Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “transduction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1979

Non-random distribution of transduction termini in transductants from the integrated R plasmid, R100-1.

Tra+ and tra- derivatives of drug resistance plasmid, R100-1, were isolated by phage P1 from an Hfr donor with integrated R100-1 and then analyzed by complementation tests with tra- point mutants of Flac. Tra+ derivatives of R100-1 carrying tetracycline resistance alone and those carrying all six drug-resistrance genes could support transfer of tra- point mutants of Flac except Flac traJ, whereas all of tra- derivatives of R100-1 failed to complement any one of tra- point mutants of Flac. This suggests that these tra- derivatives of R100-1 carrying tetracycline resistance gene are deleted for all the transfer genes impaired in the Flac point mutants tested. We assume a "hot point", probably a specific base sequence similar to an IS element, at the left of the tetracycline gene (Fig. 1) becomes a transduction terminus in transduction of the integrated R100-1 by phage P1. Complementation analysis of tra- derivatives carrying five resistance genes except the tetracycline gene led us to a supposition that a gene(s), probably analogous to traJ of the F plasmid, is located on R100-1 near the tetracycline gene which plays an important regulatory role for self-transfer as well as for the complementation of tra- Flac mutants.

Base Sequence↗
PubMed1977

The frequency of P1 transduction of the genes of Escherichia coli as a function of chromosomal position: preferential transduction of the origin of replication.

The frequencies with which the generalized transducing phage P1 transduced 26 selected markers on the E. coli. chromosome were measured. The frequencies were found to vary relative to argH+ = 1 from a maximum of 6.8 near the origin of replication to a minimum of 0.23 for a marker not far from the terminus. The low frequencies obtained for some markers were shown not to result from poor expression under the selective conditions employed. When plotted as a function of marker position on the chromosome the frequencies were found to exhibit a series of peaks and troughs which correspond to those in gene density noted by Bachmann et al. (1976). The possible relationship of these results to the structure of the E. coli chromosome and to the mechanism of generalized transduction are discussed.

Chromosome Mapping↗
PubMed1976

Transduction of leucine auxotrophs of Proteus mirabilis to prototrophy or antibiotic resistance by P. mirabilis high frequency transducing bacteriophages.

High frequency transducing (HFT) phages 5006MHFTk and 5006MHFTak for kanamycin or ampicillin plus kanamycin resistance, derived from Proteus mirabilis strains PM5006(R394) and PM5006(R394) respectively, transduced (at low multiplicities of infection, m.o.i.) antibiotic resistance and prototrophy to PM5006 leu-I at high frequency. Simultaneous transduction of these markers occurred at very much lower frequencies. The latter result was correlated with the proportion of multiply-infected bacteria which, due to the great transducing potential of the phage, could register as transductants. Each HFT lysate was thus heterogenous with regard to high frequency transducing phage. Apart from the additional antibiotic resistance marker carried by one phage, no other difference between the two lysates was detected. High segregation frequencies of antibiotic-resistant or prototrophic transductants indicated transduction by lysogenization. Although antibiotic-sensitive segregants of antibiotic-resistant prototrophic transductants occurred at high frequency, no auxotrophic segregants of these transductants were found. This suggests transduction by a double cross-over event in the leucine region. Most transductants, even at low m.o.i., were lysogenically converted to homologous phage non-adsorption as a result of interaction between the transducing phage genome and the resident cryptic prophage. They could, however, be retransduced by appropriate phage lysates; thus, lysogenic conversion to non-adsorption was not absolute. Some prototrophic transductants were non-lysogenic although their segregants liberated low-titre phage. The latter anomaly, and the fact that the leucine marker and antibiotic resistance were not cotransduced, are explained by the mode of integration of the phage into the host chromosome in relation to the resident cryptic prophage and the leucine region.

Adsorption↗
PubMed1975

[Suppresion of the R-factor transduction transmission of antibiotic resistance markers in E. coli by distamycin A].

