El Tor cholera at the contemporary stage of the seventh pandemia: pathogen evolution, clinical and epidemiological features, laboratory diagnostics

The phenotypic and molecular genetic properties of 133 strains of genetically modified (genovariant) Vibrio cholerae O1 El Tor biovar isolated from patients in Dagestan (1993, 1994, 1998), and compared with 246 strains of a typical toxigenic cholera vibrio El Tor biovar isolated in 1970–1990 at the Caucasus Region. It was found that 48.7% of the studied genetically modified strain variants had mixed phenotypic properties of the El Tor and classic biovars that evidences about a need to include the marker genes of the classical biovar (ctxBCl+, rtxC–) and the El Tor biovar (ctxBEl+, rtxC+) into the existing biotyping scheme. The genes of the El Tor biovar, isolated from patients in Dagestan, contain in addition to the El Tor ones, the genes of the classical biovar (ctxBCl and/or rstRCl), as well as the typical toxigenic cholera vibrios of El Tor, islands of persistence (EPI), pathogenicity (VPI-1 and VPI-2) and pandemicity (VSP-I and VSP-II). However, only the El Tor biovar genovariants were found to bear an integrative and conjugative SXT element with antibiotic polyresistance genes. Epidemic cholera outbreaks caused by the El Tor biovar genovariants that occurred in 1993–1998 at the Caucasus Region, correspond to classical (Asian) cholera based on disease severity. The epidemiological features of modern cholera were studied: the main way for transmission via fecal-oral route for typical El Tor cholera vibrio is waterborne, whereas for the El Tor gene variant — household. Primary infections upon water drinking and using domestic water from surface water bodies infected with typical El Tor vibrios occur outside the family hearth. In case of cholera caused by hybrid El Tor variants, infection is transmitted among family members via domestic factors under low sanitary level. The development of laboratory diagnostics and epidemiological surveillance of modern El Tor cholera is based on the development of PCR test systems taking into account the evolutionary genome transformations.

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The evolution of the pathogen and the clinical and epidemiological features of the recent cholera (el tor)

Epidemiology and Infectious Diseases (Russian Journal) ◽

10.17816/eid40707 ◽

2012 ◽

Vol 17 (5) ◽

pp. 31-35

Author(s):

V. N. Savelyev ◽

I. V. Savelyeva ◽

B. V. Babenyshev ◽

A. N. Kulichenko

Keyword(s):

Genetic Structure ◽

Vibrio Cholerae ◽

Causative Agent ◽

Genetically Modified ◽

Causative Factor ◽

Prevention Measures ◽

Cholera Outbreak ◽

The Caucasus ◽

Epidemiological Features ◽

El Tor

In a comparative perspective studied cholera outbreak in the Caucasus due to typical toxigenic and genetically modified (hybrid) El Tor variant strains have been studied. Revealed features of the genetic structure of the genome, factors and ways of transmission of the causative agent of modern cholera El tor should be considered when improving the program of epidemiological supervision in terms of enhancing antiepidemic and prevention measures in cholera, the causative factor of which are of hybrid variants of Vibrio cholerae El tor.

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MLVA-TYPING OF CLINICAL STAMPS OF GENETICALLY CHANGED VIBRIO CHOLERAE BIOTYPE EL TOR INSULATED IN RUSSIA AND UKRAINE IN THE PERIOD OF SEVENTH PANDEMIC CHOLERA

Journal of microbiology epidemiology immunobiology ◽

10.36233/0372-9311-2018-6-37-43 ◽

2018 ◽

pp. 37-43

Author(s):

I. V. Savelieva ◽

A. N. Kulichenko ◽

V. N. Saveliev ◽

D. A. Kovalev ◽

O. V. Vasilieva ◽

...

