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1.
J Gen Virol ; 102(7)2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34227934

RESUMO

Members of the family Inoviridae are non-enveloped flexible filamentous bacteriophages (600-2500×6-10 nm) with supercoiled, circular, positive-sense, single-stranded DNA genomes of 5.5-10.6 kb, encoding 7-15 proteins. They absorb to the pili of Gram-negative bacteria and replicate their DNA by a rolling-circle mechanism with progeny released from cells by extrusion without killing the host. Phage DNA can persist extra-chromosomally or integrate into the bacterial genome. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Inoviridae, which is available at ictv.global/report/inoviridae.


Assuntos
Bactérias Gram-Negativas/virologia , Inoviridae/classificação , Genoma Viral , Especificidade de Hospedeiro , Inoviridae/genética , Inoviridae/fisiologia , Inoviridae/ultraestrutura , Vírion/ultraestrutura , Replicação Viral
2.
Mol Genet Genomics ; 296(3): 551-559, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33575837

RESUMO

The genus Habenivirus which includes Ralstonia virus ϕRSM encodes a site-specific integrase of a small serine recombinase belonging to the resolvase/invertase family. Here we describe the integrative/excisive recombination reactions mediated by ϕRSM integrase using in vitro assays. The products of attP/attB recombination, i.e. attL and attR, were exactly identical to those found in the prophage ϕRSM in R. solanacearum strains. The minimum size of attB required for integration was determined to be 37 bp, containing a 13 bp core and flanking sequences of 4 bp on the left and 20 bp on the right. ϕRSM integrative recombination proceeds efficiently in vitro in the absence of additional proteins or high-energy cofactors. Excision of a functional phage genome from a prophage fragment was demonstrated in vitro, demonstrating two-way activity of ϕRSM1 integrase. This is the first example of a small serine recombinase from the resolvase/invertase group that functions in integrative and excisive recombination for filamentous phages. This serine integrase could be used as a tool for several genome engineering applications.


Assuntos
Bacteriófagos/genética , Inoviridae/genética , Integrases/genética , Recombinação Genética/genética , Serina/genética , Proteínas Virais/genética
3.
Sci Rep ; 10(1): 6737, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317653

RESUMO

Bacteriophages are abundant in human biomes and therefore in human clinical samples. Although this is usually not considered, they might interfere with the recovery of bacterial pathogens at two levels: 1) by propagating in the enrichment cultures used to isolate the infectious agent, causing the lysis of the bacterial host and 2) by the detection of bacterial genes inside the phage capsids that mislead the presence of the bacterial pathogen. To unravel these interferences, human samples (n = 271) were analyzed and infectious phages were observed in 11% of blood culture, 28% of serum, 45% of ascitic fluid, 14% of cerebrospinal fluid and 23% of urine samples. The genetic content of phage particles from a pool of urine and ascitic fluid samples corresponded to bacteriophages infecting different bacterial genera. In addition, many bacterial genes packaged in the phage capsids, including antibiotic resistance genes and 16S rRNA genes, were detected in the viromes. Phage interference can be minimized applying a simple procedure that reduced the content of phages up to 3 logs while maintaining the bacterial load. This method reduced the detection of phage genes avoiding the interference with molecular detection of bacteria and reduced the phage propagation in the cultures, enhancing the recovery of bacteria up to 6 logs.


Assuntos
Bactérias/virologia , Inoviridae/classificação , Myoviridae/classificação , Podoviridae/classificação , RNA Ribossômico 16S/genética , Siphoviridae/classificação , Líquido Ascítico/microbiologia , Líquido Ascítico/virologia , Bactérias/classificação , Bactérias/genética , Hemocultura/métodos , Capsídeo/química , Líquido Cefalorraquidiano/microbiologia , Líquido Cefalorraquidiano/virologia , Filtração/métodos , Humanos , Inoviridae/genética , Inoviridae/isolamento & purificação , Lisogenia/fisiologia , Tipagem Molecular/métodos , Myoviridae/genética , Myoviridae/isolamento & purificação , Podoviridae/genética , Podoviridae/isolamento & purificação , Soro/microbiologia , Soro/virologia , Siphoviridae/genética , Siphoviridae/isolamento & purificação , Urina/microbiologia , Urina/virologia
4.
Mar Genomics ; 53: 100767, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32171709

