VIROLOGY Flashcards
Smallest infectious agent (?)
20 nm – 200 nm
Electron microscope (?) – larger size
20x20 nm – 250x300 nm
– contain no enzymes associated with energy
obligate parasite
Either [?] (bacteria is both)
RNA or DNA
Metabolism is entirely dependent on the [?] for biosynthesis
host cell
Requires [?] in order to replicate
living cells
largest DNA
Poxviridae (pox virus)
smallest DNA
Parvoviridae
largest RNA
Paramyxoviridae
smallest RNA
Enteroviridae (enetro virus)
Eschunna Code of ancient Mesopotamia
23 BC
Bite of mad dogs to affect human disease or “Rabies”
23 BC
The Natural History of Man
Aristotle
Reviewed madness in dogs
Aristotle
1796
Edward Jenner
Used cowpox to vaccinate against smallpox
Edward Jenner
VARIOLATION by Chinese
Edward Jenner
With Sarah Nelmes (milkmaid)
Edward Jenner
Small pox has been long eradicated
Edward Jenner
1885
Louis Pastuer
experimented with rabies vaccination
Louis Pastuer
termed ”virus” and “vaccination”
Louis Pastuer
experimented cholera, anthrax, rabies
Louis Pastuer
1886
John Buist
scottish pathologist
John Buist
stained lymph from skin lesions of a smallpox
John Buist
“elementary bodies” - infectious part of the microorganism
John Buist
Smallpox virus particles
John Buist
described the first “filterable” infectious agent called TMV
Dmitri Iwanowski
smallest virus; smaller than bacteria; isolated in plants (leaf of tobacco)
Tobacco Mosaic Virus (TMV)
first to discriminate viruses and other infectious agents
Dmitri Iwanowski
1892
Dmitri Iwanowski
1898
Martinus Beijerinick
extended Iwanowski’s work with TMV (Tobacco Mosaic Virus)
Martinus Beijerinick
developed the concept of the virus as a distinct entity
Martinus Beijerinick
demonstrated foot and mouth disease
Friedrich Loeffier (1852-1915) and Paul Frosch (1860-1928)
first to prove that viruses also affects plants and animals
Friedrich Loeffier (1852-1915) and Paul Frosch (1860-1928)
1900
Walter Reed
demonstrated that yellow fever is spread by mosquitos/insect vectors
Walter Reed
proved that poliomyelitis is a virus
Karl Landsteiner and Erwin Popper (1868-1943)
proved that viruses also infects humans
Karl Landsteiner and Erwin Popper (1868-1943)
1908
Karl Landsteiner and Erwin Popper (1868-1943)
demonstrated that a virus (Rous sarcoma virus) can cause cancer in chickens
Francis Peyton Rous (1879-1970)
1911
Francis Peyton Rous (1879-1970)
discovered viruses infecting bacteria (bacteriophage)
Frederick Twort (1877-1950)
1915
Frederick Twort (1877-1950)
1917
Felix d’Herelle (1873-1949)
coins the term “bacteriophage”
Felix d’Herelle
1938
Max Theller (1899-1972)
developed a live attenuated vaccine against yellow fever transmitted via mosquito)
Max Theller (1899-1972)
1940
Helmuth Ruska (1908-1973)
used an electron microscope which showed complete virus particles or virions
Helmuth Ruska (1908-1973)
1941
George Hirst
demonstrated that influenza virus agglutinates red blood cells
George Hirst
demonstrated that bacteriophages mutate
Salvador Luria (1912-1991) and Alfred Hershey (19081997)
have an antigenic variation
Salvador Luria (1912-1991) and Alfred Hershey (19081997)
1945
Salvador Luria (1912-1991) and Alfred Hershey (19081997)
discovered interferon
Alick Isaacs and Jean Lindemann
protein part of the natural defenses (intact skin, macrophages, wbcs)
Alick Isaacs and Jean Lindemann
1957
Alick Isaacs and Jean Lindemann
proposed a “slow virus” is responsible for the prion disease kuru or zombie
Carleton Gajdusek
Kuru can be transmitted to chimpanzees
Eats human brains
Cannibalism
Carleton Gajdusek
– human disease
Classic Creutzfeld Disease
– infects sheeps and goats
Scrapie
demonstrated that bacteriophage T4 uses host cell ribosomes
Sydney Brenner, Francois Jacob, and Matthew Meselson
1961
Sydney Brenner, Francois Jacob, and Matthew Meselson
discovered Hepatitis B Virus (HBV)
Baruch Blumberg
First to develop anti-hepa B vaccine
Baruch Blumberg
1963
Baruch Blumberg
Aka non-A, non-B hepatitis
Hepatitis C Virus (HCV)
First infectious agent to be identified by molecular cloning of the genome
Hepatitis C Virus (HCV)
1989
Hepatitis C Virus (HCV)
1989: Hepatitis C Virus (HCV)
Hepatitis C Virus (HCV)
Function: encode proteins required for viral penetration, transmission and replication
NUCLEIC ACID
RNA: plus stranded and minus stranded
NUCLEIC ACID
- can serve directly as mRNA
plus stranded
- anti-mRNA; needs the synthesis of a complementary RNA polymerase
minus stranded
All DNA viruses are double stranded except
PARVOVIRIDAE
All RNA viruses are single stranded except
REOVIRIDAE
May be linear or circular
NUCLEIC ACID
protein coat that encloses the genetic material
CAPSID
protects the nucleic acid and enables virus to attach to and enter host cell
CAPSID
Helical or Icosahedral
CAPSID
: protein subunits
Capsomere
complex of nucleic acid and capsid
NUCLEOCAPSID
nucleic acid genome surrounded by a symmetric protein coat
NUCLEOCAPSID
– the relationship of the nuclelc acid with the protein molecules yields a single rotational axis.
