VIROIDS AND PRIONS

-SURAJ .P. BEGOOR

PRIONS

What are PRIONS???•Infectious agent •Composed of single sialoglycoproteins called PrP 27-30•No nucleic acidMass of 27000-30000Da•145 amino acids•Carboxyl terminus contains phosphotidylionisitol glycolipids whose components are ethanol,phosphate, myoinositol and stearic acid.

HOW CAN A PROTEIN BE INFECTIOUS

Fig(a) and (b) :Microscopic "holes" are characteristic in prion-affected tissue sections, causing the tissue to develop a "spongy" architecture

A

B

DISEASES CAUSED Cattle -Bovine spongiform

encephalopathy (BSE) or mad cow disease.

Sheep and goat- scrapie

Humans-1. Creutzfeldt–Jakob disease (CJD)2. Fatal familial insomnia (FFI)3. Kuru. etc

SIGNS AND SYMPTOMS The first symptom of CJD is rapidly

progressive dementia, leading to memory loss, and hallucinations.

Physical problems such as Stammering. jerky movements. Irritation over no issues. The disease has also been shown to result

from use of human growth hormone obtained from the pituitary glands of persons who died from Creutzfeldt–Jakob Disease.

•1730’s found in English sheep •1950-kuru•1960’s-transmittance nature•1980’s- CJD•1982- Dr. Stanley Prusnier coins the term prion.•1990s- mad cow disease•2005- new variant of CJD from beef.

History of prion

Alcohol ACID STANDARD AUTOCLAVE

METHODS. BOILING The contaminated soil is

carefully scooped up and put through a multistage incinerator that reaches up to 1200 -2000degrees F and it is further treated.

CAN PRIONS BE KILLED?

VIROIDSVIROIDS

VIROIDS Viroids are plant pathogens.  Viroids were discovered,

initially characterized, and named by Theodor Otto Diener, plant pathologist at the Agricultural Research Service in Maryland, in 1971.

246-469 nucleotides The first viroid to be

identified was Potato spindle tuber viroid (PSTVd). Some 33 species have been identified.

MULTIPLICATION Viriods multiply inside the nucleus of

infected plant cell by “rolling circle” mechanism, using the host enzymes.

Produce a long monomeric strand of RNA which are cut into monomers ,each monomers then join to form an individual circular viriod.

After replication , the progeny RNAs move to neighbouring healthy cells though the connecting plasmodesmata or distinct parts of the plants through phloem.

DISEASES Potato spindle tuber

disease. 1st viroid to be

identified. Natural hosts is

potatoes and tomatoes All potatoes and

tomatoes are susceptible to PSTVd and there is no form of natural resistance.

POTATO SPINDLE TUBER

DISEASE

Coconut Cadang Cadang disease

Coconut cadang-cadang viroid (CCCVd)

Every year one million coconut palms are killed by CCCVd and over 30 million coconut palms have been killed since Cadang-cadang has been discovered.

REFRENCES  Google scholars.org.in National Institutes of Health. (2010). NINDS

Transmissible Spongiform Encephalopathies Information.

Cell and molecular biology by Gerald karp. Boundless. “Prions.” Boundless Microbiology. McGraw hill animations Wikipedia http://www.eppo.org/QUARANTINE/virus/

Coconut_cadang_cadang_viroid/CCCVD0_ds.pdf

Haseloff, J.; Mohamed, N.A.; Symons, R.H. (1982) Viroid RNAs of cadang-cadang disease of coconuts. Nature 299, 316-321.

ANY QUESTIONS???