Isolation of Additional Bacteriophages with Genomes of Segmented Double-Stranded RNA

Abstract

Eight different bacteriophages were isolated from leaves ofPisum sativum, Phaseolus vulgaris,Lycopersicon esculentum, Daucus carota sativum,Raphanus sativum, and Ocimum basilicum. All contain three segments of double-stranded RNA and have genomic-segment sizes that are similar but not identical to those of previously described bacteriophage φ6. All appear to have lipid-containing membranes. The base sequences of some of the viruses are very similar but not identical to those of φ6. Three of the viruses have little or no base sequence identity to φ6. Two of the viruses, φ8 and φ12, contain proteins with a size distribution very different from that of φ6 and do not package genomic segments of φ6. Whereas φ6 attaches to host cells by means of a pilus, several of the new isolates attach directly to the outer membrane. Although the normal hosts of these viruses seem to be pseudomonads, those viruses that attach directly to the outer membrane can establish carrier states in Escherichia coli or Salmonella typhimurium. One of the isolates, φ8, can form plaques on heptoseless strains of S. typhimurium.

Genomic and gene-expression comparisons among phage-resistant type-IV pilus mutants ofPseudomonas syringaepathovarphaseolicola

“…Our study addresses this limitation and lends more power to the phage ϕ6/Pph model system, because such work can now harness affordable re-sequencing approaches to compare ancestral and derived strains of bacteria. Also, recent studies show that Cystoviruses are readily found in the terrestrial phyllosphere in temperate environments, especially in association with bacteria residing on or within common legumes such as white clover plants (Mindich et al . 1999; Silander et al .…”

ORIGINAL ARTICLE: Coinfection rates in φ6 bacteriophage are enhanced by virus‐induced changes in host cells

“…Viruses that suppress superinfection frequently do so by downregulating the host receptor (Marschall et al 1997;Breiner 2001;Michel et al 2005); we therefore reasoned that upregulation of the /6 receptor -the host pilus (Vidaver et al 1973;Bamford et al 1976Bamford et al , 1987Roine et al 1996)could enhance coinfection by making host cells more susceptible to infection. We also reasoned that a related bacteriophage, /12, whose receptor (LPS (Mindich et al 1999)) is constitutively expressed (Whitfield and Valvano 1993) should be incapable of enhancing coinfection. Our observation that /6, but not /12, bacteriophage attach at a higher rate in populations with a higher proportion of infected hosts is consistent with these predictions and suggests the following model of coinfection enhancement in /6.…”

“…The double-stranded RNA bacteriophages /6 (Vidaver et al 1973) and /12 (Mindich et al 1999) were used in this study. /6 and /12 use as their receptor the host pilus (Vidaver et al 1973;Bamford et al 1976Bamford et al , 1987, and lipopolysaccharide (LPS) (Mindich et al 1999), respectively. The /6 strain used in this study was reconstructed from cloned genome segments (Gottlieb et al 1992) of a wildtype /6 isolate (Vidaver et al 1973).…”

“…We further examined the relationship between coinfection enhancement in /6 and the use of host pilus as the phage receptor by comparing the effect of infection on attachment rate in /6 and its close relative /12. We made this comparison because /6 uses the facultatively expressed (Roine et al 1996) host pilus as its receptor (Bamford et al 1987;Gottlieb et al 1988), while /12 binds to host LPS (Mindich et al 1999) which is constitutively expressed (Whitfield and Valvano 1993). If the ultimate cause of coinfection enhancement is upregulation of bacteriophage receptor, then viruses such as /6 -whose receptor is inducible -will be capable of enhancement, while viruses such as /12 -whose receptor is constitutively expressed -will be incapable of enhancement.…”

A bioassay-based protocol for chemical neutralization of human faecal wastes treated by physico-chemical disinfection processes: A case study on benzalkonium chloride

“…Therefore, enveloped bacteriophages φ6 (Vidaver et al, 1973) are currently discussed as suitable surrogates due to several of their advantageous characteristics such as the non-human pathogenic nature of both φ6 and P. syringae, their bacterial host (Wei et al, 2009) which allows their handling under bio safety level 1 (equivalent to minimal containment) (Gallandat and Lantagne, 2017). In addition, φ6 is easily cultivated, can be analysed rapidly using established culture techniques such as plaque assays and iscompared to other enveloped bacteriophages of the family Cystoviridae (Mindich et al, 1999) well described and characterized in literature (Laurinavicius et al, 2004). Still, a recent study by de Carvalho et al (2017) indicates that even though φ6 shows behavioural similarities to enveloped enteric viruses of the highest public health relevance, certain limitations in regards of their persistence towards temperature and their decay rate in deionized and natural waters exist.…”