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Innovative tools for detection of plant pathogenic viruses and bacteria.

Detection of harmful viruses and bacteria in plant material, vectors or natural reservoirs is essential to ensure safe and sustainable agriculture. The techniques available have evolved significantly in the last few years to achieve rapid and reliable detection of pathogens, extraction of the target from the sample being important for optimising detection. For viruses, sample preparation has been simplified by imprinting or squashing plant material or insect vectors onto membranes. To improve the sensitivity of techniques for bacterial detection, a prior enrichment step in liquid or solid medium is advised. Serological and molecular techniques are currently the most appropriate when high numbers of samples need to be analysed. Specific monoclonal and/or recombinant antibodies are available for many plant pathogens and have contributed to the specificity of serological detection. Molecular detection can be optimised through the automatic purification of nucleic acids from pathogens by columns or robotics. New variants of PCR, such as simple or multiplex nested PCR in a single closed tube, co-operative-PCR and real-time monitoring of amplicons or quantitative PCR, allow high sensitivity in the detection of one or several pathogens in a single assay. The latest development in the analysis of nucleic acids is micro-array technology, but it requires generic DNA/RNA extraction and pre-amplification methods to increase detection sensitivity. The advances in research that will result from the sequencing of many plant pathogen genomes, especially now in the era of proteomics, represent a new source of information for the future development of sensitive and specific detection techniques for these microorganisms.

Bacteria↗

Sequence requirements and an optimization strategy for short antimicrobial peptides.

Short antimicrobial host-defense peptides represent a possible alternative as lead structures to fight antibiotic resistant bacterial infections. Bac2A is a 12-mer linear variant of the naturally occurring bovine host defense peptide, bactenecin, and demonstrates moderate, broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria as well as against the yeast Candida albicans. With the assistance of a method involving peptide synthesis on a cellulose support, the primary sequence requirements for antimicrobial activity against the human pathogen Pseudomonas aeruginosa of 277 Bac2A variants were investigated by using a luciferase-based assay. Sequence scrambling of Bac2A led to activities ranging from superior or equivalent to Bac2A to inactive, indicating that good activity was not solely dependent on the composition of amino acids or the overall charge or hydrophobicity, but rather required particular linear sequence patterns. A QSAR computational analysis was applied to analyze the data resulting in a model that supported this sequence pattern hypothesis. The activity of selected peptides was confirmed by conventional minimal inhibitory concentration (MIC) analyses with a panel of human pathogen bacteria and fungi. Circular-dichroism (CD) spectroscopy with selected peptides in liposomes and membrane depolarization assays were consistent with a relationship between structure and activity. An additional optimization process was performed involving systematic amino acid substitutions of one of the optimal scrambled peptide variants, resulting in superior active peptide variants. This process provides a cost and time effective enrichment of new candidates for drug development, increasing the chances of finding pharmacologically relevant peptides.

Amino Acid Sequence↗

A new variant of Brucella melitensis.

Brucella melitensis is highly pathogenic and constitutes a serious risk to public health. In Argentina, biovar 1 has been isolated from infected animals, but the Rev.1 strain vaccine is not authorised for use. This report describes nine atypical B. melitensis isolates obtained from humans. These isolates grew slowly, produced small colonies and were susceptible to penicillin and dyes, similar to the B. melitensis Rev.1 vaccine strain, but were inhibited by streptomycin 2.5 mg/L. The isolation of such atypical B. melitensis variants has never been reported from animals in Argentina, and could indicate the emergence of a new mutant variant.

Adolescent↗

Genetic evidence for predisposition to acute leukemias due to a missense mutation (p.Ser518Arg) in ZAP70 kinase: a case-control study.

