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Frontiers in Immunology 2023The pathogenic can be parsed into specific variants (pathovars) depending on their phenotypic behavior and/or expression of specific virulence factors. These pathogens... (Review)
Review
The pathogenic can be parsed into specific variants (pathovars) depending on their phenotypic behavior and/or expression of specific virulence factors. These pathogens are built around chromosomally-encoded core attributes and through acquisition of specific virulence genes that direct their interaction with the host. Engagement of pathovars with CEACAMs is determined both by core elements common to all as well as extrachromosomally-encoded pathovar-specific virulence traits, which target amino terminal immunoglobulin variable-like (IgV) regions of CEACAMs. Emerging data suggests that engagement of CEACAMs does not unilaterally benefit the pathogen and that these interactions may also provide an avenue for pathogen elimination.
Topics: Escherichia coli; Phenotype; Virulence; Virulence Factors
PubMed: 36865539
DOI: 10.3389/fimmu.2023.1120331 -
Microbiology Spectrum May 2024Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses in the swine industry. Frequent mutations and recombinations account for...
Isolation and pathogenicity comparison of two novel natural recombinant porcine reproductive and respiratory syndrome viruses with different recombination patterns in Southwest China.
Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses in the swine industry. Frequent mutations and recombinations account for PRRSV immune evasion and the emergence of novel strains. In this study, we isolated and characterized two novel PRRSV-2 strains from Southwest China exhibiting distinct recombination patterns. They were designated SCABTC-202305 and SCABTC-202309. Phylogenetic results indicated that SCABTC-202305 was classified as lineage 8, and SCABTC-202309 was classified as lineage 1.8. Amino acid mutation analysis identified unique amino acid substitutions and deletions in ORF5 and Nsp2 genes. The results of the recombination analysis revealed that SCABTC-202305 is a recombinant with JXA1 as the major parental strain and NADC30 as the minor parental strain. At the same time, SCABTC-202309 is identified as a recombinant with NADC30 as the major parental strain and JXA1 as the minor parental strain. In this study, we infected piglets with SCABTC-202305, SCABTC-202309, or mock inoculum (control) to study the pathogenicity of these isolates. Although both isolated strains were pathogenic, SCABTC-202305-infected piglets exhibited more severe clinical signs and higher mortality, viral load, and antibody response than SCABTC-202309-infected piglets. SCABTC-202305 also caused more extensive lung lesions based on histopathology. Our findings suggest that the divergent pathogenicity observed between the two novel PRRSV isolates may be attributed to variations in the genetic information encoded by specific genomic regions. Elucidating the genetic determinants governing PRRSV virulence and transmissibility will inform efforts to control this devastating swine pathogen.IMPORTANCEPorcine reproductive and respiratory syndrome virus (PRRSV) is one of the most critical pathogens impacting the global swine industry. Frequent mutations and recombinations have made the control of PRRSV increasingly difficult. Following the NADC30-like PRRSV pandemic, recombination events involving PRRSV strains have further increased. We isolated two novel field PRRSV recombinant strains, SCABTC-202305 and SCABTC-202309, exhibiting different recombination patterns and compared their pathogenicity in animal experiments. The isolates caused higher viral loads, persistent fever, marked weight loss, moderate respiratory clinical signs, and severe histopathologic lung lesions in piglets. Elucidating correlations between recombinant regions and pathogenicity in these isolates can inform epidemiologic tracking of emerging strains and investigations into viral adaptive mechanisms underlying PRRSV immunity evasion. Our findings underscore the importance of continued genomic surveillance to curb this economically damaging pathogen.
Topics: Porcine respiratory and reproductive syndrome virus; Animals; Swine; Porcine Reproductive and Respiratory Syndrome; China; Recombination, Genetic; Phylogeny; Virulence; Mutation; Genome, Viral
PubMed: 38511956
DOI: 10.1128/spectrum.04071-23 -
Biochemical Society Transactions Apr 2021Cells from all domains of life release extracellular vesicles (EVs), packages that carry a cargo of molecules that participate in communication, co-ordination of... (Review)
Review
Cells from all domains of life release extracellular vesicles (EVs), packages that carry a cargo of molecules that participate in communication, co-ordination of population behaviours, virulence and immune response mechanisms. Mammalian EVs play an increasingly recognised role to fight infection, yet may also be commandeered to disseminate pathogens and enhance infection. EVs released by bacterial pathogens may deliver toxins to host cells, signalling molecules and new DNA to other bacteria, and act as decoys, protecting infecting bacteria from immune killing. In this review, we explore the role of EVs in infection from the perspective of both the pathogen and host, and highlight their importance in the host/pathogen relationship. We highlight proposed strategies for EVs in therapeutics, and call attention to areas where existing knowledge and evidence is lacking.
