MICR103A - Introduction to Viruses

this is a complete infective virus particle that may be identical to the nucleocapsid

virions

more complex virions includes/contains? (2)

nucleocapsid and envelope

these are the smallest infectious agents causing disease in plants

viroids

a protein shell that encloses the nucleic acid core

capsid

the capsid together with the enclosed nucleic acid

nucleocapsid

this is the morphologic units seen on the surfaces of icosahedral virus particles; represent clusters of structure units

capsomeres

the capsid is made up of _____________, which are protein subunits that assemble into a protective shell around the viral genome.

capsomeres

an organism where it is involved/mediates in transduction

bacteriophages

true or false

bacteriophages are bacteria that infects bacteria

false. bacteriophage is a virus that infects bacteria

viruses that infect bacterial cells

bacteriophages

the outer coat that some viruses acquire as they penetrate or are budded from the nuclear or cytoplasmic membrane

envelope

true or false

envelope always contain altered host-cell membrane components

true

morphologic units composed of structural units embedded in the envelope

peplomers

general term to describe situations where mixed infections result in enhanced yields of one or both viruses in the mixture

complementation

the mechanism by which a particular base sequence in messenger RNA produces a specific amino acid sequence in a protein

translation

the means by which specific information encoded in a nucleic acid chain is transferred to messenger RNA

transcription

required by certain defective closely related viruses

to replicate

helper virus

functionally deficient particles in some aspect of replication and may interfere with the replication of normal viruses

defective virus

viruses that cannot reproduce from their own nucleic acid and virions are non-infectious; require a helper virus for transmission and multiplication

satellite virus

Many attribute the beginning of virology to the work of ____________________ (1892) on the transmission of tobacco mosaic virus

Ivanovsky and Beijerinck

true or false

tobacco mosaic virus is the first known virus

true

when was the TMV (tobacco mosaic virus) crystallized?

1935

when was the TMV (tobacco mosaic virus) viewed in electron microscope?

1939

in 1898, they applied the filtration criteria to a disease in cattle that later would be known as foot and mouth disease

Loeffler and Frosch

in 1922, who described bacteriophages that parasitized bacterial cells causing them to swell and burst

D'Herelle

in 1898, who investigated myxoma virus?

Sanarelli

true or false

myxoma virus is a disease in horse

false. rabbits.

in 1901, who investigated the fowl plague virus (avian influenza virus)

Centanni, Lode, and Gruber.

in 1902, who investigated the rinderpest virus?

Nicolle and Adil-Bey

in 1902, who investigated the pseudorabies virus?

Aujeszky

in 1903, who investigated the rabies virus?

Remlinger and Riffat-Bay

in 1905, who investigated the canine distemper virus?

Carré

in 1911. who investigated rous sarcoma virus

Rous

true or false

rous sarcoma virus is the second tumor virus

false. first.

in 1927, who investigated the newcastle disease virus?

Doyle

in 1938, who used an electron microscope for the first time to visualize a virus?

Kausche, Ankuch, and Ruska

in 1938, what specific virus did Kausche, Ankuch, and Ruska used to view in the electron microscope?

tobacco mosaic virus (TMV)

in 1948, who made a significant advancement in the field of cell culture by successfully cultivating isolated mammalian eggs

Sanford, Earle, and Likely

in 1957, who discovered interferon

Isaacs and Lindemann

in 1961, who first isolated avian influenza virus from wild bird reservoir?

Becker

in 1981, who discovered the feline coronavirus?

Pedersen

what year was the outbreak of severe acute respiratory syndrome?

2002

what year was the development of molecular tools and computer software for "next generation sequencing" and metagenomic analyses

2008

what year was the declaration of the global eradication of rinderpest?

2011

what year was the recognition of middle east respiratory syndrome

2012

what year was the reemergence of the ebola in west africa?

2014

true or false

viruses are filterable agents that could NOT be cultivated on artificial media

true

true or false

all viruses are obligate intracellular parasites

true

true or false

all obligate intracellular parasites are viruses

false

give examples of members from certain bacterial genera that is also unable to replicate outside a host cell (4)

Ehrlichia, Anaplasma, Legionella, and Rickettsia

true or false

mimiviruses are greater than 300nm

true

true or false

viruses are inert particles inside living cells

false. outside.

true or false

inside the cell, viruses utilize host cell processes to produce its proteins and nucleic acid to replicate itself

true

true or false

viruses contain only one type of nucleic acid that carries the information for replicating the virus

true

true or false

some viruses contain nucleic acid molecules other than their genomic DNA or RNA

true

give an example of a virus that contain nucleic acid molecules other than their genomic DNA or RNA

retrovirus

an enzyme that converts RNA to DNA

reverse transcriptase

considered among the simplest of viruses; virion is composed of viral structural proteins and DNA

Parvovirus (family: Parvoviridae)

what viruss comprises viral proteins and RNA

Picornaviruses (family: Picornaviridae)

these are more complex with envelope; matures by budding through different host cell membranes that are modified by the insertion of viral proteins

Herpesviridae and Paramyxoviridae

what are some of the chemical composition of the virion?

glycoproteins and presence of lipid envelope

the major type of protein present on the exterior of the membrane of enveloped viruses

glycoproteins

what separates viruses into 2 distinct classes

presence of lipid envelope

the presence of lipid envelope separates viruses into 2 distinct classes which are?

enveloped - inactivated by organic solvents

non-enveloped - resistant to organic solvents

what are the two main classification systems in naming virus

- ICTV (International Committee on Taxonomy of Viruses) established in 1966

- Baltimore classification system

the suffix -virales is used in what taxonomic ranking of virus?

order

the suffix -viridae is used in what taxonomic ranking of virus?

family

the suffix -virinae is used in what taxonomic ranking of virus?

sub family

the suffix -virus is used in what taxonomic ranking of virus?

genus

true or false

viruses can simply be divided into RNA viruses and DNA viruses

true

baltimore classification system is developed by?

david baltimore

baltimore classification system has how many classes based on genome type and mode of replication and transcription

seven (7)

two major distinction of virion RNA

positive sense/polarity and negative sense/polarity

true or false

the size of animal RNA viral genomes ranges <2 kb (Deltavirus) to >30kb (Coronaviridae)

kb = kilobases

true

a major distinction of virion RNA wherein it is of the same sense as mRNA and is directly capable of translation to protein

positive sense/polarity

a major distinction of virion RNA wherein the genomic nucleotide sequence is complementary to the of mRNA and it requires transcription of the genome to generate mRNA equivalents

negative sense/polarity

is considered diploid (2 copies of their genome); contains two whole-genomic positive-sense RNAs

retroviridae

true or false

DNA viruses characteristics include:

- overall structure of genome is less complex

- either single molecule of single-stranded (ss)DNA or single molecule of double-stranded (ds)DNA

true

a process of reproduction that resembles an assembly line

replication

a phenomenon wherein various parts of the virus come together from different parts of the host cell to form new virus particles

replication

what are the 5 steps of replication of viruses

1. The virus attaches to a host cell

2. Enters the cell

3. Intact virus particle ceases to exist (uncoating)

4. Viral genome directs the production of new viral macromolecules

5. Assembly and appearance of new progeny virus particles

a period of time between the penetration of the virus particle into the host cell and the production of the first new virus particle

eclipse

true or false

disrupting cells during eclipse period will interrupt the release of significant numbers of infectious virus particles

true

true or false

if eclipse period is uninterrupted, single infectious particle can replicate to produce thousands of progeny virus particles

true

uses reverse transcriptase to create a DNA copy of their RNA genome

retroviridae