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Order Caudovirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
As described in the ninth official ICTV report by Lavigne et al. (2012), the Caudovirales order originally consisted of the three huge families of the tailed bacteriophages infecting bacteria and archaea, which were classified by the structure of their tails: Myoviridae with the long contractile tails, Siphoviridae with the long noncontractile tails, and Podoviridae with the short noncontractile tails. Figure 1.1 demonstrates typical images (we will call them portraits) of the representatives of these three great classical families.
Intestinal phages interact with bacteria and are involved in human diseases
Published in Gut Microbes, 2022
The Escherichia virus PDX is a member of the strictly lytic Myoviridae family. It was reported that Myoviridae phage PDX killed a disease-associated enteroaggregative E. coli (EAEC) isolated from a child from rural Tennessee and an EAEC isolated from a child from Columbia in a dose-dependent manner. Cepko LCS et al. further found that EAEC reduced the β-diversity of the human microbiota, while Myoviridae phage PDX could kill EAEC without causing dysregulation of the human microbiome.17 Lytic phages were injected into conventional mice colonized with a group of identified human symbiotic bacteria. Longitudinal tracking of each microbial response using high-throughput sequencing and quantitative PCR showed that phages T4, F1, B40-8, and VD13 lysed only their susceptible bacteria E. coli, Clostridium sporogenes, Bacteroides fragilis and Enterococcus faecalis, respectively. These phages showed no significant effect on other symbiotic bacteria.18 An in vitro small intestine model was used to analyze the effects of a DSM 1058 phage preparation on preselected target E. coli strains and nontarget bacterial populations. It was found that the phage preparation of E. coli DSM 1058 affected only the population number of E. coli. However, other “symbiotic” bacterial species included in the intestinal model, such as Streptococcus salivarius, Streptococcus lutetiensis and E. faecalis, were not affected.19
Fabrication of gelatin/silk fibroin/phage nanofiber scaffold effective against multidrug resistant Pseudomonas aeruginosa
Published in Drug Development and Industrial Pharmacy, 2021
W. A. Sarhan, H. G. Salem, M. A. F. Khalil, I. M. El-Sherbiny, H. M. E. Azzazy
The (MDR) P. aeruginosa strain was utilized to isolate a specific phage from sewage sediment samples collected from different Egyptian hospitals. The isolated phage produced well-defined clear plaques with a diameter range of 2 to 3 mm. Morphological characterization of the isolated phage (Phg) by transmission electron microscope illustrated that the phage has an icosahedral head of 71 nm in diameter and a contractile tail of 110–115 nm in length (Figure 1(a)). Thus, the phage was categorized as a representative of the Myoviridae family [13,39]. The latent period of the isolated Phg was 30 min while its burst size was 617 Phg per cell (Figure 1(b)). The burst size was calculated as the ratio of the mean yield of phage that infected the bacterial cells to the mean phage particles liberated.
“I will survive”: A tale of bacteriophage-bacteria coevolution in the gut
Published in Gut Microbes, 2019
Luisa De Sordi, Marta Lourenço, Laurent Debarbieux
Reductionist approaches using E. coli and its bacteriophages have successfully deciphered major mechanisms of molecular biology.21-23 By lifting the reductionist approach to the next level of complexity, namely the study of the intestinal microbiota, we recently described the coevolution of one bacteriophage with multiple host strains within the mouse gut.24 We studied P10, a virulent bacteriophage from the Myoviridae family, infecting the E coli strain LF82, and we assessed its ability to adapt to E. coli strain MG1655, to which it was initially unable to bind and therefore could not infect. Such host-range expansion was observed, but only occurred during coevolution in the gut of conventional mice hosting E. coli strains LF82 and MG1655 within their microbiota. In planktonic in vitro cultures or in the gut of dixenic mice colonized solely by the two E. coli strains, this event was never detected. Based on these findings, we hypothesized that the mouse microbiota played a crucial role in promoting adaptation. Indeed, we showed that this adaptation was initiated by the infection of an intermediate host, E. coli strain MEc1, which we isolated from the murine microbiota. Mixing bacteriophage P10 in vitro with the three E. coli strains also promoted viral host-range expansion. This adaptation was accompanied by genomic differentiation in the bacteriophage population: a single point mutation in a tail fibre-encoding gene was found to be sufficient to promote host adaptation, but additional mutations were required to optimise the infectious cycle.