VIRUS Siti Fatimah Mohd Noor
LEARNING OUTCOME
To understand that virus is not an organisms
Identify virus component
Briefly discuss the virus life cycle
BRIEF HISTORY OF VIRUS
“Term was originally 1st virus discovered
“Virus” originates from used by Pasteur to was tobacco mosaic
Latin word “poison”. describe infectious disease virus (TMV) in
agent for rabies. 1890s.
In 1930s: TMV was
Distinguished from
isolated and purified. By 1950s science of
bacteria by being
Electron microscope virology was well
“filterable agents” in
was used to observe established.
early 1900s.
viruses.
INTRODUCTION TO VIRUS
A small infectious agent that replicates only inside the living cells of
Definition
other organisms.
Viruses can infect all types of life forms, from animals and plants to bacteria
and archaea
Acelullar (absents of nucleus, organelles, cytoplasm, plasma membrane)
VIRUS ARE NOT AN ORGANISMS!
On their own they can do
It do not metabolize nothing until they enter a living
cell
They can only reproduce inside
They cannot move or grow
a host cell
VIRUS SIZE
GENERAL CHARACTERISTICS OF VIRUS
Obligatory intracellular parasites (can be maintained only inside living cells)
Contain genetics material
Contain a protein coat
(DNA or RNA)
Some are enclosed by an envelope Some viruses have spikes
Some viruses have their own enzyme
CHARACTERISTICS OF VIRUS
Most viruses infect only specific types of cells in one host
Host range is determined by specific host attachment sites and cellular factors
Depend on host cell ribosomes, enzymes, and nutrients for protein production
Viruses replicate through replication of their nucleic acid and synthesis of the viral
protein.
Viruses do not multiply in chemically
Smaller than a most cells
defined media
STRUCTURE OF
VIRUS MATERIALS FUNCTIONS
Contain genetics information
Genetics material (DNA or
to replicate themselves in
RNA) in the inner core
host cells
Capsid and sometimes Covering the genetics
envelope material
To attach specific receptor
of host
Glycoprotein spike – arise
• Specific to their hosts
from envelope that antigenic
• They attack specific
cells.
VARIOUS SHAPE OF VIRUS
VIRUS LIFE CYCLE
LYTIC CYCLE LYSOGENIC CYCLE
Viral DNA destroys Cell DNA, Viral DNA merges with Cell DNA
takes over cell functions and and does not destroy the cell.
destroys the cell. The Virus does not produce
The Virus replicates and progeny.
produces progeny phages. There are no symptoms of viral
There are symptoms of viral infection.
infection. Temperate viral replication takes
Virulent viral infection takes place.
place.
LYTIC CYCLE
LYSOGENIC CYCLE
VIRUS INFECTION IN HUMAN
Coxsackie virus (CSV) infection is classically Smallpox is an infectious disease caused by a virus
associated with hand, foot, and mouth disease called the Variola virus. Smallpox is usually contracted
(HFMD). through inhaling the virus.
VIRUS INFECTION IN PLANTS
Tobacco mosaic virus (TMV) infection
Various virus infection in plants parts.
in tobacco plants.
ITS PLAY TIME!
QUIZ 1: https://create.kahoot.it/kahoots/my-kahoots
QUIZ 2: https://quizizz.com/admin/quiz/5bac31d8379c7600191f282a/virus
