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What are virulence genes? 

Serotype
Medicine
Escherichia coli
Shiga toxin
Legionella
Best insight from top research papers

A large portion of annual deaths worldwide are due to infections caused by disease-causing pathogens. These pathogens contain virulence genes, which encode mechanisms that facilitate infection and microbial survival in hosts. More recently, antimicrobial resistance (AMR) genes, also found in these pathogens, have become an increasingly large issue. While the National Center for Biotechnology Information (NCBI) Pathogen Detection Isolates Browser (NPDIB) database has been compiling genes involved in microbial virulence and antimicrobial resistance through isolate samples, few studies have identified the genes primarily responsible for virulence and compared them to those responsible for AMR. This study performed the first multivariate statistical analysis of the multidimensional NPDIB data to identify the major virulence genes from historical pathogen isolates for Australia, China, South Africa, UK, and US—the largely populated countries from five of the six major continents. The important virulence genes were then compared with the AMR genes to study whether there is correlation between their occurrences. Among the significant genes and pathogens associated with virulence, it was found that the genes fdeC, iha, iss, iutA, lpfA, sslE, ybtP, and ybtQ are shared amongst all five countries. The pathogens E. coli and Shigella, Salmonella enterica, and Klebsiella pneumoniae mostly contained these genes and were common among four of the five studied countries. Additionally, the trend of virulence was investigated by plotting historical occurrences of gene and pathogen frequency in the annual samples. These plots showed that the trends of E. coli and Shigella and Salmonella enterica were similar to the trends of certain virulence genes, confirming the two pathogens do indeed carry important virulence genes. While the virulence genes in the five countries are not significantly different, the US and the UK share the largest amount of important virulence genes. The plots from principal component analysis and hierarchical clustering show that the important virulence and AMR genes were not significantly correlated, with only few genes from both. The Enterohemorrhagic Escherichia coli (EHEC) is one of the most common E. coli pathotypes reported to cause several outbreaks of foodborne illnesses. EHE C is a zoonotic pathogen, and ruminants, especially cattle, are considered important reservoirs for the most common EHEC serotype, E. coli O157:H7. Humans are infected indirectly through the consumption of food (milk, meat, leafy vegetables, and fruits) and water contaminated by animal feces or direct contact with carrier animals or humans. E. coli O157:H7 is one of the most frequently reported causes of foodborne illnesses in developed countries. It employs two essential virulence mechanisms to trigger damage to the host. These are the development of attaching and effacing (AE) phenotypes on the intestinal mucosa of the host and the production of Shiga toxin (Stx) that causes hemorrhagic colitis and hemolytic uremic syndrome. The AE phenotype is controlled by the pathogenicity island, the locus of enterocyte effacement. The induction of both AE and Stx is under strict and highly complex regulatory mechanisms. Thus, a good understanding of these mechanisms, and major proteins expressed, and environmental cues involved in the regulation of the expression of the virulence genes is vital to finding a method to control the colonization of reservoir hosts, especially cattle. Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Pathogenic microbes contain certain abilities to cause infections or diseases in hosts during interactions. Virulence factors aggravate the defense mechanisms of the host to establish infections. The nature and type of virulence factors determine the pathogenicity of microorganisms. This report addresses the several varieties of virulence mechanisms developed by the microorganisms (fungi, bacteria, and virus) which comprise virulence factors or genes. These virulence factors can be enzymes, toxins, lipids

