|Group:||Group IV ((+)ssRNA)|
f2 was the first RNA-containing bacteriophage to be isolated, reported in 1961. Tim Loeb and Norton Zinder searched for and discovered two phages in filtered samples of raw New York City sewage that grew on male (F+) but not female (F−) E. coli. The first phage was f1, which produced cloudy plaques; the second phage was f2, which produced clear plaques.
- van Duin, J.; Tsareva, N. (2006). "Single-stranded RNA phages. Chapter 15". In Calendar, R. L. The Bacteriophages (Second ed.). Oxford University Press. pp. 175–196. ISBN 0195148509.
- Loeb, T.; Zinder, N. D. (1961). "A bacteriophage containing RNA" (PDF). Proc. Natl. Acad. Sci. USA. 47 (3): 282–289. doi:10.1073/pnas.47.3.282.