Biological and Physical Properties of Viruses

filterable agents

what were viruses first described as?

obligate intracellular parasites

viruses can be broadly defined as:

biomechanical machinery of host cell

what do viruses depend on for replication

bacteria and archaea

what are some examples of prokaryotes

fungi, protozoa, and algea

what are some examples of eukaryotes

prokaryotes or eukaryotes

viruses are neither

electron microscope

what is needed to see virus?

smaller

viruses are _______ than bacteria

visible in light microscope

even the largest bacteria are barely what?

18 nm (parvo) to 300 nm (pox)

what do viruses range from - in terms of size?

no

can viruses replicate on their own

no

are viruses made of cells

our own genetic material

we carry viral genomes as part of what?

rna, dna

virus genomes may be ______ or ______ but not both.

Capsid, envelope

Viruses may have a naked ______ or an ______ morphology.

division

virus components are assembled and do not replicate by what?

human viruses

Viruses that infect humans are called ______ ____ but are considered along with the general class of animal viruses

bacteriophages

Viruses that infect bacteria are referred to as:

plant viruses

viruses that infect plants are called:

virus

an intracellular "microorganism" containing a DNA or RNA genome and a protein coat, and, in some cases, a lipoprotein envelope

mechanism of reproduction

THE FUNDAMENTAL difference between viruses and other infectious agents is in their what?

energy or substrates

Viruses lack the capacity to make _____ __ ______ cannot make their own proteins, and cannot replicate their genome independently of the host cell

the biochemical rules of the cell

To use the cell's biosynthetic machinery, the virus must be adapted to what?

other humans or from the environment

Infection can be acquired from what?

encounter

infection can be aquired from other humans or from the environment

sexual contact, vertical transmission, and environmental routes

what are examples of the direct routes that we can encoutner a virus

respiratory, GI, and transcutaneous

what are some examples of environemtal routes that a virus can be transmitted

entry of virus

Delivery of the genome into the cell

control the cell and replicate

Genome encodes proteins that permit the virus to do what?

nerves to the CNS or through blood to many organs

Viral infection can spread through what?

incubation period

Viral infection is often characterized by an _____ ______ during which the virus replicates within the host before disease symptoms become evident

acute, latent, chronic

viral infection can be:

host response to the infection

Damage may be due to direct effects of viral replication on host cells or to the?

antiviral antibodies

Some viral infections are diagnosed by the detection of

virion (virus particle- nm)

can be thought of as a delivery system that surrounds a payload

complete virus particle

virion short definition

nucleic acid core of virus

DNA or RNA - nucleoproteins

protein coat of virus

capsid, nucelocapsid, spikes & VAP, protection

rigid

capsid structure is

harsh environmental conditions

capsid structure can withstand what?

viral attachment protein (VAP or spike)

for attachment

fecal-oral

capsids can be transmitted by which route

capsid

Single- or double-layer protein shell surrounding the viral nucleic acid

nucleocapsid

Nucleic acid and the capsid are often referred to as the:

promoter and capsomers

Capsids are composed of subunits ____ ___ _______ arranged in symmetric pattern

self-assemble

physical interactions between subunits permit the subunits to ____ ___ to form the virus capsid (virion)

spikes/VAP

Surface structures that mediate the interaction of the virus with the target cell are called?

prevent virus infection

Antibodies generated against the VAP can do what?

inactivates

what happens to the virus whenever VAPs are removed

enveloped virus

lipid envelope (lipid bi layer)

infectivity

envelope is essential for what?

icosahedral (spherical), helical, complex

symmetry of capsid can be the following:

TMV (tobacco mosaic virus)

example of helical symmetry in a virus

non-enveloped

helical symmetry is:

Helical capsid

RNA helix with associated nucleoproteins

icosahedral symmetry

repeating subunits (few proteins), sub units can self assemble - efficient with the largest volume possible VERY STRONG

complex virus structures

The general principles of symmetry are often used to build part of the virus shell

T4 bacteriophage

Both helical and icosahedral structure

poxvirus

what is anedxample of complex symmetry

icosahedral, spherical, rod-like, bulllet, and filamentous

what are some examples of virus shape

no

are morphology and symmetry the same category

self-assembly from subunits

virions assemble by which of the mechanisms?

T

T/F capsids can survive the gastric contents of the stomach

F

T/F VAPs specifically recognize and bind to receptors on the host cell surfaces. It is exclusive to the enveloped viruses

F

T/F symmetry determines that # of viral proteins, morphology refers to the overall shape and structure of the virus

it is more infective due to the envelopes role in cell entry

what is a fun fact about enveloped viruses

helical

TMV has protein subunits that spiral around the RNA genome in a ___ arrangement

all viruses, regardless of genome, are surrounded by a protein coat

what best describes a generl property of all viruses

dsRNA circular

which is not a typical genetic materail presents inviruses