BACKGROUND: The apparent lack of additional missense mutations data on mixed-phenotype leukemia is noteworthy. Single amino acid substitution by these non-synonymous single nucleotide variations can be related to many pathological conditions and may influence susceptibility to disease. This case-control study aimed to unravel whether the ZAP70 missense variant (rs104893674 (C > A)) underpinning mixed-phenotype leukemia. METHODS: The rs104893674 was genotyped in clients who were mixed-phenotype acute leukemia-, acute lymphoblastic leukemia- and acute myeloid leukemia-positive and matched healthy controls, which have been referred to all major urban hospitals from multiple provinces of country- wide, IRAN, from February 11' 2019 to June 10' 2023, by amplification refractory mutation system-polymerase chain reaction method. Direct sequencing for rs104893674 of the ZAP70 gene was performed in a 3130 Genetic Analyzer. RESULTS: We found that the AC genotype of individuals with A allele at this polymorphic site (heterozygous variant-type) contribute to the genetic susceptibility to acute leukemia of both forms, acute myeloid leukemia and acute lymphoblastic leukemia as well as with a mixed phenotype. In other words, the ZAP70 missense variant (rs104893674 (C > A)) increases susceptibility of distinct cell populations of different (myeloid and lymphoid) lineages to exhibiting cancer phenotype. The results were all consistent with genotype data obtained using a direct DNA sequencing technique. CONCLUSION: Of special interest are pathogenic missense mutations, since they generate variants that cause specific molecular phenotypes through protein destabilization. Overall, we discovered that the rs104893674 (C > A) variant chance in causing mixed-phenotype leukemia is relatively high.

Humans↗

Contributions of ATM mutations to familial breast and ovarian cancer.

This study addresses the prevalence of ATM mutations and the association with breast cancer in Austrian families selected for a history of breast or ovarian cancer or both [hereditary breast and ovarian cancer (HBOC)]. In 270 HBOC families previously screened for BRCA1 and BRCA2 mutations, 137 different sequence alterations of ATM were identified. Seven of these were mutations presumed to cause ataxia telangiectasia based on their effect on the ATM protein, including five that caused a protein truncation and two missense mutations in the catalytic kinase domain of the highly conserved COOH terminus of the protein. The seven mutations were found in 10 families (3.7%). In addition, one missense variant, L1420F, was observed in 13 HBOC families (4.8%) but was not observed in any of the 122 healthy volunteers with no history of breast cancer. In addition, the variant segregated with breast cancer in some of the families, suggesting that it may be pathogenic for breast cancer. Sixty-two additional variants of potential significance were observed in 65 HBOC families, but not in healthy controls. These variants included 24 sequence alterations with possible effects on splicing or protein-protein interactions. This study indicates that there is a significant prevalence of ATM mutations in breast and ovarian cancer families and adds to a growing body of evidence that ATM mutations confer increased susceptibility to breast cancer.

Adult↗

Identification and characterization of RbmA, a novel protein required for the development of rugose colony morphology and biofilm structure in Vibrio cholerae.

Phase variation between smooth and rugose colony variants of Vibrio cholerae is predicted to be important for the pathogen's survival in its natural aquatic ecosystems. The rugose variant forms corrugated colonies, exhibits increased levels of resistance to osmotic, acid, and oxidative stresses, and has an enhanced capacity to form biofilms. Many of these phenotypes are mediated in part by increased production of an exopolysaccharide termed VPS. In this study, we compared total protein profiles of the smooth and rugose variants using two-dimensional gel electrophoresis and identified one protein that is present at a higher level in the rugose variant. A mutation in the gene encoding this protein, which does not have any known homologs in the protein databases, causes cells to form biofilms that are more fragile and sensitive to sodium dodecyl sulfate than wild-type biofilms. The results indicate that the gene, termed rbmA (rugosity and biofilm structure modulator A), is required for rugose colony formation and biofilm structure integrity in V. cholerae. Transcription of rbmA is positively regulated by the response regulator VpsR but not VpsT.

Bacterial Proteins↗

Distribution of HPV16 and 18 intratypic variants in normal cytology, intraepithelial lesions, and cervical cancer in a Mexican population.

