Transcript Promise for the new way to fight HIV

Virus Veni, Vidi, Vici ?
Izabela Tworowska, PhD
Department of Biochemistry and Cell Biology
[email protected]
Part I
Viruses - structure
1. contain nucleic acid, either DNA or RNA (but not both),
and a protein coat (encases the nucleic acid).
2. some viruses enclosed by an envelope of fat and protein molecules.
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The smallest virus:
satellite tobacco necrosis virus (STNV)
plant virus, not enveloped; 17 nm in diameter;
consists of 60 protein subunits and RNA;
Satellite virus- depends on co-infection with the helper virus
(providing missing replication function)
Animal (human) satellite virus: Hepatitis delta virus (HDV)
cannot survive w/o the helper virus Hepatitis B virus (HBV)
Capsid
the protein shell that encloses the nucleic acid;
capsid + nucleic acid = nucleocapsid
three functions:
nucleic acids protected from digestion by enzymes
contains special sites (spikes) on its surface (attach to a host cell)
provides proteins allowing the virus to penetrate the host cell
Envelope
glycoprotein envelope surrounds the nucleocapsid;
composed of two lipid layers;
glycoprotein’s spikes on the envelope
Nucleic Acids
few groups of viruses use DNA; most are single-stranded RNA viruses;
RNA viruses may contain:
plus strand RNA – direct synthesis (translation) of viral protein
negative strands RNA- first synthesis messenger RNA , then viral protein synthesis
VIRUS- where, why, how ?
Where do they come from?
.
.
Occupy the “gray area” between living and non-living organisms
Speculated form of proto-life
(unlikely that they preceded cellular life during the Earth's early evolution).
Viruses started as rogue segments of genetic code
(adapted to a parasitic existence)
How do they replicate?
Cannot survive without a host cell
synthesize proteins,
generate or store energy in the form of the adenosine
triphosphate (ATP)
Complementary Strand
(mirror strand)
Viruses can have different genomes
Eryhtrovirus
Herpes simplex
HIV
Polio, HIV, Influenza
Reovirus
HBV -partially ss, mainly dsDNA
The relative size of some viruses
http://www.usq.edu.au
The relative size of some viruses –how big?
http://www.usq.edu.au
NOBODY IS SAFE !
Viruses can infect animals, plants, or bacteria.
(viruses cannot penetrate plant cell walls,
plant viruses are transmitted by insects or
other organisms)
Classification of viruses into families:
type and size of their nucleic acid,
size and shape of the capsid
presence of the envelope
Bacterial virus
T4 Bacteriophage
Shapes of viral capsid
rods, filaments
Tobacco mossaic virus
Enterobacteria phage
the simplest way to arrange non-symmetrical
components and place in circle to form discs.
spheres
Hepatitis B
Polio virus
icosahedral symmetry,
(20 triangular facets )
Advantage of the subunits structure of the viruses: greater genetic stability
head- tail structure
T4 bacteriophage
Virus life cycle
1. the virus attaches to the target cell
2. the viral nucleic acids enters the cell
3. the host cell synthesizes the proteins
encoded in the viral genome and
replicates the virus’s DNA or RNA
4. the new viral proteins and the nucleic
acids assemble into new viruses
5. the new viruses are released from the
cell
HIV life cycle
Guess, who am I ?
Virion , Viroid or Prion ?
Virion
virus infective form (outside the cell)
contains at least one unique protein synthesized by
specific genes in its nucleic acid.
Viroid (meaning "virus-like")
disease-causing organism
contains only nucleic acid and has no structural/functional proteins
Prion ("virus-like")
composed primarily of a ‘’infectious agent’’ – protein
Spongiform encephalopathies
The Prion Hypothesis
The infectious agent (protein) has
been called a prion.
A prion has been defined as "small
proteinaceous infectious particles
which resist inactivation by
procedures that modify nucleic
acids". The discovery that proteins
alone can transmit an infectious
disease has come as a considerable
surprise to the scientific community.
from Corey Wilson’s lecture
Spongiform Encephalopathies
Host
Date
Scrapie (Several countries eg. UK)
Sheep
1936
Transmissible Mink Encephalophathy (TME)
Mink
1956
Kuru (people New Guinea)
Humans
1966
Creutzfeld-Jacob Disease
(Uniform world-wide incidence), 1 per million per annum
Humans
1968
Bovine Spongiform Encephalopathy (BSE)
Cattle
1988
Feline Spongiform Encephalopathy (FSE)
Domestic cat
1991
Disease and accurance
Buckminster Fuller (1893-1983)
architect, mathematician
invented the geodesic dome
US Pavilion at Expo '67,
by Buckminster Fuller and Shoji Sadao, at Montreal, Canada, 1967.
http://www.greatbuildings.com/architects/Fuller_and_Sadao.html
FULLERENES (BUCKYBALL)
Buckminsterfullerene, C60,
the molecule that started it all.
(eta2-C70-Fullerene)-carbonyl-chlorobis(triphenylphosphine)-iridium
J.Am.Chem.Soc., 113, p8953,1991
The Royal Swedish Academy of Sciences has
awarded the 1996 Nobel Prize for Chemistry
jointly to:
•Professor Robert F. Curl, Jr.,
Rice University, Houston, USA
•Professor Sir Harry W. Kroto FRS,
University of Sussex, Brighton, UK
•Professor Richard E. Smalley,
Rice University, Houston, USA
for their discovery of fullerenes
DNA buckyballs
DNA buckyballs
used for drug delivery
as containers for chemical reactions
Science News, August 29, 2005
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See next on Thursday!