Paramyxoviruses

Fackrel@Uwindsor.ca

paramyxo.ppt

Paramyxoviruses

• Structure

• Classification

• Multiplication

• Clinical manifestations

• Epidemiology

• Diagnosis

• Control

Baron’s Web Site

Paramyxoviridae

• Paramyxovirus - parainfluenza, mumps

• Pneumovirus - respiratory syncytial virus

• Morbillivirus - measles

Rubella virus is a member of the Togaviridae!!!

Structure: Paramyxoviridae

• Enveloped 150-300 nm

• helical, pleomorphic symmetry

• SS RNA ,antisense monopartite

PPT Slide

Viral Proteins

• RNA-directed RNA polymerase

• Hemagglutinin
  • parainfluenza
  • measles

• Neuraminidase
  • parainfluenza

Neuraminidase & hemagglutinin activities are different sites of the same protein

Fusion protein causes syncytia formation

Multiplication

• Antisense strand -> sense RNA
  • RNA directed RNA polymerase

• Viral proteins

• sense RNA template for antisense strands

• capsid assembly

Paramxyovirus

Parainfluenza virus

Mumps virus

Measles virus

Parainfluenza Viruses

Paraflu:Clinical manifestions

• mild or severe infections

• lower and upper respiratory tract

• particularly in children

Paraflu: Classification

• types 1,2,3,4 in humans

• type 4 subtypes A & B

Paraflu: Epidemiology

• occurs worldwide

• usually endemic

• primarily in young children

• reinfections common

Paraflu: Diagnosis

• clinical symptoms nonspecific

• Isolate virus

• Detect viral antigens

• Detect rise in specific antibodies

No vaccine is available for Parainfluenza

Mumps virus

Mumps:Clinical manifestions

• systemic febrile infection

• children & young adults

• swelling of salivary glands
  • Parotid gland

• meningitis common

• encephalitis can occur

• orchitis oophoritis in adults

Single mumps serotype

• shared antigens with paraflu type 1

Mumps:Pathogenesis

• droplet infection

• viremia

• spreads to glands & nervous tissue

• inflammation & cell death

Mumps:Epidemiology

• worldwide

• endemic in urban areas

• intermittant in rural areas
  • epidemic 2-7 years

• peak incidence Jan-May

Mumps:Diagnosis

• TYPICAL

• clinical diagnosis

• ATYPICAL

• isolate virus

• viral antigen in saliva of CSF

• Detect specific IgM

• Detect rising titer of IgG

Mumps: Defenses

• Interferon

• humoral immunity

• cell mediated immunity

• lifelong protection

Mumps:Control

• live attentuated vaccine

• long term protection

• reinfections can occur

Morbillivirus

Measles virus

Measles: Clinical manifestions

• coryza, conjunctivitis, fever rash

• maculopapular rash 1-3 days later

• Complications

• otitis, pneumonia, encephalitis

• SSPE (subacute sclerosing panencephalitis)-rare

Measles: Pathogenesis

• viremia

• multiples in cells of :
  • lymphatic system
  • respiratory system
  • skin
  • brain

Measles:Host Defenses

• Interferon

• Humoral immunity

• Cell mediated immunity

• Life long protection

Measles: Epidemiology

• worldwide

• endemics & epidemics

• mainly late winter-early spring

Measles Incidence

Measles: Diagnosis

Typical

• clinical manifestations

Atypical

• Isolate virus

• Detect specific IgM

• Detect increase in IgG

Measles: Control

Active vaccination

• Live attentuated virus vaccine

• long lasting protection

Passive immunity

• measles hyperimmunoglobulin

WHO MeaslesVaccination Strategy

• "catch-up" everyone aged 1-14 years

• "keep-up" 90% of children at age 12 months;

• "follow-up" 3-5 years

WHO Report

Pneumovirus

Respiratory syncytial virus

RSV:Clinical manifestions

• upper & lower respiratory tract infection

• frequent in young children

• significant in elderly

RSV: Pathogenesis

• droplets

• direct contact

• infects ciliated epithelium of respiratory mucosa

• localized

Antibody Dependent Cytotoxicity

RSV: Host Defenses

• interferon

• cell mediated immunity

• Humoral immunity

• Secretory immunity ( sIgA)

• reinfection possible

RSV: Epidemiology

• worldwide

• temperate climates

• epidemic winter and early spring

• infants & young children

RSV: Diagnosis

• nonspecific clinical symptoms

• Isolate virus

• Detect viral antigen

• Detect IgM, IgA

• Detect icrease in IgG

RSV: Control

• no vaccine

• ribavrin as aerosol

• isolate patients in hospitals