Topics: Animals; Bacteria; Bacterial Infections; Drug Resistance, Microbial; Extracellular Vesicles; Host-Pathogen Interactions; Humans; Inflammation; Signal Transduction; Virulence
PubMed: 33860784
DOI: 10.1042/BST20200788 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Sep 2017Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of... (Review)
Review
Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of extracellular polymeric substances. Biofilm formation is a microbial defense response to biotic and abiotic stresses, and a key factor for survival in adverse environments. A wide variety of microorganisms can colonize distant tissues of higher plants, such as leaves, vascular network and roots, and adhere to the surface of the tissues to form biofilms. The dynamic processes in forming biofilms in response to plant internal environment are key steps required for full virulence of phytopathogenic bacteria. Exploring the mechanisms involved in regulation of bacterial biofilms is important for understanding the plant-pathogens interactions. In this review, we summarized the research progresses related to the biofilms of bacterial phytopathogens, including biofilm characteristics, essential regulatory mechanisms and key signals affecting the transition between a planktonic lifestyle and multicellular behavior.
Topics: Bacteria; Biofilms; Host-Pathogen Interactions; Plant Diseases; Plants; Virulence
PubMed: 28956407
DOI: 10.13345/j.cjb.170079 -
Virulence Dec 2019Opportunistic commensal and environmental fungi can cause superficial to systemic diseases in humans. But how did these pathogens adapt to infect us and how does... (Review)
Review
Opportunistic commensal and environmental fungi can cause superficial to systemic diseases in humans. But how did these pathogens adapt to infect us and how does host-pathogen co-evolution shape their virulence potential? During evolution toward pathogenicity, not only do microorganisms gain virulence genes, but they also tend to lose non-adaptive genes in the host niche. Additionally, virulence factors can become detrimental during infection when they trigger host recognition. The loss of non-adaptive genes as well as the loss of the virulence potential of genes by adaptations to the host has been investigated in pathogenic bacteria and phytopathogenic fungi, where they are known as antivirulence and avirulence genes, respectively. However, these concepts are nearly unknown in the field of pathogenic fungi of humans. We think that this unnecessarily limits our view of human-fungal interplay, and that much could be learned if we applied a similar framework to aspects of these interactions. In this review, we, therefore, define and adapt the concepts of antivirulence and avirulence genes for human pathogenic fungi. We provide examples for analogies to antivirulence genes of bacterial pathogens and to avirulence genes of phytopathogenic fungi. Introducing these terms to the field of pathogenic fungi of humans can help to better comprehend the emergence and evolution of fungal virulence and disease.
Topics: Adaptation, Physiological; Animals; Evolution, Molecular; Fungi; Genes, Fungal; Host-Pathogen Interactions; Humans; Mice; Virulence; Virulence Factors
PubMed: 31711357
DOI: 10.1080/21505594.2019.1688753 -
Cold Spring Harbor Perspectives in... Aug 2014We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus... (Review)
Review
We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus neoformans/gattii, and Aspergillus fumigatus. Where appropriate or relevant, we introduce findings on other species associated with human infections. In particular, we focus on rapid advances involving genetic, genomic, and population genetic approaches that have reshaped our view of how fungal pathogens evolve. Rather than being asexual, mitotic, and largely clonal, as was thought to be prevalent as recently as a decade ago, we now appreciate that the vast majority of pathogenic fungi have retained extant sexual, or parasexual, cycles. In some examples, sexual and parasexual unions of pathogenic fungi involve closely related individuals, generating diversity in the population but with more restricted recombination than expected from fertile, sexual, outcrossing and recombining populations. In other cases, species and isolates participate in global outcrossing populations with the capacity for considerable levels of gene flow. These findings illustrate general principles of eukaryotic pathogen emergence with relevance for other fungi, parasitic eukaryotic pathogens, and both unicellular and multicellular eukaryotic organisms.
Topics: Drug Resistance, Fungal; Fungi; Humans; Hyphae; Mycoses; Reproduction; Self-Fertilization; Virulence
PubMed: 25085958
DOI: 10.1101/cshperspect.a019281 -
Microbiology Spectrum Jun 2016Bacterial pathogens must endure or adapt to different environments and stresses during transmission and infection. Posttranscriptional gene expression control by... (Review)
Review
Bacterial pathogens must endure or adapt to different environments and stresses during transmission and infection. Posttranscriptional gene expression control by regulatory RNAs, such as small RNAs and riboswitches, is now considered central to adaptation in many bacteria, including pathogens. The study of RNA-based regulation (riboregulation) in pathogenic species has provided novel insight into how these bacteria regulate virulence gene expression. It has also uncovered diverse mechanisms by which bacterial small RNAs, in general, globally control gene expression. Riboregulators as well as their targets may also prove to be alternative targets or provide new strategies for antimicrobials. In this article, we present an overview of the general mechanisms that bacteria use to regulate with RNA, focusing on examples from pathogens. In addition, we also briefly review how deep sequencing approaches have aided in opening new perspectives in small RNA identification and the study of their functions. Finally, we discuss examples of riboregulators in two model pathogens that control virulence factor expression or survival-associated phenotypes, such as stress tolerance, biofilm formation, or cell-cell communication, to illustrate how riboregulation factors into regulatory networks in bacterial pathogens.