Helical Symmetry
Helical Symmetry
TMV
Influenza virus
– the nucleic acids ere condensed at the core of the structure and is surrounded by the protein coat
Icosahedral Symmetry
Icosahedral Symmetry
Adenovirus
Some large viruses have no regular symmetry
bacteriophage
characterized by
20 triangle faces, 12 corners/apices & 30 edges
the complete virus particle
(w/o ourter membrane or capside) – more infectious
naked
outer membrane surrounding the capsid aids in the attachment to host cell
ENVELOPE
Glycoprotein that functions as attachment or as an enzyme
SPIKES
A complete viral particle
VIRION
With circular RNA, molecules
VIROID
Without capsid and envelope
VIROID
Viroid-like particles
VIRUSOIDS
Passengers in virus capsids
VIRUSOIDS
believed to consist of a single type of protein molecule without Nucleic Acid content
PRIONS
most common cause of scrapie and CJD
PRIONS
a receptor-binding protein – for attachment to different cells, then command as virus cell particle
VIRAL PROTEINS
Viral enzymes:
NEURAMIDASE
RNA polymerase:
TRANSCRIPTASE
DNA polymerase:
REVERSE TRANSCRIPTASE
CENTRAL DOGMA
– DNA converted to RNA
– mRNA converted to protein
Transcription
Translation
Bacterial virus (?)
bacteriophage
Plant virus (?)
TMV
Some arthropod-borne viruses (arbovirus); transmitted in a complex cycle Involving:
Birds
Herbivores
Mosquitoes
Ocassionally humans
Mosquitoes – most common:
malaria, dengue, chikungunya, west nile virus
: can infect several mammalian species, some of which act as vectors and transmit the disease to humans
Rabies virus
- can infect both humans and ducks, as a result of gene interchange between strains of predominantly avian and strains of predominantly human
Influenza Viruses
the naked nuclerc acids of
most plus strand RNA and most are infectious
the RNA’s from the double stranded and from the minus-strand RNA viruses are
not infectious
According to Type of Genetic Material
RNA
DNA
According to Shape of Capsid
Helical
Icosahedral
Presence or Absence of Envelope
Naked
Enveloped
the Initial stage in the infections stage of any virus.
ADSORPTION
The virus adheres to specific recaptors, usual flycoproteins, on the host cef’s plasma membrane
ADSORPTION
Attachment and recognition
ADSORPTION
may be accomplished by membrane fusion or receptor mediated endocytosis
PENETRATION
process by which different classes of viruses enter the host cell in which they are able to replicate
VIROPEXIS
Non enveloped viruses may enter via translocation or pinocytosis, enveloped viruses typical enter via fusion once inside the host cell
PENETRATION
the nucleocapsids migrate into the cytoplasm, where cytoplasmic proteases or Viral proteases digest the protein layers, releasing the nucleic acid
UNCOATING
infectious agent cannot be recovered from culture
UNCOATING
involves replication of the nuclelc acid, the site of which is variable and synthesis of viral proteins in the cytoplasm
SYNTHESIS
structural proteins, genomes and enzymes are assembled
ASSEMBLY
: viral envelopes are acquired from host’s cell membrane, may not result to rapid cell death
Budding
causes rapid host cell death
Lysis
Replication in the cytoplasm or nucleus
Naked Virus
Budding
Enveloped
