Bacteriophage - basic principle

Virus structure Bacteriophage T4 has a complex capsid: DNA enclosed inside an icosahedral head attached to a tail complex composed of tail sheath and tail fibers Enveloped viruses such as influenza virus: has nucleic acids enclosed inside a capsid; a phospholipid and glycoprotein envelope surrounds the capsid Adenovirus; has icosahedral capsid with glycoprotein spikes Tobacco mosaic virus (TMV) - one of the first viruses to be identified; rod-shaped virus; has a helical capsid with spiral RNA Tail fibers Tail sheath Nucleic acid (DNA/RNA) Capsomeres of capsid shell Membranous envelope Icosahedral head Capsomeres of capsid shell Glycoprotein spikes Nucleic acid (RNA)

Bacteriophage - testing Lytic T-phage does not attack Enterobacter aerogenes; note the absence of plaque in the lawn of E. aerogenes Lytic T-phage is specific to E. coli B strain; note the patch of lysis (plaque) in the lawn (confluent growth on the surface of the medium) of E. coli B