Keyword(s):

Phylogenetic Analysis ◽

Vibrio Cholerae ◽

Genetically Modified ◽

Cholera Vibrio ◽

Separate Branch ◽

Comparative Aspect ◽

The Russian Federation ◽

Time Periods ◽

El Tor ◽

Mlva Typing

Aim. Conduct in a comparative aspect MLVA-typing of genetically altered cholera vibrio biovar El Tor, isolated from patients during the epidemic (1994) and outbreaks (1993, 1998) in Dagestan with isolates in Mariupol (Ukraine) in 1994-2011 in Moscow (2010, 2012), India (1964, 2006, 2007), Bangladesh 1991, 1994, 2001, 2004) and to establish Phylogenetic connections between strains of cholera vibrios isolated in different years in these territories, to ascertain the source of their drift. Materials and methods. MLVA-tyP-ing was carried out in PCR at 5 variable loci of 35 clinical strains of genetically modified Vibrio cholerae byotyPe El Tor. The obtained amPlicon was studied in the system of automatic caPillary electroPhoresis ExPerion («Bio Rad Laboratories», USA). For Phylogenetic analysis, along with MLVA-genotyPes, 35 strains of Vibrio cholerae from the Institute's collection used Published genotyPes of strains isolated in India, Bangladesh, Haiti. Results. The investigated strains of cholera vibrio are referred to 21 MLVA-tyPes, divided into 2 main clades and 1 seParate branch with clonal clusters and subclusters, each of which contains closely related strains of cholera vibrio genovariants having a different degree of Phylogenetic relationshiP - full or Partial identity of allelic Profiles of five variable loci. The sources of drift of genetically modified Vibrio cholerae byotyPe El Tor to Russia and Ukraine from disadvantaged cholera of India, Bangladesh, Azerbaijan and the countries of the Middle East have been established. Conclusion. The obtained data testify to the PolymorPhism of MLVA-tyPes of genetically altered strains of cholera vibrio of the biologist El Tor, evolved in different years and caused ePidemics or outbreaks of cholera in different territories during different time Periods of the course of the seventh cholera Pandemic, and also suggest the Polyclonal origin of the Vibrio cholerae biovar El Tor and the source of their drift to the territory of the Russian Federation and Ukraine.

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African Swine Fever Virus Georgia 2007 with a Deletion of Virulence-Associated Gene9GL(B119L), when Administered at Low Doses, Leads to Virus Attenuation in Swine and Induces an Effective Protection against Homologous Challenge

Journal of Virology ◽

10.1128/jvi.00969-15 ◽

2015 ◽

Vol 89 (16) ◽

pp. 8556-8566 ◽

Cited By ~ 55

Author(s):

Vivian O'Donnell ◽

Lauren G. Holinka ◽

Peter W. Krug ◽

Douglas P. Gladue ◽

Jolene Carlson ◽

...

Keyword(s):

African Swine Fever Virus ◽

Genetically Modified ◽

African Swine Fever ◽

Fever Virus ◽

The Caucasus ◽

Caucasus Region ◽

Homologous Virus ◽

Virulent Virus ◽

Virulent Phenotype ◽

Highly Virulent

ABSTRACTAfrican swine fever virus (ASFV) is the etiological agent of an often lethal disease of domestic pigs. Disease control strategies have been hampered by the unavailability of vaccines against ASFV. Since its introduction in the Republic of Georgia, a highly virulent virus, ASFV Georgia 2007 (ASFV-G), has caused an epizootic that spread rapidly into Eastern European countries. Currently no vaccines are available or under development to control ASFV-G. In the past, genetically modified ASFVs harboring deletions of virulence-associated genes have proven attenuated in swine, inducing protective immunity against challenge with homologous parental viruses. Deletion of the gene9GL(open reading frame [ORF] B119L) in highly virulent ASFV Malawi-Lil-20/1 produced an attenuated phenotype even when administered to pigs at 10650% hemadsorption doses (HAD50). Here we report the construction of a genetically modified ASFV-G strain (ASFV-G-Δ9GLv) harboring a deletion of the9GL(B119L) gene. Like Malawi-Lil-20/1-Δ9GL, ASFV-G-Δ9GL showed limited replication in primary swine macrophages. However, intramuscular inoculation of swine with 104HAD50of ASFV-G-Δ9GL produced a virulent phenotype that, unlike Malawi-Lil-20/1-Δ9GL, induced a lethal disease in swine like parental ASFV-G. Interestingly, lower doses (102to 103HAD50) of ASFV-G-Δ9GL did not induce a virulent phenotype in swine and when challenged protected pigs against disease. A dose of 102HAD50of ASFV-G-Δ9GLv conferred partial protection when pigs were challenged at either 21 or 28 days postinfection (dpi). An ASFV-G-Δ9GL HAD50of 103conferred partial and complete protection at 21 and 28 dpi, respectively. The information provided here adds to our recent report on the first attempts toward experimental vaccines against ASFV-G.IMPORTANCEThe main problem for controlling ASF is the lack of vaccines. Studies on ASFV virulence lead to the production of genetically modified attenuated viruses that induce protection in pigs but only against homologous virus challenges. Here we produced a recombinant ASFV lacking virulence-associated gene9GLin an attempt to produce a vaccine against virulent ASFV-G, a highly virulent virus isolate detected in the Caucasus region in 2007 and now spreading though the Caucasus region and Eastern Europe. Deletion of9GL, unlike with other ASFV isolates, did not attenuate completely ASFV-G. However, when delivered once at low dosages, recombinant ASFV-G-Δ9GL induces protection in swine against parental ASFV-G. The protection against ASFV-G is highly effective after 28 days postvaccination, whereas at 21 days postvaccination, animals survived the lethal challenge but showed signs of ASF. Here we report the design and development of an experimental vaccine that induces protection against virulent ASFV-G.

