A detailed assignment presenting information about poliomyelitis , piovirus and polio vaccination. Polio virus is first virus in history to be obtained in crystalline form . Poliomyelitis has been life threatening disabling disease in human history before vaccination. Vaccination is only method to defeat the virus . Once we will get 0% of infected cases then we will stop the oral polio vaccination. Oral poilo vaccination is more effective in preventing epidemic of poliomyelitis caused by wild polio virus than IPV .

1. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
1
POLIO
Polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus. The
virus spreads from person to person and can infect a person’s spinal cord, causing paralysis (can’t
move parts of the body).
Caused by : Enterovirus C
Family : Picornaviridae ,( Single stranded RNA, + Strand Nonenveloped ( 28-30 nm)
PICORNAVIRIDAE
 Picornaviruses are Single stranded RNA
viruses. They are the smallest viruses and
the prefix Pico (small) plus RNA gives
these viruses their name. The RNA within
the virion is called sense strand (or +
strand) , because it can act as mRNA.
After attachment, penetration, and
uncoating are completed, the single
stranded viral RNA is translated into two
principals proteins , which inhibit the host
cell’s synthesis of RNA and protein and
which form an enzyme called RNA -
dependent RNA Polymerase.
 This enzyme catalyzes the synthesis of
another strand of RNA , which is
complementary in vase sequence to the
original infecting strand . This new strand
, called an antisense strand ( or – strand)
,
 Serves as a template to produce
additional +strand. The + strand may
serve as mRNA for the translation of
capsid proteins may become incorporate
into capsid proteins to form a new virus ,
or may serve as a template for continued RNA multiplication. Over viral RNA and viral
protein are synthesized, maturation occurs.
Descriptive Epedimiology : Collection of data that describes the occurrence of disease under
study .
Retrospective : looking backward after the episode has ended .
Prospective: looking forward , the epidemiologist choose a group of people who are free of
a particular disease to study .
Prospective studies were used to test the Salk polio vaccine in 1954 and 1995.

2. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
2
Naturally acquired passive immunity:
If mother Is immune to polio , the newborn will be temporarily immune to this disease as
well
Certain antibodies are also passed from mother to her nursing infants in breast milk,
especially in first secretions called colostrum. In infants , the passive immunity generally
lasts only as long as the transmitted antibodies persist ---- usually a few weeks or months.
POLIOMYELITIS :
It is an enteric infection caused by polioviruses. A poliovirus, the causative agent of polio, is
a serotype of the species Enterovirus C, in the family of Picornaviridae. There are three
poliovirus serotypes: types 1, 2, and 3. Poliovirus is composed of an RNA genome and a
protein capsid.Polio viruses are transmitted by faecal-oral route . The world wide prevalence
has decreased by more than 99% due to improved socio-economic conditions and
availability of vaccines . Properties of Polio Virus :
1 Morphology:
Polio virus show the following features :
 Polio virus was first animal virus to be purified and obtained in crystalline form.
 The virus are spherical particles about 27 nm in diameter
 The virion is composed of 60 subunits, each consisting of four viral proteins (VP1 – VP4)
 The viral protein VP1 contains the major antigenic site for combination with type-
specific neutralising antibodies .
 The viral genome is single stranded positive-sense RNA which can be directly translated
by host ribosomes to form a polyprotein , which is divided into 11 different proteins.
2 Viral Replication:
Poliovirus are cytolytic; they replicate in cytoplasm of the host cells .
They show high host specificity restricted to primates ( both human and non-human
primates such as monkeys and apes) . This is due to presence of specific receptor that is
present only on primate cell membrane.
However , purified viaral RNA without capsid protein can enter and replicate in many non
primate cell by avoiding the cell membrane receptors .
How Virion of Polio virus causes infection?
1. Firstly Virion binds to specific receptor on cell membrane and enters the cell.
2. Once inside the cell , the virion uncoated by removing the capsid and release the
RNA genome.
3. The RNA serves as mRNA and is translated into a very large polypeptide known as
non-capsid viral protein.

3. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
3
4. Subsequently, the viral protein is utilised by the viral enzyme protease to form
capsid proteins of progeny virions as well as several non-capsid proteins including
RNA polymerase
5. RNA polymerase initiates the synthesis of progeny RNA genomes .
6. This is followed by assembly of progeny virions by coating of genomes RNA with
capsid proteins in cell cytoplasm.
7. The release of progeny virions occur by the lysis and death of the cells, but not by
budding form the cell membrane.
3 Antigenic properties:
Polioviruses are classified into 3 serotypes ( type 1,2,and 3)
 Type 1 is most common Polio Virus and cause most epidemics of poliomyelitis.
 Type 2 strain is usually associated with endemic infections
 Type 3 occasionally cause epidemics
Two antigens C ( colourless or capsid ) and D ( dense ) are recognized by enzyme-linked
immunosorbent assay or precipitation test
 The C antigen, also known as heated or H antigen is associated with empty , non-
infectious virus . It is less specific and reacts with heterotypic Sera.
 The D antigen, also known as the nature of N antigen is associated with the whole
Virion. It is specific and is type specific.
Antibodies against D antigen are protective ; hence the potency of injectable polio vaccine is
measured in terms of D antigen unit.
4 Other Properties:
 Poliovirus is sensitive to heat and is readily inactivated at 55°C for 30 minutes m
 It is sensitive to formaldehyde and oxidizing disinfectants.
 The viruses are readily destroyed by chlorination in water , but the presence of
organic matter delays inactivation n
 Poliovirus are resistant to lipid soluble agents (ether, chloroform and bike) ,
proteolytic enzymes of the intestines and detergents .
 They survive in faeces for months at 4°C and for years at -20°C .
 They survive for days to several weeks in faeces at room temperature depending on
the environmental conditions sucha s temperature, moisture, acidity etc
 Polioviruses are killed by Lyophilisation .

4. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
4
Clinical Syndromes of POLIOMYELITIS
Poliovirus causes a wide spectrum of illness in unvaccinated people. Incubation period is
usually 10 days but may vary from 4 days to 4 weeks.
Asymptomatic illness
 Most patients ( 90 – 95%) infected with poliovirus are asymptomatic.
 This results when viral infection is confined to oropharynx and intestine.
Abortive Poliomyelitis
 It is minor illness
 Occurs in approximately 5% of infected people.
 This is febrile illness characterised by fever, headache , sore throat, loss of appetite,
vomiting, and abdominal pain .
 Neurological symptoms are typically absent.
 The duration of this illness is less than 5 days.
Non – paralytic Poliomyelitis
 It is also known as aseptic meningitis
 It is cause by invasion of virus into the CNS .
 The symptoms of Non-paralytic poliomyelitis are similar to those of abortive
Poliomyelitis but are more intense.
 Stiffness of posterior muscles of the neck , trunk and limbs is present in addition to
the symptoms of minor illness .
 This condition occurs in 1-2% of infected patients
Paralytic Polio
 This is the major Illness
 It occurs in 0.1-2% of individuals infected with poliovirus.
 This is most severe manifestation of poliomyelitis and appears after 3-4 days after
the abortive Poliomyelitis has subsided
 This condition is caused due to invasion of virus from blood to anterior horn cells of
the spinal cord and the motor cortex of the brain.
 Depending on various tissues or organs affected and intensity of neuronal infection,
poliomyelitis may be of two types as follows ;
Paralytic Poliomyelitis:
 Paralytic Poliomyelitis or spinal paralysis is characterised by spinal paralysis
involving one or more limbs.
 Asymmetrical flaccid paralysis with no sensory loss is typical manifestation.
 This condition is mostly caused by type 1 poliovirus.
 This condition is seen in some of the vaccinated individuals following
vaccination.
 This occurs due to reversion of attenuated vaccine viruse type 2 and 3 to
virulence types.

5. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
5
 In this condition there maybe paralysis of only one limb such as one leg or
there may be complete flaccid paralysis of both the legs and hands .
 The condition may progress to death or may recover completely with
residual paralysis.
Bulbar poliomyelitis:
 This is caused due to the involvement of cranial nerves , most commonly 9th
,
10th
and 12th
.
 This condition tends to be more severe with involvement of the muscles of
pharynx , vocal cords and respiration.
 The condition may cause death in 75% of the patients
Post poliomyelitis Syndrome :
 This condition is squeal of poliomyelitis, which may develop 20-40 years
after injection with poliovirus.
 The condition is seen in 20-80% of patients who have recovered from
poliomyelitis.
 Recurrence of weakness or fatigue is observed in this condition and it
usually involves the muscles that were initially affected by poliovirus.
Epidemiology of Polio virus
Polio virus mainly affects children. However, individuals of any age
may also develop the disease.
 Most epidemics of paralytic Poliomyelitis are caused by
poliovirus type 1, less commonly by type 3 .
 Poliovirus type 2 is a common cause of paralytic
Poliomyelitis in India and is causative of inapparent illness in
Western countries.
 It is major public health problem in developing countries.
Significance progress has been made in reducing the
prevalence of poliomyelitis in India . India was declared to
be free in the year 2014
Treatment
No antivirals are available for treatment of poliomyelitis.

6. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
6
Transmission and source of infection
 Infected humans excreting poliovirus in their stool are the
major reservoir of infection.
 Infected stool is major source
 Virus secreted in throat secretions during early stage of
infection.
 The polio virus is transmitted:
 Primarily by the faecal-oral route by ingestion of food
and water contaminated with human faeces
 By inhalation or through fomites contaminated with
respiratory secretions.
 Poor sanitation, low socioeconomic status and
crowded living conditions facilitate transmission of
infection.
 Immunocompromised patients such as those with
HIV infection, B cell dysfunction and IgA deficiency
are particularly at high risk of developing
poliomyelitis when exposed to poliovirus.
Prevention And Control
Polio vaccine are the key component in prevention of polio and have
played an important role in the effort to eradicate polio worldwide.
Vaccination
Public health officials estimate that polio will be eradicated within a few years
because of the polio vaccine .
 Vaccination is frequently the only feasible method
of controlling viral disease.
 Controlling a disease doesn’t necessarily require
that everyone be immune to it .
 If most of population is immune, a phenomenon
called herd immunity, outbreaks are limited to
sporadic cases because there are not enough

7. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
7
susceptible individuals to support the spread of
epidemics.
 Two types of vaccine used are as follows :
 INACTIVATED POLIO VACCINE
 Also called Salk vaccine
 It was developed by Jonas Salk in 1956 for immunisation
against poliomyelitis.
 The vaccine contain formalin inactivated strains of three
serotypes of poliovirus grown in monkey kindness cell
culture.
 The vaccine is given to children by deep subcutaneous or
intramuscular injections in 3 doses .
 The vaccine is given at 2 months , 4 months and at 4
years .
 It doesn’t cause development of Vaccine associated
poliomyelitis (VAP)
 The injection of the vaccine elicits the production of
higher IgG antibody titres in serum, but it doesn’t
stimulate the production of detectable level of secretory
IgA in the gut ,
 Hence it doesn’t prevent alimentary tract infection.
 The main advantage of this vaccine is that since it uses
killed viruses , it can safely be used for immunisation in
immunocompromised hosts.
 The disadvantage of this vaccine are
1. It is not as immunogenic as oral polio vaccine
2. It doesn’t induce local mucosal immunity in the gut.
3. It needs to be administered parenterally which
shows poor compliance.In 1995 , more than 100
cases of paralytic Poliomyelitis occurred with the

8. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
8
vaccination of company Cutter ( called as CUTTER
INCIDENT) .
That company used inactivated virus.
 Live Attenuated Oral Polio Vaccine
 It also called as Sabin Vaccine .
 It was developed by Albert Sabin in year 1962.
 It contains live Attenuated strains of three serotypes of
poliovirus cultured in monkey kidney cells or human
diploid cells.
 The vaccine is given orally, which causes natural infection.
 It elicits the production of both Local secretory IgA
antibodies in pharynx and alimentary tract and hormonal
IgG antibodies in serum.
 The vaccine virus i excreted for several weeks in faeces
during which the vaccine virus spread occur in close
contacts, inducing or boosting immunity in them.
 The 1st dose is given to infants at age of 1.5 months along
with DPT.
 2ND dose 2.5 months.
 3rd dose 3.5 months .
 4th dose 16-24 months .
 Oral polio vaccine has been used since 1960s.
 OPV is mainly responsible to prevent Polio throughout the
world.
 The advantages of this live vaccine are
 It induces a call mucosal immunity.
 It provides appropriate herd immunity.
 It is cost effective
 The shelf life is 4 months if stored at 4 – 8 °C
 The shelf life is 2 years if stored at temperature -2°C.

9. Assignment on POLIO
By Asma Jamal Khan ( 4th
Semester, Pharm-D)
9
Difference between Polio Salk (killed) and Sabin Vaccine
Killed vaccine
Salk
Live Attenuated vaccine
Sabin
Administered parentally Administered orally
Less cost effective Most cost effective
Stimulate systemic antibodies response
only without intestinal immunity. Wild
strain intestinal infection can occur.
Stimulate local immunity within gut .
Administering booster doses periodically
may be required in maintaining
immunity
Immunity from live vaccines remain as
natural active immunity and it lasts
longer
Not effective to stop epidemic Effective to stop epidemic