Some mechanisms of inhibition by distamycin A of transduction of antibiotic resistance markers of R-factors (RI drd and R222) with the moderate phage PI kc in E. coli were studied. The kinetics of the transduction of the R-factor markers was investigated in comparison with the stages of interaction of PI kc phage particles with bacterial cells of E. coli K-12 carrying the R-factors such as RI and R222 -- phage PI kc -- E. coli C6000. Later the effect of distamycin A on transduction of the above R-factors was studied using the same system. It was shown that distamycin A in concentrations of 75 gamma/ml suppressed the transduction of the R-markers when added to the transduction mixture simultaneously with the phage. The transduction rate decreased 15 times if the drug was added 5 minutes after beginning of the phage contact with the recipient culture. Addition of distamycin A at the 20th minute of the experiment induced no inhibition of the transduction of the R-factor markers. Preliminary 18-hour exposure to distamycin A of the recipient culture and phagolysates possessing transduction capacity resulted in decreased rates of the transduction of the antibiotic resistance markers 35 to 40 times. No inhibitory effect of distamycin A on the process of phenotypic manifestation of the antibiotic resistance markers of the R-factors was noted. The experiments showed that distamycin A affected the early stages of interaction of the transducing particles with the recipient culture, possibly the process of penetration of the transducing DNA of the R-factors into the cells of the recipient culture.

Anti-Bacterial Agents↗
PubMed1978

Frequency of F116-mediated transduction of Pseudomonas aeruginosa in a freshwater environment.

Transduction of Pseudomonas aeruginosa streptomycin resistance by a generalized transducing phage, F116, was shown to occur during a 10-day incubation in a flow-through environmental test chamber suspended in a freshwater reservoir. Mean F116 transduction frequencies ranged from 1.4 X 10(-5) to 8.3 X 10(-2) transductants per recipient during the in situ incubation. These transduction frequencies were comparable to transduction frequencies determined in preliminary laboratory transduction experiments. The results demonstrate the potential for naturally occurring transduction in aquatic environments and concurrent environmental and ecological ramifications.

Bacteriophages↗
PubMed1976

[Transduction transmission of the extrachromosomal markers of antibiotic resistance in staphylococcal populations].

Transduction of extrachromosomal markers of resistance to penicillin and erythromycin in staphylococcal strains isolated from patients was studied. Two transduction methods were compared, i. e. transduction with a phage filtrate of the donor culture resistant to erythromycin and transduction on mixed cultivation of the donor and recipient. A higher transduction rate was observed with the latter method. Mixed cultivation of the donor cultures resistant to penicillin or erythromycin and the recipient strains of the wild type sensitive to these antibiotic resulted in transduction of the respective markers. Transductants which acquired prophage 6 simultaneously with marker Egg became donors of erythromycin resistance.

Anti-Bacterial Agents↗
PubMed1977

Transduction of M+- and SOR+-markers in group A streptococci.

Phagolysates obtained in passage of the virulent phage CA1 on M+ SOR+-cultures of streptococcus, serotype 22, offered a possibility of transduction of the M22+-sign to M-SOR--strains of serotype T12. Transductants were selected in direct bactericidal test with subsequent determination of their type in the indirect bactericidal test with homo- and heterologous immune sera. The UV-lysates of the lysogenic M+ SOR+-cultures of serotypes 4, 22, and 49 offered a possibility of transducing both signs conjointly. In this case transductants were selected by the SOR-phenotype in the dishes with serum agar. All the transductants retained the T-serotype of the recipient's strain and segregated M-- and SOR--clones with high frequency. There were for the first time obtained in streptococcus of group A proofs of transduction of M+- and SOR+-signs pointing to their determination by different, but closely conjoint genes. Conditions of the marker transduction, selection and study of transductant were chosen, they opened new possibilities for genetic analysis of the virulence of streptococcus, group A.

