It is a non-cellular organism made of genetic material and protein that can
infect the living cells by causing disease. They have nucleic acids and can
evolve and they don’t grow in size. They must depend on a host cell to
synthesize their proteins and to make copies of themselves. Study of viruses is
known as virology and people who study viruses are known as virologists.
Types of Viruses
|
DNA VIRUS
|
RNA VIRUS
|
|
If the virus contains nucleic acid DNA
|
If the virus contains nucleic acid RNA
|
Steps For Virus Infection
It involves the placing of viral DNA into a host cell, replication of that
material and the release of the new viruses.
Steps For Virus Replication
|
S.NO
|
PHASE
|
DETAILS
|
|
1
|
Attachment
|
It attaches itself to the target cell.
|
|
2
|
Penetration
|
It is brought into the target cell.
|
|
3
|
Uncoating and Replication
|
The enveloped virus loses its envelope, viral RNA is released into the nucleus,
where it is replicated.
|
|
4
|
Assembly
|
Viral proteins are assembled.
|
|
5
|
Egress (Release)
|
It releases new virions / viral particles. Some viruses kills the host cell and
remaining will leave the infected cells by budding the membrane without killing
he cells.
|
Viruses are not cells; they are a strand of genetic material within a protective
protein coat called a capsid. They infect organisms include eukaryotes and
prokaryotes. They inside the cell use the cell’s ATP, ribosomes, enzymes other
cellular parts to replicate. Antibiotics don’t effect on viruses. Vaccine
can prevent viral diseases & produces immunity. Only for few diseases vaccines
are available.
Virus Transmission Ways
|
S.NO
|
ROUTE
|
EXAMPLE
|
|
1
|
SKIN CONTACT
|
HPV (warts)
|
|
2
|
RESPIRATORY
|
Cold viruses, measles, mumps, rubella
|
|
3
|
FAECAL-ORAL
|
echo, Hepatitis A, Rotavirus, polio
|
|
4
|
MILK
|
HIV, HTLV-1, CMV
|
|
5
|
TRANSPLACENTAL
|
Rubella, HIV
|
|
6
|
SEXUALLY
|
HIV
|
|
7
|
INSECT VECTOR
|
Dengue fever
|
|
8
|
ANIMLA BITE
|
Rabies
|
Virus Residence
|
S.NO
|
VIRUS
|
ANIMAL RESERVOIR
|
|
1
|
Influenza
|
Birds, pigs, horses
|
|
2
|
Rabies
|
Bats, dogs, foxes
|
|
3
|
Lassa and Hanta viruses
|
Rodents
|
|
4
|
Ebola and marburg viruses
|
Monkeys
|
|
5
|
HIV-1 and -2
|
monkeys and Chimpanzees,
|
|
6
|
Newcastle disease
|
Poultry
|
|
7
|
West Nile virus
|
Birds
|
Virus Characteristics
1. They are enclosed in a protective envelope.
2. They have spikes, which helps them to attach to the host cell.
3. They do not respire, do not metabolize and do not grow but they do reproduce.
4. They contain a protein coat called the capsid.
5. They have a nucleic acid core containing DNA or RNA.
6. Ribosomes and enzymes are absent which are needed for metabolism.
7. They are considered both as living and non living things, viruses are
inactive when present outside of host cells and are active in side of host
cells. They use raw materials and enzymes of the host cell to reproduce and
cause several infections.
ZOONOSIS:It a disease which can be transmitted to humans from
animals.
Antibodies defence To Viral Infections
Antibodies are used to provide immunity against the virus. They are 5 types
of antibodies present in human body. They were
|
S.NO
|
ANTIBODY
|
DETAILS
|
|
1
|
IgA (immunoglobin A)
|
Found in mucosal areas purpose is autoimmune diseases
|
|
2
|
IgD (immunoglobin D)
|
It purpose is unknown
|
|
3
|
IgE (immunoglobin E)
|
Found in lungs, skin, and mucous membranes. Its purpose Allergy
Response.
|
|
4
|
IgG (immunoglobin G)
|
eliminate infection and reduce toxins
|
|
5
|
IgM (immunoglobin M)
|
Involved in
|
|
S.NO
|
VIRUS
|
HOST
|
TRANSMISSION
|
DISEASE
|
|
1
|
Marburg
|
Human, monkeys, bats
|
Zoonosis, fomite
|
Hemorrhagic fever
|
|
2
|
Ebola
|
Human, monkeys, bats
|
Zoonosis, contact
|
Hemorrhagic fever
|
|
3
|
Hantavirus
|
Human, rodents
|
Zoonosis, urine, saliva
|
Renal or respiratory syndrome
|
|
4
|
bird flu
|
Human, birds, pigs
|
Respiratory or Zoonosis, animal contact
|
Flu
|
|
5
|
Lassa
|
Human, rats
|
Zoonosis, fomites
|
Hemorrhagic fever
|
|
6
|
Junin
|
Human, rodents
|
Zoonosis, fomite
|
Hemorrhagic fever
|
|
7
|
Crimea
|
Human, vertebrates, ticks
|
Zoonosis, arthropod bite
|
Hemorrhagic fever
|
|
8
|
Machupo
|
Human, monkeys, mouse
|
Zoonosis, fomite
|
Encephalitis
|
|
9
|
Dengue
|
Human, mosquitoes
|
Zoonosis, arthropod bite
|
Hemorrhagic fever
|
|
10
|
Nipah
|
Human, bats
|
Human, bats
|
Encephalitis
|
|
11
|
yellow fever
|
Human, monkeys, mosquitoes
|
Zoonosis, arthropod bite
|
Hemorrhagic fever
|
|
12
|
Influenza
|
Human, birds, pigs
|
Respiratory or Zoonosis, animal contact
|
Flu
|
|
13
|
SARS
|
Human, palm civet
|
Zoonosis
|
Respiratory
|
|
14
|
Kunjin
|
Human, horses, birds, mosquitoes
|
Zoonosis, arthropod borne
|
Encephalitis
|
Home
Back
|