ORTHOMYXOVIRUS and PARAMYXOVIRUS

RNA VIRUSES
RICHARD DAVID SILVESTRE, RMT, MSMT ©

RNA VIRUS
PARAMYXOVIRUS
ORTHOMYXOVIRUS (respiratory tract)
■ Influenza ■ Measles
– A ■ Mumps
– B
■ RSV
– C (most antigenetic stable)
■ Parainfluenza
Distinguished by internal
ribonucleoprotein
PARAMYXOVIRUS
STRUCTURE AND
CHARACTERISTICS
(single stranded virus,
linear non segmented
RNA virus
all members are
antigenetically stable
3 proteins complex with

viral RNA
3 proteins for viral
envelope
M protein – during
assembly
HN – attachment F –
hemolysin activity
PROPERTIES OF PARAMYXOVIRUS
(labile but highly infectious)
MEASLES
■ Also known as English, 9 Day, Hemorrhagic or Black Measles

■ Measles virus is present in blood, urine, nasopharyngeal secretions
in infected individuals
■ Maximum contagiousness occurs during the prodromal (Catarrhal)
Stage by droplet spray
■ Contagious 1 to 2 days before until 5 days after onset of the
characteristic rash
■ The rash begins on the head and spreads over most of the body in
24 hours in a descending fashion and fades in the same manner.
■ The severity of the illness is related to the severity of the rash.
■ Fever respiratory symptoms and rash
Incubation Period (igG fast infection IgM
acute infection)
Treatment, prevention and Control
■ Vitamin A
■ Vaccine
■ Contraindication to vaccine:
– Pregnancy (prevent congenital rubella syndrome)
– Allergy to eggs or neomycin
– Immune compromise
– Recent immunoglobulin administration
PARAINLUENZA VIRUS
■ Parainfluenza Virus ssRNA virus enveloped, pleomorphic morphology

■ 5 serotypes:
■ 1, 2, 3, 4a and 4b
■ No common group antigen
■ Closely related to Mumps virus
■ Respiratory droplets is the mode of infection
■ Adults mild upper RT
■ Infants severe lower RT
■ Incubation period is 2-5 days
Clinical Manifestations Laboratory Diagnosis
■ Croup (laryngotraheobroncitis) - ■ Detection of Antigen - a rapid

most common manifestation of diagnosis can be made by the
parainfluenza virus infection. detection of parainfluenza antigen
from nasopharyngeal aspirates and
■ However other viruses may induce throat washings.
croup e.g. influenza and RSV.
■ Virus Isolation - virus may be readily
■ Other conditions that may be isolated from nasopharyngeal
caused by parainfluenza viruses aspirates and throat swabs.
include:
– Bronchiolitis, ■ Serology - a retrospective diagnosis
may be made by serology. CFT most
– Pneumonia, widely used.
– Flu-like tracheobronchitis, and
■ Ribavirin
– Corza-like illnesses.
MUMPS
■ Mumps occur worldwide and in spread by direct contact,

aerosolization of respiratory secretions, and fomites.
■ It affects both sexes and 85% of the infections occur in
persons under 15 years of age.
■ Epidemics are most frequently in the winter and spring.
■ Virus can be isolated from saliva 6 days before and 9
days after the onset of parotid swelling, the illness can be
transmitted 1 day before until 3 days after swelling.
■ Incubation period is usually days.
■ Bed bugs and saliva
Clinical Manifestation
■ The onset is characterized by fever, muscle pain, headache, malaise, and pain and
swelling of the parotid glands lasting 3 to 7 days.
■ Complications:
– Orchitis (necrosis of spermatocyte)
– meningitis
– post-infection encephalitis
– Deafness
– Prevention: Live attenuated mumps vaccine administered at 15 months and 11
to 12 years.
– Infection confers life-long immunityTransplacental antibodys protect the infant
for first 6 months of life.
– Saliva csf and urine
Respiratory Syncytial Virus (RSV)
■ ssRNA eveloped virus

■ belong to the genus Pneumovirus of the
Paramyxovirus family.
■ Considerable strain variation exists, may be
classified into subgroups A and B by
monoclonal sera.
■ Both subgroups circulate in the community at
any one time.
■ Causes a sizable epidemic each year.
Clinical Manifestation
■ Most common cause of severe lower respiratory tract disease in

infants,
■ responsible for 50-90% of Bronchiolitis and
■ 25-40% of BronchopneumoniaOther manifestations include croup
(10% of all cases).
■ In older children and adults, the symptoms are much milder:
– it may cause a corza-like illness or bronchitis.
Orthomyxovirus (single stranded, segmented with 8 segments helical with envelope, cannot undergo
transctiprion) Segment 1 2 3 = polymerase segment 4 = hemmaglutinin 5 = nucleocapsid 6 = neuramidase 7= membrane protein (matrix protein
assembly) M2= uncoating and hemaglutinin production
Antigenic Variation (Antigenic drift – minor change antigenic shift genetic reasortment
both influenza A and B for outbreaks and epidemics – involves h or n antigen in influenza A for pandemic and epidemics
)
Pathology and Pathogenesis
■ Infection is acquired by the respiratory route causing • Incubation period 2-3 days.
upper respiratory tract infection.
Symptoms may include:
■ Virus multiplies in the epithelium and destroys the cilia, • shivering,
followed by transient viremia.
• headache,
■ Complications may include secondary bacterial infection • Malaise and
– Reye’s syndrome :A rare but potentially fatal • aching in the limbs and back.
disease of the liver), children with fever due to
influenza especially type B should avoid taking
• The temperature rises rapidly
aspirin as this may lead to Reye's syndrome to around 39 ºC.
aspirin intake association. The severity of influenza is
proportional to age.
Primary influenza pneumonia
Secondary bacterial pneumonia = staph
aureus, pneumococcus, bar syndrome,
Most common death is pneumonia
Immune Response
■ Antibodies
– Anti-hemagglutinin, the most important, it prevents virus from attaching to
cells.
– Anti-neuraminidase, prevents the release from host cells.
– IgA antibodies prevent infection, they act at the mucus surfaces of the
respiratory tract “local antibodies”
■ Interferon
– Non-specific inhibitors of influenza
■ Cell-mediated immunity
– Cytotoxic T cellsAlveolar macrophages
Treatment and Prevention
■ Treatment
– Amantadine (inhibit uncoating which targets m2 protein for influenza A)
– Rimantadine (same)
– Oseltamivir (inhibits n antigen h antigen binds to shalic acid influenza a and b in
first 24 to 48 hrs of infections)
– Zanamivir (same but through inhalation)
■ Prevention: Vaccine
■ Trivalent or Quadrivalent inactivated or split vaccine (Trivalent 2 a string a 1 b 2 a and 2
b)
– Live attenuated influenza vaccine (LAIV) adapted and through intranasal
THANK YOU!!!

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RNA VIRUSES

RICHARD DAVID SILVESTRE, RMT, MSMT ©

3 proteins complex with

■ Also known as English, 9 Day, Hemorrhagic or Black Measles

■ Parainfluenza Virus ssRNA virus enveloped, pleomorphic morphology

■ Croup (laryngotraheobroncitis) - ■ Detection of Antigen - a rapid

■ Mumps occur worldwide and in spread by direct contact,

■ ssRNA eveloped virus

■ Most common cause of severe lower respiratory tract disease in

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