Bacteriophages↗
PubMed1975

Transduction of various R factors by Plkc phage.

Transduction of R-factors with phage Rlkc was studied. Six of the R-factors controlled resistance to single antibacterial drugs, such as tetracycline, levomycetin, ampicillin, neomycin, streptomycin and nitrofurans. When the donor strains produced bacteriocins, treatment of the transducing lysates with trypsine increased the yield of the R+-transductants. Transduction of the resistance determinants was not in most cases accompanied with lysogenization of the recipient cells. It was confirmed that transduction with phage Rlkc provided division of the R-factors into 2 groups, i. e. those with the resistance determinants possessing transferability after transduction and those with the determinants possessing no such ability. It was supposed that one of the causes of the R+-transductant inability to transferance of the resistance determinants on conjugation was their intergration into the recipient chromosomes on transduction.

Ampicillin↗
PubMed1977

Transduction of penicillinase production and other antibiotic-resistance markers in Staphylococcus epidermidis.

Transduction of resistance from a multiply antibiotic-resistant strain of Staphylococcus epidermidis sub-group II was studied using the typing phage 108. The effect of increasing doses of ultraviolet radiation on the transducing phage was used to indicate the chromosomal or plasmid nature of the genes. Tetracycline and chloramphenicol resistance behaved as plasmid genes and streptomycin resistance as a chromosomal marker. It was also possible to transduce penicillin resistance (Pc) due to penicillinase production (bla+) using a low level of benzylpenicillin (0.03 microgram ml-1) for recovery. Approximately 10(-5) transductant colonies per phage input were obtained and ultraviolet kinetics indicated that Pc was plasmid carried. Pc transductants fell into two categories. In one group PC was stable as in the donor strain and transductants had the same phage sensitivity as the recipient. In the other, Pc was unstable at 37 degrees C and the instability was enhanced by growth at approximately 43.5 degrees C; these transductants also gained genes for restriction and modification of certain phages. Transductants that subsequently lost bla+ also lost the restriction and modification characters.

Anti-Bacterial Agents↗
PubMed1976

Derivation and properties of Proteus mirabilis systems for high frequency transduction of streptomycin--sulphonamide and streptomycin-sulphonamide--kanamycin resistances.

Properties of two transducing systems with phages capable of high frequency transduction (HFT) of streptomycin and sulphonamide resistance markers of the V group plasmid R905, and of these markers plus the kanamycin resistance marker derived from a previously described HFT phage 5006MHFTak, are described. Transducing particles of the former phage, named 5006MHFTsus, were detected using the replica-plate technique in an ultraviolet-induced lysate of Proteus mirabilis strain PM5006 transduced to streptomycin and sulphonamide resistance by phage 5006M grown on PM5006 carrying R905. Phage 5006MHFTsusk was also detected by the replica-plate technique in ultraviolet-induced lysates of of phage 5006MHFTsus transductants retransduced to ampicillin and kanamycin resistance by phage 5006MHFTak. Both phages were serologically identical to the parent phage 5006M. Ultraviolet-induced lysates transduced their markers to PM5006 at frequencies of about 5 X 10(-2)/plaque-forming unit adsorbed for both the phages. With phage 5006MHFTsusk, this frequency was increased about 10-fold by simultaneous infection of recipients with homologous non-transducing phage, while phage 5006MHFTsus transductions only underwent a twofold increase. Transductants took about 60 min to express complete resistance to 50 mug streptomycin/ml, and resistance to 1600 mug sulphadiazine/ml was complete within 120 min after phage adsorption. Phage 5006MHFTsusk was slightly more resistant to ultraviolet inaction of its transducing potential and reasons are given for the belief that transductants of both phages are heterogenote-like. Both phage lysates were also capable of generalized transduction and, like previously described HFT phages, lysates transduced the leucine marker at increased frequencies. Using previously described extra- and intra-species phages hosts, it was found that the phages could transduce in single infection and were defective in the lysogenic conversion function as well as in a maturation step. Possible modes of formation of the HFT particles are discussed9

Ampicillin↗
PubMed1978

Bacteriophage P22-mediated specialized transduction in Salmonella typhimurium: identification of different types of specialized transducing particles.

