chapter 13 (The Innate Immune Response) Flashcards
viruses (from latin word for poison)
acellular particles capable of infecting host cells and causing disease
Not-free-living-require a host in which to multiply
viruses
obligate intracellular parasites are also….
viruses
true or false. Viruses use host metabolic systems and usually disrupt normal host cell function.
true
name some characteristics/features of viruses:
do not have a plasma membrane because they are acellular
-contain a single type of nucleic acid- either DNA or RNA
- surrounded by a protein coat
-may or may not have additional envelope of lipids
true or false
features of viruses:
Have very few of their own enzymes and take over enzymes of their host.
true
Is it true that viruses can infect Animals, Plants, Protozoa, and Bacteria
true
Host Range:
Most viruses are specific for a ___ ___ ____
name an example.
single host species
example: some viruses recognize the fimbriae of a certain bacterial species
Viral size:
electron microscope is required to view viruses
-range from 20-1000 nm in length.
Viral Architecture:
All viruses have at least two parts:
- Nucleic acid
- Capsid
- Envelope
Nucleic acid:
True or false: Can have either DNA or RNA as genetic material-not both
true
nucleic acid can either be what strands?
can be single stranded or double stranded , can be linear or circular
is it true that nucleic acid :
can be in several pieces-segmented
true
name the characteristics :capsid
protein coat surrounding the nucleic acid
made up of individual proteins called, capsomeres
nucleic acid and capsid- nucleocapsid
minimum required structure for a virus
Envelope:
Not present in all viruses
Lipid bilayer (membrane) acquired from the host cell
External coating around the nucleocapsid
Additional viral proteins inserted into the envelope- called spikes
Morphology (shape) of viruses
Polyhedral
Helical
Enveloped
Complex
- usually icosahedral-shape with 20 triangular faces
2.Long rods-can be rigid or flexible
3.Roughly spherical-dictated by lipid bilayer
4.Polyhedral head with a helical tail (only found in bacteriophage)
classification of viruses: based on (three) name them:
nucleic acid type
capsid structure
presence of envelope
describe the classification of viruses based on nucleic acid type:
DNA or RNA, single stranded or double stranded, segmented or single molecule
describe the classification of viruses based on capsid structure:
polyhedral, helical
naming of viruses:
family-ends with suffix is what?
viridae
Naming of viruses:
genus-ends with suffix
virus
define species in naming virus
specific epithets are not used instead they are given a descriptive name
name example of family, genus
family: herpesvirdae
genus: simplexvirus
name an example of species,and name its responsibility
human herpesvirus 2 virus responsible for genital herpes
Multiplication of animal viruses :
1. Adsorption
2.Penetration
1.adsorption -attachment to host cell
-viruses have attatchment sites-recognize protein or glycoprotein of host membrane
2.Penetration entry into host cell , naked virus enters the cell via endocytosis
most enveloped viruses enter by fusion-lipids of envelope fuse with host cytoplasmic membrane.
Multiplication of animal viruses:
3. Uncoating
4.Biosynthesis
- viral nucleic acid is freed from the capsid
- Viral nucleic acids are replicated
-DNA replication occurs in the nucleus
-RNA replication occurs in the cytoplasm
Viral proteins (capsomeres) are synthesized in the cytoplasm
Biosynthesis relies on the host metabolic machinery. For example replication and transcription enzymes, ribosomes
Multiplication of animal viruses:
5.Maturation and assembly
6.Release
5.New virions are assembled
- capsomeres form from the capsid
nucleic acid enters the capsid -forms the nucleocapsid
6.Naked virus- burst out,rupture host cell- host cell dies
Enveloped viruses- bud out, virus pushes through cytoplasmic membrane
- steady release of mature viruses
-host cell stays alive for a long time
what are the six multiplication of animal viruses
1.adsorption
2.Penetration
3.Uncoating
4.Biosynthesis
5.Maturation and assembly
6.Release
Interactions between viruses and animal hosts :
Define if this is infact true or its false.
