5. GENOME STRUCTURE
Retroviruses are dsRNA virus. The retroviral genome
is organized with internally located coding regions
flanked by 5 and 3’ untranslated regions. which
function in viral replication . The RNA genome is
7000–10,000 Nucleotides long.
10. ADENOVIRUS
Discover:-
Adenoviruses were first discovered
in 1953 by “Wallace Rowe” & his
colleagues.
Adenoviruses are medium-sized (90–100nm) , non developed virus
containing a double stranded DNA genome. Their name derives from
their initial isolation from human adenoids in 1953.They Cause
respiratory, eye, and intestinal infections
11. GENOME STRUCTURE
The adenovirus genome is linear, dsDNA have 26 and
48 kbp Adenovirus replication is a protein-primed
process that occurs in the nucleus .Although this is
larger than other viruses in its baltimore group. DNA
replication process finished in 40 h, an infected cell
produces approximately one million copies of viral
DNA.
17. VIROIDS
Viroids are among smallest infectious molecule.
They are only larger than prions. They are cause over
20 plant diseases.About 30 distinct viroids have been
identified.
Naked RNA molecules
VIROIDS No capsid
No coatings
18. Discover:-
“Theodor Otto Diener” is an american
plant pathologist agriculture research
service in maryland in 1971and
discover the virods.
19. They are too small to encode for even a single enzyme
Don’t know how they cause disease
They infect only plants :
EXAMPLE:
tomatoes
potatoes
cucumbers
citrus trees
chrysanthemums
20. The first viroid was identified was the
potato spindle tuber viroid [PSTVd.]
21. Animal disease
But, they may be involved in animal diseases like:
arthritis
encephalopathies
cancerous lymphomas
22. GENOME STRUCTURE
viroids are circular ssRNAs about 250-370 nuclotides
long.Viroid genome are extremely small in size .It
affect only plants. requires host cell DNA-dependent
RNA polymerase to replicate.
25. PRION
Prions are infectious agent that can replicate without
genetic material. They are also called
Proteinaceous particle
Slow viruses
They are self-propagating misfolded conformer protein that
is responsible for a number of disease that affect the brain
and other neural tissue.
27. GENOME STRUCTURE
prpC prpSC
They have no
nucleic acids, it is
a product of a
human gene,
termed the PRNP
gene, found on
chromosome 20.
This gene contains
two exons
separated by a
single intron.
28. Prions cause “8” known animal diseases all 8 are
neurological diseases.
They are,
Mental derangement
Loss of muscle control
Progressive and fatal etc..
29. Other diseases :
Eg. Kuru
Is an incurable degenerative neurological disorder,
caused by a prion found in humans.
30. A newly discovered prion disease attacks the PNS
rather than the brain causing
Chronic diarrhea.
31. some evidence prions may be involved in:
Parkinsons disease
Alzheimers disease
Huntington’s disease
32. PrPC (prion protein) is present in
“normal” form but, their
abnormal form of prion protein is
PrPSc.
Newly produced PrPSc molecules
convert more normal molecules to
the abnormal form through
unknown mechanism.
33. Neural Loss :
Evidence suggests that PrPC must be present for
neural degeneration to occur
Interaction of PrPSc with PrPC may cause PrPC to
crosslink and trigger apoptosis
PrPC conversion causes neuron loss, PrPSc is the
infectious agent
34. All prion caused diseases
–have no effective treatment
–result in progressive degeneration of the brain and
eventual death