Introduction to Virology Flashcards
comprise an enormous proportion of our environment
viruses
Current estimates of the number of individual viruses
on earth
- considerably exceed the total number of
stars in the known universe that is
100 sextillion
biomass of bacterial viruses exceeds all of Earth’s
___by more than 1,000
-fold
elephants
more than 10^30 ___particles in the world’s
oceans,
bacteriophage
also known informally as a phage is a virus that infects and replicates within bacteria and archaea
bacteriophage
- average human body contains approximately 10^13
cells, outnumbered 10
-fold by ___ and as much as
100
-fold by ___particles.
bacteria
virus
are loaded with myriad plant and
insect viruses, as well as hundreds of bacterial species
that harbor their own constellations of viruses.
intestinal tracts
most devastating human diseases have been or
still are caused by
viruses
deadly viruses
small pox
yellow fever
poliomyelitis
influenza
measles
AIDS
Viruses are responsible for approximately __%
of the human cancer burden
20
541–542 Pandemic
Plague of Justinian
Plague of Justinian is caused by
Y. pestis
1346–1350 pandemic causing 75-200M deaths
Black Death
The Black Death is caused by
Yersinia pestis
1899–1923 pandemic causing 75 million deaths
sixth cholera pandemic
sixth cholera pandemic is caused by
vibrio cholerae
1918–1920 pandemic causing 100 million deaths
spanish flu
spanish flu is caused by
H1N1
h1n1 is also sometimes known as
swine flu
1957–1958 pandemic causing 1-4 million deaths
asian flu
asian flu is caused by
h2n2
1968–1969 pandemic causing 1 million deaths
Hong Kong Flu
2009–2010 pandemic causign 151,700-575,400 deaths
swine flu
swine flu is caused by
h1n1
2020 pandemic causing 6,794,272 deaths
COVID-19
COVID-19 is caused by
SARS-Cov-2
____ account for an estimated 12% to 20% of
cancers worldwide.
human tumor viruses
virus that cause Burkitt’s Lymphoma, Hodgkin’s Disease, and Nasopharyngeal
Carcinoma
Epstein-Barr virus
virus that cause Cervical Carcinoma, Anal Carcinoma,
Oropharyngeal Carcinoma, Penile Carcinoma
Human Papillomaviruses 16 and 18
viruses that cause Kaposi’s Sarcoma, Primary Effusion
Lymphoma, Multicentric Castleman’s Disease
Kaposi’s Sarcoma-Associated Herpesvirus
virus that cause Hepatocellular Carcinoma
Hepatitis B virus and Hepatitis C virus
virus that cause T-cell Leukemia
Human Adult T-cell Leukemia Virus Type 1 (HTLV-1)
virus that causes Merkel Cell Carcinoma
- Merkel Cell Polyomavirus
reduction of a wild animal population by selective slaughter
culling
2011 outbreak hit the entire ___
peninsula and resulted in the culling of
nearly 3.5 million cattle, pigs and other
animals in South Korea alon
Korean
culling of cattle, pigs, and other animals in south Korea was done to
prevent spread of swine flu
Specific for each invertebrates,
vertebrates, plant, fungi, bacteria
host range and requirements
host range and requirements
Requires specific ___ on
the host cell
attachment
If there is no ___ ___complex, then there is no viral infection happening
attachment receptor
receptor sites for viruses
cell wall
fimbriae
flagella
are a;achments
for animal virus.
cell membranes
orchid leaves has symptoms of ringspots resulting from a strain of ____
tobacco mosaic virus
Infected ___excrete more than 1013 calicivirus particles daily.
whales
Infected whales excrete more than 1013 ____particles daily.
calicivirus
viruses comprise 94% of all ____ ____-containing particles in the oceans …15 times
more abundant than the Bacteria and Archaea.
nucleic acid
Viral infections in the ocean kill 20 to 40% of marine microbes daily…release
essential nutrients that supply ___at the bottom of the ocean’s food
chain, as well as carbon dioxide and other gases that affect the climate of the
earth
phytoplankton
mice latently infected with some murine _____are resistant to infection
with the bacterial pathogens Listeria monocytogenes and Yersinia pestis.
herspevirus
mice latently infected with some murine herpesviruses are resistant to infection
with the bacterial pathogens ___ and ___
Listeria monocytogenes
Yersinia Pestis
what is the term for cross-species infections of humans are
occurring with increasing frequency
zoonotic
are recent examples
of viral diseases to emerge from zoonotic infections.
ebola hemorrhagic fever
SARS
zoonotic diseases can be spread through (5)
direct
indirect
vector-borne
foodborne
waterborn
Hand, foot, and mouth disease (HFMD) is caused by a virus in the enterovirus family, most commonly the
coxsackievirus A16
- Every cell in our body contains ___ DNA
viral
what viruses make up
about 5 to 8% of our DNA
human endogenous retroviruses
how did human endogenous retroviruses make up 5 to 8 percent of our DNA
- from infections of germ cells that have
occurred over millions of years during our
evolution
it becomes part of a host’s genome when it injects its DNA into the host’s cells, especially
germlike cells like sperm or eggs.