OBJECTIVE: Several intratype variants of HPV16 and 18 have been identified. These variants are associated with populations from different geographic regions, and show a differential distribution among the severity of the cervical lesion, most likely due to different pathogenic potential. The objective of this study was to investigate the variant distribution of HPV16 and 18 in a Mexican population and its association with the severity of the cervical lesion and the histological lineage of cervical cancer. METHODS: HPV types 16 and 18 detection was performed in 412 samples of preinvasive and invasive specimens from patients attending a Primary Health-Care Center, an Early Cervical Lesion Clinic, or a Cancer Center. Distribution of HPV variants was correlated with the cytological findings and tumor cell types using contingency tables. Statistical difference was tested with the Fisher's Exact Test or its Fisher-Freeman-Halton extension for RXC tables. Alpha value was set at the P < 0.05. RESULTS: Among the 277 women included in this study without cancer, 63.5% (176 cases) had a normal cytology; from the remaining 101 women, 53.5% were LSIL (54 cases), and 46.5% HSIL (47 cases). From a total of 135 invasive carcinomas, 78.5% were squamous (106 cases); 6.6% adenocarcinoma (9 cases); 9.6% adenosquamous (ADSC) (13 cases); and 5.1% were undifferentiated carcinoma (7 cases). HPV16 E and AA-a were evenly distributed among preinvasive and invasive lesions. However, the isolate AA-c was exclusively found in cervical cancer. HPV18 Var-1(E) was almost exclusively found in invasive lesions, while the HPV18 Var-2(Af) predominated in normal or preinvasive lesions. In invasive cancer, this variant was found only in squamous tumors. CONCLUSIONS: The differential distribution of HPV16 and 18 variants in cervical lesions we found further supports experimental data on the different pathogenic potential of HPV16 and 18 variants for cervical cancer development.

Cervix Uteri↗

Structure of the variant glycoproteins and surface coat of Trypanosoma brucei.

The pathogenic African trypanosomes have a unique mechanism for antigenic variation. Each cell is covered by a surface coat consisting of about seven million essentially identical glycoprotein molecules drawn from a large repertoire of variants, each encoded by an individual gene. Amino acid sequence variation extends throughout the molecule but reduces from the amino terminus to the carboxy terminus, where certain features, especially the grouping of cysteine residues, are quite conserved. The range of diversity within the thousand or so variant glycoprotein genes that exist in each cell is large. New variants may arise instantaneously by segmental gene conversion. Variant surface glycoproteins are synthesized with amino terminal signal sequences and hydrophobic carboxy terminal tails. The tails are extraordinarily conserved. After synthesis, they are replaced by a complex glycolipid structure in which myristic (dodecanoic) acid serves to anchor the polypeptide to the surface membrane. Enzymic cleavage of myristic acid releases variant glycoproteins from the surface coat.

Amino Acid Sequence↗

A recurrent CCDC82 frameshift variant associated with syndromic neurodevelopmental disorder in a consanguineous Pakistani family.

BACKGROUND: Intellectual disabilities (IDs) are part of neurodevelopmental disorders (NDDs) and are genetically heterogeneous conditions characterized by impairments in cognition, learning, and adaptive functioning. Despite advances in gene discovery, many individuals, particularly those from understudied populations, remain without a molecular diagnosis. Recent reports implicate CCDC82 (HGNC: 26282) as an autosomal recessive ID gene, although the phenotypic spectrum and biological context remain incompletely defined. METHODS: Exome sequencing (ES) was performed in a consanguineous Pakistani family (PKMR06A) with four affected individuals presenting with moderate to severe ID. Variant segregation was confirmed by Sanger sequencing. In silico analyses, including pathogenicity prediction, protein structural modeling, and domain intolerance assessment, were used to evaluate the functional consequences of the identified variant. Spatiotemporal gene expression patterns were examined using bulk and single-cell human brain transcriptomic datasets. RESULTS: Clinically, affected individuals of family PKMR06A presented with early childhood global developmental delay, speech delay, hypotonia, gait abnormalities, spasticity, and mild facial dysmorphism. Genetic screening revealed a recurrent rare homozygous frameshift variant in CCDC82 (NM_024725.4): c.373del; p.(Asp125Ilefs*6), segregating with disease in all available affected individuals of the family. The identified c.373del variant was absent from the gnomAD database and was classified as pathogenic (PVS1, PM2, and PP1) based on ACMG/AMP criteria. The c.373del variant is predicted to introduce a premature termination codon, p.(Asp125Ilefs*6), leading to deletion of essential coiled-coil domains from the encoded protein, supporting a loss-of-function mechanism. In silico, transcriptomic analyses demonstrated preferential CCDC82 expression during prenatal human brain development, providing developmental context for the neurodevelopmental phenotype associated with the identified truncating variant. CONCLUSIONS: This study expands the mutational landscape of CCDC82 and provides additional clinical and molecular evidence supporting its role in autosomal recessive NDD. The findings reinforce the importance of CCDC82 in human neurodevelopment and highlight the value of genomic investigation in underrepresented populations.

