Poliovirus is an enterovirus that causes the acute infectious disease poliomyelitis. It is spherical and 27nm in diameter with an icosahedral capsid containing its single-stranded RNA genome. It infects and replicates in the intestinal tract and sometimes spreads to the central nervous system, destroying motor neurons and potentially causing flaccid paralysis. While most infections are asymptomatic, it can cause a range of illnesses from minor to paralytic. Diagnosis involves isolating the virus from specimens through cell culture and identification, and treatment involves vaccination to develop protective antibodies.

1. Poliovirus

2. Poliovirus
• Poliomyelitis is an acute infectious disease that
in its serious form affects the central nervous
system.
• The destruction of motor neurons in the spinal
cord results in flaccid paralysis. However, most
poliovirus infections are subclinical.

3. Morphology poliovirus
• Size: The virion is a spherical particle, about 27 nm
in diameter
• Capsid: It consists of a capsid shell of 60 subunits,
each consisting of four viral proteins (VP1-VP4),
arranged in icosahedral symmetry.
• Genome: The genome is a single strand of positive
sense RNA.
• The virus can be crystallised, and arrays of virus
crystals can be seen in the cytoplasm of infected
cells.

5. Resistance poliovirus
1.Poliovirus is resistant to ether, chloroform, proteolytic enzymes of
the intestinal contents and detergents.
2. It is stable at pH 3.
3. In feces, virus can survive for months at 4°C, for years at –20 or –
70°C and at room temperature for several weeks,
4. They are inactivated when heated at 55°C for 30 minutes.

6. Resistance poliovirus
5. Drying rapidly inactivates enteroviruses by ultraviolet
light, and usually by drying.
6. Formaldehyde and oxidizing disinfectants destroy the
virus.
7. Chlorination destroys the virus in water but organic
matter delays inactivation.
8. Poliovirus does not survive lyophilization well

7. Antigenic structure

8. Host Range and Cultivation
 Primary monkey kidney cultures are used for diagnostic
cultures and vaccine production. The infected cells round
up and become refractile and pyknotic.
 Eosinophilic intranuclear inclusion bodies may be
demonstrated in stained preparations.
 Well-formed plaques develop in infected monolayers
with agar overlay.

9. Pathogenesis

10. Clinical features
1. Asymptomatic Illness
2. Abortive Poliomyelitis: The Minor Illness
3. Nonparalytic Poliomyelitis or Aseptic Meningitis
4. Paralytic Poliomyelitis: The Major Illness
5. Progressive Postpoliomyelitis Muscle Atrophy

11. Laboratory Diagnosis

12. Specimens
• Blood, CSF, throat swabs and feces.
• Polioviruses may be isolated from the patient’s
pharynx during the first few days of illness, from
the feces for as long as 30 days, but from the CSF
only rarely but can be obtained from the spinal
cord and brain, postmortem unlike other
enteroviruses.

13. Culture
• Primary monkey kidney cells are usually
employed.
• The virus growth is indicated by typical
cytopathic effects in 2-3 days.
• An isolated virus is identified and typed by
neutralization with specific antiserum.

14. Serological Tests
• Serodiagnosis is less often employed.
Antibody rise can be demonstrated in paired
sera by neutralization or complement fixation
tests.

15. Prophylaxis
1. Inactivated polio vaccine (lPV)—Salk killed
polio vaccine.
2. Oral polio vaccine (OPV)—Sabin live polio
vaccine.

16. Immunisation schedule
• Primary course of 3 doses of OPV at one-month
intervals, commencing the first dose when infant is
6 weeks old.
• One booster dose of OPV is recommended 12 to 18
months later

17. Clinical Syndromes
• The incubation period is brief-from 2 to 4
days.
• Usual symptoms in adults include sneezing,
nasal obstruction, nasal discharge, and sore
throat; other symptoms may include headache,
mild cough, malaise, and a chilly sensation.