virus
- conservation of some of the viral sequences in
___ genomes suggests that they may have
been selected for beneficial properties over
evolutionary time
vertebrate
When researchers began to analyze the human
genome, they found that about ___ percent of the
genetic code that’s there actually came from
viruse
8
mechanism of virus when they infect humans
A virus injects its DNA into a host cell
The virus uses enzymes to convert its RNA genes into DNA
The virus uses enzymes to cut into the host’s chromosomes
The viral DNA embeds itself into the host’s chromosomes
The host cell copies its own DNA, including the viral DNA
The viral DNA can be passed on to the next generation
non coding DNA and RNA sequences that are removed from a gene during the process of RNA splicing
introns
segments of DNA that are transcribed into RNA and become part of a mature messenger RNA (mRNA) molecule
exons
are important since it allows a single gene to code for multiple proteins with different functions, thus increasing the complexity of gene expression and adaptation within an organism; they can also act as regulatory elements influencing transcription and mRNA stability
intervening sequences
the process of removing non-coding regions of DNA, called introns, to produce a mature mRNA that codes for proteins.
splicing
studies that focus on viral ____ of cellular mechanisms
have provided unique insights into cellular biology and
functioning of host defenses.
reprogramming
led to the understanding that DNA carries the genetic information, a foundation of modern molecular biology
study of bacteriophages
Studies of ___viruses established many fundamental
principles of cellular function, including the presence of
intervening sequences in eukaryotic genes.
animal
study of ____(____) viruses revealed the genetic basis
of this disease.
cancer (Transforming)
viral genomes as vehicles for the delivery of ___to cells and
organisms for both scientific and therapeutic purposes.
genes
are to introduce genes into various cells and
organisms to study their function has become a standard method
in biolog
viral vectors
___ ___ are the foolproof methods to identify the microorganism
genetic studies
therapeutic use of viruses included
gene therapy vectors
immunogens for vaccine
oncolytic virotherapy
novel therapeutic proteins
Virus in humans from ___ of animals than in
___
domestication
hunting
Viruses in ___ tropic are endemic.
tropics
exposure to viruses more common in ___ than in temperate climates
tropics
Viruses established in what size of communities
large,settled
Less virulent viruses such as ___ (3) enter into a long term relationship with their hosts, first to become adapted to reproduction in the earliest human populations
modern retroviruses
herpesviruses
papillomaviruses
mycotymovirus has little to no effect on host fungus called
Fusarium graminearum
An image of “rabid” ___from an
ancient Greek vase
hector
An Egyptian
stele, or stone tablet… depicting a man
with a withered leg and the “drop foot”
syndrome characteristic of
polio
aws that outline the
responsibilities of the owners of rabid
dogs date from before 1000 B.C.
mesopotamian
probably endemic in the Ganges River basin by 500BC. and
subsequently spread to other parts of Asia and Europe, has played an
important part in human history.
small pox virus
smallpox virus … probably endemic in the ___River basin by 500BC. and
subsequently spread to other parts of Asia and Europe, has played an
important part in human history.
Ganges
Other viral diseases known in ancient times include
mumps
influenza
suggested to have caused the scourge of the tropical trade -
basis for legends about ghost ships, such as the Flying Dutchman, in which
an entire ship’s crew perished mysteriously.
yellow fever
cultivation of marvelously patterned ___ , which were of enormous value
in 17th-century Holland
tulips
inoculation of healthy
individuals with material from a
smallpox
variolation
fatality rate when variolated
1-2%
fatality rate of adults and babies with variola when naturally infected
25% (40% in babies)
variolation is widespread in which countries by the 11th century
China and India
variolation is introduced in ___ in 1721
England
variolation is introduced to the US army in 1776 by
George Washington
used cowpox infected material obtained from the hand of Sarah Nemes, a milkmaid from his home to successfully vaccinate James Phipps
Edward Jenner
first deliberately attenuated viral vaccine
Louis Pasteur
inoculated
rabbits with material from brain of cow
suffering from rabies and then used
aqueous suspensions of dried spinal
cords from these animals to infect other
rabbits.
Louis Pasteur
resulting preparations caused mild
disease (i.e., were attenuated) yet
produced effective immunity against
rabies
vaccination
a vaccine for __ ___ virus was
developed in 1935, and an ___
vaccine was available in 1936.
yellow fever
influenza
The word “vaccine” comes from the Latin word vacca, which means “cow”. English physician Edward Jenner coined the term after he discovered that ___could prevent smallpox
cowpox
Koch’s postulate 1
The organism must be regularly
associated with the disease and
its characteristic lesions.
koch postulate 2
The organism must be isolated
from the diseased host and
grown in culture.
koch postulate 3
The disease must be reproduced
when a pure culture of the
organism is introduced into a
healthy, susceptible host.
koch postulate 4
The same organism must be
reisolated from the experimentally infected host (Box 1.4).
