23 - Negative Strand and DS RNA Viruses (Stapleton) Flashcards
naked - strand RNA viruses
reovirus
enveloped - strand RNA viruses
orthomyxovirus
paramyxovirus
rhabdovirus
bunyavirus
orthomyxovirus causes
influenza A, B, C
orthomyxovirus characteristics
segmented genomes (8) enveloped - strand influenza type determined by proteins (HA and NA)
each segment of orthomyxovirus
each segment encodes one influenza gene
influenza attachment
HA precursor (HA0) is processed to HA1 and HA2 by serine protease in lung HA1 attaches to human sialic acid with a 2,6 linkage
influenza entry
enters endosome with low pH
M2 protein pumps protons into virion to facilitate uncoating
influenza genome replication
occurs in nucleus
RDRP makes + strand copy (template to make more - strand)
influenza egress
removal of sialic acids from surface by NA release virion
antigenic drift
minor differences
influenza A and B
due to RDRP infidelity
causes regional epidemics
antigenic shift
major differences influenza A only!! due to reassortment of HA and NA from other types Species mixing (birds, humans) pigs as mixing pot for new strains causes pandemics
pandemics of influenza
have avian and swine connection
antigenic shift
seasonal (winter)
barriers preventing spread from fowl to pigs and humans
humans have 2,6 linkage, birds have 2, 3 linkage
HA on virions in pro protein form, requires proteases in trachea and lung to process into infectious form
single amino acid residues increases replication (PB2)
transmission of flu
Aerosol droplets
replication in respiratory tract
desquamation of ciliated cells=influenza
also primary viral pneumonia with secondary bacterial infections, leading to bacterial pneumonia
detection of flu
swab viral culture DFA antibody staining RT-PCR serology rapid flu diagnostic test
flu treatment
M2 ion channel inhibitors-amantadine
neuraminidase inhibitor
neuraminidase inhibitor
block cell surface sialic acid to prevent cleavage and release of flu A and B
flu vaccine
seasonal
inactivated trivalent vaccine
attenuated inhaled vaccin
types of paramyxovirus
mumps measles parainfluenza RSV metapneumovirus
paramyxovirus characteristics
enveloped helical non segmented replicate in cytoplasm transmitted by saliva, respiratory secretions
paramyxoviruses that become systemic
mumps, measles
good immunity post infection
mumps
swelling of cheeks and under jaw
parotitis
male sterility due to replication in testis
measles
rubeola
koplik spots
high fevers
can progress to pneumonia or encephalitis
causes of encephalitis from measles
infection of neurons
post infectious encephalitis
subacute sclerosing pan encephalitis (SSPE)
mumps and measles treatment
no antiviral
live attenuated vaccine with rubella (MMR)
vaccine grown in chicken eggs
parainfluenza 4
mild URI
parainfluenza 1,2,3
severe RI
no treatment or vaccine
leading cause of croup
RSV
bronchilitis
LRI
virus kills infected epithelial cells causing plugs of dead cells
no vaccine
RSV symptoms
bronchiolitis (leading cause) pneumonia encephalitis effecing immunocompromised and elderly winter infeciton
rhabdoviridae types
rabies virus
vesicular stomatitis virus
rhabdoviridae characteristics
enveloped
helical
bullet shape
- strand RNA
rabies transmission
from wild animals, unvaccinated domestic animals, bats
shed in saliva
passed through bites or aerosol in bat caves
rabies disease process
virus enters through bite
replicates in muscle
infects peripheral nerve and moves retrograde
replicates in DRG and travels up spinal cord
infects brain
virus travels back down nerves
pathology of rabies
negri bodies (inclusion bodies) in cytoplams
rabies treatment/prevention
no antiviral treatment
post exposure prophylaxis-wound care, passive immunization (human immunoglobulins), active immunization (killed virus)
pre exposure prophylaxis (killed virus vaccine)
bunyavirus
infects humans and animals
types of bunyavirus
hantavirus (sin nombre-4 corners, sin nombre like-yosemite)
california encephalitis
la crosse virus
hantavirus
zoonosis
carried by deer mice
spread to humans through aerosolization of virus in rodent excreta
la crosse virus
arbovirus amplifying host in small mammals vector of mosquitoes or ticks dead end host in human causes encephalitis
reoviridae types
reovirus
rotavirus
reoviridae structures
naked
icosahedral
dsRNA
segmented
rotavirus characteristics
fecal oral spread
no antiviral
2 vaccines (3 doses)
rotavirus infections
infants and young children
severe gastroenteritis
high infant mortality due to dehydration
damage to intestinal epithelium
