibody titers of 2^6.40 against homologous strain YC_GVI-1 and 2^4.00 against heterologous strain JS96_GI-19. Furthermore, vaccination of chickens with this strain conferred complete protection (100%) against JS96_GI-19. The findings provide novel insights into the molecular evolution and antigenicity of YC_GVI-1, offering key information for improving IBV surveillance and vaccine development. Full article

Background/Objectives: Parasporin PS2Aa1, recently designated as Mpp46Aa1, is recognized for its selective anticancer activity against various human cell lines. In this study, specific regions of the native protein were fragmented, and targeted amino acid substitutions were introduced to improve cytotoxic selectivity and potency. Methods: The modified fragments were evaluated individually and in combination with curcumin, a polyphenol with well-documented anticancer properties, and Sacha inchi-derived matrices, known for their antioxidant and antiproliferative activities. Results: Experimental results demonstrated that the substituted variant designated T104L-G108W exhibited superior anticancer activity compared to the native peptide P102-K11. Synergism assays revealed that curcumin-bioconjugated peptides were more effective against the tested cell lines, whereas combinations with Sacha inchi reduced cytotoxicity, suggesting possible interference in the mechanisms of action. Functional assays, including caspase 3/7 and 9 activation, Annexin V-Cy3 staining, and cell viability analysis with 6-CFDA, confirmed increased sensitivity in SiHa and HeLa cell lines, particularly for peptide T104L-G108W. Conclusions: Collectively, these findings support the effectiveness of a substitution-based strategy in improving parasporin fragments and underscore the therapeutic potential of peptide T104L-G108W as a novel anticancer candidate. Furthermore, this study provides preliminary evidence that natural biomolecules can be optimized through targeted modifications and rational combinations, establishing a framework for the development of sustainable and selective therapeutic approaches in cancer treatment. Full article

Despite its ecological and economic importance, Hampala macrolepidota (Cyprinidae: Smiliogastrinae) remains taxonomically debated, having undergone historical reclassifications across multiple taxonomic ranks. These challenges highlight the urgent need for integrative genomic analyses to resolve its phylogeny and assess genome-wide diversity, establishing a baseline for effective management and conservation. In this study, the newly assembled mitogenome of H. macrolepidota from within its native range in Lake Dibawah, West Sumatra, Indonesia, was sequenced. The mitogenome spanned 17,104 bp, encoded 37 genes and a control region, and exhibited a nucleotide composition biased toward adenine and thymine. The protein-coding genes (PCGs) predominantly utilized ATG as the initiation codon and showed a higher proportion of hydrophobic compared to hydrophilic amino acids. The nonsynonymous (Ka) and synonymous (Ks) substitution ratios were below ‘1’, which indicates negative selection on most of the PCGs within Hampala and other Smiliogastrinae species. Mitogenome-wide analysis revealed overall high intraspecific genetic diversity (≥2.7%) in the native Indonesian population compared to mainland populations in Southeast Asia. The Bayesian and maximum-likelihood phylogenetic analyses elucidated matrilineal evolutionary relationships within the subfamily Smiliogastrinae, with the Hampala species forming a monophyletic cluster. The present mitogenome-based phylogenetic topologies also supported the taxonomic placement of several species in the revised classification, which previously were classified under the genera Puntius and Barbus, respectively. Additionally, the investigation of partial mitochondrial COI and Cytb genes further elucidated the population genetic structure of H. macrolepidota across Southeast and East Asia. The observed genetic divergence (0–4.2% in COI and 0–4.5% in Cytb), together with well-resolved phylogenetic clustering and the presence of both shared and distinct haplotypes among Indonesian samples, provides strong evidence for long-term population isolation and local adaptation. These patterns are most plausibly driven by historical hydrological dynamics, paleo-drainage connectivity, and persistent geographic barriers that have structured population divergence over time. In addition, this study emphasizes the need to generate mitogenomes of seven additional Hampala species from Southeast Asia to better understand their evolutionary patterns. Further, broader sampling of wild H. macrolepidota populations across their biogeographical range will be essential to strengthen understanding of their genetic diversity and guide effective conservation strategies. Full article