Topics: Adaptation, Physiological; Bacteria; Bacterial Physiological Phenomena; Gene Expression Regulation, Bacterial; RNA, Small Untranslated; Virulence; Virulence Factors
PubMed: 27337442
DOI: 10.1128/microbiolspec.VMBF-0028-2015 -
International Journal of Molecular... Aug 2023is a devastating fungal pathogen that causes severe crop losses worldwide. It is of vital importance to understand its pathogenic mechanism for disease control. Through...
is a devastating fungal pathogen that causes severe crop losses worldwide. It is of vital importance to understand its pathogenic mechanism for disease control. Through a forward genetic screen combined with next-generation sequencing, a putative protein kinase, Cak1, was found to be involved in the growth and pathogenicity of . Knockout and complementation experiments confirmed that deletions in caused defects in mycelium and sclerotia development, as well as appressoria formation and host penetration, leading to complete loss of virulence. These findings suggest that Cak1 is essential for the growth, development, and pathogenicity of . Therefore, Cak1 could serve as a potential target for the control of infection through host-induced gene silencing (HIGS), which could increase crop resistance to the pathogen.
Topics: Virulence; Ascomycota; Gene Silencing; High-Throughput Nucleotide Sequencing
PubMed: 37628791
DOI: 10.3390/ijms241612610 -
Microbiological Research Jan 2021Candida auris is a worrisome fungal pathogen of humans which emerged merely about a decade ago. Ever since then the scientific community worked hard to understand... (Review)
Review
Candida auris is a worrisome fungal pathogen of humans which emerged merely about a decade ago. Ever since then the scientific community worked hard to understand clinically relevant traits, such as virulence factors, antifungal resistance mechanisms, and its ability to adhere to human skin and medical devices. Whole-genome sequencing of clinical isolates and epidemiological studies outlining the path of nosocomial outbreaks have been the focus of research into this pathogenic and multidrug-resistant yeast since its first description in 2009. More recently, work was started by several laboratories to explore the biology of C. auris. Here, we review the insights of studies characterizing the mechanisms underpinning antifungal drug resistance, biofilm formation, morphogenetic switching, cell aggregation, virulence, and pathogenicity of C. auris. We conclude that, although some progress has been made, there is still a long journey ahead of us, before we fully understand this novel pathogen. Critically important is the development of molecular tools for C. auris to make this fungus genetically tractable and traceable. This will allow an in-depth molecular dissection of the life cycle of C. auris, of its characteristics while interacting with the human host, and the mechanisms it employs to avoid being killed by antifungals and the immune system.
Topics: Antifungal Agents; Biofilms; Candida; Candidiasis; Drug Resistance, Fungal; Fungi; Humans; Microbial Sensitivity Tests; Mutation; Phenotype; Transcriptome; Virulence; Virulence Factors; Whole Genome Sequencing
PubMed: 33096325
DOI: 10.1016/j.micres.2020.126621 -
Frontiers in Cellular and Infection... 2018Iron is an absolute requirement for both the host and most pathogens alike and is needed for normal cellular growth. The acquisition of iron by biological systems is... (Review)
Review
Iron is an absolute requirement for both the host and most pathogens alike and is needed for normal cellular growth. The acquisition of iron by biological systems is regulated to circumvent toxicity of iron overload, as well as the growth deficits imposed by iron deficiency. In addition, hosts, such as humans, need to limit the availability of iron to pathogens. However, opportunistic pathogens such as are able to adapt to extremes of iron availability, such as the iron replete environment of the gastrointestinal tract and iron deficiency during systemic infection. has developed a complex and effective regulatory circuit for iron acquisition and storage to circumvent iron limitation within the human host. As can form complex interactions with both commensal and pathogenic co-inhabitants, it can be speculated that iron may play an important role in these interactions. In this review, we highlight host iron regulation as well as regulation of iron homeostasis in . In addition, the review argues for the need for further research into the role of iron in polymicrobial interactions. Lastly, the role of iron in treatment of infection is discussed.
Topics: Candida albicans; Candidiasis; Gastrointestinal Tract; Gene Expression Regulation, Fungal; Homeostasis; Host-Pathogen Interactions; Humans; Immunity; Iron; Microbial Interactions; Symbiosis; Virulence
PubMed: 29922600
DOI: 10.3389/fcimb.2018.00185