Genetics

Kaper, James B.; Baldini, Mary M.

doi:10.1007/978-1-4757-9688-9_4

Cited by 10 publications

(12 citation statements)

References 141 publications

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“…Almost all recent cholera pandemics have emanated from this region of the world. 22 Patients of group O were more susceptible in an outbreak of gastrointestinal infections caused by Escherichia coli O157 in Scotland in 1996. A total of 87.5% of patients who died were group O.…”

Section: Infectious Diseases and Selection For Abo Blood Group Antigensmentioning

confidence: 99%

The relationship between blood groups and disease

Anstee

2010

Blood

381

349

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The relative contribution of founder effects and natural selection to the observed distribution of human blood groups has been debated since blood group frequencies were shown to differ between populations almost a century ago. Advances in our understanding of the migration patterns of early humans from Africa to populate the rest of the world obtained through the use of Y chromosome and mtDNA markers do much to inform this debate. There are clear examples of protection against infectious diseases from inheritance of polymorphisms in genes encoding and regulating the expression of ABH and Lewis antigens in bodily secretions particularly in respect of Helicobacter pylori, norovirus, and cholera infections. However, available evidence suggests surviving malaria is the most significant selective force affecting the expression of blood groups. IntroductionHirszfeld and Hirszfeld 1 showed the frequencies of blood groups A and B differ between populations. Their observations raised fundamental questions regarding the causes of these differences, which were eloquently summarized by Mourant et al 2(p1) :Were the differences the result of random genetic drift and founder effects, in small populations which later multiplied and stabilized the original, fortuitous, frequencies, or were they the result of natural selection, arising from differences in fitness between the various blood groups, fitnesses which themselves depended upon locally determined features of the external environment?Mourant et al concluded that "most workers now agree that both processes are operative, but their relative importance remains in question." 2 We now have detailed information concerning almost all the genes giving rise to blood group polymorphisms, the structure of the gene products and the antigens themselves, and in many cases functional information sufficient to delineate mechanisms of interaction with external agents. [3][4][5] In addition, studies on the tracking of Y chromosome and mtDNA haplotypes in human populations provide us with unprecedented information concerning the significance of genetic drift and founder effects in determining the genetic background of different world populations. 6 Given this new information, it seems an appropriate time to revisit these questions and ask whether we are any nearer understanding the relative importance of natural selection and founder effects in determining the distribution of human blood groups. Infectious diseases and selection for ABO blood group antigensThe molecular basis of the ABO blood group system was elucidated in 1990. 7 The gene encodes a glycosyltransferase, which transfers N-acetyl D-galactosamine (group A) or D-galactose (group B) to the nonreducing ends of glycans on glycoproteins and glycolipids. The group O phenotype results from inactivation of the A1 glycosyltransferase gene, and the nonreducing ends of the corresponding glycans in group O subjects express the blood group H antigen ( Figure 1A). The ABH antigens are not confined to red cells but are widely expressed i...

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Section: Infectious Diseases and Selection For Abo Blood Group Antigensmentioning

confidence: 99%

The relationship between blood groups and disease

Anstee

2010

Blood

381

349

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“…Although, V. cholerae contains more than 200 serotypes based on its O antigen, only serotypes O1 and O139 are known as the causative agents of epidemic and pandemic cholera outbreaks (Bag et al, 2008). These serotypes are characterized by their ability to produce cholera toxin that is encoded by ctx gene (Kaper et al, 1995), which has been used for specific detection of choleragenic V. cholerae in environmental samples (Karunasagar et al, 1997). Certain phenotypic and genetic properties are used to categorise Vibrio cholerae O1 into two biotypes: classical and El Tor.…”

Section: Vibrio Cholerae and Cholera Biotypesmentioning

confidence: 99%

“…This bacterial species has both a tendency to trigger epidemics with pandemic potential and the ability to stay endemic in all affected areas. In the epidemic setting, the entire population is susceptible to infection at the start of the epidemic due to little or naturally acquired immunity to cholera (Kaper et al, 1995;Faruque et al, 2007a). In contrary in highly endemic areas, the population had prior exposure to V. cholerae and at least some immunity to reinfection (Faruque et al, 2007a).…”