RESUMO

The seawater temperature rise can promote the growth of potentially pathogenic Vibrio species. In the North Sea, V. parahaemolyticus strains have been isolated and characterized. These strains contain prophages that may contribute to the emergence of pathogenic strains in the marine environment. Here, we present the genome structure and possible biological functions of the inducible phage vB_VpaI_VP-3218, a novel filamentous phage carried by the V. parahaemolyticus strain VN-3218. Prophages of the strain VN-3218 were induced with mitomycin C and the DNA from the phage induction was sequenced. Two incomplete prophages were identified, only one complete phage genome with length of 11,082 bp was characterized. The phage vB_VpaI_VP-3218 belongs to the Inoviridae family and shows close homology to the Saetivirus genus. This phage can integrate into the chromosomal host genome and carries host-related regions absent in similar phage genomes, suggesting that this phage might integrate in other Vibrio host genomes from the environment. Furthermore, this phage might have a role in pathogenicity due to potential zonula occludens toxin genes. Based on its genomic similarity, the genome of vB_VpaI_VP-3218 phage probably integrates into the lysogen's chromosome and replicates as episome. This study complements prophage induction and bioinformatic studies applied to non-model species of potentially pathogenic Vibrio species. The characterization of this phage provides new insights with respect to the presence of filamentous phages in environmental V. parahaemolyticus strains, which might have a role in the emergence of new pathogenic strains in the North Sea.


Assuntos
Genoma Viral , Inoviridae/genética , Prófagos/genética , Vibrio parahaemolyticus/virologia , Mar do Norte , Ativação Viral
5.
Nat Microbiol ; 4(11): 1895-1906, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31332386

RESUMO

Bacteriophages from the Inoviridae family (inoviruses) are characterized by their unique morphology, genome content and infection cycle. One of the most striking features of inoviruses is their ability to establish a chronic infection whereby the viral genome resides within the cell in either an exclusively episomal state or integrated into the host chromosome and virions are continuously released without killing the host. To date, a relatively small number of inovirus isolates have been extensively studied, either for biotechnological applications, such as phage display, or because of their effect on the toxicity of known bacterial pathogens including Vibrio cholerae and Neisseria meningitidis. Here, we show that the current 56 members of the Inoviridae family represent a minute fraction of a highly diverse group of inoviruses. Using a machine learning approach leveraging a combination of marker gene and genome features, we identified 10,295 inovirus-like sequences from microbial genomes and metagenomes. Collectively, our results call for reclassification of the current Inoviridae family into a viral order including six distinct proposed families associated with nearly all bacterial phyla across virtually every ecosystem. Putative inoviruses were also detected in several archaeal genomes, suggesting that, collectively, members of this supergroup infect hosts across the domains Bacteria and Archaea. Finally, we identified an expansive diversity of inovirus-encoded toxin-antitoxin and gene expression modulation systems, alongside evidence of both synergistic (CRISPR evasion) and antagonistic (superinfection exclusion) interactions with co-infecting viruses, which we experimentally validated in a Pseudomonas model. Capturing this previously obscured component of the global virosphere may spark new avenues for microbial manipulation approaches and innovative biotechnological applications.


Assuntos
Archaea/virologia , Bactérias/virologia , Biologia Computacional/métodos , Inoviridae/classificação , Vírus de Archaea/classificação , Vírus de Archaea/genética , Bacteriófagos/classificação , Bacteriófagos/genética , Genoma Viral , Inoviridae/genética , Aprendizado de Máquina , Filogenia
6.
Arch Virol ; 160(3): 865-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25559667

RESUMO

Filamentous bacteriophage RS611 (ϕRS611), which infects the phytopathogen Ralstonia solanacearum, had a circular single-stranded DNA genome that was characterized as an Ff-type phage belonging to the family Inoviridae. The ϕRS611 genome was composed of 6386 bases with a G + C content of 62.1 % and contained 11 putative open reading frames. The ϕRS611 genome showed high similarity to those of Ralstonia phages RSS0 and RSS1. However, approximately 900-nucleotide deletions were found in the region corresponding to open reading frames 10 and 11 of ϕRSS0 and ϕRSS1.


Assuntos
Vírus de DNA/genética , DNA Viral/química , DNA Viral/genética , Genoma Viral , Inoviridae/genética , Inovirus/genética , Ralstonia solanacearum/virologia , Composição de Bases , Vírus de DNA/isolamento & purificação , DNA Circular/genética , Inoviridae/classificação , Inoviridae/isolamento & purificação , Inovirus/classificação , Inovirus/isolamento & purificação , Dados de Sequência Molecular , Fases de Leitura Aberta , Análise de Sequência de DNA , Deleção de Sequência , Homologia de Sequência , Sintenia
7.
Arch Virol ; 157(9): 1643-50, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22614810