The temperate bacteriophage P22 mediates both generalized and specialized transduction in Salmonella typhimurium. Specialized transduction by phage P22 is different from, and less restricted than, the well characterized specialized transduction by phage lambda, due to differences in the phage DNA packaging mechanism. Phage lysates produced by induction of lysogenic strains contain very high frequencies of supQ newD- and proA,B-specialized transducing particles (10(-2)/PFU and 10(-3)/PFU, respectively), most of which are produced by independent aberrant excision events of various types. In a model, 12 different modes of transduction mechanisms were characterized by: (i) the structure of the specialized transducing genomes after injection into a new host cell, i.e., linear or circular, and (ii) the requirements for the transduction process, i.e., host recombination functions, phage integration functions, or presence of a prophage. By using different recipient strains and phage helper strains, it was possible to show that most specialized transducing particles (ca. 99%) contain linear genomes that cannot circularize upon injection into a new host cell and that require the presence of an integrated prophage as a site for a recombinational event to give rise to a transductant. Only 0.1% of all specialized transducing particles were shown to transduce by integration, suggesting that transducing genomes containing terminally redundant ends represent only a minor fraction of all transducing particles that are produced. However, it should be pointed out that the frequency (approximately 10(-5)/PFU) of these specialized transducing genomes that can circularize upon injection into a new host cell is as high as or even higher than the frequency of specialized transducing particles of phage lambda. The remaining approximately 1% of all specialized transducing particles can transduce by any one of the other mechanisms described.

Adsorption↗
PubMed2013

A survey of ex vivo/in vitro transduction efficiency of mammalian primary cells and cell lines with Nine natural adeno-associated virus (AAV1-9) and one engineered adeno-associated virus serotype.

BACKGROUND: The ability to deliver a gene of interest into a specific cell type is an essential aspect of biomedical research. Viruses can be a useful tool for this delivery, particularly in difficult to transfect cell types. Adeno-associated virus (AAV) is a useful gene transfer vector because of its ability to mediate efficient gene transduction in numerous dividing and quiescent cell types, without inducing any known pathogenicity. There are now a number of natural for that designed AAV serotypes that each has a differential ability to infect a variety of cell types. Although transduction studies have been completed, the bulk of the studies have been done in vivo, and there has never been a comprehensive study of transduction ex vivo/in vitro. METHODS: Each cell type was infected with each serotype at a multiplicity of infection of 100,000 viral genomes/cell and transduction was analyzed by flow cytometry + . RESULTS: We found that AAV1 and AAV6 have the greatest ability to transduce a wide range of cell types, however, for particular cell types, there are specific serotypes that provide optimal transduction. CONCLUSIONS: In this work, we describe the transduction efficiency of ten different AAV serotypes in thirty-four different mammalian cell lines and primary cell types. Although these results may not be universal due to numerous factors such as, culture conditions and/ or cell growth rates and cell heterogeneity, these results provide an important and unique resource for investigators who use AAV as an ex vivo gene delivery vector or who work with cells that are difficult to transfect.

Animals↗
PubMed2021

Adeno-associated Virus (AAV) Capsid Chimeras with Enhanced Infectivity Reveal a Core Element in the AAV Genome Critical for both Cell Transduction and Capsid Assembly.

