Fragments of Genetic MaterialThe very basis of life, self-replicating molecules, are threatened by their own renegade progeny. These genetic cowboys may soon bring our species the edge of extinction. If we can out maneuver them in time, we may not only cure disease, but also create life. We will soon be playing god with only a fraction of the wisdom. It may be the ultimate risk, but can we afford not to take it? "Paying the cost to be the boss" Muddy Waters.
B. Adenoviruses - respiratory infections
C. Papovaviruses - Warts
D. Poxviruses - Smallpox; Cowpox
HSV1 - Cold Sores
HSV2 - Genital Herpes
VZV - Chicken Pox, Shingles
CMV - neonatal fever
EBV - Infectious Mononucleosis
F. Hepadnaviruses - Hepatitis B
Enteroviruses - Polio, Hep A
Rhinoviruses - common colds
B. Togaviruses - encephalitis, Rubella
C. Flaviviruses - Yellow Fever, Dengue
D. Coronaviruses - URI, colds
E. Rhabdoviruses - Rabies
F. Filoviruses - Ebola
G. Paramyxoviruses - Measles, Mumps
H. Orthomyxoviruses - Influenza
I. Bunyaviruses -
J. Arenaviruses - (HFS)
HTLV I & II - Leukemia
HIV - AIDS
N. Reoviruses - respiratory and LDT infections
They are small bits of naked RNA (246 - 375 nucleotides long). Each is too small to code for a gene (like introns), but somehow cause disease in crops (potatoes and citrus fruits). 25 different viroid sequences have been determined and numerous variants identified :
A. Avocado sunblotch viroid
B. Peach latent mosaic viroid
C. Potato spindle tuber viroid
D. Coconut cadang cadang viroid
E. Tomato plant macho viroid
F. Citrus bent leaf viroid
G. Pear blister canker viroid.
Small proteins that are thought to activate dormant lethal genes within you. All cause fatal, degenerative diseases of the nervous system.A. Scrapie: sheep
B. TME (transmissible mink encephalopathy): mink
C. CWD (chronic wasting disease): muledeer, elkD. BSE (bovine spongiform encephalopathy): cows E. CJD: Creutzfeld-Jacob Disease (Humans)
F. GSS: Gerstmann-Straussler-Scheinker syndrom(Humans)
G. FFI: Fatal familial Insomnia (Humans)
H. Kuru (Humans)
I. Alpers Syndrome (Humans)These original classifications were based on a clinical evaluation of a patients family history symptoms are still widely used, however more recent and accurate molecular diagnosis of the disease is gradually taking the place of this classification.
The diseases are characterised by loss of motor control, dementia, paralysis wasting and eventually death,typically following pneumonia. Fatal Familial Insomnia presents with an untreatable insomnia and dysautonomia. Details of pathogenesis are largely unknown.
Infection Parameters: Acquired infection (diet and following medical procedures such as surgery, growth hormone injections, corneal transplants) i.e. infectious agent implicated. Also hereditary mendelian transmission where it is an autosomal and dominant trait.
Virusoids or satellite RNAs (sRNA) are also several hundred nucleotides long circular and single stranded. They depend on a helper virus for replication. This helper virus also encapsidates them.
A. Barley yellow dwarf virusoid: Helper - Luteovirus.
B. Tobacco ringspot virusoid: Helper - Nepovirus
C. Subterranean clover mottle virusoid: Helper - Sobemovirus
D. Hepatitus delta antigen virusoid : Helper - Hepatitus Virus (Human)
Virusoids replicate in the cytoplasm using an RNA-dependent RNA polymerase. This enzymic activity is common in plants but not found in animal cells.
It is not known if viroids and virusoids are ancestral to modern viruses or have degenerated from other more complicated viruses. They can be spread by vegetative propagation, within seeds or by direct inoculation either by insects or man.