RESUMO

In this study, a novel filamentous phage, φSHP1, of the environmental Stenotrophomonas maltophilia strain P2 was isolated and characterized. Electron microscopy showed that φSHP1 resembled members of the family Inoviridae and was about 2.1 µm long. The 6,867-nucleotide genome of φSHP1 was a circular single-stranded DNA and had a replication form designated pSH1. Ten putative open reading frames (ORFs) were found in the φSHP1 genome, and six predicted proteins showed similarity to proteins in databases. Tricine sodium dodecyl sulfate polyacrylamide gel electrophoresis of φSHP1 displayed one major structural polypeptide of approximately 4.0 kDa. N-terminal sequencing showed that it was the mature product of ORF5 and that its N-terminal 27 amino acid residues had been cleaved off from the predicted nascent protein. Finally, phylogenetic trees were constructed to analyze the phylogenetic relationship of φSHP1 to other known filamentous phages. φSHP1 appears to be the first reported Stenotrophomonas filamentous phage.


Assuntos
Inoviridae/classificação , Inoviridae/isolamento & purificação , Inovirus/classificação , Inovirus/isolamento & purificação , Stenotrophomonas maltophilia/virologia , Análise por Conglomerados , DNA Circular/genética , DNA Viral/química , DNA Viral/genética , Eletroforese em Gel de Poliacrilamida , Inoviridae/genética , Inoviridae/ultraestrutura , Inovirus/genética , Inovirus/ultraestrutura , Microscopia Eletrônica , Dados de Sequência Molecular , Peso Molecular , Fases de Leitura Aberta , Filogenia , Análise de Sequência de DNA , Proteínas Virais/química , Proteínas Virais/isolamento & purificação
8.
Water Res ; 43(15): 3759-64, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19555992

RESUMO

Genotyping of F-specific RNA phages is currently one of the most promising approaches to differentiate between human and animal fecal contamination in aquatic environments. In this study, a total of 18 river water and sediment samples were collected from the Tonegawa River basin, Japan, in order to describe the genogroup distribution of F-specific RNA and DNA phages using genogroup-specific real-time PCR assays. F-specific phages were detected in nine (100%) river water and six (67%) sediment samples. Eighty-five phage plaques were isolated from these samples and subjected to real-time PCR assays specific for the phages. F-specific RNA phages of human genogroups (II and III) were detected in 32 (38%) plaques, whereas those of animal genogroups (I and IV) were detected in 17 (20%) plaques. No correlation was observed between the genogroup distribution of F-specific RNA phages and the occurrence of human adenovirus genomes, suggesting that genotyping of the phages alone is inadequate for the evaluation of the occurrence of viruses in aquatic environments. SYBR Green-based real-time PCR assay revealed the presence of F-specific DNA phages in four (5%) plaques, which were further classified into two genogroups (fd- and f1-like phages) by sequence analysis. Thirty-two (38%) plaques were not classified as the F-specific phage genogroups, indicating the limited applicability of these real-time PCR assays to a wide range of aquatic environmental samples worldwide.


Assuntos
Sedimentos Geológicos/virologia , Inoviridae/classificação , Leviviridae/classificação , Reação em Cadeia da Polimerase/métodos , Rios/virologia , Adenoviridae/classificação , Impressões Digitais de DNA , Monitoramento Ambiental , Genótipo , Humanos , Inoviridae/genética , Inoviridae/isolamento & purificação , Japão , Leviviridae/genética , Leviviridae/isolamento & purificação
9.
Methods Mol Biol ; 394: 213-34, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18363238

RESUMO

Out of 177 surveyed bacteriophages, 161 (91%) are tailed and belong to the Myoviridae, Siphoviridae, and Podoviridae families (43, 55, and 59 viruses, respectively). Sixteen filamentous or isometric phages are members of the Inoviridae, Leviviridae, Microviridae, and Tectiviridae families (9%). Many tailed phages belong to established phage genera (P22, T1, T5, and T7), which are widespread in enterobacteria and other Gram-negatives of the Proteobacteria phylum.


Assuntos
Fagos de Salmonella/ultraestrutura , Salmonella/virologia , Bacteriófago P22/ultraestrutura , Tipagem de Bacteriófagos , Inoviridae/classificação , Inoviridae/ultraestrutura , Leviviridae/classificação , Leviviridae/ultraestrutura , Microscopia Eletrônica de Transmissão , Microviridae/classificação , Microviridae/ultraestrutura , Myoviridae/classificação , Myoviridae/ultraestrutura , Podoviridae/classificação , Podoviridae/ultraestrutura , Fagos de Salmonella/classificação , Siphoviridae/classificação , Siphoviridae/ultraestrutura , Tectiviridae/classificação , Tectiviridae/ultraestrutura
10.
Arch Virol ; 151(4): 663-79, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16308675