Section: Vibrio Cholerae and Cholera Biotypesmentioning

confidence: 99%

Vibrio cholerae and Cholera biotypes

Momba¹,

El‐Liethy²

2019

Water and Sanitation for the 21st Century: Health and Microbiological Aspects of Excreta and Wastewater Management (Global Wate

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“…Of particular concern are the recently published results indicating that some of the clinically isolated El Tor variants produce different levels of cholera toxin, including some isolates that produce higher levels than classical biotype strains (16). Although evidence has been presented demonstrating that the El Tor biotype has globally displaced the classical biotype (19,42), the emergence of El Tor variants has warranted the use of standard genotypic and phenotypic assays to determine the biotype background of new isolates. Standard phenotypic assays, including polymyxin B resistance, hemolysis assays, phage sensitivities, and the Voges-Proskauer tests, are frequently employed in some combination (4,11,45).…”

mentioning

confidence: 99%

Characterization of Vibrio cholerae O1 El Tor Biotype Variant Clinical Isolates from Bangladesh and Haiti, Including a Molecular Genetic Analysis of Virulence Genes

et al. 2011

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Vibrio cholerae serogroup O1, the causative agent of the diarrheal disease cholera, is divided into two biotypes: classical and El Tor. Both biotypes produce the major virulence factors toxin-coregulated pilus (TCP) and cholera toxin (CT). Although possessing genotypic and phenotypic differences, El Tor biotype strains displaying classical biotype traits have been reported and subsequently were dubbed El Tor variants. Of particular interest are reports of El Tor variants that produce various levels of CT, including levels typical of classical biotype strains. Here, we report the characterization of 10 clinical isolates from the International Centre for Diarrhoeal Disease Research, Bangladesh, and a representative strain from the 2010 Haiti cholera outbreak. We observed that all 11 strains produced increased CT (2-to 10-fold) compared to that of wild-type El Tor strains under in vitro inducing conditions, but they possessed various TcpA and ToxT expression profiles. Particularly, El Tor variant MQ1795, which produced the highest level of CT and very high levels of TcpA and ToxT, demonstrated hypervirulence compared to the virulence of El Tor wild-type strains in the infant mouse cholera model. Additional genotypic and phenotypic tests were conducted to characterize the variants, including an assessment of biotype-distinguishing characteristics. Notably, the sequencing of ctxB in some El Tor variants revealed two copies of classical ctxB, one per chromosome, contrary to previous reports that located ctxAB only on the large chromosome of El Tor biotype strains.Vibrio cholerae is a Gram-negative, curved-rod-shaped bacterium that is the causative agent of the watery diarrheal disease cholera. The structure of the cell surface lipopolysaccharide O antigen is used to classify V. cholerae into more than 200 serogroups, of which only two, O1 and O139, possess the potential to cause epidemic or pandemic cholera. The O1 serogroup is further divided into two biotypes, classical and El Tor, which evolved from independent lineages (20, 22), and they display genotypic and phenotypic differences.V. cholerae O1 is distinguished by two of its major virulence factors, cholera toxin (CT) and the toxin-coregulated pilus (TCP). The cholera toxin is encoded by ctxA and ctxB, which are found on the CTX prophage (49), and is responsible for the manifestation of diarrheal disease with severe water and electrolyte loss. The TCP, encoded by the tcp operon in the Vibrio pathogenicity island (VPI), is required for V.

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Genetics

Cited by 10 publications

References 141 publications

The relationship between blood groups and disease

The relationship between blood groups and disease

Vibrio cholerae and Cholera biotypes

Characterization of Vibrio cholerae O1 El Tor Biotype Variant Clinical Isolates from Bangladesh and Haiti, Including a Molecular Genetic Analysis of Virulence Genes

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