Autosomal recessive↗

Candida albicans antifungal-resistant strains: studies on adherence and other pathogenicity related characteristics.

In search of adhesion-variant strains of Candida albicans the adherence of a number of polyenes and/or azole-resistant strains of this yeast was studied (C. albicans 6406, 6406/8 and 799-XL, -XS, -YS, -R and YL). For comparison C. albicans KCCC 14172, known for its high adhesion and proteinase production, was also used. All isolates showed significantly lower adhesion (P < 0.001) compared with KCCC 14172. The exception was 6406/8 which showed superior adherability to all strains tested (2.5-4.8 times more adherent). This superiority prompted us to study the possible variation between this strain and the others in parameters that contribute to pathogenicity. Strain 6406/8 had the smallest average cell size (0.5-0.75 the size of cells from other strains). Variation in proteinase production and germ-tube formation existed among strains, with strain 6406/8 producing the lowest levels of inducible proteinase (2-4-fold less than the others), as well as being the least germ-tube former (10 times less than other strains). Ultrastructural comparisons between strain 6406/8 and its parent showed that the mutant strain had a thinner cell wall with a dense floccular layer throughout the cell wall compared to the parent strain. The cytoplasmic membrane of the mutant was more conspicuous than that of the parent strain. Comparison of the pathogenicity of strain 6406/8 and its parent (6406) revealed that although the mutant strain initially showed higher colonization than the parent strain, it was cleared much faster.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Predicting functional constraints across evolutionary timescales with phylogeny-informed genomic language models.

Genomic language models (gLMs) have emerged as a powerful approach for learning genome-wide functional constraints directly from DNA sequences. However, standard gLMs adapted from natural language processing often require extremely large model sizes and computational resources, yet still fall short of classical evolutionary models in predictive tasks. Here, we introduce GPN-Star (Genomic Pretrained Network with Species Tree and Alignment Representation), a biologically grounded gLM featuring a phylogeny-aware architecture that leverages whole-genome alignments and species trees to model evolutionary relationships explicitly. Trained on alignments spanning vertebrate, mammalian, and primate evolutionary timescales, GPN-Star achieves state-of-the-art performance across a wide range of variant effect prediction tasks in both coding and non-coding regions of the human genome. Analyses across timescales reveal task-dependent advantages of modeling more recent versus deeper evolution. To demonstrate its potential to advance human genetics, we show that GPN-Star substantially outperforms prior methods in prioritizing pathogenic and fine-mapped GWAS variants; yields unprecedented enrichments of complex trait heritability; and improves power in rare variant association testing. Extending beyond humans, we train GPN-Star for five model organisms - Mus musculus, Gallus gallus, Drosophila melanogaster, Caenorhabditis elegans, and Arabidopsis thaliana - demonstrating the robustness and generalizability of the framework. Taken together, these results position GPN-Star as a scalable, powerful, and flexible new tool for genome interpretation, well suited to leverage the growing abundance of comparative genomics data.

Journal Article↗

Genetic similarity and phenotypic diversity of commensal and pathogenic strains of Candida albicans isolated from the oral cavity.

Colony phenotype and genetic similarity were assessed within and between groups of commensal and pathogenic strains of Candida albicans collected from the oral cavities of individuals in a single geographical locale. Thirty-eight percent of pathogenic isolates contained predominant or minor variant colony morphologies (other than smooth) when samples from the sites of infection were cultured on plates, while 16% of commensal isolates contained minor variant colony morphologies when samples from the sites of carriage were cultured. The genetic similarities of isolates within and between groups were assessed by DNA fingerprinting by using Southern blot hybridization with the fingerprinting probe Ca3 and analysis with the computer-assisted, automated Dendron system. Both the commensal and the pathogenic groups contained a major cluster of genetically similar C. albicans isolates representing 31 and 33% of the strains in the respective groups. When a combined dendrogram of both commensal and pathogenic isolates was generated, the major clusters of genetically similar isolates in each group mixed into one large cluster. Minor clusters in the individual dendrograms also mixed. These results suggest common clonal origins for commensal and pathogenic strains in the same geographical locale.