RESUMO

One-hundred-fifteen bacteriophage strains were isolated from alkaline hot springs in Iceland, New Zealand, Russia (Kamchatka), and the U.S.A. The phages belonged to the Myoviridae, Siphoviridae, Tectiviridae, and Inoviridae families. Over 50% of isolates were isometric or filamentous. One type of siphovirus had giant tails of over 800 nm in length. Phages were further characterized by host range, genome size, DNA restriction endonuclease digestion patterns, and temperature and pH sensitivity. Myoviruses and tectiviruses had a worldwide distribution. Most phages were narrowly host-specific and all were highly resistant against heating and alkaline and acidic pH. This is the first time that tectiviruses and filamentous phages are reported for bacteria of the Thermus-Deinococcus phylum. The presence of tectiviruses, inoviruses, and myoviruses is attributed to acquisition from ancestral gamma-proteobacteria by horizontal gene transfer.


Assuntos
Genoma Viral , Inoviridae , Myoviridae , Thermus/virologia , Microbiologia da Água , Álcalis , DNA Viral/genética , Concentração de Íons de Hidrogênio , Inoviridae/classificação , Inoviridae/isolamento & purificação , Inoviridae/fisiologia , Inoviridae/ultraestrutura , Myoviridae/classificação , Myoviridae/isolamento & purificação , Myoviridae/fisiologia , Myoviridae/ultraestrutura , Nova Zelândia , Mapeamento por Restrição , Sibéria , Especificidade da Espécie , Estados Unidos
11.
Mol Gen Mikrobiol Virusol ; (4): 3-13, 2004.
Artigo em Russo | MEDLINE | ID: mdl-15597566

RESUMO

"Mikrob" Russian Research Anti-Plague Institute, Saratov Studies of the genomic evolution of pathogenic bacteria became a priority research trend of modern molecular genetics. Vibrio cholerae, whose pathogenic properties are conditioned by the presence of virulence blocks of differing phylogenetic origins in 2 chromosomes, turned out to be a unique model object for studies of evolutionary transformations of genomes that are causative agents of extra dangerous infections. The molecular-and-genetic mechanisms underlying the change of biovariants and the emergence of a cholera agent of a new serogroup are in the focus of attention. Finally, the possibility that the new V. cholerae pathogenic clone originated due to horizontal genetic transfers and recombination phenomena is under discussion in the survey.


Assuntos
Evolução Molecular , Genoma Bacteriano , Vibrio cholerae/genética , Ásia/epidemiologia , Cólera/epidemiologia , Cólera/virologia , Transferência Genética Horizontal , Variação Genética , Humanos , Inoviridae/genética , Peru/epidemiologia , Recombinação Genética , Arábia Saudita/epidemiologia , Vibrio cholerae/patogenicidade , Vibrio cholerae O139/genética , Virulência/genética
12.
Appl Environ Microbiol ; 70(10): 5996-6004, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15466543

RESUMO

In recent years, there has been increased interest in the use of male-specific or F+ coliphages as indicators of microbial inputs to source waters. Sero- or genotyping of these coliphages can also be used for microbial source tracking (MST). Among the male-specific coliphages, the F+ RNA (FRNA) viruses are well studied, while little is known about the F+ DNA (FDNA) viruses. We have developed a reverse line blot hybridization (RLB) assay which allows for the simultaneous detection and genotyping of both FRNA as well as FDNA coliphages. These assays included a novel generic duplex reverse transcription-PCR (RT-PCR) assay for FRNA viruses as well as a generic PCR for FDNA viruses. The RT-PCR assays were validated by using 190 field and prototype strains. Subsequent DNA sequencing and phylogenetic analyses of RT-PCR products revealed the classification of six different FRNA clusters, including the well-established subgroups I through IV, and three different FDNA clusters, including one (CH) not previously described. Within the leviviruses, a potentially new subgroup (called JS) including strains having more than 40% nucleotide sequence diversity with the known levivirus subgroups (MS2 and GA) was identified. We designed subgroup-specific oligonucleotides that were able to genotype all nine (six FRNA, three FDNA) different clusters. Application of the method to a panel of 351 enriched phage samples from animal feces and wastewater, including known prototype strains (MS2, GA, Q beta, M11, FI, and SP for FRNA and M13, f1, and fd for FDNA), resulted in successful genotyping of 348 (99%) of the samples. In summary, we developed a novel method for standardized genotyping of F+ coliphages as a useful tool for large-scale MST studies.


