Viruses I Flashcards
positive RNA virus
like mRNA
-can be translated directly to proteins
negative RNA virus
need to be transcribed to mRNA first
-carry RNA-dependent RNA polymerase in their capsid
RNA dependent RNA polymerase
in negative RNA viruses - necessary to transcribe the negative RNA to mRNA that can be translated to proteins
virus structure
protein coat - capsid
-surrounds genetic material
- some viruses further enclosed by lipid bilayer with glycoproteins
- EITHER DNA OR RNA
retroviruses
RNA virus
-can incorporate into host DNA
has reverse transcriptase - viral RNA to DNA
retroviridae
only viruses with double stranded RNA genome
viruses have the genetic material
but not the enzymes to build replicas
most DNA viruses
have a negative and positive strand
negative strand of DNA viruses
read, while positive ignored
parvoviruses
have single stranded DNA
capsomer
building block of capsid
-globular protein
icosahedron
20 triangles of capsomers to form capsid
helical
capsomers bound to RNA
-colied into helical nucleoprotein capsule
naked virus
no membrane
enveloped virus
has membrane
size of pathogens
viruses are tiny
bacteria larger
-mycoplasm - smallest bacteria
HHAPPPy
herpes hepadna adeno papova parvo pox
DNA viruses**
most DNA viruses
double strand
icosahedral symmetry
replicate in nucleus
parvoviridae
single strand of DNA
poxviridae
double strand DNA
- not icosahedral
- surrounded by complex protein box
- replicates in cytoplasm
DNA viruses with envelopes
herpes
hepadna
pox
DNA viruses that are naked
papova
adeno
parvo
most RNA viruses
single stranded
enveloped
helical symmetry
replicate in cytoplasm
outcome of viral infection
1 cell death
2 transformation - uncontrolled growths
3 latent infection
4 chronic slow infection
orthomyxoviridae
all influenza viruses
paramyxoviridae
parainfluenza resp syncytial virus metapneumovirus mumps measles
high fevers, chills, headaches, malaise, myalgias, dry cough, sore throat, rhinorrhea
influenza
secondary bacterial pneumonia with influenza
staph aureus
haemophilus influenza
strep pneumoniae
8 segments of negative RNA
- spherical
- outer membrane with HA and NA
- M-protein anchors
orthomyoxyviridae
M-protein
membrane proteins in orthoxymyoxyviridae anchoring HA and NA
hemagglutinin activity
in orthoxymyoxyviridae
- can attach to host sialic acid receptors
- on surface of RBCs - clumping
- also on upper resp tract
- activate fusion
- necessary for viral absorption
neuraminidase activity
cleaves neuraminic acid in mucin
- on epithelial
- exposes sialic acid receptor
antigenic drift
with influenza
- small mutations in HA and NA
- new for immune system
type of influenza attacking humans
type A
antigen shift
complete change of HA and NA in influenza
-trading of RNA segments between animal and human strains
-responsible for pandemics
recent influenza pandemic strains
H1N1 (swine)
now H7N9 (avian)
complications of flu
spreads to lower respiratory tract
-pneumonia
infections
- staph aureus
- strep pneumonia
reyes syndrome
children given aspirin when have flu
-liver and brain disease
children with flu
give acetaminophen
-not aspirin
reyes syndrome
-liver and brain disease
bird flu
H5N1
-pandemic threat
exposure - diseased chicken or duck exposure
high fever, headache, myalgias, abdomen pain, rhinorrhea, cough, SOB, sputum, clinical pneumonia with diffuse patchy infiltrates progressing to consolidation more than one lung zone
H5N1
-bird flu
diagnosis of H5N1
RT-PCR
H7N9
avian origin
-threat for pandemic
