1.3 Respiratory Viruses Flashcards
- family orthomyxoviridae
- ssRNA, enveloped viruses with a helical nucleocapsid
- genome of 7-8 segments
- types A, B, C, D
- HA, NA, M2
influenza viruses
in influenze viruses, facilitates attachment to sialic acid rececptor
hemagglutinin (HA)
in influenza virus, facilitates release of infectious virus from cells
neuraminidase (NA)
in influenza virus, necessary for virus entry
M2 protein
influenza pathogenesis?
virus deposited on the respiratory tract epithelium, attaches to and penetrates columnar epithelial cells
normally prevents attachment of influenza virus to columnar epithelial cells?
specific secretory IgA antibodies against hemagglutinin, mucoproteins, and mucociliary apparatus
key cytokine storm mediators in influenza?
IL-6, TNF-alpha, Interferon a/b, IL-1 a/b, IFN-gamma
- point mutations in antigenic sites reduce or inhibit binding of neutralizing antibodies
- generally results in local epidemics
- occurs in influenza A and B
antigenic drift
- a sudden, major change in the antigenic structure of HA and/or NA
- results in pandemics because the populations don’t have neutralizing antibodies against the new virus
- occurs only in influenza A
antigenic shift
- two different viruses infect the same cell
- new strains emerge
genetic reassortment influenza
H1N1 resembles an _____ origin virus, reappeared as Russian flu in 1977
avian
in influenza immunity, which are the protective antigens of the virus?
HA and NA glycoproteins
influenza vaccines are ________ and given ________, the purified virus is split with a detergent and components purified
inactivated, intramuscularly
- enveloped, pleomorphic virions
- contain non-segmented, (-) ssRNA
- syncytia inducing viruses
paramyxoviruses
includes measles virus, mumps, respiratory syncytial virus, metapneumovirus
paramyxovirus
attachment protein of paramyxovirus and mumps?
HN protein
attachment protein in measles?
H glycoprotein
attachment protein in RSV?
G glycoprotein
all paramyxoviruses have a ________ protein, allows syncytia to form
F (fusion)
replication of paramyxovirus?
fusion of viral and cellular membrane through action of F protein, makes positive transcript, mRNAs translated to protein, assembly and release at plasma membrane
paramyxoviruses cause fusion of neighboring cells, mediated by F protein of virus
syncytia formation
measles rash caused by a ______ response against infected endothelial cells
T cell
-measles virus infects cells of the ______ tract, then spreads ________
respiratory tract, systematically
essential to control infection in measles, antibody is not sufficient
cell mediated immunity
requirements for measles?
cough, coryza, conjunctivitis, temp >101, maculopapular rash >3 days
most common complication of measles?
acute otitis media
slowly progressing neurodegenerative disease post-measles infection, get cognitive change then motor dysfunction followed by vegetative state
subacute sclerosing panencaphalitis
- acute, benign viral parotitis, can cause encephalitis as well as orchitis
- only one serotype, man is only reservoir
- cell mediated immunity essential, antibody not sufficient to prevent virus spread
- immunity is lifelong
mumps virus
- major cause of lower respiratory tract infections and hospital visits during infancy and childhood
- belongs to pneumovirus and paramyxovirus family
respiratory syncytial virus
at risk of severe infection with RSV?
- infants with congenital heart disease
- underlying pulmonary disease such as bronchopulmonary dysplasia
- immunosuppressed or immunocompromised
- ssRNA virus, enveloped, pleomorphic
- 5 serotypes, no antiviral therapy
parainfluenza virus
- an enveloped RNA virus, member of the family togaviridae
- RNA of positive polarity, only one serotype, humans the only reservoir
rubella virus
in non immune mothers are infected in the first trimester, 80% of neonates affected
rubella virus
- initial site of infection the upper respiratory tract, then viremia
- immunologic basis for rash
- patient infectious from 1 week before rash to 1 week after
- maculopapular rash
rubella
- infection of fetus may affect all organs, leading to fetal death or premature delivery
- 85% affected if during first trimester
- triad of cataracts, heart defects, sensorineural loss
congenital rubella syndrome
triad of symptoms in congenital rubella syndrome?
cataracts, heart defects, sensorineural deafness
what type of vaccine is MMR?
live attenuated
two viruses responsible for the common cold?
rhinovirus and coronavirus
- small non-enveloped ssRNA virus
- belong to picornavirus family
- acid labile, greater than 110 serotypes
rhinoviruses
ssRNA virus, enveloped, pleomorphic
-can causes SARS and MERS
coronavirus
