T7 bacteriophage is a virus that infects Escherichia coli bacteria and has a lytic life cycle. It was first used to describe one of seven phage types that grow lytically on E. coli in a 1945 study. T7 bacteriophage has an icosahedral capsid that is 60nm in diameter containing its 40kbp linear double-stranded DNA genome which encodes 55 proteins. It has a short life cycle of 17 minutes to replicate within and lyse its E. coli host cell.

1. T7 BACTERIOPHAGE
M.AFREEN AZEELA
III-B.SC MICROBIOLOGY

2. INTRODUCTION
 Bacteriophages are viruses
that infects and replicate only
in a bacterial cells.
 The word bacteriophage
literally means BACTERIA
EATER.

3. T7 BACTERIOPHAGE
 T7 Bacteriophage is a
virus that infects
susceptible bacterial
cells that is composed
of DNA and infects most
strains of Escherichia
coli.
 T7 has a lytic life cycle

4.  In a 1945 study by DEMEREC and FANO,T7
was used to describe one of the seven
phage type members that grow lytically
on Escherichia coli.
DISCOVERY

5. HOSTS
 T7 grows on rough strains of
Escherichia coli and some
other Enteric bacteria.
 It also infects smooth and even
capsulated strains.
 It infects E.coli0157;H7, a
strain of E.coli that can cause
foodborne illness.

6. STRUCTURE
 Complex structural symmetry.
 Capsid is icosahedral in
shape.
 Capsid – 55nm in inner
diameter.
 Head – 60nm in diameter.
 Tail – 19nm in diameter.
 Long attachment – 28.5nm in
diameter.
 Non-Enveloped.
 Tail is non-contractile.
 Tail has 6 short sub terminal
fibres.

7. GENOME
 The genome of phage T7 was among the first
completely sequenced genomes and was published in
1983.
 The head of the phage particle contains the roughly
40kbp linear dsDNA genome which encodes 55 proteins.

8. LIFE CYCLE
1.ADSORPTION
2.PENETRATION
3.REPLICATION
4.MATURATION
5.ASSEMBLY
5.RELEASE

10. TIME DURATION
T7 has a short life cycle of 17min at
37’C .
The time for the infection to the lysis
of the host cell when new phages are
released.

11. THANK YOU