orthomyxoviridae and paramyxoviridae Flashcards
The orthomyxoviruses generally cause what
the flu
with fever, muscle aches and HA
What bacterial pneumonias are common after viral orthomyxovirus infection
S aureus, H influenzae or St pneumoniae
what is the outside structure of orthomyxoviruse
has 2 types of glycoproteins
Hemagglutinin Activity HA
and Neuraminidase Activity NA which anchor to M proteins in lipid bilayer
HA hemagglutinin attach where
sialic acid R on host cells
so on RBCs and upper respiratory cells
What is the role of neuraminidase
it cleaves neuraminic acid which is important defensive component of mucin
What are the 3 types of influenza viruses? which ones are human only
A B C
BC are only human
What is antigenic drift
mutations in HA or NA
small changes
What is antigenic shift
complete change of HA or NA
when was the spanish flu and what type of virus was it
1918 H1N1
What is Reyes syndrome
children given aspirin while having flu or varicella
severe liver and brain disease
What are the 4 broad categories of Dx testing for influenza
viral isolation in culture
detection of viral proteins
detection of viral nucleic acid RNA- PCR
serological Dx 4X increase in titers over 2 week period
What are the clinical manifestations of H5N1
incubation 2-4 days have high fever, HA, mayalgias, diarrhea, abdominal pain, vomiting, sore throat and rinorrhea
cough, SOB and sputum production
** unique: clinical pneumonia with diffuse patchy infiltrates that consolidate with air bronchograms
Progresses to ARDS
How do you Dx H5N1
viral culture or reveres transcriptase PCR of viral RNA from pharyngeal or nasal washings
Ag-Ab detection of 4X increase in H5-specific Ab
What are the main differences of paramyxovirus vs ortho
negative stranded RNA is single strand- not segmented
HA and NA are same glycoprotein
have F protein
What does the fusion or F protein in paramyxoviruses do
fuse together to make multinucleated giant cells
What are teh 5 paramyxoviruses that cause human disease
parainfluenza, repiratory syncytial, metapneumonvirus, mumps and measles
Where do the paramyxoviruses manifest
lungs
upper respiratory tract - adults bad colds
lower respiratory tract- children pneumonia
what does parainfluenza virus cause
URI in adults
pneumonia in kids and elderly
What is croup
parainfluenza infection of larynx
causes wheezing and barking cough
How is Respiratory syncytial virus different from the rest of the family viruses
does not have HA or NA glycoprotein
has F protein
what is the leading cause of pneumonia in children under 6 months
RSV
what age group is generally infected by metpneumovirus
children in the year old range
can cause croup too
What is the general presentation of mumps
3 wks post exposure
parotiditis
orchitis
how does measles spread
nasopharyngeal secretions by air or direct contact
