structure, etc.: icosahedral 75 nm- much larger
than papilloma 50 nm early transcription- begins when virion reaches
nucleus strand used changes freq.; lots of
post-transcriptional splicing late transcripts- made after onset of DNA replication;
most from r-strand assembly occurs in nucleus replication: viral DNA may integrate into host
genome To transform, or not to transform- That
is the question: 8 human herpes: alpha group: HV-1 herpes simplex 1 fever blisters, brain HV-2 herpes simplex 2 genital HV-3 varicella zoster chicken pox, shingles beta group: HV-5 cytomegalovirus mono, neonatal fatality gamma group: HV-4 Epstein-Barr infectious mono, cancer other: HV-6 HBLV B cells HV-7 T cells (CD4+) HV-8 sarcoma, lymphoma infection cycles vary: structure: dense core inside capsid of tubular
monomers- 4 proteins at least 33 proteins produced- many not incorporated
into progeny linear DNA 85-150 x 106 (upper end for
CMV) transcription, translation, replication: early infection appears to depend on host enzymes considerable variation of expression under different
conditions: Baculo- & Irido- are very specific: multiple hosts
within insect family; use in pest control- need to know host range, hazards,
economic baculo- high interest in biocontrol vs. Ag pests;
forestry & medical both NPV & GV: form nuclear inclusion bodies- GV
less polyhedral may be each nucleocapsid or bundles [NPV] replication, transcription & assembly: in
nucleus NPV: host range- lepidoptera, hymenoptera, diptera
[moths, wasps, mosquitoes] most cause latent or
subclinical infection disease cycle & pathogenesis; contrast c CPV
[reovirus] Baculo's & CPV's grow well in culture, therefore
potential production opportunities; Tipula iridescent virus- most described host range: diptera, lepidoptera, coleoptera
[flies, moths, beetles] 130 nm icosahedra: may have double layered protein
capsid internal lipid bilayer- phospholipids differ from host
membrane dsDNA linear, 130-200 x 106; circularly
permuted assembly- 1st empty membranes, fill c DNA &
protein, membrane completes, then outer coat disease cycle & pathogenesis Next week: Myoviridae & Siphoviridae- same as above for
prep
Adenoviruses: humans, animals, & birds30 serotypes for human strains
generally mild respiratory infection in primary host
can cause tumors in other species14 coat proteins organized in hexons &
pentons
long peplomers- 10-30 nm; act as attachment organ
dsDNA linear 20-24 x 106; variation by
serotypes
proceeds as standard 5' to 3' mode of
replication
1. all of the above is true in permissive
cells
2. in non-permissive cells: no DNA synthesis, no late
transcription or structural proteins
Herpesviruses: human, other animals, amphibians,
fish, mollusks, fungihuman: cold sores, shingles, VD, mononucleosis,
cancer
hallmark: latent or subclinical infections very common
herpes 1-3: rapid; in many tissues; cytocidal;
latent in ganglia
herpes 4: chronic infections; lymph related; can be
latent
herpes 5: slow; fibroblasts, not cytocidalgenerally covered c tegument, which is covered c
envelope & peplomers
many enzymes coded- some relate to DNA synthesis
infectivity: whole >> nucleocapsid > naked
DNApermissive cells- rapid appearance of progeny
DNA in nucleus
early & late phase not well separated as
in adeno
rate of mRNA production exerts control on protein
synthesis
later, when host activity is shut down, viral enzymes
take overno stimulation of host mitosis as in polyoma
may integrate +/- transformation
may exist as plasmid form s Sx
may inhabit sensory neuron cell bodies
Intro to insect DNA viruses: Baculoviridae &
Iridoviridae Although insect transmit many types of virus,
some are very specific for them: some members of
poxviruses [entomopox's] & some parvoviruses
are specific for insects only
multiple orders involved
no non-insect hosts ever found other than crustaceans*concern for bees, silkworms; possible
biowarfare
*genetic engineering- alpha interferon, vaccinesfactors of production- due to increased
chemical use restrictions, more focus to seek
alternatives
Baculoviruses: 2 subgroups- nuclear polyhedrosis
virus [NPV]; granulosis virus [GV][compare c cytoplasmic polyhedrosis viruses-
reovirus group dsRNA]
helical in lipid & protein envelope-
trilaminar
dsDNA- supercoiled circular, nicked, linear
75-100 x 106
insects appear to have efficient defenses
E.g.: use in biowarfare against insect pests
Iridoviruses: diverse grpalso includes a few animal viruses [fish,
frogs, lizards, African swine fever]
genus named for 1st discovery in Tipula
paludosa [crane fly]
protein is in apparent tubules
reversible color change during dehydration &
rehydrationClinical aspects of herpes group &
Poxviridae- see CRC, ch 5 & appropriate parts of
Wagner, including ch 19, & on-line
Updated 1/25/04 by thatcher@sonoma.edu