Adult↗

Severe Early-Onset Fetal Growth Restriction: The Yield of Antenatal and Postnatal Genetic Testing.

OBJECTIVES: We evaluated the diagnostic yield of karyotype (KT) and chromosomal microarray (CMA) with isolated severe FGR diagnosed before 32&#xa0;weeks' gestation. Exome and genome sequencing (ES/GS) level data were available in a subset of this population. METHOD: We performed a retrospective review of singleton pregnancies (delivered 2022-2025) with estimated fetal weight or abdominal circumference <&#xa0;3rd percentile before 32&#xa0;weeks' gestation, no sonographic structural anomalies, and diagnostic testing (KT, CMA, ES, or GS) via amniocentesis or cord blood. Cases with abnormal cell-free DNA were excluded. RESULTS: Forty cases were included (mean diagnosis 26.8&#xa0;weeks). Testing was performed via amniocentesis in 42% and cord blood in 58%. All KT (27/40) were normal. CMA (39/40) identified one pathogenic CNV (2.5%) and three (7.5%) variants of uncertain significance (VUS). Four (10%) showed &#x2265; 1 region of absence of heterozygosity (AOH)&#xa0;>&#xa0;10Mb; one revealed maternal uniparental disomy of chromosome 6. Sequencing (N&#xa0;=&#xa0;10) detected one VUS in COL1A1. Acute viral infection was not observed in any of the cases. CONCLUSIONS: CMA was diagnostic in 2/39 (5.1%) cases, a pathogenic CNV implicating the SHOX gene, and maternal UPD 6, which were consistent with FGR. There was a remarkable rate (10%) of AOH. Further investigation, including placental studies and genome sequencing, may elucidate whether AOH is a contributing factor for FGR.

Humans↗

Histopathological features of breast cancer in carriers of ATM gene variants.

AIMS: Germline variants in the ataxia telangiectasia mutated (ATM) gene have been implicated in increased breast cancer risk. The aim of this study was to determine whether the histopathology of breast cancers occurring in ATM variant carriers is distinctive or resembles the described BRCA1 mutation-associated phenotype. METHODS: The histopathological features of breast cancers occurring in ATM variant carriers from multiple-case breast cancer families were compared with matched controls. The test group included 21 cases of in situ and/or invasive cancer from carriers of either the IVS10-6T-->G, 2424V-->G or 1420L-->F ATM variants in the absence of BRCA1 or BRCA2 mutations. An additional four invasive cancers from carriers of a pathogenic BRCA1 mutation in the context of a familial ATM variant were also examined. RESULTS: The histopathology of breast cancers in ATM variant-only carriers was not significantly different from controls and known features of BRCA1 mutation-associated cancer were rarely seen. In contrast, these features were prominent in the small group of cases with a pathogenic BRCA1 mutation. CONCLUSIONS: Breast cancer occurring in carriers of ATM variants is not associated with distinctive histopathological features and does not resemble the tumour phenotype commonly observed in BRCA1 mutation carriers.

Adult↗

[The role of biomarkers CK7, Vim and P53 in the development of subtypes of endometrial carcinoma].

OBJECTIVE: Analyzing the protein expression of biomarkers CK7, Vim, and P53 to investigate their possible pathogenic roles in the development of variant subtypes of endometrial carcinoma. METHODS: Biomarkers CK7, Vim, and P53 were immunohistochemistry-stained among 131 endometrial carcinoma specimens including 93 endometroid, 8 adenoacanthoma, and 32 rare subtypes of adenosquamas carcinoma, clean cell carcinoma, and papillary carcinoma, which had been confirmed clinically and pathologically, and studied statistically with Fisher test and Cochran-Mantel-Haenszel (CMH) Test. RESULTS: Positive correlation was demonstrated among CK7, Vim, and P53 expression levels. The CK7 protein expression is increased, while the Vim and P53 are decreased in the subtype of endometrioid carcinoma. The clinical staging of endometriroid carcinoma is positively correlated with the expression of Vim. The positive rate of Vim and P53 is correlated with cytological differentiation of the carcinoma cells. CONCLUSION: Biomarkers CK7, Vim, and P53 are playing pathogenic roles, assuming as a mutual transcriptional modulator, and Vim but not P53 is likely the favorable prognostic factor, in the development of variant subtypes of endometrial carcinoma in addition to a evaluating the treatment.