“ failures of the paradigm that bacterial or fungal agents are responsible for all diseases led to the
identification of a new class of infectious agents— submicroscopic pathogens that came to be called
___.
viruses
first virus to be discovered
tobacco mosaic virus
when did TMV discovered
1895
latter part of the 20th century, new methods developed to associate particular viruses
with disease based on ____ evidence of infection.
immunological
virus cultivation cannot be used in culture-____methods, but instead culture-____methods
dependent
independent
high-throughput nucleic acid sequencing methods and bioinformatics tools allow
detection of viral genetic material directly in environmental or biological samples -
approach called
viral metagnomics
Thus, “metagenomic Koch’s postulates” have been proposed (2)
(i) using molecular markers such as genes or full genomes to detects samples from
diseased subjects from that of healthy control subjects
(ii) inoculating a healthy individual with a sample from a diseased subject results in
transmission of the disease as well as the molecular markers.
metagenomic koch’s postulate 1 states
(i) using ___ ____ such as genes or full genomes to detects samples from
diseased subjects from that of healthy control subjects ;
molecular markers
metagenomic koch’s postulate
ii) inoculating a healthy individual with a sample from a diseased subject results in
transmission of the ____ as well as the ____ markers.
disease
molecular
in 1886, he showed that tobacco mosaic disease was transmissible
Adolf Mayer
in 1892, he i filtered sap of diseased tobacco and found that the agent
passed through the porcelain filter – no identification
Dmitri Ivanowski
in 1898, he termed the submicroscopic agent responsible for tobacco mosaic disease
contagium vivum fluidum - an infectious fluid
Beijenrick
when did Beijenrick term the submicroscopic agent responsible for tobacco mosaic disease
1898
tobacco mosaic disease is termed what by Beijenrick
contagium vividum fluidum
“infectious filterable agents comprised small
particle”
who stated in 1898
Friedrich Loeffler and Paul Frosch
came to the same conclusion regarding the cause of foot-and mouth disease; could be passed from
animal to animal, with great dilution at each passage, the causative agent had to be reproducing and
thus could not be a bacterial toxin.
Friedrich Loeffler and Paul Frosch
discovered viruses that cause chicken leukaemia in 1908
Ellerman and Bang
s discovered that
solid tumours of chickens could be transmitted by cell-free filtrates - first indications that some viruses
can cause cancer
Rous
– bacteria as host to viruses by
Twort
– discovered and named bacteriophages (bacteria eater) by
D’Herelle
isolated the tobacco mosaic virus
Wendell Stanley
extensively purified tobacco mosaic virus and showed it to be nucleoprotein
containing ribonucleic acid (RNA).
Bawden and Pirie
worked with the
viruses called bacteriophages (because they “eat” bacteria), in the early 1940s.
Max Delbruck
Salvador Luria
found that phages infect bacteria and multiply within them until they filled the cells, which then
burst open. They also found that the phages consisted entirely of DNA and protein, like
chromosomes.
Max Delbruck
Salvador Luria
phages consisted entirely of
DNA and protein (like chromosomes)
application of cowpox virus for vaccination agaisnt smallpox, inflammation origins of virology and immunology
Edward Jenner
Development of Rabies Vaccine
Louis Pasteur
Emile Roux
first demo of filterable plant virus: tobacco mosaic virus
D. Ivanovsky
M. Beijenrick
first demo of filterable animal virus: foot and moudh disease virus
F. Loeffler
P. Frosch
first filterable plant virus
tobacco mosaic virus
first filterable animal virus
foot and mouth disease virus
first human virus
yellow fever virus
discovered yellow fever virus, first use of consent form for human clinical investigation, identify mosquito as transmitting agent, control of virus by elimination of mosquito breeding sites
J. Caroll
J. Lazear
A. Agramonte
W. Reed
C. Finlay
W. Gorgas
first demonstration of leukemia causing virus retrovirus
V. Ellerman
O. Bang
H. Vallee
H. Carre
leukemia causing virus
retrovirus
first report of virus causing immunosuppression
C. von Piquet
virus causing immunosuppression
c. Von Piquet
isolation of poliomyelitis irus
K. Landsteiner
E. Popper
discovery of measles virus
J. Goldberger
first demonstration of a stolid tumor virus: Rous Sarcoma Virus
P. Rous
discovery of bacteriophages
F. Twort
Bacteriophages, plaque assay
F d’Herelle
used 16s rRNA gene for the three domains but viruses do not have.
