viruses

1. Presented by: Bharat Kumar under supervision Mr. C.M. NAGAR

2. 1. History of Virology
2. Introduction
3. Morphology of viruses
4. Replication of Viruses

3. A Brief History of Virology
1892 beginning of virology
Dmitri Iwanowski showed that
ceramic filtered extracts from
diseased plants could transmit
disease to other plants.
1898
Martinus Beijerinick work on TMV Freidrich
Loeffler & Paul Frosch work on foot-and-mouth
disease in cattle
1915-1917
Bacteriophages (eaters of bacteria)Frederick Twort & Felix d’Herelle
discovered viruses which infect bacteria.
1880 – Germ Theory
Robert Koch & Louis
Pasteur Pasteur
identified rabies to be
cause by an agent he
termed “virus” from the
Latin for ‘poison’.

4. A VIRUS is either DNA or RNA, that is protected by a
protein coat called a CAPSID.
DNA CAPSID
VIRUS
Viruses are parasites that invade cells.

5. • Viruses infect Bacteria
These viruses are called Bacteriophages
• Viruses infect Plants
One example is the Tobacco Mosaic Virus
• Viruses infect Animals
One example is the common cold
Viruses usually infect a specific host including:

6. Virus invades cell
Virus forces cell to make copies of virus
Eventually so many copies are made,
the cell explodes,
releasing all of the new viruses
When your cells
make viruses
instead of
operating
normally, YOU
get sick

7. H-1 parvovirus,
lambda X 174
Bacteriophage
lambda,
Bacteriophage T4
Cowpea mosaic virus,
Poliovirus
Reovirus type 3
Rous sarcoma,
Mammary tumour
virus
Hepatitis-B
virus, Humans
Rodent and
Birds

8. Shape: Cuboid, coiled, bullet shaped, filamentous etc.
Size: Size varies form 20 nm to 30 nm in diameter.
Viral structure: Helical (TMV), Polyhedral (adenovirus),
Complex (vaccinia)
Viral envelop: It is made up of protein, lipids and
carbohydrates.
Nucleic acid: DNA or RNA.

9. Deferent type of morphology of viruses

10. V - Release
• Assembly of virus
DNA and protein
coat into whole new
viruses
• Leaving the cell
Phase I
Phase II
Phase IV Phase VPhase III
I, II, III - Viruses enter cell
• Attachment to cell membrane
• Penetration inside cell
• Losing virus protein coat
IV - Replication
• viral genome replicates
using the host's cellular
machinery