Assuntos
Colífagos/genética , Animais , Colífagos/classificação , Colífagos/isolamento & purificação , DNA Viral/genética , DNA Viral/isolamento & purificação , Fezes/virologia , Genótipo , Humanos , Inoviridae/classificação , Inoviridae/genética , Inoviridae/isolamento & purificação , Leviviridae/classificação , Leviviridae/genética , Leviviridae/isolamento & purificação , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Microbiologia da Água
13.
Lett Appl Microbiol ; 38(4): 333-8, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15214735

RESUMO

AIM: To isolate bacterial viruses that infect the ruminal cellulolytic bacterium Ruminococcus albus. METHODS: Four phages infecting R. albus AR67 were isolated under anaerobic conditions using the soft-agar overlay technique. The phages were characterized on morphology, solvent stability, nucleic acid type and digestion characteristics. Two phages, phiRa02 and phiRa04 comprised icosahedral virions with linear double-stranded DNA and appeared to belong to the family Podoviridae [corrected] The other two phages are most likely filamentous phages with circular single-stranded DNA of the family Inoviridae. SIGNIFICANCE OF THE STUDY: Viruses of the family Inoviridae [corrected] have not previously been isolated from rumen bacteria. The phages isolated in this study are the first phages shown to infect the cellulolytic bacteria of the rumen. This suggests that the cellulolytic populations of the rumen are subject to lytic events that may impact on the ability of these bacteria to degrade plant fibre and on the nutrition of the animal.


Assuntos
Inoviridae/isolamento & purificação , Inovirus/isolamento & purificação , Ruminococcus/virologia , Tectiviridae/isolamento & purificação , Anaerobiose , DNA/isolamento & purificação , DNA/metabolismo , Impressões Digitais de DNA , Enzimas de Restrição do DNA/metabolismo , DNA Circular/isolamento & purificação , DNA Circular/metabolismo , DNA de Cadeia Simples/isolamento & purificação , DNA de Cadeia Simples/metabolismo , DNA Viral/isolamento & purificação , DNA Viral/metabolismo , Inoviridae/classificação , Inoviridae/fisiologia , Inoviridae/ultraestrutura , Inovirus/classificação , Inovirus/fisiologia , Inovirus/ultraestrutura , Nucleocapsídeo/ultraestrutura , Tectiviridae/classificação , Tectiviridae/fisiologia , Tectiviridae/ultraestrutura
14.
Appl Environ Microbiol ; 69(11): 6507-14, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14602607

RESUMO

Male-specific (F+) coliphages have been investigated as viral indicators of fecal contamination that may provide source-specific information for impacted environmental waters. This study examined the presence and proportions of the different subgroups of F+ coliphages in a variety of fecal wastes and surface waters with well-defined potential waste impacts. Municipal wastewater samples had high proportions of F+ DNA and group II and III F+ RNA coliphages. Bovine wastewaters also contained a high proportion of F+ DNA coliphages, but group I and IV F+ RNA coliphages predominated. Swine wastewaters contained approximately equal proportions of F+ DNA and RNA coliphages, and group I and III F+ RNA coliphages were most common. Waterfowl (gull and goose) feces contained almost exclusively F+ RNA coliphages of groups I and IV. No F+ coliphages were isolated from the feces of the other species examined. F+ coliphage recovery from surface waters was influenced by precipitation events and animal or human land use. There were no significant differences in coliphage density among land use categories. Significant seasonal variation was observed in the proportions of F+ DNA and RNA coliphages. Group I F+ RNA coliphages were the vast majority (90%) of those recovered from surface waters. The percentage of group I F+ RNA coliphages detected was greatest at background sites, and the percentage of group II F+ RNA coliphages was highest at human-impacted sites. Monitoring of F+ coliphage groups can indicate the presence and major sources of microbial inputs to surface waters, but environmental effects on the relative occurrence of different groups need to be considered.


Assuntos
Colífagos/isolamento & purificação , Fator F/genética , Fezes/virologia , Microbiologia da Água , Poluição da Água/análise , Animais , Aves , Bovinos , Colífagos/genética , Gansos , Humanos , Inoviridae/genética , Inoviridae/isolamento & purificação , Leviviridae/genética , Leviviridae/isolamento & purificação , Fagos RNA/genética , Fagos RNA/isolamento & purificação , Estações do Ano , Eliminação de Resíduos Líquidos
15.
Res Microbiol ; 154(4): 245-51, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12798228

RESUMO

Bacteriophages are classified into one order and 13 families. Over 5100 phages have been examined in the electron microscope since 1959. At least 4950 phages (96%) are tailed. They constitute the order Caudovirales and three families. Siphoviridae or phages with long, noncontractile tails predominate (61% of tailed phages). Polyhedral, filamentous, and pleomorphic phages comprise less than 4% of bacterial viruses. Bacteriophages occur in over 140 bacterial or archaeal genera. Their distribution reflects their origin and bacterial phylogeny. Bacteriophages are polyphyletic, arose repeatedly in different hosts, and constitute 11 lines of descent. Tailed phages appear as monophyletic and as the oldest known virus group.


