Transcript Picornaviruses

Picornaviruses
Picornaviruses
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Small (pico)
RNA
Naked capsid
>230 members
5 genera
Picornaviruses
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5 genera
Enterovirus
Rhinovirus
Heparnavirus
Cardiovirus
Aphtovirus
Picornaviruses
Enteroviruses
At least 72 serotypes
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Polioviruses
Coxsackieviruses
Echoviruses
International Virus Taxonomi
committee
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Enterovirus genus (EV):
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Poliovirus
and EV A, B, C and D.
Parechovirus cinsi (PeV): echovirus 22 ve 23
Picornaviruses
Enteroviruses (EV)
At least 72 serotypes
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Polioviruses
Coxsackieviruses
Echoviruses
Human parechoviruses 1-3 (HPeV)
Picornaviridae
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Enterovirus
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Poliovirus type 1, 2, and 3
Coxsackie A virus types 1 to 22 and 24
Coxsackie B virus types 1 to 6
Echovirus (ECHO virus) types 1 to 9, 11 to 27, and 29 to 34
Enterovirus 68 to 71
Rhinovirus types 1 to 100+
Cardiovirus
Aphtovirus
Heparnavirus
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HAV
Picornaviruses
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Enteroviruses
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Capsid very resistant
facilitates transmission
by the fecal-oral route
Infection initiated in the gastrointestinal tract
“Rarely cause enteric disease”
Infections are usually asymptomatic
Picornaviruses/Replication
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The specifity of the picornavirus interaction
for cellular receptors is the major determinant
of the target tissue tropism and disease
VP1 and “canyon”
80% of rhinoviruses and several serotypes of
of coxsackieviruses recognize ICAM-1
polio
a different molecule
Enteroviruses/Pathogenesis&Immunity
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The diseases produced by the enteroviruses
are determined mainly by differences in
tissue tropism and cytolytic capacity of the
virus
Poliovirus with the narrowest tissue tropism
recognize a receptor expressed on
anterior horn cells of the spinal cord, dorsal
root ganglia, motor neurons, skeletal muscle
cells, and few other cells
Enteroviruses/Pathogenesis&Immunity
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Portal of entry:
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Most enteroviruses are cytolytic
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URT
Oropharynx
Intestinal tract
Excp: HAV
Viral shedding
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From oropharynx
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From the intestine (> 30 days)
Enteroviruses/Pathogenesis&Immunity
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“Antibody is the major protective immune
response to the enteroviruses”
Enteroviruses/Epidemiology
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“The enteroviruses are exclusively human
pathogenes”
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Spread by the fecal-oral route
Asymptomatic shedding can occur
Poor sanitation and crowded living conditions
foster transmission of the viruses
Enterovirus epidemics
sewage
contamination of water supplies
Outbreaks in schools & day care centers (summer)
Spread via resp. tract
coxsackie & echov.
Enteroviruses/Epidemiology
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Poliovirus has been eliminated from the Western
Hemisphere, but
“not from the world”
Polio cause more severe disease in late
childhood, the adolescent years, or adulthood
Coxsackie A
mor severe in adults than
children
Coxsackie B & some echo“s” can be particularly
harmful to infants
Enteroviruses/Clinical syndromes
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Poliovirus infections
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Asymptomatic illness (90%)
Abortive poliomyelitis (minor illness)
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Nonparalytic poliomyelitis or aseptic meningitis
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Nonspecific febrile illness (5%)
1 to 2%, symptomes of the minor illness + CNS sm
Paralytic polio, the major illness
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0.1 to 2.0%
Enteroviruses/Clinical syndromes
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Poliovirus infections
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Paralytic poliomyelitis
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Asymmetrical flaccid paralysis with no sensory loss
Poliovirus type 1 is responsible for 85% of cases
Vaccine-associated disease (reversion of type 2&3)
Recovery, within 6 months to 2 years
Bulbar poliomyelitis
More severe, 75% death, iron lungs (1950’s)
Postpolio syndrome (30-40 years later) in 2080% of the original victims)
Enteroviruses/Clinical syndromes
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Coxsackievirus and echovirus infections
Herpangina
 Several types of Coxsackie A
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Hand-foot-and-mouth disease ( a vesicular exanthem)
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Usually caused by coxsackievirus A16
Pleurodynia (Bornholm’s disease)(Devil’s grip)
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Fever + unilateral low thoracic, pleuritic chest
pain
Coxsackie B
Enteroviruses/Clinical syndromes
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Coxsackievirus and echovirus infections
Myocardial and pericardial infections*
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Coxsackie B
Occur sporadically in older children and adults
Most threatening in newborns
Febrile illness, sudden unexplained onset of
heart failure
high mortality
Enteroviruses/Clinical syndromes
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Coxsackievirus and echovirus infections
Viral (aseptic meningitis)*
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Acute febrile illness + CNS symptoms
Petechia or a rash
Summer and autumn outbreaks with Echo 11
Fever, rash and common cold-like symptoms
Other diseases
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Acute hemorrhagic conjunctivitis
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Enterovirus 70 and coxsackie A24
Enteroviruses/Clinical syndromes
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Coxsackievirus and echovirus infections
Other diseases
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Acute hemorrhagic conjunctivitis
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Enterovirus 70 and coxsackie A24
transplacental infection
Insulin-dependent diabetes
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Coxsackie B
PeV
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Respiratory infections
Gastrointestinal infections
Enteroviruses/Laboratory Diagnosis
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Nükleic acit detection
Isolation
Serology: Antibody
Enteroviruses/Treatment
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Pleconaril
new antiviral drug
Enteroviruses/ Prevention & control
“The prevention of paralytic polyomyelitis is one
of the triumphs of modern medicine”
Poliovirus vaccines:
1. IPV, developed by Jonas Salk
2. OPV, developed by Albert Sabin (live
attenuated)
'Poliosuz Ülke Sertifikası’
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Rutin aşılama çalışmalarına ek olarak Ulusal Aşı
Günleri (UAG) ve Mop-up gibi destek aşılamalar
düzenlemesi gerekmiştir.
1998 yılında tip 1 poliovirüse bağlı son çocuk felci
vakası Ağrı ilinde saptanmıştır.
Bu vaka aynı zamanda DSÖ Avrupa bölgesi’nin de
son polio vakası olmuştur.
Türkiye, Dünya Sağlık Örgütü Avrupa bölgesi ile
birlikte 21 haziran 2002 tarihinde çocuk felci
hastalığından (polio) arındırılmış olarak
sertifikalandırılmıştır.
Iron lung
Polio sekeli
Rhinoviruses
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Most important cause of the common cold
and URTI
ICAM-1
Unable to replicate in the GIT
Labile to “ pH”
Grow best @ 33oC
Infection can be initiated by as little as 1
(one) infectious viral particle
“Runny nose”
Rhinoviruses
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Most important cause of URTI ~ 50%
Common cold:
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Enteroviruses
Coronaviruses
Adenoviruses
Parainfluenza viruses
Rhinoviruses
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Common cold symptoms
Sneezing
 Rhinorrhea
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Mild sore throat
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Headache
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Malaise
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Cough
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Fever & rigors
nasal obstruction
Rhinoviruses
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The clinical syndrome of the common cold
is usually so characteristic that laboratory
diagnosis is unnecessary!!