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Open access•Journal Article•DOI
Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in Listeria monocytogenes Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.
Sofia V. Poimenidou, Marion Dalmasso, Konstantinos Papadimitriou, Edward M. Fox, Panagiotis N. Skandamis, Kieran Jordan 
05 Jun 2018-Frontiers in Microbiology
33 Citations
Virulence genes are key components of pathogenicity islands in Listeria monocytogenes, including prfA, plcA, hly, mpl, actA, and plcB, influencing strain virulence and epidemiology.
Book Chapter•DOI
Virulence Factors and Their Associated Genes in Microbes
Mukesh Meena, Mukesh Meena, Mukesh Meena, Prashant Swapnil, Andleeb Zehra, Mohd Aamir, Manish Kumar Dubey, Chandra Bali Patel, Ram Sanmukh Upadhyay 
01 Jan 2019
32 Citations
Virulence genes are specific genes in microbes that encode virulence factors, such as enzymes, toxins, and flagella, enabling pathogens to cause infections and evade host defenses.
Open access•Journal Article•DOI
Investigation of Virulence Genes Detected in Antimicrobial-Resistance Pathogens Isolates for Five Countries across the World
Kevin Cui, Iris Gong, Alvin Dong, Jacob Yan, Max Wang, Zuyi Huang 
02 Dec 2020
3 Citations
Virulence genes encode mechanisms that aid pathogens in causing infection and surviving in hosts. They were studied alongside antimicrobial resistance genes in pathogens from five countries.
Journal Article•DOI
Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients
Xiao-Yong Zhan, Chao-Hui Hu, Qing-Yi Zhu 
12 Jan 2016-Archives of Microbiology
4 Citations
Virulence genes are specific DNA regions present in pathogenic bacteria, absent in nonpathogenic strains, and associated with bacterial pathogenicity, as observed in Legionella strains in the study.
Journal Article•DOI
Regulation Mechanisms of Virulence Genes in Enterohemorrhagic Escherichia coli.
Benti Deresa Gelalcha, Selina M Brown, Hannah E Crocker, Getahun E. Agga, O Kerro Dego 
03 Aug 2022-Foodborne Pathogens and Disease
5 Citations
Virulence genes are crucial for Enterohemorrhagic Escherichia coli (EHEC) to cause illness by triggering attaching and effacing phenotypes and producing Shiga toxin, controlled by complex regulatory mechanisms.

