Term
Orthomyxo virus:
Influenza types A, B, C
morphology
virulence
clinical
antigenic drift vs shift |
|
Definition
type A: pandemics, human & animal strain
B & C: human only strains
Negative (-) SS RNA
segmented (8)
lipid containing envelope
helical symmetry
replicates in the nucleus!
Hemagglutinin (HA) glycoprotein: binds to RBC and cells of the URT, cleaved HA activates fusion
Neuraminidase (NA) glycoprotein: breaks down neuraminic acid, an imp component of mucin
The Flu: fever, runny nose, cough, etc
Complications:
-secondary bacgterial pneumonias in the elderly
-*Reyes syndrome* in children who take aspirin; get brain and liver disease
Drift: small mutations, minor changes in antigenicity of HA or NA -> epidemics
Shift: only type A, reassortment, major changes -> pandemics |
|
|
Term
Paramyxovirus: Parainfluenza
morphology
virulence
clinical |
|
Definition
-, SS RNA
Unsegmented
Lipid containing envelop
Helical symmetry
replicates in cytoplasm
-see cytoplasmic inclusions
Glycoproteins with combined HA and NA activity (glycoproteins don't form such prominent spikes as on influenza virus)
*F-protein*: fusion protein, results in multinucleated giant cells ("syncytial cells)
-fate of host cell: synctium formation
M protein lines the inner surface of the envelope
URT in adults: bronchitis, pharyngitis, rhinitis
Viral pneumo in children, elderly and immuno-compromised
*Croup*: children develop barking cough due to infxn and swelling of the larynx and trachea
-chest retraction
-virus inhibits Na+ absorption, activates Cl- secretion across tracheal epithelium -> airway edema
Bronchiolitis in children |
|
|
Term
Paramyxo virus: Respiratory Syncytial Virus
morphology
virulence
clinical
dx
misc |
|
Definition
same as all paramyxo viruses
F-protein allows fusion of env with host cell plasma membrane
No HA or NA glycoproteins
Attaches via G proteins to cells of the nasal mucosa and URT
Most common cause of pneumonia in infants < 6 mo
-possible fever, wheezing, cyanosis
Acute otitis media
Colds and bronchitis in: older children, adolescents, adults
Can also infect the eye
RSV rest kits: immunoassay, rapid qualitative detection of RSV Ag (F-protein)
#1 virus assoc with childhood acute resp tract illness requiring hospitalization, esp < 1 yo
Mucosal edema
I/c mucin secretion
Cell necrosis, bronchoconstriction
Peribronchal lymphocytes may infiltrate |
|
|
Term
Paramyxovirus: Mumps
morphology
virulence
clinical
misc |
|
Definition
same as other paramyxo: neg SS, unseg, lipid in env, helical, cytoplasmic rep
glycoproteins with combined HA & NA activity
F-protein
Parotid gland swelling (painful)
*Orchitis in males*
Meningitis
Encephalitis
Acute fever
Only one antigenic type
Salivary gland enlargements w/ release of amylase
EIA:
IgM: + > 1.20, dx of acute infxn
IgG: + > 1.09, determines immunity |
|
|
Term
Paramyxovirus: Measles (rubeola)
morphology
virulence
clinical
Misc |
|
Definition
same as above (neg SS RNA, unseg, lipid containing env, helical, cytoplasmic rep)
HA, but no NA
F protein
Prodrome: high fever, hacking cough, conjunctivitis
*Koplik's spots*: small red based blue-white centered lesions in the mouth
Rash: from head, then to neck and toso, then to feet
Complications:
-pneumonia, eye damage, myocarditis, encephalitis
-20% risk of fetal death if acquired by a pregnant woman early in pregnancy
-*Subacute Sclerosing Panencephalitis*: slow form of encephalitis that occurs many yrs after a measles infxn
Biopsy of rash or Koplik's spots reveals multinucleated giant cells
Red nuclear & cystoplasmic inclusions - very small and dark |
|
|