Assuntos
Bacteriófagos , Evolução Biológica , Bacteriófagos/química , Bacteriófagos/classificação , Bacteriófagos/crescimento & desenvolvimento , Bacteriófagos/ultraestrutura , Caudovirales/química , Caudovirales/crescimento & desenvolvimento , Caudovirales/fisiologia , Caudovirales/ultraestrutura , Corticoviridae/química , Corticoviridae/crescimento & desenvolvimento , Corticoviridae/ultraestrutura , Cystoviridae/química , Cystoviridae/crescimento & desenvolvimento , Cystoviridae/ultraestrutura , Fuselloviridae/química , Fuselloviridae/crescimento & desenvolvimento , Fuselloviridae/ultraestrutura , Inoviridae/química , Inoviridae/crescimento & desenvolvimento , Inoviridae/ultraestrutura , Leviviridae/química , Leviviridae/crescimento & desenvolvimento , Leviviridae/ultraestrutura , Lipothrixviridae/química , Lipothrixviridae/crescimento & desenvolvimento , Lipothrixviridae/ultraestrutura , Microviridae/química , Microviridae/crescimento & desenvolvimento , Microviridae/ultraestrutura , Rudiviridae/química , Rudiviridae/crescimento & desenvolvimento , Rudiviridae/ultraestrutura , Tectiviridae/química , Tectiviridae/crescimento & desenvolvimento , Tectiviridae/ultraestrutura
16.
J Clin Microbiol ; 39(11): 4086-92, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11682534

RESUMO

We report sporadic cases of a severe gastroenteritis associated with Vibrio cholerae serogroup O141. Like O1 and O139 serogroup strains of V. cholerae isolated from cholera cases, the O141 clinical isolates carry DNA sequences that hybridize to cholera toxin (CT) gene probes. The CT genes of O1 and O139 strains are carried by a filamentous bacteriophage (termed CTX phage) which is known to use toxin-coregulated pili (TCP) as its receptor. In an effort to understand the mechanism of emergence of toxigenic O141 V. cholerae, we probed a collection of O141 clinical and environmental isolates for genes involved in TCP production, toxigenicity, virulence regulation, and other phylogenetic markers. The collection included strains isolated between 1964 and 1995 from diverse geographical locations, including eight countries and five U.S. states. Information collected about the clinical and environmental sources of these isolates suggests that they had no epidemiological association. All clinical O141 isolates hybridized to probes specific for genes encoding CT (ctx), zonula occludens toxin (zot), repetitive sequence 1 (RS1), RTX toxin (rtxA), the major subunit of TCP (tcpA), and the essential regulatory gene that controls expression of both CT and TCP (toxR). In contrast, all but one of the nonclinical O141 isolates were negative for ctx, zot, RS1, and tcpA, although these strains were positive for rtxA and toxR. The one toxigenic environmental O141 isolate was also positive for tcpA. Ribotyping and CT typing showed that the O141 clinical isolates were indistinguishable or closely related, while a toxigenic water isolate from Louisiana showed a distantly related ribotype. Nonclinical O141 isolates displayed a variety of unrelated ribotypes. These data support a model for emergence of toxigenic O141 that involves acquisition of the CTX phage sometime after these strains had acquired the pathogenicity island encoding TCP. The clonal nature of toxigenic O141 strains isolated from diverse geographical locations suggests that the emergence is a rare event but that once it occurs, toxigenic O141 strains are capable of regional and perhaps even global dissemination. This study stresses the importance of monitoring V. cholerae non-O1, non-O139 serogroup strains for their virulence gene content as a means of assessing their epidemic potential.


Assuntos
Toxina da Cólera/genética , Cólera/microbiologia , Proteínas de Fímbrias , Fímbrias Bacterianas/genética , Regulação Bacteriana da Expressão Gênica , Inoviridae/genética , Vibrio cholerae/patogenicidade , Microbiologia da Água , Adulto , Idoso , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Técnicas de Tipagem Bacteriana/métodos , Toxina da Cólera/classificação , Humanos , Pessoa de Meia-Idade , Ribotipagem , Sorotipagem , Vibrio cholerae/classificação , Vibrio cholerae/genética , Vibrio cholerae/virologia , Virulência/genética
17.
J Clin Microbiol ; 38(6): 2156-61, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10834969

