Phage infection detection

Messenger RNA. In 1956, Volkin and Astra-chan29 30 detected a rapidly labeled and labile RNA in phage-infected bacterial cells. Studies of enzyme induction also suggested the existence of mRNA. 

J.R. Biard and L.B. Kish, "Enhancing the sensitivity of the SEPTIC bacterium detection method by concentrating the phage-infected bacteria via DC electrical current", Fluct. Noise Lett. 5 (2005)L153-L158. 

The chart in Fig. 2 shows an alternate path for the formation of dUMP by direct deamination of dCMP. This may be how cytidine could be converted to thymidylate in the cases cited above [125,126]. However, this deaminase is not usually detected in E. coli but is induced by infection with T(even) phages [132,133]. It has also been purified from chick embryo and mammalian tissues, and its properties have been extensively analyzed [134-136]. It acts as a typical allosteric enzyme in both the phage-infected E. coli and animal systems. Homotropic substrate interaction is evident, and this is modified by dCTP as an activator, and by dTTP (sometimes dGMP) as an allosteric inhibitor. This type of control apparently functions to regulate the level of dTTP by feedback inhibition and by activation when the supply of dTTP is depleted. Cytidine deaminase (EC 3.5.4.5) isolated from sheep liver [137] appears to have the same allosteric properties, with the same positive and negative effectors, as those of dCMP deaminase. The latter enzyme is also induced by phage infection in B. subtiUs, and in contrast to the deaminase from all other sources it does not show allosteric inhibition or activation by any nucleotide [138]. 

Recent attention has been directed to the use of bacteriophages for bacterial infection detection and treatment (Vandenheuvel et al., 2013 Yilmaz et al., 2013 Sillankorva and Azeredo, 2014). Phages have been reported as being used as targeted drug vehicles for the eradication of S. aureus by endowing them with a targeting moiety on their surface and the antibiotic chloramphenicol (Yacoby et al., 2006 they have also been used to inhibit Chlamydia trachomatis intracellular infections (Bhattarai etal., 2012). 

The infected system was shown to contain deoxymidine 5-phosphate this observation is interesting, since this nucleotide has not yet been shown to be present in normal cells. The nucleotide is presumably used for the synthesis of thymidine 5-triphosphoric acid. Detectable quantities of 5-(hydroxymethyl)cytosine or of 5-(hydroxymethyl)cytosine nucleotides were not present, despite the fact that this base is a normal constituent of the phage deoxyribonucleic acid. Explanations for this observation are that (a) the amount present in the acid-soluble fraction at any given moment is too small for detection by the methods of anal3rsis employed, or (b) the newly synthesized 5-(hydroxymethyl)cytosine is directly incorporated into deoxyribonucleic acid. 

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