paramyxovirus.ppt

PARAMYXOVIRUSES
 Family Paramyxoviridae
 ssRNA – single piece
 Helical nucleocapsid, enveloped
 Spherical, 100-300nm diameter

Classification
Five genera-
1. Respirovirus- human parainfluenza v-1,3
2. Rubulavirus- human parainfluenza V-2,4
3. mumps virus
4. Morbillivirus- measles virus
5. Pneumovirus- Human respiratory synctial virus
6. Metapneumovirus- human metapneumo virus

PROPERTIES OF ORTHOMYXOVIRUS
AND PARAMYXOVIRUS
Property orthomyxovirus paramyxovirus
viruses Influenza A,B,C Measles,mumps,
RSV,& parainfluenza
genome Segmented Non segmented
Virion RNA
polymerase
yes yes
Capsid helical helical
Envelope yes yes
size Smaller(110 nm) Larger( 150 nm)
Surface spikes H&N diff. spikes H&N same spikes
Giant cell formation no yes

Parainfluenza Virus
 Surface spikes: H & N same spike, fusion on different
spike
 Both humans and animals infected
 Four serotypes: 1, 2, 3 & 4
 MOT: respiratory droplet

Parainfluenza infections spreads
through respiratory tract…
 The infection is acquired
through inhalation of
infected droplet nuclei or
directly through contact
with infected secretions.
The incubation period is
generally 2-6 days

Parainfluenza virus causes
Respiratory infection in young
 They are the second most common cause of
respiratory tract infection in younger children
 No viremia
 Clinical:
 1&2- major cause of group; children < 6 y/o
 Laryngitis
 Pneumonia
 Common cold- 4
 Pharyngitis
 Otitis media

LAB DIAGNOSIS
 1. direct demonstration- immunofluorescence
ELISA
2. isolation –primary human or monkey kidney cells
continous cell lines(H292)
haemadsorption of guinea pig RBC
3. Serology- CFT, ELISA

MEASLES VIRUS
 Single serotype
 H- target of neutralizing Ab
 Humans are the natural
host
 MOT –RT and conjunctiva.
 1-5 year age group.

 MOT-respiratory secretions
 Spherical,helical nucleocapsid, no
neuraminidase spikes
 I.P- 10-12 days
 PATHOGENESIS- lymphoid tissue
of RT-bloodstream(primary
viremia)- RE system (secondary
viremia)- epithelial surfaces.
 High fever, cough, conjunctivitis.
KOPLIK’S SPOTS
 Maculopapular rash- neck, then rest
of the body
 Recovery- 10-14 days

LAB DIAGNOSIS
 1. Direct demonstration-nmultinucleated giant cells
virus particles in exfoliated
nasal cells by IF
 2. Isolation- during prodromal phase till upto 2 days
post rash.
primary human embryo kidney, monkey
kidney cells- CPE- MNGC with both intracytoplasmic
and intranuclear IB
3. Serology- specific IgM Ab by ELISA, HI and CFT
for paired sera- 4 fold rise is diagnostic.

PROPHYLAXIS
 1. Active immunisation
live attenuated- at 9 months
Firstly Edmonston strain- vaccination measles, then
schwartz strain- effective only after 15 months
Edmonston –Zagreb strain- passage in human diploid
cells- 1 dose, S/C route
MMR vaccine-single dose, S/C
LA vaccine- intranasal aerosol
2. Passive immunisation-pooled sera containing Ab

 Both live and killed vaccines exist.
 In India Measles vaccination is a part of
universal vaccination programme of
Government of India since 1990 with a
dramatic decline in the incidence of the
disease.
Prevention

Mumps virus
 H and N + fusion protein on envelope spikes
 Humans are the natural host
 thermolabile

Mumps
 Nasal or URT epithelial cells- blood-
salivary glands, testes,ovaries,
pancreas, meninges and kidneys
 Shed in the saliva 2 days before to 9
days after the onset of salivary gland
swelling
 (+) virus in urine up to 14 days after
onset of symptoms

 Malaise and fever is followed within a day by painful swelling
of one or both of the parotid (salivary) glands
 A possible complication in males after puberty is orchitis -
painful swelling of one or both testicles.
 Inflammation of the ovary and pancreas can also occur.
 Disease is usually self-limiting within a few days
 Aseptic meningitis (usually resolving without problems) or
postexposure encephalitis (can prove fatal) are the most
serious complications associated with mumps.
Mumps virus

Diagnosis
 1. cell culture
 Specimen-saliva, spinal fluid or urine
 Monkey kidney cell
 CPE- cell rounding and giant syncytia formation
 2. serology- 4 fold rise in Ab titer in HI or CF
 Ab vs S antigen- current infection
 Ab Vs V antigen- past infection
 Prevention: vaccine, attenuated vaccine

Prevention and treatment
 Treatment: none
 Prevention: live attenuated vaccine, used with
measles and rubella virus vaccines (MMR)
 Not a part of universal immunization programme.

Respiratory Syncytical Virus
 Most important cause of pneumonia and
bronchiolitis in infants
 Fusion proteins- syncytia formation
 Humans and chimpanzees- natural host
 2 serotype: A & B
 MOT: respiratory droplet

Clinical
 1. infants- bronchiolitis,
pneumonia
 2. young children- otitis
media
 3. older children and adults-
common cold
 Diagnosis:
immunofluorescence
 Isolation in cell culture- + CPE
 serology

Treatment
 Aerosolized Ribavirin
 Ribavirin + hyperimmune globulins
 Prevention
 NO VACCINE
 Palivizumab-prophylaxis, monoclonal ab vs. fusion protein

General Concepts
 Enveloped virus ss-positive-sense RNA.
 Belongs to Togavirus family
 Replication in cytoplasm and bud at
plasma membrane
 Cause Rubella( German measles, 3-days
measles)

Epidemiology
 Occurrence: worldwide in prevalence
 Mode of Transmission: Droplet infection;
fomites;
 Mild infection (3 day fever) with
maculopapular rash post-auricular and
cervical lymphadenopathy. In adults it gives
joint pains. Antibodies give life long
immunity.
 In India 85% get infection by adolescence.
 Incubation period: 2-3 weeks

32
Pathogenesis
Rubella enters and infects the
nasopharynx and then spreads
to the lymph nodes and RE
system. The resulting viremia
spreads the virus to other
tissues and the skin. In
susceptible (seronegative)
pregnant woman, the virus
infects the placenta and then
spreads to developing fetus.
Virus
Congenital
infection

Lab Diagnosis
 Current rubella infection, particularly in
pregnant women can be confirmed by
- Presence of virus specific IgM antibodies in
acute phase serum; or
- 4-fold rise in virus specific antibody (IgG)
titers between acute and convalescent-phase
serum specimens by ELISA

MMR vaccine
• Composition : live attenuated virus
Measles / Mumps / Rubella
• Vaccination schedule: at 15-24 months and
at 4 to 6 years or before high school
• Efficiency: 95% lifelong immunization with a
single dose

paramyxovirus.ppt

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