Porcine circovirus 3 (PCV3), first reported in 2016, is associated with diverse clinical conditions, including porcine dermatitis and nephropathy syndrome, reproductive disorders, and systemic inflammation, and affects pigs of all ages. To investigate the prevalence and genetic evolution of PCV3 in Hunan Province, China, 700 lymph node tissue specimens were collected from slaughterhouses and hazard-free disposal centers across 14 prefecture-level cities between 2021 and 2024 and screened using real-time quantitative PCR (qPCR). Epidemiological investigation revealed an overall PCV3 positivity rate of 29.4% (206/700) in the province. The highest prevalence was observed in Yiyang City (56%, 28/50), whereas no positive samples were detected in Zhuzhou City (0/30). Among the positive samples, 34 specimens from different cities with Ct values < 25 were selected for Cap gene amplification and sequencing. Phylogenetic analysis showed that PCV3c was the predominant genotype (67.6%, 23/34), followed by PCV3a (32.4%, 11/34), while PCV3b was not detected. We identified twelve amino acid substitution sites within Cap proteins. Furthermore, B-cell linear epitope prediction and homology modeling of the Cap protein identified seven linear epitopes, with ten amino acid variation sites located within these epitopic regions. This study enriches the molecular epidemiological data of PCV3 in southern China and provides a reference for future PCV3 control strategies. Full article

To improve the gel quality of low-salt shrimp surimi gel (SSG) from Pacific white shrimp (Litopenaeus vannamei), L-arginine (L-Arg), L-lysine (L-Lys), and L-proline (L-Pro) were used as partial substitutes for NaCl. The effect of the three amino acids on gel properties, protein conformation, microstructure, and in vitro digestion of low-salt SSG were systematically analyzed. Macro-/microstructural analyses revealed that L-Arg, L-Lys, and L-Pro promoted denser three-dimensional networks in low-salt SSG with smaller pore sizes. Compared with the low-salt control (LC) group, the addition of L-Arg, L-Lys, and L-Pro significantly increased the gel strength of low-salt SSG. Cooking loss was significantly decreased from 10.80% (LC group) to 1.89–4.31%. Protein solubility and turbidity results demonstrated that all amino acids markedly enhanced protein solubilization and inhibited protein aggregation. L-Arg and L-Lys mainly promoted hydrogen and disulfide bonds, but reduced hydrophobic interactions and ionic bonds. L-Arg impaired digestibility only in the gastric phase, whereas L-Lys suppressed digestibility across both gastric and intestinal phases. Through molecular docking technology, ASN-238 and LYS-187 of myosin (the dominant gel-forming protein) are the key shared binding residues with three amino acids. These findings suggest that amino acids provide a feasible approach to specifically modulate the gel characteristics of low-salt surimi products. Full article

The MATα_HMGbox and HMG-box_ROX1-like domains of the MAT1-1-1 and MAT1-2-1 proteins, respectively, play essential roles in DNA binding and the subsequent regulation of gene transcription, controlling Ophiocordyceps sinensis sexual reproduction. Alternative splicing, differential occurrence and transcription of the MAT1-1-1 and MAT1-2-1 genes have been demonstrated in Hirsutella sinensis (GC-biased Genotype #1 of the 17 O. sinensis genotypes), suggesting self-sterility under heterothallic or hybrid outcrossing. In this study, the MATα_HMGbox domains of MAT1-1-1 proteins in wild-type Cordyceps sinensis isolates were shown to cluster into 5 clades in the Bayesian clustering tree and belong to diverse stereostructure morphs under 19 AlphaFold codes. The HMG-box_ROX1-like domains of MAT1-2-1 proteins, on the other hand, were shown to cluster into 2 branched Bayesian clades and belong to stereostructure morphs under 25 AlphaFold codes. Correlation analysis revealed that 1–3 amino acid substitutions in the DNA-binding domains of the mating proteins resulted in altered hydrophobicity and secondary and tertiary structures of the DNA-binding domains of the proteins, especially altered stereostructures of the hydrophobic cores formed by 3 critical α- helices within the functional domains of the proteins. Fungal origin analysis revealed possible heterospecific fungal sources of mating proteins with stereostructure variations in wild-type C. sinensis isolates, suggesting that alterations in DNA binding function and the subsequent regulation of mating-related gene transcription are involved in ensuring the accuracy and genetic diversity of heterothallic and hybrid reproduction of O. sinensis during the lifecycle of the C. sinensis insect–fungal complex. Full article

