generally non-path to adults; young at risk structure: ss DNA 1.5 x 106 d in
interesting shape- not circular, usually minus strand- mRNA copies made directly 3 open reading frames; overlapping & nested
mRNAs replication: occurs in nucleus, host enzymes transcription - assembly: assembly is in nucleus both transmitted easily within families; course lasts
3 wks papilloma grp- warts, cervical CA, papillomas,
skin tumors polyoma grp- multifocal tumors, lymphomas Papilloma viruses: target cell- differentiating epithelial cells in basal
layer structure & replication: icosahedral capsid c 1 major protein monomer Polyoma viruses: transformation c no replication prototype: SV40- simian virus structure & replication: [Note: other
polyoma & SV40- not close relatives] replication by theta mode transcription & translation: early genes --> 2 proteins: T & t [tumor
Ags] abortive infection & transformation: E.g.: JC
virus trophic for glials
Parvoviridae: literally means "small virus"3 genera:
parvoviruses- mammals
densoviruses- arthropods
adeno-assoc viruses (AAV)- mammals & man
dependent on adeno- or herpesviruses
feline parvo- panleukopenia: all types of WBC low
dogs- thought to be mutant of mink parvo: worldwide since
1978
human- B19 1st noted in 1975 in blood donors [sans
any Sx]B19 causes acute aplastic phase in several
hereditary
hemolytic Dz's; fifth diseaseorganized in Y-shaped
hairpin folds
capsid- icosahedral assembly of 2-3 large proteins
Y-shaped DNA: appears to aid in integration &
latencyusually only during S & G2 phase of cell
cycle
transcription only from ds forms of DNA
[RF]
Dz: aplastic crisis- in pts c variety of hemolytic
Dz's:sickle cell most common assoc.
fifth Dz: #5 rash p rubella, morbilli measles, scarlet
fever, pseudoscarlatina
both produce lasting immunity
Papovaviridae: Big news!! dsDNA!! circular: models
for cellular DNAcan transform cells in some cases
larger in size; genomic info all on 1
strand
rare if at all integrated in host DNA; remains as
plasmidgenomic info on 2 strands (compare c
ambisense)
large number of species & apparent strains
if in preferred host- little damage
if in different host- freq. malignancies
not studied as much as polyomas due to
restricted cell tropism
some are easily isolated from animals showing no
Sx
some produce tumors in variety of organs
** in contrast to RNA viruses which transform
& replicate
icosahedral capsid c 3 proteins
circular ds DNA can integrate into host genome
genes for structural proteins: show overlap &
read-thru
do not req. hosts actively synth DNA as do
parvo-
polyoma are smallest which regulate for early
& late RNAs
1. early- close to origin,
counterclockwise
2. late- opposite direction, clockwise on other
strand
3. untranscribed- mid section: many housekeeping fxns
late genes --> 3 coat proteins
Next up: Adeno- & Herpes- viridae; Baculo- & Irido-
viridae
Updated 1/25/04 by thatcher@sonoma.edu