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.
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.