Adeno-associated viruses (AAV) have attracted significant attention in the field of gene and cell therapy due to highly effective delivery of therapeutic genes into human cells. The ability to generate recombinant AAV vectors compromised of unique or substituted protein sequences has led to the development of capsid variants with improved therapeutic properties. Seeking novel AAV vectors capable of enhanced transduction for therapeutic applications, we have developed a series of unique capsid variants termed AAV X-Vivo (AAV-XV) derived from chimeras of AAV12 VP1/2 sequences and the VP3 sequence of AAV6. These AAV variants showed enhanced infection of human primary T cells, hematopoietic stem cells, and neuronal cell lines over wildtype parental viruses, and superiority over AAV6 for genomic integration of DNA sequences by AAV alone or in combination with CRISPR gene editing. AAV-XV variants demonstrate transduction efficiency equivalent to AAV6 at multiplicities of infection 2 logs lower, enabling T cell engineering at low AAV doses. The protein coding sequence of these novel AAV chimeras revealed disruptions within the assembly-activating protein (AAP) which likely accounted for observed lower virus yield. A series of genome alterations, reverting the AAP sequence back to wildtype AAV6, had a negative impact on the enhanced transduction seen with AAV-VX, indicating overlapping functions within this sequence for both viral assembly and effective T cell transduction. Our findings show these AAV-XV variants are highly efficient at cell transduction at low dose and demonstrates the importance of the AAP coding region in both viral particle assembly and cell infection.IMPORTANCE A major hurdle to the therapeutic potential of AAV in gene therapy lies in achieving clinically meaningful AAV doses, and secondarily, ability to manufacture commercially viable titers of AAV to support this. By virtue of neutralizing antibodies against AAV that impede patient repeat-dosing, the dose of AAV for in vivo gene delivery has been high, which has resulted in unfortunate recent safety concerns and deaths in patients given higher-dose AAV gene therapy. We have generated new AAV variants possessing unique combinations of capsid proteins for gene and cell therapy applications termed AAV-XV, which have high levels of cell transduction and gene delivery at lower MOI. Furthermore, we demonstrate a novel finding, and an important consideration for recombinant AAV design, that a region of the AAV genome encoding the capsid viral protein and AAP is critical for both virus yield and the enhancement of infection/transduction.

Journal Article↗
PubMed2009

Directed evolution of adeno-associated virus for glioma cell transduction.

Glioblastoma multiforme (GBM) is a serious form of brain cancer for which there is currently no effective treatment. Alternative strategies such as adeno-associated virus (AAV) vector mediated-genetic modification of brain tumor cells with genes encoding anti-tumor proteins have shown promising results in preclinical models of GBM, although the transduction efficiency of these tumors is often low. As higher transduction efficiency of tumor cells should lead to enhanced therapeutic efficacy, a means to rapidly engineer AAV vectors with improved transduction efficiency for individual tumors is an attractive strategy. Here we tested the possibility of identifying high-efficiency AAV vectors for human U87 glioma cells by selection in culture of a newly constructed chimeric AAV capsid library generated by DNA shuffling of six different AAV cap genes (AAV1, AAV2, AAV5, AAVrh.8, AAV9, AAVrh.10). After seven rounds of selection, we obtained a chimeric AAV capsid that transduces U87 cells at high efficiency (97% at a dose of 10(4) genome copies/cell), and at low doses it was 1.45-1.6-fold better than AAV2, which proved to be the most efficient parental capsid. Interestingly, the new AAV capsid displayed robust gene delivery properties to all glioma cells tested (including primary glioma cells) with relative fluorescence indices ranging from 1- to 14-fold higher than AAV2. The selected vector should be useful for in vitro glioma research when efficient transduction of several cell lines is required, and provides proof-of-concept that an AAV library can be used to generate AAV vectors with enhanced transduction efficiency of glioma cells.

Capsid Proteins↗
PubMed2026

Evaluation of transduction properties and vaccine efficacy of a simian adenovirus type 25-based vector.