Chloroplasts are key organelles in plants that carry out photosynthesis, convert light energy into chemical energy, and synthesize organic compounds. In this study, a stably heritable chlorophyll-deficient mutant was screened from the ethyl methanesulfonate-induced mutation library of Wuyunjing 21 (WYJ21). This mutant was designated as chlorophyll deficient 6 (cde6). The cde6 mutant exhibits a low chlorophyll content, photosynthetic defects, an impaired chloroplast structure, a significant reduction in the number of stacked thylakoid layers, and a yellow-green leaf phenotype in the early tillering stage. Through MutMap analysis, it was found that the cde6 mutant harbors a single-base mutation (T→A) in the LOC_Os07g38300 gene. This mutation results in an amino acid substitution from valine (Val) to aspartic acid (Asp) in the encoded protein, thereby affecting the protein’s structure and function. The mutation of CDE6 leads to decreased expression of genes related to chloroplast development and chlorophyll biosynthesis. Further studies revealed that the CDE6, a potential chloroplast ribosome recycle factor, leads to high temperature sensitivity in rice when mutated. As high-temperature stress is a primary constraint to global rice productivity, the identification of CDE6 provides a genetic target for improving thermotolerance. In conclusion, these findings demonstrate that CDE6 plays a crucial role in chloroplast biogenesis and provide new insights into its regulatory function in high-temperature tolerance. Full article

Vif and Vpr are HIV-1 accessory proteins that create optimal conditions for viral replication. They are considered as potential targets for the development of therapeutic agents. Natural amino acid substitutions in these proteins have previously been associated with disease progression. The aim of this study was to analyze the genetic diversity of Vif and Vpr in HIV-1 group M clades. A total of 5286 sequences were downloaded and analyzed. For 37 clades in group M, the consensus sequences, amino acid natural variation, and clade-specific amino acid residue substitutions (CSSs) were evaluated. Structural analysis and modeling of consensus sequences were performed for subtypes A1, B, C, and D. The average conservation degree in the HIV-1 group M was 86.4% for Vif and 91.3% for Vpr. In both proteins, the lowest amino acid diversity was observed in sub-subtype A6, and the highest in subtype B. In consensus sequences, the substitutions, which might influence pathogenesis, have been determined: in Vif—22H (11_cpx, 91_cpx) and 136P (A6, 01_AE, 15_01B, 59_01B, 89_BF1, 103_01B, 111_01C, 133_A6B), in Vpr—41N (06_cpx) and 55A (B, 07_BC, 35_01D, 56_cpx, 66_cpx, 66_BF1, 71_BF1, 85_BC, 137_0107). In functional motifs, CSSs associated with changes in the chemical properties of amino acid residues were noted. These findings could be taken into account for the development of therapeutic drugs in the future. No correlation was observed between the subtypes and the spatial organization of the oligomeric structures of Vif and Vpr. Using the structural analysis and modeling, it has been shown for the first time that Vif can interact with APOBEC3G as an oligomer. Full article

Avian influenza viruses are predominantly associated with waterfowl and shorebirds, and are rarely detected in other avian hosts in nature. In 2021, an H1N1 virus was isolated from a Fieldfare Turdus pilaris in Zaporizhzhia Oblast, Ukraine. A phylogenetic analysis revealed that all eight gene segments belonged to the Eurasian low-pathogenic avian influenza lineages. The highest nucleotide identity of the HA gene was observed with viruses detected in Georgia, Sweden, and Ukraine (99.11%), while the NA gene showed the greatest identity to viruses from Western Europe (99.14–99.57%). Genetic analysis of the HA cleavage site showed a sequence (PSIQSR↓GLF) that contained a single basic amino acid. No deletions were detected in the stalk region of NA gene, and no specific mutations in PB2 protein were found. However, several amino acid substitutions were identified in the HA gene (D204E, S207T, and D239G) that may affect the binding affinity to specific antibodies. The occurrence of this virus in a wild, seemingly healthy thrush indicate that additional surveillance in poorly studied ecological groups such as Passeriformes is warranted. Full article