RESUMO

A specific serotype, O3:K6, of Vibrio parahaemolyticus has recently been causing epidemics of gastroenteritis in Southeast Asia, Japan, and North America. To examine whether the new O3:K6 strains possess characteristics that may exacerbate outbreaks, we compared V. parahaemolyticus O3:K6 strains with non-O3:K6 strains using strains isolated from individuals with traveler's diarrhea at Kansai Airport Quarantine Station, Osaka, Japan. All 24 O3:K6 strains possessed a common plasmid, pO3K6 (DNA size, 8,782 bp, with 10 open reading frames [ORFs]). The gene organization of pO3K6 was similar to that of Vf33, a filamentous phage previously described in V. parahaemolyticus. We isolated a phage (phage f237) from the culture supernatant of V. parahaemolyticus O3:K6 strain KXV237, which formed a turbid plaque on an indicator strain. The genome of f237 was single-stranded DNA, and the double-stranded DNA obtained by treatment of the genome with DNA polymerase was identical to that of pO3K6 when analyzed by agarose gel electrophoresis after HindIII digestion. Furthermore, the N-terminal amino acid sequence of the f237 major coat protein was found in ORF4 of pO3K6. Our results showed that pO3K6 is a replicative form of f237. Among the ORFs found in the f237 genome, the sequence of ORF8 had no significant homology to those of any proteins in databases. ORF8 was located on a region corresponding to the distinctive region of Vf33, and its G+C content was apparently lower than that of the remaining DNA sequence of f237. By colony hybridization, ORF8 was detected only in O3:K6 strains isolated since 1996 and was not found in O3:K6 strains isolated before 1996 and clinical V. parahaemolyticus strains other than those of serotype O3:K6. Thus, this study shows that f237 is exclusively associated with recent V. parahaemolyticus O3:K6 strains. The ORF8 gene can be a useful genetic marker for the identification of the recently widespread O3:K6 strains of V. parahaemolyticus.


Assuntos
Diarreia , Surtos de Doenças , Inoviridae/isolamento & purificação , Viagem , Vibrioses/epidemiologia , Vibrio parahaemolyticus/virologia , Japão , Dados de Sequência Molecular , Fases de Leitura Aberta , Plasmídeos/genética , Mapeamento por Restrição , Análise de Sequência de DNA , Vibrio parahaemolyticus/patogenicidade
18.
J Appl Microbiol ; 88(1): 5-21, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10735238

RESUMO

Low concentrations of all types of bacteriophages in groundwater limit their power to predict the presence of enteric viruses. There is little concordance in the literature regarding phage detection methods, thus making comparisons extremely difficult. Different authors have used different hosts, phage concentration methods, and end-point determinations. Also, markedly different volumes of sample have been employed, varying from 1 litre to 400 l. Bacteriophage concentration methods are not reproducible. There has been marked variability among groups in the natural substrates used (for example, beef extract), the type of adsorbing filter used, centrifugation instruments and conditions, and the delivery of the concentrate to the host cells. There is no consensus on the best bacterial host strain. Currently, several are employed with each showing differential sensitivities and specificities. In particular, host stability must be considered. Host stability has two components: the ability of the host to continue to be receptive to the bacteriophage after continued sub-culture, and the lack of lysogenic or temperate bacteriophage in the host cell line which may be randomly and unpredictably activated. There is a lack of consistent recovery of bacteriophages from individual faecal specimens. In particular, only approximately 3% of individual humans carry the FRNA phages. While there is some evidence to indicate that the phages multiply in sewage, it is not clear how they do so since the host pili should not be produced at lower temperatures. These ecological factors need to be understood. Of all the phages thus far studied, Bacteroides fragilis HSP40 has the highest recovery rate from individual people. However, Bacteroides, being an anaerobe, is a difficult host for routine laboratory analysis. Methods for the enumeration of F(+)-specific phages and Bacteroides phages are complex, time-consuming, costly and not reproducible. Conversely, somatic coliphage methods are simpler and results can be available in 4-6 h. The occurrence of phages and viruses in groundwater depends on physicochemical characteristics that control their fate and transport in the groundwater/aquifer environment. There are very little actual data taken from the field that allow an understanding of the ecology and life span of phages in their natural environment. Moreover, the ability of phages to serve as a source of food for other microbes needs to be understood. There has been a lack of association of bacteriophage recovery with gastroenteritis outbreaks due to enteric viruses. There is only a small epidemiological database concerning the occurrence of enteric viruses in groundwater.