Although human adenovirus serotype 5 (Ad5) is widely used as a vaccine vector for infectious diseases due to its high transduction efficiency, pre-existing immunity to Ad5 in many people reduces vaccine efficacy. To address this limitation, simian Ad vectors, such as ChAdOx1 and ChAdOx2, have been explored as alternative vaccine platforms. ChAdOx2 is based on simian Ad25 (SAd25), but the fundamental characteristics of gene transduction by SAd25-based vectors have not been fully elucidated. This study aimed to characterize the gene transduction efficiency, tissue distribution, and immunogenicity of an SAd25-based vector in comparison with those of the Ad5 vector following various routes of administration. Compared with intravenous administration of the Ad5 vector, intravenous administration of the SAd25 vector showed distinct biodistribution patterns, including reduced liver accumulation and predominant expression in the lung. Transduction by the SAd25 vector was not inhibited by human serum, whereas transduction by the Ad5 vector was inhibited, indicating that the SAd25 vector, but not the Ad5 vector, can evade pre-existing Ad immunity. Although intramuscular administration of the SAd25 vector induced lower transgene product-specific antibody production than intramuscular administration of the Ad5 vector, gene expression and Ad genome distribution mediated by the SAd25 vector, but not the Ad5 vector, were localized only to the muscle at the administration site. Intranasal administration of the SAd25 vector induced an antigen-specific antibody response in serum more rapidly than intranasal administration of the Ad5 vector. The SAd25 vector induced antigen-specific antibody production in bronchoalveolar lavage fluid (BALF) that was comparable to that induced by the Ad5 vector. These findings provide essential insights into the biological characteristics of the SAd25 vector, supporting its potential as a safe and effective vaccine vector.

Animals↗
PubMed1978

Studies on transduction process by SPP1 phage.

The conditions for optimal transduction efficiency of the Bacillus subtilis phage SPP1 have been investigated. By irradiating transducing lysates with u.v. light we have been able to obtain a fivefold increase in the number of transductants and to reduce strongly the interference caused by infective particles. Any dependence of SPP1 transduction on PBSX induction has been ruled out by the use of xin mutants, which are unable to induce the defective phage. SPP1 mediated transduction is susceptible to the restriction and modification system of B. subtilis. The rec functions involved in the recombination of the SPP1 transduced DNA fragment are probably identical to those required in DNA transformation and heterologous PBS1 transduction.

Bacillus subtilis↗
PubMed1976

Novel genotypes among transductants made with bacteriophage P1 lysates from an F14 merogenote strain of Escherichia coli K-12.

Among P1 transductants in Escherichia coli K-12 that were selected for the proximal and distal markers from the large F14 merogenote, a variety of unusual genotypes were found. As earlier workers had found, one class of these could transfer the proximal genes (argH, metB) and distal genes (ilvEDAC) of the F14 during conjugation. These F14 genes could be transferred into RecA recipients, indicating that they were carried on an F-merogenote rather than on an Hfr chromosome. The transduced F-merogenotes could transfer other F14 genes (metE, rha) as well. Transfer kinetic analysis showed that all of the latter transduced F-merogenotes that were examined were indistinguishable from the parental F14 in the order of transfer and the genetic distance between proximal and distal markers. This suggests that the whole F14 had been received somehow by the primary transductional recipients, a remarkable possibility since the F14 is much larger than the largest deoxyribonucleic acid segment normally transduced by P1. The mechanism of this phenomenon is not yet known. Many of the transductants did not transfer any of the F14 markers tested. Some of these transductants segregated certain F14 genes, indicating they were carried on self-replicating genetic elements, but others were not cured of F14 markers, even by acridine orange. Cotransductional analysis of this group was consistent with the hypothesis that the F14 markers in some of these strains had integrated into the chromosome in the expected manner, since in these latter the F14 alleles were linked to the expected chromosomal genes. Other strains among the stable transductants had acquired new linkages in that genes previously separated by several minutes could now be cotransduced. These latter included the novel cotransductional linkages of rbs-ilv-argH, rbs-ilv-argH-metB, and ilvD-argH-purD. Such strains might have been formed as a result of insertion into the chromosome of small circles derived from F14.

Acridines↗