Adult↗

Molecular analysis of the pathogenicity locus and polymorphism in the putative negative regulator of toxin production (TcdC) among Clostridium difficile clinical isolates.

The pathogenicity locus (PaLoc) of Clostridium difficile contains toxin A and B genes and three accessory genes, including tcdD and tcdC, which are supposed to code for the positive and negative regulators of toxin expression, respectively. Different studies have described variations in C. difficile toxin A and B genes, but little is known about C. difficile variants for the accessory genes. The PaLoc of several C. difficile clinical isolates was investigated by three different PCR methods with the aim to identify variant strains. Of the toxinogenic C. difficile strains examined, 25% showed variations. No correlation between C. difficile variant strains and key patient groups was found. Interestingly, all of these strains showed a variant tcdC gene. Three different tcdC alleles were identified, and one of these had a nonsense mutation which reduced the TcdC protein from 232 to 61 amino acids. It is possible that different TcdC variants affect toxin production differently, a hypothesis with important implications for the pathogenic potential of variant C. difficile strains.

Amino Acid Sequence↗

Prevention and treatment of bronchopneumonia in mice caused by mouse-adapted variant of avian H5N2 influenza A virus using monoclonal antibody against conserved epitope in the HA stem region.

The effects of monoclonal antibody (MAb) C179 recognizing a conformational epitope in the middle of the hemagglutinine (HA) stem region were examined in a mouse model in the experiments of prevention and treatment of lethal bronchopneumonia caused by influenza A virus of H5 subtype. To model the lethal infection, avian nonpathogenic strain A/mallard duck/Pennsylvania/10218/84 (H5N2) was adapted to mice. This resulted in highly pathogenic pneumovirulent mouse-adapted (MA) variant, which was characterized. Three amino acid changes were found in the HA1 subunit of HA of MA virus. One of these was located inside the region of the conformational epitope recognized by MAb C179. However, this substitution was not significant for the recognition of HA and virus neutralization by MAb C179 in vitro and in vivo. Intraperitoneal administration of two different concentrations of MAb C179 one day before or two days after the virus challenge significantly decreased mortality rate. These results suggest that MAb C179 is efficient not only in the prevention and treatment of H1 and H2 influenza virus bronchopneumonia, as was reported previously, but also of H5-induced bronchopneumonia as well, and demonstrate in vivo the existence of a common neutralizing epitope in the HAs of these three subtypes.

Animals↗

Missense mutations but not allelic variants alter the function of ATM by dominant interference in patients with breast cancer.

The human genetic disorder ataxia-telangiectasia (A-T) is characterized by hypersensitivity to ionizing radiation and an elevated risk of malignancy. Epidemiological data support an increased risk for breast and other cancers in A-T heterozygotes. However, screening breast cancer cases for truncating mutations in the ATM (A-T mutated) gene has failed largely to reveal an increased incidence in these patients. It has been hypothesized that ATM missense mutations are implicated in breast cancer, and there is some evidence to support this. The presence of a large variety of rare missense variants in addition to common polymorphisms in ATM makes it difficult to establish such a relationship by association studies. To investigate the functional significance of these changes we have introduced missense substitutions, identified in either A-T or breast cancer patients, into ATM cDNA before establishing stable cell lines to determine their effect on ATM function. Pathogenic missense mutations and neutral missense variants were distinguished initially by their capacity to correct the radiosensitive phenotype in A-T cells. Furthermore missense mutations abolished the radiation-induced kinase activity of ATM in normal control cells, caused chromosome instability, and reduced cell viability in irradiated control cells, whereas neutral variants failed to do so. Mutant ATM was expressed at the same level as endogenous protein, and interference with normal ATM function seemed to be by multimerization. This approach represents a means of identifying genuine ATM mutations and addressing the significance of missense changes in the ATM gene in a variety of cancers including breast cancer.

Alleles↗