Carl Woese
provide
evidence that the association between viruses and their
hosts is as ancient as the origin of the hosts themselves
amino acid sequences of viral and cellular proteins and
that of the nucleotide sequences of the genes
says viruses have no relics of ribosomal
proteins or having encoded enzymes for energy
metabolism
genetic evidence
Analysis of the sequence relationship between various
retro- viruses found in mammalian genomes demonstrates
____ of some types before major groups of
mammals diverged.
integration
A hypothesis for DNA viruses as
the origin of eukaryotic ___
____
replication protein
viruses were presented entirely in negative things such as:
they could not be seen
* could not be cultivated in the absence of cells and,
* most important of all, were not retained by
bacteria- proof filters.
key characteristic of viruses
: they are small parasites that require a host in which they replicate.
elative ease with which tobacco mosaic virus could be crystallized was a direct
result of both its structural ___ and the ability of many particles to associate
in __ ___
simplicity
regular arrays
viruses are shaped as
helical or spherical
absolute dependence on a
living host for reproduction: they
are
obligate parasites
*Transmission of plant viruses by applying ___of an infected plant to a scratch
made on the leaf of a healthy plant
extracts
Lab animals as tool for investigation; developments thru __ ___systems were used
cell culture systems
example of cell culture systems
bacterial cells
cell lines
. viral genome comprises
DNA or RNA
as subject in the determination of DNA as carriers of hereditary
information in Hershey and Chase’s experiment
bacteriophage
process where viruses convert RNA to DNA (
reverse transcription
viruses convert RNA to DNA (reverse transcription) needs the enzyme
reverse transcriptase
directs the synthesis of viral components by
cellular systems within an appropriate host cell
viral genome
In this phase, the virus exists outside of a host cell. It’s essentially inert and doesn’t show any signs of life
inanimate phase
Once a virus infects a host cell, it enters the
multiplying phase
. Infectious progeny virus particles, called
virions
, are formed
by de novo self-assembly from newly synthesized components.
virions
being the vehicle for transmission
virions
viruses lack cellular characteristic and is therefore classified as ___
subcellular
size of viruses
20-1000 nm
virust particle
virion
virus Have few or no ____for metabolism – direct cell machinery for its
own use
enzymes
genetic material of virus can be
DNA or RNA
virus can have ___ or ___ stranded RNA/DNA
single
double
how many proteins does viruses code at most
4
viruses has ___ surrounding the n.a.
protein coat
viruses can have an envelope made of ___
phospholipids
viruses are ___, meaning they must be inside a host to multiply
obligate intracellular parasites
can viruses be grown on culture media?
no
can integrate to host
genes - conversion to cancer
cells
viral genes
units commonly used in descriptions of virus particles or their components are the ___ and the ___
nanometer and angstrom
viruses can be seen using what microscope
light (some)
electron microscope (all)
etiologic agent of COVID-19
Severe Acute Respiratory
Syndrome coronavirus 2
(SARS-CoV-2)
size of SARS-CoV-2
140 nm
- Around the world, health
officials have agreed that
wearing ___can prevent
the spread of the virus
between individuals.
mask
…remove at
least 95% of all particles
with an average diameter
of 300 nm or less
n95 masks
acellular infectious agents include
prions
viruses
cellular microorganisms include
prokaryotes (archaea and bacteria)
eukaryotes (algae, fungi, protozoa)
intracellular parasites?
Typical Bacteria
Rickettsias
Chlamydias
Viruses
TB - No
R - Yes
C - Yes
V - Yes
intracellular parasite that is a bacteria
rickettsias and chlamydias
plasma membrane
Typical Bacteria
Rickettsias
Chlamydias
Viruses
T - Yes
R - Yes
C- Yes
V - No
Typical Bacteria
Rickettsias
Chlamydias
Viruses
binary fission
T - Yes
R- Yes
C - Yes
V - No
Typical Bacteria
Rickettsias
Chlamydias
Viruses
pass through bacteriological filters
T - no
R - no
C - Yes
V - Yes
Typical Bacteria
Rickettsias
Chlamydias
Viruses
possess both DNA and RNA
T - Yes
R - Yes
C - Yes
V - No
ATP generating metabolism
Typical Bacteria
Rickettsias
Chlamydias
Viruses
T - YEs
R - Yes
C - No
V - No
Typical Bacteria
Rickettsias
Chlamydias
Viruses
ribosomes?
T - Yes
R- Yes
C - Yes
V - No
Typical Bacteria
Rickettsias
Chlamydias
Viruses
sensitive to antibiotics
T - Yes
R - Yes
C - Yes
V - No
Typical Bacteria
Rickettsias
Chlamydias
Viruses
sensitive to interferon
T
R
C - no
V - yes
SarsCOV contain either __ or __ as genetic material
DNA or RNA