Host defense plays major role in outcome of viral infection which protects against otherwise lethal infection
True
Interactions between viruses and animal hosts: most healthy humans carry a number of:
viruses and antibodies to viruses
Interactions between viruses and animal hosts:
if virus is transferred from the immune host to another individual it cannot result in infection
false, it does lead into infection
Categories of animal virus infection:
Acte infections:
usually short duration
disease symtoms results from tissue damage
- lysis of host cells- release and spread of virus particles
acute infections: name the other two characteristics you have not mentioned
host defense systems gradually eliminate virus
- may take days or months
Host may develop long lasting immunity
ex mumps polio,influenza
Acute infection with late complications :
After acute infections, ______
some non-infectious particles remain
- can cuase serious disease after years later such as measles– subacute sclerosing panencephalitis
Fatal brain disorder-occurs up to ten years after recovery from measles.
Persistan tviral infections:
Virus is continously present in your body, but may or not cause diease. True or false
true
persistent viral infections:
can infected host serve as a resorvoir, meaning they can transmit virus to others?
yes that is indeed true
latent viral infections:
describe three characteristics
Acute infection followed by symptomless period
the virus integrates a copy of its DNA into host cell chromosome and remains dormant (Provirus)
Disease can be reactivated years later
ex: varicella zoster virus (herpes family)
varicella zoster virus (herpes family)
causes- chicken pox (Varicella) in children
remains latent for years- no disease
can reactivate later to cause shingles (herpes-zoster)
Chronic viral infection:
after the acute priod, infectious virus remains present at all times
- may or may not cause noticeable symptoms
chronic viral infection:
ex: hepatitis B(serum hepatitis virus)
is it transmitted by blood, or sexually transmitted
both of them
can hepatitis B (serum hepatitis virus) may have ________ , what are some symptoms
may have acute period, fever,nausea, jaundice
hepatitis B (serum hepatitis virus) after the acute period, what happens?
virus numbers stay high for the rest of the patient’s life , and may cause cirrhoris or liver cancer after many years.
Viruses and Human Tumors:
define tumor, benign tumor,and malignan tumor :
tumor-abnormal growth of tissue
benign tumor- does not spread
Malignan tumor -metatasize and invade nearby tissues (ie. cancer)
Viruses and Human Tumors:
Cell growth is controlled by two types of genes:
Proto-oncogenes - Genes that stimulate cell growth
Tumor suppressor genes- Genes that inhibit cell growth
mutations in these genes can lead to uncontrolled cell growth, tumor formation and cancer
Cancer causing viruses (oncogenic viruses)
explain it using this:
Carry oncogenes -
Most are DNA viruses
genes that interfere with the cell’s control mechanisms
Integrate viral DNA into the host chromosome as a provirus
Oncogenes continue to be expressed
virus associated with cancers in human are
hepatitis b and hepatitis C
Epstein-barr virus
Human papillomavirus (HPV)
hepatits B and hepatitis C are
believed to have cause almost all cases of liver cance
Epstein-Barr virus
causes infectious mononucleoisis
may cause lymphoma (cancer of white blood cells ) and some cancers of the nose and throat
Human Papillo mavirus (HPV0
sexually transmitted-genital warts believed to cause almost all cases of cervic cancer
what may cause lymphoma (cancer of white blood cells) and cancer of nose and throat?
epstein-barr virus
Virus-like infectious particles
Viroids
Naked RNA
No protein coat
results in some diseases in plants and not yet found in animal
Virus-like infectious particles
Prions
Infectious protein particles
No genetic material (RNA or DNA)
linked to several human and animal diseases
transmissible spongiform encephalopathies
sponge like holes in brain
Mode of infection:
they are seem to be transmitted through_____
and set an example:
they are seem to be transmitted through food
an example would be sheep infected with prions- scrapie
eaten by cows- mad cow disease
eaten by humans-variant Creutzfeuld jakob disease
mode of infection:
are they usually destroyed by high temperature and name an example on how they CAN be destroyed
not usually destroyed by high temperatures
can be destroyed by autoclaving in a solution of sodium hydroxide (strong base)
true or false:
mode of infection:
onset of disease in humans occurs several years after infection? how does it accumlate in the brain? and is there any treatment?
this is true, and not clear why-or how it accumulates in the brain
always fatal - no treatment or cure.
