Single-Stranded RNA Phages

Abstract

Abstract The single-stranded RNA coliphages were discovered by Tim Loeb and Norton Zinder in 1961 as the result of a search for phages whose infection cycle depends on E. coli F-pili, normally used for bacterial conjugation. Loeb and Zinder plated filtered samples of raw New York City sewage on E. coli strains and screened for phages that would produce plaques on male (F) but not female (F-) bacteria. The first isolate, named f1, turned out to be a filamentous phage with a single-stranded DNA genome; the second isolate, named f2, was an RNA-containing phage. Since f2 made clear plaques, Loeb and Zinder decided to concentrate their work on this phage (107). f2 and close relatives such as MS2 and R17 represented a superb source of pure messenger RNA that could be produced in large amounts: up to 1013 phage particles per milliliter are made within a few hours after infection of bacterial cultures, and the phages can be easily purified. RNA phages also attracted attention because scientists were intrigued about how their RNA genomes were replicated.