This study comprehensively characterizes the PEBP gene family in Cymbidium sinense, an orchid with a prolonged vegetative phase that limits its industrial production. Genome-wide analysis identified six CsPEBPs, classified into FT-like, TFL1-like, and MFT-like subfamilies. Evolutionary, gene structure, and collinearity analyses revealed both conservation and lineage-specific diversification of these genes. CsFTL3, a distinctive FT-like member, displayed notably high expression during the bud undifferentiated stage, followed by a sharp downregulation upon floral initiation. Functional studies identified CsFTL3 as a key floral repressor. Heterologous overexpression in Arabidopsis delayed flowering time from 32.0 days (wild-type) to 63.0–75.3 days (transgenic) and increased rosette leaf number from 12.6 to 33.0–34.5, while its knockdown via virus-induced gene silencing (VIGS) in C. sinense accelerated floral bud development and upregulated flowering-promoter genes. Phylogenetically, CsFTL3 falls within the flowering repressor FT-I clade, and multiple sequence alignment identified critical amino acid substitutions (Y134S, W138L, Q140E) that likely underpin its functional divergence from typical flowering promoters. Furthermore, promoter analysis revealed an enrichment of light-, hormone-, and stress-responsive cis-elements, and its expression was modulated by gibberellin (GA), abscisic acid (ABA), and low-temperature treatments. Predicted protein–protein interaction and transcriptional regulatory networks provide preliminary insights into its complex regulation. We conclude that CsFTL3 acts as a crucial floral inhibitor, integrating environmental and endogenous cues to repress flowering. These findings offer fundamental insights into the molecular mechanisms of flowering in orchids and provide a valuable genetic resource for molecular breeding programs aimed at achieving precise flowering time control. Full article

Canine parvovirus type 2 (CPV-2) is a primary etiological agent of acute gastroenteritis in domestic dogs. Although molecular and serological evidence have confirmed its circulation in wild carnivores, the clinical impact of spillover events in wildlife hosts remain insufficiently characterized. In this study, we investigated CPV-2 from wild coyote pups (Canis latrans) presenting with clinical gastroenteritis in northeastern Mexico. CPV-2 was successfully isolated in MDCK cells, and whole-genome sequencing was performed on two isolates, B55 and B56 (GenBank accession numbers PQ065988 and PQ065989). A comprehensive analysis identified 23 nucleotide mutations, eight of which were missense mutations resulting in amino acid substitutions in structural (VP) and non-structural (NS) proteins. Notably, amino acid substitution L354V was identified in the NS1 helicase domain of both isolates, a region critical for viral replication. Phylogenetic analysis confirmed that isolates B55 and B56 cluster within the CPV-2c subtype, showing high genetic relatedness to circulating Mexican and US canine strains which strongly suggests recent cross-species transmission between domestic dogs and wild coyotes. This study provides the first complete genomic characterization of a clinical CPV-2 infection in wild coyotes in Mexico, underscoring the immediate risk of CPV-2c transmission at the domestic animal–wildlife interface. Full article

Fast-twitch and slow-twitch muscle fibers not only differ in metabolic characteristics and physiological functions but also significantly influence the texture of livestock meat. RNA editing represents an important post-transcriptional regulatory process that can influence both gene expression and the resulting protein function. However, studies on RNA editing events in yak muscle remain limited. This study systematically identified RNA editing events in yak biceps femoris (BF, n = 3) and obliquus externus abdominis (OEA, n = 3) using transcriptomic data, discovering 17,713 unique editing sites, most located in non-coding regions. Within coding regions, 3350 sites were detected, with 1195 resulting in non-synonymous amino acid substitutions. Further analysis revealed that 785 sites potentially affected miRNA binding sites, suggesting RNA editing may participate in miRNA-mediated gene regulation. Tukey’s post hoc test (p < 0.05) identified 242 sites (involving 170 genes) with significantly different editing levels between BF and OEA. KEGG pathway analysis indicated that genes with differential RNA editing were predominantly associated with pathways involved in muscle fiber type transitions, including the MAPK and calcium signaling pathways. Collectively, this study maps the RNA editing landscape in yak muscle tissue and identifies distinct, fiber-type-specific RNA editing patterns between oxidative and glycolytic muscle fibers, including differences in editing levels and site distributions, supporting a potential association between RNA editing and muscle fiber type transformation. Full article