Assuntos
Bacteriófagos/isolamento & purificação , Água Doce/microbiologia , Animais , Bacteriófagos/crescimento & desenvolvimento , Bacteroides fragilis/virologia , Colífagos/crescimento & desenvolvimento , Colífagos/isolamento & purificação , Humanos , Inoviridae/crescimento & desenvolvimento , Inoviridae/isolamento & purificação , Leviviridae/crescimento & desenvolvimento , Leviviridae/isolamento & purificação , Saúde Pública , Medição de Risco , Salmonella/virologia
19.
J Bacteriol ; 181(21): 6779-87, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10542181

RESUMO

CTXphi is a lysogenic, filamentous bacteriophage. Its genome includes the genes encoding cholera toxin (ctxAB), one of the principal virulence factors of Vibrio cholerae; consequently, nonpathogenic strains of V. cholerae can be converted into toxigenic strains by CTXphi infection. O139 Calcutta strains of V. cholerae, which were linked to cholera outbreaks in Calcutta, India, in 1996, are novel pathogenic strains that carry two distinct CTX prophages integrated in tandem: CTX(ET), the prophage previously characterized within El Tor strains, and a new CTX Calcutta prophage (CTX(calc)). We found that the CTX(calc) prophage gives rise to infectious virions; thus, CTX(ET)phi is no longer the only known vector for transmission of ctxAB. The most functionally significant differences between the nucleotide sequences of CTX(calc)phi and CTX(ET)phi are located within the phages' repressor genes (rstR(calc) and rstR(ET), respectively) and their RstR operators. RstR(calc) is a novel, allele-specific repressor that regulates replication of CTX(calc)phi by inhibiting the activity of the rstA(calc) promoter. RstR(calc) has no inhibitory effect upon the classical and El Tor rstA promoters, which are instead regulated by their cognate RstRs. Consequently, production of RstR(calc) renders a CTX(calc) lysogen immune to superinfection by CTX(calc)phi but susceptible (heteroimmune) to infection by CTX(ET)phi. Analysis of the prophage arrays generated by sequentially integrated CTX phages revealed that pathogenic V. cholerae O139 Calcutta probably arose via infection of an O139 CTX(ET)phi lysogen by CTX(calc)phi.


Assuntos
Proteínas de Bactérias , Inoviridae/genética , Inoviridae/fisiologia , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Vibrio cholerae/virologia , Proteínas Virais/genética , Proteínas Virais/metabolismo , Sequência de Bases , DNA Viral/análise , Inoviridae/isolamento & purificação , Lisogenia , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Transdução Genética , Vibrio cholerae/crescimento & desenvolvimento , Replicação Viral
20.
Infect Immun ; 66(12): 5819-25, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9826360

RESUMO

Toxigenic Vibrio cholerae strains are lysogens of CTXPhi, a filamentous phage which encodes cholera toxin. The receptor for CTXPhi for invading V. cholerae cells is the toxin-coregulated pilus (TCP), the genes for which reside in a larger genetic element, the TCP pathogenicity island. We analyzed 146 CTX-negative strains of V. cholerae O1 or non-O1 isolated from patients or surface waters in five different countries for the presence of the TCP pathogenicity island, the regulatory gene toxR, and the CTXPhi attachment sequence attRS, as well as for susceptibility of the strains to CTXPhi, to investigate the molecular basis for the emergence of new clones of toxigenic V. cholerae. DNA probe or PCR assays for tcpA, tcpI, acfB, toxR, and attRS revealed that 6.85% of the strains, all of which belonged to the O1 serogroup, carried the TCP pathogenicity island, toxR, and multiple copies of attRS, whereas the remaining 93.15% of the strains were negative for TCP but positive for either one or both or neither of toxR and attRS. An analysis of the strains for susceptibility to CTXPhi, using a genetically marked derivative of the phage CTX-KmPhi, showed that all TCP-positive CTX-negative strains and 1 of 136 TCP-negative strains were infected by the phage either in vitro or in the intestines of infant mice. The phage genome integrated into the chromosome of infected V. cholerae O1 cells forming stable lysogens. Comparative analysis of rRNA gene restriction patterns revealed that the lysogens derived from nontoxigenic progenitors were either closely related to or distinctly different from previously described clones of toxigenic V. cholerae. To our knowledge, this is the first demonstration of lysogenic conversion of naturally occurring nontoxigenic V. cholerae strains by CTXPhi. The results of this study further indicated that strains belonging to the O1 serogroup of V. cholerae are more likely to possess the TCP pathogenicity island and hence to be infected by CTXPhi, leading to the origination of potential new epidemic clones.


Assuntos
Toxina da Cólera/genética , Cólera/microbiologia , Inoviridae/genética , Vibrio cholerae/patogenicidade , Vibrio cholerae/virologia , Animais , DNA Ribossômico/genética , Surtos de Doenças , Microbiologia Ambiental , Técnicas de Transferência de Genes , Genes Bacterianos , Humanos , Lisogenia , Camundongos , Polimorfismo de Fragmento de Restrição , Sorotipagem , Vibrio cholerae/classificação
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