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The Evolution of Phenotypic Properties and Molecular Genetic Organization of Genomes of Vibrio Cholerae O1 El Tor Variant Strains Isolated from Patients and Environmental Objects in the Caucasus in 1970–1998

ЗДОРОВЬЕ НАСЕЛЕНИЯ И СРЕДА ОБИТАНИЯ - ЗНиСО / PUBLIC HEALTH AND LIFE ENVIRONMENT ◽

10.35627/2219-5238/2020-333-12-56-61 ◽

2020 ◽

pp. 56-61

Author(s):

VN Savelyev ◽

DA Kovalev ◽

IV Savelyeva ◽

TV Taran ◽

EI Podoprigora ◽

...

Keyword(s):

Vibrio Cholerae ◽

Molecular Genetic ◽

Laboratory Diagnosis ◽

Classical Type ◽

Phenotypic Properties ◽

The Caucasus ◽

Genetic Characteristics ◽

Environmental Objects ◽

Vibrio Cholerae O1 ◽

El Tor

Summary. Introduction: The formation of highly pathogenic strains of Vibrio cholerae resistant to antibiotics determines the pathogenesis, clinical picture, epidemiology, and laboratory diagnosis of cholera. It is necessary to study the structure of the genome of V. cholerae of any serological groups isolated during routine monitoring of environmental objects or patients with acute intestinal infections in order to detect toxigenic genes inherent to epidemic strains of V. cholerae O1. Our objective was to study changes in phenotypic properties and molecular genetic bases of persistence, epidemic and pathogenetic potential of El Tor variant of Vibrio cholerae O1 isolated from patients and environmental objects in the Caucasus in 1970–1998. Materials and methods: We studied phenotypic and molecular genetic characteristics of 32 V. cholerae O1 strains isolated from patients and environmental objects in the Caucasus (1970–1998) using a microbiological assay and PCR test, respectively. Results: We established that the following biotypes of V. cholerae O1 were found in the Caucasus: a) El Tor, ctxA–, and Hly+ nontoxigenic strains of V. cholerae O1, typical in their phenotypic and molecular genetic properties. Their toxigenic potential is represented by exo- and endotoxins different from the enterotoxin of toxigenic V. cholerae; b) toxigenic El Tor, ctxABEL+, rtхC+, and Hly– variant biotypes of V. cholerae O1, typical in their phenotypic, molecular and genetic properties during outbreaks of invasive cholera, producing a CT-2 enterotoxin and containing genes responsible for persistent, pathogenic and pandemic potential, and c) typical in terms of their main phenotypic characteristics but molecularly genetically altered variants (hybrids) of El Tor variant of Vibrio cholerae O1 including El Tor ctxABCL+, rtxC+, Hly–. Conclusions: The main manifestation of evolutionary changes in a typical toxigenic vibrio of the El Tor variant biotype was the replacement of the ctxBEl gene in its genome with the ctxBCL gene encoding the classical type of enterotoxin (CT-1), which significantly increased the persistent, toxic, epidemic, and pandemic potential of genetically modified variants of El Tor biotype Vibrio cholerae. The genome of these strains contains an integrative and conjugative element SXT with genes for antibiotic multiresistance.

