PicoRNA Viruses (Small RNA virus)

1
PicoRNA Viruses(Small RNA virus)
2
Pico RNA Viruses

• Structure
• Classification
• Multiplication
• Clinical manifestations
• Epidemiology
• Diagnosis
• Control

Barons Web Site
3
Structure

• Icosahedral
• 20-30 nm
• C32
• Non enveloped
• ss RNA
• sense strand
• VPAg covalently bound to 5
• 3 poly A tail

4
Picornaviridae Classification

• Rhinovirus- nasal cavity
• Enterovirus- alimentary tract
• poliovirus
• coxcackievirus
• echovirus
• Enterovirus
• Apthovirus
• hoof and mouth
• cloven hooved animals humans
• Cardiovirus- rodents

5
Multiplication

• Multiply in cytoplasm
• sense ssRNA acts as mRNA
• Replication associated with cytoplasmic membrane

6
Multiplication
7
Polio
8
Polio

• Early undifferentiated febrile
• Gastrointestinal
• Spinal bulbar poliomyeltis
• Paralytic polio - irreversible

9
Polio Pathogenesis

• Humans only natural host
• trophic for epithelial cells
• gene product of chromosome 19
• HLA- 3 HLA-7 increased risk

10
Poliovirus Pathogenesis

• Virus ingested
• Multiples tonsils upper respiratory tract
• Passes through stomach
• Multiples in Payers Patches
• Migrates to regional lymph nodes

11
Poliovirus Pathogenesis

• Virus passes into blood via lymph nodes
• virus crosses Blood-Brain barrier into CNS
• Virus shed in Feces

12
FDR ( 1921)
13
Diagnosis
14
Epidemiology Polio

• Stable survive for long periods
• sewage
• water
• food

Cockroachs transient vectors
15
Koprowki tests live vaccine (1950)

• Jonas Salks injectable vaccine effective (1954)

16
Control

• Oral vaccine
• Albert Sabin
• 1961

Future of Vaccines
17
Polio incidence 1987
18
Polio Incidence 1997
19
(No Transcript)
20
Enterovirus Pathogenesis
21
Rhinoviruses Viruses

• Clinical manifestations
• Epidemiology
• Diagnosis
• Control

22
Rhinovirus Pathogenesis
coryza
Nasal Secretions
Nasopharynx
Common cause of serious lower respiratory tract
infection in children
23
Rhinovirus Clinical Manifestations

• Coryza - common cold
• mucous secretions
• watery eyes
• sneezing

Symptoms induced when Virus stimulates histamine
release from mast cells Antihistamines reduce
symptoms
24
Rhinovirus Multiplication

• Hosts humans chimps
• Grow epithelial cells
• Multiples best at 33 C
• sensitive to pH 3.0
• Restricted nasopharynx
• occasionally lungs
• especially newborn

25
Rhinovirus Epidemiology

• spread via nasal secretions
• Primarily Contaminated hands
• Autoinoculate nasopharynx and eyes
• Secondarily Repiratory droplets aerosols

26
Rhinovirus Diagnosis

• Clinical symptoms
• Tissue culture
• Serology-impractical
• Over 115 serotypes
• immunity is serotype specific

27
Rhinovirus Control

• Control symptoms
• Improve personal hygiene
• Ribavrin shortens duration
• prophylactic interferon nasal sprays

28
DONE!!!