Background: Genetic mutations have proven to be the epicenters of cancer and disease progression. Traditional WXS sequencing and BLOSUM scoring can be used to infer the evolutionary conservation of amino acid substitutions, though these approaches are not informed by probable base pair sequence changes. Within gene mutation analysis, most tools focus on amino acid conservation or codon switching independently, limiting their ability to contextualize observed mutations against stochastic mutational processes. In the clinical setting, variants of unspecified significance remain difficult to interpret, as clinicians are often unable to determine whether observed mutations arise from oncogenic selection or from stochastic mutational degradation. Methods: We analyzed mutation sequences from the TCGA BRCA cohort for TP53 and PIK3CA and developed a model that integrates BLOSUM scoring with statistical modeling of base pair changes to evaluate deviation from codon-aware neutral expectations. Observed mutational distributions were compared against a stochastic neutral model to assess statistical significance. Results: Within the TCGA BRCA cohort, TP53 mutations were significantly more evolutionarily radical than expected under the codon-aware neutral model, while PIK3CA mutations were significantly more evolutionarily conservative, as determined using chi-square testing. These opposing patterns are consistent with the distinct functional roles of TP53 and PIK3CA in oncogenesis, where TP53 is inhibited through disruptive loss-of-function mutations, whereas PIK3CA is recurrently mutated in a manner that preserves protein structure and promotes constitutive pathway activation. This contrast reflects selective pressure toward disabling tumor suppressor function while maintaining persistent oncogenic signaling. Conclusions: Codon-aware neutral modeling provides a statistical framework for distinguishing mutations that deviate from stochastic expectations and may aid in the interpretation of variants of unspecified significance. By contextualizing mutational severity relative to neutral processes, this approach offers insight into tumor evolution and may support prognostic assessment without relying on predefined gene-level neutrality. Full article

To investigate the molecular characteristics of H3N2 canine influenza viruses circulating in Jiangsu, China, we isolated a H3N2 strain (A/Canine/Nanjing/CnNj01-2025) from a dog presenting with respiratory signs at the Veterinary Teaching Hospital of Nanjing Agricultural University. All eight gene segments were sequenced and compared with those of two human H3N2 strains and five avian H3N2 strains. Antigenicity and receptor-binding properties were also assessed. Phylogenetic analysis revealed that the canine isolate descended from the avian lineage and formed an independent evolutionary clade, while the human strains were more distantly related to the avian lineage. Glycosylation analysis of the HA protein revealed that the canine strain carried seven N-glycosylation sites, including a unique site at residue 97/81 (HA/H3 numbering), which serves as a molecular signature of the canine strain. Several amino-acid substitutions were identified in major antigenic sites, including D97/81N, A176/160T, N204/188D, V212/196I, and W237/222L. Analysis of internal genes showed that the canine strain harbored PB2 292T and 590S mammalian adaptation mutations, which are also present in human strains. Hemagglutination inhibition (HI) assays of the canine strain indicated moderate serologic cross-reactivity with a human H3N2 antiserum (16-fold reduction), whereas avian strains showed no cross-reactivity. Receptor-binding assays demonstrated that the virus retained predominant α-2,3 sialic acid binding, comparable to that of avian influenza viruses, and gained a modest affinity for human-type α-2,6 sialic acid receptors. Therefore, the canine H3N2 virus has undergone significant antigenic drift, developed partial serological cross-reactivity with human strains, and acquired detectable but limited binding affinity for human-type receptors. Overall, our findings suggest that the current canine H3N2 influenza virus exhibits distinct genetic and antigenic variations from human and avian strains. Continuous molecular and serological surveillance of canine influenza viruses is therefore warranted to monitor their evolutionary trends and assess the potential for cross-species transmission. Full article