Picornaviridae

Assistant Professor & Consultant Virologist

College of Medicine & KKUH

By: Dr.Malak El-Hazmi

Picornaviruses

Nonenveloped , icosahedral , ss (+) RNA

Enterovirus

Members of the Family Picornaviridae

Genus Species

Poliovirus

Coxsackieviruses

Echoviruses

Enteroviruses ( 68-71)Hepatovirus

Parechovirus

Rhinovirus

Kobuvirus

Cardiovirus

Aphthovirus

Erbovirus

Teschovirus

Characteristics of Human Picornaviruses

Property RhinoVs Enteroviruses ParechoVs

Polio Coxsackie A B

Echo Entero

Serotypes >100 1-3 1-24 1-6 1-34 68 -71 1-4

Acid pH (3.0) Labile Stable

Temp 33oC 37oC

Site Nose GIT

Usual Host range of human enteroviruses: animal and tissue culture spectruma

aMany enteroviral strains have been isolated that do not conform to these categoriesbNew types, beginning with type 68, are now assigned enterovirus type numbers instead of coxsackievirus or echovirus numbers. Types 68-71 have been identified.CType 23 has been found to be the same as echovirus 9.dEchovirus 8 was determined to be the same serotype as echovirus 1 ; echovirus 10 has been reclassified as a reovirus type 1, echoviruses 22 & 23 as parechoviruses types 1& 2, echovirus 28 as human rhinovirus 1 A, and echovirus 34 as coxsackievirus A24.

Cytopathic effect Illness & Pathology

Virus Antigenic typesb

Monkey Kidney tissue culture

Human Tissue culture

Suckling Monkey mouse

Polioviruses 1-3 + + - +

Coxsackieviruses, gp A 1-24c ± ± (+) flaccid -

Coxsackieviruses, gp B 1-6 + + (+) spastic -

Echoviruses 1-34d + ± - -

Enteroviruses 68-71 + + - -

Reservoir : Human

Spread : Fecal - oral route (mainly) Inhalation of Infectious aerosols Direct & indirect contact of

eye secretions

(Crowded, Poor hygiene & Sanitation)

Age : children > adults Seasonal distribution:

summer & fall

Epidemiology Excreta from human

Hand Sewage Solid waste landfills

Water Supply

Shellfish

Man

Pathogenesis

Echo,coxHFM

Most EVs are cytolytic, some cause immunopath mech

Coxsackievirus

Syndrome Poliovirus Types 1-3

Group A Types 1-24

Group B Types 1-6

Echovirus Types 1-34

Enterovirus Types 68-71

Neurologic Aseptic meningitis Paralysis Encephalitis

1-31-3

Many7,9

2,5-7,9

1-62-51-5

Many2,4,6,9,11,30

2,6,9,19

7170,7170,71

Skin and mucosa Herpangina Hand-foot-and-mouth disease Exanthems

2-6,8,105,10,16Many 5 2,4,6,9,11,16,18

7171

Cardiac and muscular Pleurodynia (epidemic myalgia) Myocarditis, pericarditis

1-51-5

1,6,91,6,9,19

Ocular Acute hemorrhagic conjunctivitis 24 70

Respiratory Colds Pneumonia Pneumonitis of infants Pulmonary edema

21,24

9,16

1,3,4,54,5

4,9,11,20,2568

71

Gastrointestinal Diarrhea Hepatitis

18,20-22,242

4,9 5Many2

4,9

Other Undiff. Febrile illness Generalized disease of infants Diabetes mellitus

1-3

1-61-53,4

11

Human enteroviruses & commonly associated clinical syndromes.1

1Examples are not all-inclusive. Other enterovirus types may be associated with a given disease:2Causality not established

Herpangina

Hand , Foot & Mouth disease

Coxsackievirus

Syndrome Poliovirus Types 1-3

Group A Types 1-24

Group B Types 1-6

Echovirus Types 1-34

Enterovirus Types 68-71

Neurologic Aseptic meningitis Paralysis Encephalitis

1-31-3

Many7,9

2,5-7,9

1-62-51-5

Many2,4,6,9,11,30

2,6,9,19

7170,7170,71

Skin and mucosa Herpangina Hand-foot-and-mouth disease Exanthems

2-6,8,105,10,16Many 5 2,4,6,9,11,16,18

7171

Cardiac and muscular Pleurodynia (epidemic myalgia) Myocarditis, pericarditis

1-51-5

1,6,91,6,9,19

Ocular Acute hemorrhagic conjunctivitis 24 70

Respiratory Colds Pneumonia Pneumonitis of infants Pulmonary edema

21,24

9,16

1,3,4,54,5

4,9,11,20,2568

71

Gastrointestinal Diarrhea Hepatitis

18,20-22,242

4,9 5Many2

4,9

Other Undiff. Febrile illness Generalized disease of infants Diabetes mellitus

1-3

1-61-53,4

11

Human enteroviruses & commonly associated clinical syndromes.1

1Examples are not all-inclusive. Other enterovirus types may be associated with a given disease:2Causality not established

Pathway to CNS by: Blood Peripheral nerves

Causing destruction of

motor neurons of AHCs

Rarely affects brain stem

(bulber poliomyelitis)

Pathogenesis of polio:

Pathogenesis of Polio :

Immunity: IgA & IgG = Lifelong type-specific immunity

Poliovirus Infections

Minor Illness

No illness

Major Illness 1- Nonparalytic poliomyelitis (Aseptic meningitis)

2- Paralytic poliomyelitis: (Flaccid paralysis)

Abortive poliomyelitis (No CNS involvement)

90-95%

Asymptomatic 4-8%

1-2%

Poliovirus Infections : Bulber poliomyelitis

( brain stem)

Post polio syndrome

Lab Diagnosis of Enteroviruses Virus isolation:

• Samples: Stool (best) .Rectal, throat swabs ,

conjunctival swab, CSF• Inoculate in MKC & HDF

All EVs grown except some strains of Cox A viruses• Observe for CPE• Identify the type by Neutralization Test

CSF in aseptic meningitis; lymphocytosis

Glucose level N to slightly , Protein level N or slightly

Isolation rate is variable

EV RNA detected in CSF by RT-PCR Serology (limited value)

• IgM • ≥ 4 fold rise in AB titer b/t Acute & Convalescent sera

Management Rx:

No antiviral Rx

Prevention: Sanitation & Hygienic measures Poliovirus vaccines

a- Inactivated polio vaccine

(IPV)

(Salk, Killed) (S/C or IM)

b- Live-attenuated polio vaccine

(OPV)

(Sabin, oral)

Important Features of Polio VaccinesAttribute Killed (IPV) Live (OPV)

3 types (trivalent) Yes Yes Prevents disease Yes Yes

Route of administration Injection Oral

Induces humoral IgG Yes Yes

Induces intestinal IgA No Yes

Interrupts transmission No Yes

Affords 2o protection by spread to others

Causes disease in the immun ed No Yes

Reverts to virulance No Yes (rarely)

No Yes

No Yes Co-infection with other EVs

may impair immunization

Requires refrigeration No Yes

Duration of immunity Shorter Longer

Poliovirus Vaccine

Adverse reactions ; local reactions (IPV) Vaccine -Associated Paralytic Poliomyelitis (OPV)

adult , immuno ed

4 doses of PV;

2, 4 , 6-18 ms

& 4 - 6 yrs

Pediarix contains IPV, DTaP & HB vaccines

Polio Vaccination of Adults

Indications: Travelers to polio-endemic countries Selected laboratory workers HCWs

IPV; 0, 1-2 ms, 6-12 ms

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