Viruses are obligate intracellular parasites that contain genetic material in the form of DNA or RNA. The tobacco mosaic virus was the first virus discovered and has a rod-like structure containing RNA surrounded by a protein coat. Yellow fever virus causes a mosquito-borne illness with symptoms of fever, muscle pain, and vomiting. Its transmission can be prevented through vaccination. Lumpy skin disease virus is a poxvirus that causes nodules on the skin and mucous membranes of cattle. Bacteriophages are viruses that infect bacteria and have been used therapeutically to treat bacterial infections.

1. Submitted by-HARPREET SINGH
SGTB KHALSA COLLEGE
SHRI ANANDPUR SAHIB

2. HISTORY :
•Meaning : Poison
•Term given by : PASTEUR
•TMV was first discovered virus.
•D.J Lvanowsky (1892) – it recognise certain
microbes as casual organism of mosaic disease of
tobacco. They were first to be smaller then bacteria
because they passed through bacteria proof filters.

3. • M.W. Beijerinek (1898)- demonstrated that
the exact of the infected plant of tobacco that
could cause infection in healthy plants ans it is
called fluid as Contagium vivum fluidum.
• W.M Stanely (1953)- showed that virus could
be easily crystallised and crystals constant
largely of proteins.
• Virus are obligate parasite.

4. • Animal virus was discovered by Loeffler and
Frosch.
• SPECIFIC FEATURES OF VIRUS:
• They are submicroscopic ,obligate , intracellular
parasite which contains genetic material either
RNA or DNA.
• They enter into host cell and captures its all
metabolic activites .
• Virus is containing link between living and non-
living because of its biotic and abiotic chartacters.

5. Biotic (living) charaters-
• It contains nucleic acids so it is capable of
protein synthesis.
• It can multiply in host cell.
• It is pathogenic and shows mutation and
specificity towards host.

6. Abiotic (non living ) charaters:
• It lacks protoplasm ,enzyme, physiological
processes like respiration.
• It can be cystallized but can not be grown in
culture media.

7. Chemical composition-
• NUCLEIC ACID – virus contains either DNA OR RNA but
never both.
• In genetic material in plant virus in single stranded RNA
, in animal virus it is ssRNA or dsDNA
• dsDNA – Pox virus
• ssDNA – M13 phage
• dsRNA – wound tumor virus
• ssRNA – HIV virus
• dsDNA - Lumpy virus (LSD)

8. TOBACCO MOSAIC VIRUS
INTRODUCTION: Tobacco mosaic virus (TMV) is a
plant virus that belongs to the genus Tobamovirus.
It is named so because it majorly infects tobacco
plants, potatoes, tomatoes and other members of
the Solanaceae family. The infection creates a
mosaic like pattern, mottling and discoloration of
the leaves.

9. • Structure
• The tobacco mosaic virus (TMV) has a rod-like appearance
that is 300 nm long with a diameter of 18 nm.
• It is covered by a protein shell called capsid that encloses
the virus’s genetic material.
• The genetic material is a single-stranded RNA molecule.
• The capsid is made up of 2130 molecules of coat proteins
that assemble in a rod-like helical structure possessing 16.3
proteins per helix turn.
• The RNA is found in a coiled manner inside the capsid coat
and is made up of approximately 6395 nucleotides.

11. TREATMENT AND MANAGEMENT
• One of the common control methods for TMV
is sanitation, which includes removing infected
plants and washing hands in between each
planting. Crop rotation should also be employed
to avoid infected soil/seed beds for at least two
years. As for any plant disease, looking for
resistant strains against TMV may also be
advised. Furthermore, the cross protection
method can be administered, where the stronger
strain of TMV infection is inhibited by infecting
the host plant with a mild strain of TMV, similar
to the effect of a vaccine.

12. YELLOW FEVER VIRUS
• Yellow fever is a viral infection spread by a particular type
of mosquito. The infection is most common in areas of
Africa and South America, affecting travelers to and
residents of those areas.
• In mild cases, yellow fever causes a fever, headache, nausea
and vomiting. But yellow fever can become more serious,
causing heart, liver and kidney problems along with
bleeding. Up to 50% of people with the more-severe form
of yellow fever die of the disease.
• There's no specific treatment for yellow fever. But getting a
yellow fever vaccine before traveling to an area in which
the virus is known to exist can protect you from the
disease.

13. YELLOW FEVER VIRUS

14. SIGN and SYMPTOMS
• fever,
•muscle pain
• prominent backache
• headache
• loss of appetite
• nausea or vomiting.

15. •TREATMENT
Vaccination is the most important means of
preventing yellow fever.
The yellow fever vaccine is safe, affordable
and a single dose provides life-long
protection against yellow fever disease. A
booster dose of yellow fever vaccine is not
needed.

16. LUMPY SKIN DISEASE VIRUS

17. LUMPY SKIN
DISEASE VIRUS
Lumpy skin disease (LSD) is an
infectious disease in cattle caused by
a virus of the family Poxviridae, also
known as Neethling virus.

18. • The disease is characterized by fever,
enlarged superficial lymph nodes and
multiple nodules (measuring 2–5
centimetres (1–2 in) in diameter) on the
skin and mucous membranes (including
those of the respiratory and gastrointestinal
tracts).
• Infected cattle also may develop swelling
in their limbs and exhibit lameness.

19. •The virus has important economic
implications since affected animals tend
to have permanent damage to their skin,
lowering the commercial value of their
hide.
Additionally, the disease often results
in chronic debility, reduced milk
production, poor growth, infertility,
abortion, and sometimes death.

20. •CLASSIFICATION
• Lumpy skin disease virus (LSDV) is double-
stranded DNA virus. It is a member of
the capripoxvirus genus of Poxviridae.
• Brick shaped structure

21. Precautions
• To provide artificial immunity for animals.
• Use antibiotics
• Control the body temperature of animal.
• movement control (quarantine)
• Proper vaccination.

22. BACTERIAL VIRUSES
• Bacteriophages ,( virus that infact bacteria)
• meaning – bacteria eater , virus is parasitic
for bacteria
• Discovered by – Frederick (in england ) in 1915

23. General characterstics
• Thousands of varieties of phages exist, each of
which may infect only one type or a few types of
bacteria
• Phages are classified in a number of virus families;
some examples include Inoviridae, Microviridae,
Rudiviridae, and Tectiviridae.
• Like all viruses, phages are simple organisms that
consist of a core of genetic material (nucleic acid)
surrounded by a protein capsid.

24. • The nucleic acid may be
either DNA or RNA and may be double-
stranded or single-stranded.
• Bacterial Viruses are widely distributed in the
nature.

25. Replication

26. • Adsorption- Anchoring of bacteriophage to the
bacterial cell wall with the help of tails fibres.
• Penetration- The phage DNA gets injected into
bacteria.
• Replication and synthesis- The bacterial DNA is
disrupted and the viral genome takes charge of
bacterial machinery. It starts making proteins
required for replication and other structural
proteins.
• Assembly- Phage components are assembled into
new viral particles.
• Lysis and release- Bacterial cells are lysed and new
viral particles are liberated to infect other cells.

27. IMPORTENCE
• Bacteriophages are used for various purposes. They
are widely used in medical and research.
• Phage therapy- They are used as antibiotics against
bacteria due to the same mode of action.
• They are used in the food industry to kill bacteria in
meat or cheese products.
• Bacteriophages are used for diagnostic purposes.
• They act as a model in research and studies.
• They are used as a cloning vector in genetic
recombination technique.