Related Questions

What are the genetic factors that contribute to the virulence of Staphylococcus aureus in humans?5 answersStaphylococcus aureus is a pathogenic bacterium that causes skin and soft tissue infections in humans. Several genetic factors contribute to its virulence. In a study by Rodrigues et al., specific virulence patterns associated with clinical and subclinical mastitis strains in cattle and human origin were identified. These patterns included the presence of adhesion genes (cflA, fnbA, ebpS, spa, sdrC, coa, emp, vWF, atl, sasH, sasA, and sasF) and toxin genes (aur, hglA, hglB, and hglC) in clinical mastitis strains. Poh et al. investigated the expression of S. aureus virulence factors in atopic dermatitis (AD) skin sites and found that many virulence factors were expressed at the AD skin sites, including adhesins, proteases, toxins, and immune modulators. Cruz et al. studied the gene expression profile of S. aureus USA300 LAC strain in human skin explants and identified 12 upregulated virulence factors, including alpha-hemolysin. Adame-Gómez et al. compared the genetic diversity and virulence profiles of S. aureus strains isolated from food, humans, and animals and found that the seA, saK, and hlB genes were commonly present in the strains. These studies highlight the diverse genetic factors that contribute to the virulence of S. aureus in humans, including adhesion genes, toxin genes, proteases, and immune modulators.
How do cholera toxin and other virulence factors contribute to pathogenesis?5 answersCholera toxin (CT) and other virulence factors contribute to the pathogenesis of cholera by inducing severe diarrhea and disrupting barrier function. CT, encoded by the gene ctxAB, is directly responsible for the severity of the disease. CT binds to GM1 ganglioside receptors on the apical membrane of intestinal epithelial cells and catalyzes ADP ribosylation of α subunits of stimulatory G proteins, leading to increased intracellular cAMP. Increased intracellular cAMP in human intestinal epithelial cells accounts for the profuse diarrhea and severe fluid loss in cholera. In addition to CT, V. cholerae possesses other virulence factors that contribute to survival, colonization, and virulence in the host. These factors are regulated by an intricate program involving extracellular signaling inputs. The innate immune response to V. cholerae infection is also influenced by the presence of cholera toxin and other secreted factors, which modulate the host response and contribute to bacterial persistence and virulence.
What is the virulence genes in pseudomonas aeruginosa ?2 answersPseudomonas aeruginosa has been found to possess several virulence genes, including RelBE, HigBA, exoenzyme S, exotoxin A, PilB, LasB, OPRL, PLCH, ToxA, algD, and plcN. These genes play a significant role in the pathogenicity and antibiotic resistance of P. aeruginosa. The RelBE and HigBA genes are involved in biofilm formation and have been linked to antibiotic resistance. The exoenzyme S and exotoxin A genes are present in all P. aeruginosa isolates and are associated with bacterial virulence. The PilB gene is detected in approximately 56.6% of isolates, while the LasB gene is found in all bacterial isolates. The OPRL and LasB genes are the most frequent virulence genes in P. aeruginosa strains, followed by PLCH and ToxA. The nan1 gene is the least commonly expressed virulence gene. The algD, lasB, plcN, and plcH genes are found in all carbapenem-resistant and carbapenem-sensitive P. aeruginosa isolates.
What is the meaning of the genes which were preserved in the same manner as the pathogen virulence gene?3 answersThe preservation of certain genes in the same manner as pathogen virulence genes suggests that these genes may play a role in the regulation or modulation of pathogenicity. These genes, known as antivirulence genes (AVGs), are present in bacteria such as Shigella, Salmonella, Yersinia pestis, and Francisella tularensis subspecies. AVGs can be involved in various functions within the microbe, including metabolism, biofilm synthesis, lipopolysaccharide modification, and host vasoconstriction. The inactivation or deletion of these AVGs is necessary for the full expression of the pathogen phenotype. The presence of AVGs in pathogenic bacteria provides insights into pathogen evolution and offers potential targets for drug and vaccine development. The preservation of these genes suggests that they may have important roles in the fine-tuning of pathogenicity and the successful incorporation of virulence factors into the microbe's genome.
Does the expression of virulence genes influence the colonization capacity of microorganisms?5 answersThe expression of virulence genes can influence the colonization capacity of microorganisms. In the case of Bacillus cereus, the presence of virulence genes was detected in all isolates obtained from contaminated meat and milk products, indicating their potential to cause disease in humans. Similarly, in Vibrio parahaemolyticus, the expression of immune and toxic genes was found to be highest in post-larvae stages of Penaeus monodon, which correlated with increased mortality rates in the shrimp. This suggests that the expression of virulence genes contributes to the pathogenicity of V. parahaemolyticus. Furthermore, studies have shown that subsets of bacteria with higher expression of virulence factors emerge during infection and are more resistant to antibiotics, indicating a link between virulence factor expression, slowed growth, and antibiotic tolerance. Overall, these findings highlight the importance of virulence gene expression in the colonization and pathogenicity of microorganisms.
Which genes are involved in virulence factor for Mycobacteriun tuberculosis?5 answersSeveral genes are involved in the virulence factors of Mycobacterium tuberculosis (Mtb). One important gene is ESAT-6, which is secreted by the pathogen and plays a role in hijacking macrophage function to establish successful infection and transmission. Another gene, hbhA, is responsible for adherence of Mtb to non-phagocytic cells and the formation of intracytosolic lipid inclusions. Additionally, there are genes involved in modulating the physiology of Mtb to evade the host immune system and persist within macrophages, such as those involved in cell entry, fatty acid degradation, mycolic acid synthesis, and phagosome acidification inhibition. Furthermore, the gene Rv2577 has been identified as a potential alkaline phosphatase/phosphodiesterase enzyme, playing a role in Mtb virulence. These genes and their functions are crucial for the pathogenicity and survival of Mtb.

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