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1. ANIMAL VIRUSES
Dr. Muhammad khurram

2. ANIMAL VIRUSES
Animal viruses are self replicating,
intracellular parasites that
completely rely on host animal cell
for reproduction. They use the
host's cellular components to
replicate, then leaves the host cell to
infect other cells.

3. THE BALTIMORE CLASSIFICATION OF VIRUSES
Animal viruses are classified in the following 7
groups according to relationship between virion,
nucleic acid & mRNA transcription :
Group1. ds DNA viruses
Group2. ss DNA viruses
Group3. ds RNA viruses
Group4. (+) sense ss RNA viruses
Group5. (-) sense ss RNA viruses
Group6. ss RNA reverse transcribing viruses
Group7. ds DNA reverse transcribing viruses

4. Group1. ds DNA viruses:the mRNA
is synthesized on a ds DNA
genome template.following are
eg. Of some viruses 1.
adenoviruses
2.herpes virus
3. papovavirus
4. poxvirus

5. 1. Adenoviruses
• virions are naked ,
non enveloped. 90-100
nm diameter & have
icosahedral symmetry.
•The penton fibers with
a globular head are
involved in the process
of attachment of the
virus to the host cell.
•Hexons consists of
protein II with a
central core, invoved
in the stabilization &
assembly of particles.

6. Diseases caused by adenoviruses are :
1. respiratory disease
2.conjunctival pneumonia
3.acute hemorrhagic cyctitis
4.acute gastroenteritis

7. 2.Herpes virus
•The nucleocapsid is
spherical icosahedral &100
nm in diameter , enclosed in
glycoprotein lipid envelop.
•Glycoprotein are visible as
“spikes” that are projected
from the surface.
•The nucleic acid is linear ds
DNA which is converted into a
circular DNA molecule upon
slight digestion .
•Disease caused by herpes
virus : herpes simplex I ( cold
sores), herpes simplex II
(genital sores) & varicellovirus
(chicken pox. Shingles) .

8. 3. Papovavirus
• Capsid is of 45-55 nm
diameter, naked ,
icosahedral, virion
consists of DNA &
protein. capsid is made
up of 72 capsomers.
•Virus enter the cell &
migrates to the nucleus
for replication.
•Disease:
•Papilomavirus (cervical
cancer,human warts)
•Polyomavirus (cause
tumor in mice)

9. 4. poxvirus
•Poxvirus are brick
shaped (240-
300nm),dsDNA
genome (130-260kb) &
naturally associated
with enzyme
•Virions are
enveloped . Viral
multiplication is
started by viral
transcriptase, the
viral components are
synthesized &
assemble in the
cytoplasm of the host
cell.

10. Grpoup 2. ssDNA
virus: parvovirus
•Parvovirus are
linear, average
genome size of 5000
nucleotide, smallest
virus with 18-28 nm
diameter.
•Viral capsid s made
up of 2-4 protein
form naked
icosahedral structure.
•Diseases:
•Human parvovirus
B19
•Erythema

11. Group3. (+) ss RNA
virus:1. corona virus
•Corona virus are
enveloped, helical
&60-200 nm
diameter.genomes size
are 16-21kb.
•it replicates in the
cytoplasm.
•Diseases :
•Respiratory
syndrome
•Severe acute
respiratory syndrome

12. 2.Picorna virus
Virions naked ,icosahedral.
Capsid is composed of 60
copies of 4 structiural
protein .
Viral genome are linear
7.1-8.9 kb size
Diseases:
poliovirus (polio)
Rihinovirus( common cold)
Hepatitis A virus (hepatitis
A)

13. 3.Togavirus
•Envelop consists of
80 trimer spikes . The
spikes consists of
glycoprotein that
help in attachment
protein to receptor of
host cell membrane.
•Eg. Alpha virus
•Eastern equine
encephalitis virus
•Yellow fever virus
•Rubella virus

14. Group 4. (-) ssRNA
viruses
1.Rhabdovirus
Envelop with spikes
made up of gly
coprotein linked
matrix protein
contain nucleocapsid
Eg. Mumps virus ,
rabies virus

15. 2. Orthomyxo virus

16. Group 5. ds RNA virus :eg. reovirus
Group6. ss RNA RT virus :
eg.reterovirus
Group 7. ds DNA RT virus: eg
Hepadna virus.

17. THANK YOU