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Identification of Vibrio cholerae O1 strains of the El Tor biovar sensitive to polymyxin B and their molecular genetic analysis

Journal of microbiology epidemiology immunobiology ◽

10.36233/0372-9311-138 ◽

2021 ◽

Vol 98 (5) ◽

pp. 538-547

Author(s):

S. P. Zadnova ◽

Ya. M. Krasnov ◽

N. A. Plekhanov ◽

A. A. Kritskiy ◽

V. V. Kutyrev

Keyword(s):

Vibrio Cholerae ◽

Environmental Samples ◽

Genetically Modified ◽

Polymyxin B ◽

Molecular Genetic Analysis ◽

Photometric Method ◽

Snp Analysis ◽

Parsimony Method ◽

Cholera Vibrio ◽

El Tor

The aim of the work was the identification and genetic characterization of Vibrio cholerae O1 strains of the El Tor biovar sensitive to polymyxin B among isolates imported to Russia.Materials and methods. We used 56 toxigenic and non-toxigenic strains of V. cholerae isolated from patients and from the environmental samples on the territory of Russia in 1970-2020. Resistance to polymyxin B was determined according to MR4.2.2218-07. The ability of strains to form a biofilm on the abiotic surface was assessed by a photometric method. Nucleotide sequences of genes were determined using UGENE 1.32 and MEGA X software. Phylogenetic analysis and tree construction were performed using "maximum parsimony" method in MEGA X software.Results and discussion. Two genetically modified strains of V. cholerae O1 biovar El Tor, M1509 and 3265/80, which were imported to Russia from India in 2012 and 2014, respectively, were identified. The analysis of 12 genes responsible for the resistance of V. cholerae O1 biovar El Tor strains to polymyxin B demonstrated that these strains contain the allele of the carRS gene, which is typical for all strains of cholera vibrio sensitive to polymyxin B. Study of V. cholerae M1509 and 3265/80 phylogeny based on SNP analysis showed that they fall into the same cluster with isolates containing the carRS allele isolated in India (2015) and Bangladesh (2018). V. cholerae M1509 and 3256/8 strains had the ability to form a biofilm similar to those observed in other genetically modified strains of cholera vibrio included into analysis.Conclusion. Highly virulent strains of the cholera agent with altered diagnostically significant features are imported into Russia, which should be taken into account when identifying V. cholerae O1 biovar El Tor strains isolated from patients and environmental samples during monitoring studies.

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Epidemiological features of the seventh pandemic of cholera at stage IV and monitoring thereof

NATURE AND SCIENCE ◽

10.36719/2707-1146/04/74-77 ◽

2020 ◽

Vol 03 (04) ◽

pp. 74-77

Author(s):

Kh.H. Jafarova ◽

◽

E.F. Vahabov ◽

F.Sh. Taghiyeva ◽

V.Ch. Jalilov ◽

...

Keyword(s):

International Health ◽

Stage Iv ◽

Epidemiological Surveillance ◽

Global Level ◽

International Health Regulations ◽

Modern Period ◽

Epidemiological Features ◽

Health Institutions ◽

El Tor ◽

Health Regulations

The topical issues of cholera touched upon in the modern period indicate the significance of the problem at the global level. The continuing trend of an increase in morbidity, the importation of cholera leading to large outbreaks and epidemics, the presence of endemic foci on three continents of the world, the spread of genome-altered variants of El Tor cholera vibrios with epidemic and pandemic potential indicate a generally unfavorable prognosis for cholera at the global level. This dictates the need to implement a set of measures in the system of epidemiological surveillance of cholera and to ensure the readiness of the Ministry of Health institutions to carry out those regulated by international health regulations. Key words: cholera, pandemic, endemic territories, factors of distribution, Vibrio cholerae, 0139 (Bengal), prognosis

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