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Paramyxoviruses
미생물학교실
권 형 주
Genus Human Pathogen
Mobillivirus Measles virus (rubeola, 홍역 – maculopapular rash)
ParamyxovirusParainfluenza viruses 1 to 4
Mumps virus
PneumovirusRespiratory syncytial virus –upper respiratory tract infection
Metapneumovirus
- Cell-cell fusion•Syncytia formation•Multinucleated giant cells
- New group• Zoonosis-causing viruses• Nipah virus• Hendra virus
- Live vaccine•Measles viruses•Mumps viruses• only one serotype
Paramyxoviruses (from Greek para-, beyond, -myxo-, mucus or slime, plus virus, from Latin poison, slime)
STRUCTURE and REPLICATION- Negative-sense, single-stranded RNA- Envelope-the order of the protein-coding regions differs for each genus- orthomyxoviruses : segmented genome
Replication of paramyxoviruses
Measles Virus ( 홍역바이러스 )- Measles is still one of the most prominent causes of disease (45 million cases per year) and death (1 to 2 million per year) worldwide in unvaccinated populations
Pathogenesis and Immunity
Family : Paramyxoviridae
Genus : Mobillivirus
- Host – only human- cell fusion, giant cells- cell-to-cell spread escape antibody control- Hemagglutinin(+), Neuraminidase (-)- Highly contagious- respiratory droplets
- Time course of measles virus infection.- 초기증상 : cough, conjunctivitis, coryza, and photophobia (CCC and P)- Koplik’s spots, rash- SSPE (subacute sclerosing panencephalitis, 아급성경화범뇌염 )-rare
- Maculopapular measles rash : T cells targeted to measles-infected endothelial cells lining small blood vessels rash (lifelong immunity)
- Encephalitis 1) direct infection of neurons 2) a postinfectious encephalitis :
immune mediated 3) SSPE – a defective variant of
measles
Epidemiology- Development of effective vaccine
programs
Clinical Syndromes- Incubation periods : 7-13 days- 초기증상 ( 발진전 ) : High fever, CCC and p- After 2 days of illness : Koplik spots - A typical mucous membrane lesions - first day or two after the rash appears - mouth, conjunctivae, vagina- 발진 (exanthem of measles) : starts belows the ears and spreads over
the body : maculopapular rash- Complications : Pneumonia, bacterial
superinfection
Prevention
Parainfluenza Virus- Respiratory viruses : mild cold-like symptoms, serious respiratory
tract disease- Human pathogens : four serotypes
Clinical Syndromes- Types 1, 2, 3 : respiratory tract syndromes - mild cold-like upper respiratory tract infection (coryza,
pharyngitis, mild bronchitis, wheezing, fever) - Bronchiolitis - Pneumonia - Croup (laryngotracheobronchitis)
Laboratory Diagnosis- Isolated from nasal washing and respiratory
secretion- Grow well in primary monkey kidney cells- Hemagglutination- Serotype (antibody) ; hemagglutination inhibition- RT-PCR
- Administration of nebulized cold or hot steam- No specific antiviral agents- Killed vaccine : ineffective- No live attenuated vaccine
Treatment, Prevention, and Control
Mumps Virus- 볼거리 , 볼치기 ( 귀밑샘염 )- Parotitis ( 이하선염 ) : painful swelling of the salivary
glands- Isolated in embryonated eggs in 1945- Cell culture in 1955- Human pathogen : One serotype
- Recovered from saliva, urine, pharynx, stensen duct, cerebrospinal fluid
- Grow well in monkey kidney cells- Formation of multinucleated giant cells- Hemadsorption of guinea pig
erythrocytes: hemagglutinin- MMR vaccine- Antiviral agents are not available
Respiratory Syncytial Virus (RSV)호흡기세포융합바이러스
Family : ParamyxoviridaeGenus : PneumovirusSubgroups : A and B- Fatal acute respiratory tract
infection- Infants, young children
RSV Virion, Genome and Proteins
plasmamembrane
budding virion
(EM by Tony Kalica, LID/NIAID)150 nm
NS2NS1
M2-1
M2-2
Single-stranded negative-sense RNA, 15.2 kb
3´ 5´ G FSHMN P L
ribonucleocapsid
envelope spikes
nonstructural
NS1NS2
inhibit host type I interferon response
regulation of RNA synthesis
M2-2
unassigned
inner envelope face
assemblyM
M2-1
transcription processivity factor
RNA-binding
phosphoprotein
polymerase
N
PL
Neutralizationtargets
SH
G attachment
fusion
unknownF
RSV –syncytium formation
- Virus infections almost always occur in the winter. - Infants : lower respiratory infection (bronchiolitis and pneumonia) - Children : mild to pneumonia - Adults : mild symptoms
• Symptom : bronchiolitis, pneumonia, mechanical ventilation, and respiratory failure in infants.
Laboratory Diagnosis
Treatment, Prevention, and Control
- RT-PCR- Immunofluorescence and enzyme immunoassay test
- Ribavirin ( 제한적 ) : inhalation(nebulization)- Passive immunization :anti-RSV Ig ( 제한적 )- No vaccine is currently available- Inactivated vaccine : severe RSV disease : heightened immunologic response (Th2 immune
response ?)