Micro Chapter 13: Viruses, Viroids, and Prions

DNA viruses have to travel to the nucleus of the host cell to have its DNA. replicated by the _____ __________ enzyme of the cell

DNA polymerase

what type of retrovirus causes leukemia?

HLTV 1 & 2

which of the viruses mentioned above cause STD's

HPV, HSV2

for which of the herpes viruses is there a vaccine available (only one)?

HSV 3

which of the viruses mentioned is thought to cause chronic fatigue syndrome?

HSV4

which of the viruses mentioned above causes rare infections which are typical in AIDS patients?

HSV8 and HSV 5

which would be antigenic? capsid or nucleic acid

capsid proteins

molecular structure of capsid and nucleic acid

capsid: proteins nucleic acid: DNA or RNA

receptor sites for bacteriophages are found in which bacterial cell structures?

cell wall, fimbriae, flagella or bacterial cell

what is adsorption

chemical attraction and exact fit

plaques

circular zones of clearing, form in the lawn due to cell lysis caused by the phage

reverse transcriptase

copies an RNA template to make a single stranded piece of DNA

what type of virus causes gastroenteritis?

enteric virus

enveloped viruses

envelope is a lipid bilayer outside of the capsid; in addition to the basic viral components (nucleocapsid) they have a lipid protein core that surrounds the capsid (enveloped viruses are more susceptible to disinfectants bc these chemicals damage the envelope making it non-infectious)

what mechanism do enveloped viruses and naked viruses use to enter host cell

enveloped viruses use: membrane fussion naked viruses use: endocytosis

lysozymes

enzymes produced during late transcription which will weaken the host's cell membrane causing its lysis

arboviruses are respiratory viruses

false

enteroviruses are a genus of viruses that infect the respiratory tract

false

what is uncoating

frees nucleic acid from protein capsid

retroviruses

group of viruses that have a single stranded RNA genome; their enzyme reverse transcriptase synthesizes a DNA copy that is then integrated into the host cell chromosome

which of the hepatitis viruses cause liver tumors?

hep c

which of the viruses mentioned are transmitted through indirect contact?

hepatitis A (eating utensils, food) hepatitis B & C (blood, contaminated needles) HSV 3 (respiratory droplets)

two types of viral proteins that help virus take over it's host

nucleases: an enzyme that degrades the host's DNA other early viral proteins: proteins that modify the host's RNA polymerase do not recognize cell's promoters, but rather recognize and transcribe the viral promoters and genes

identify transmission for the viruses

polyovirus: enteric rabies virus: zoonotic rotavirus: enteric HIV: sexually transmitted HSV 2: sexually transmitted rhinovirus: respiratory west nile virus: zoonotic influenza virus: respiratory norovirus: enteric

integrase

protein that keeps the viral genome integrated into the host DNA

both bird and human influenza viruses can infect pigs, inside pig cells these viruses will recombine their genetic material, and new influenza strains will emerge. this is called an antigenic _________

reassortment

animal viruses use their ________ proteins located in the envelope or the capsids to attach to the host cell receptors

spike

capsomeres

subunit proteins, composed of a single type of protein or several different protein subunits

viruses vs prions

viruses: acellular pathogens, no metabolic pathway, few enzymes, obligate intracellular, have outer protein layer for protection and recognition prions: proteinaceous infectious agents. composed solely of proteins, no nucleic acids. linked to slow fatal, human diseases, and animal diseases

intracellular

when virus moves into cell

animal virus replication: release

most enveloped viruses are released by: membrane fussion naked viruses are released when the host cell dies by: suicide apoptosis

in order to infect a cell, a virus _____________?

must be able to attach to the cell; viruses attach to their host cells using their surface proteins, or their spike proteins, which attach to specific proteins on the surface of the host cell

does uncoating occur in a bacteriophage infection?

no because in a bacteriophage infection only the nucleic acid enters the host cell

virion

(extracellular) a complete virus in its inert non-replicating form; also referred to as a viral particle

give the name of the herpes simplex virus (HSV) that causes the condition 1) kaposis sarcoma (cancer of blood vessels) 2) chicken pox 3) mononucleosis 4) genital herpes 5) shingles 6) cold sores 7) nasopharyngeal carcinoma 8) cytomegalovirus infections

1) HSV8 2) HSV3 3) HSV4 4) HSV2 5) HSV3 6) HSV1 7) HSV 4 8) HSV 5

label the components

1) capsid 2) nucleic acid core 3) nucleocapsid 4) capsomeres

match the type of infection with its description 1) provirus present in host cell 2) influenza virus causes this type of infection 3) HCV & HBV are examples of this type of infection 4) HAV is an example of this type of infection 5) symptoms of reactivation can differ from symptoms of initial infection

1) latent 2) acute 3) chronic 4) acute 5) latent

match the type of infection with its description 1) a viral infection that continues for years, may or may not have symptoms 2) productive viral infection 3) viral particles not detected until reactivation of infection 4) herpes viruses produce this type of infection 5) this viral infection confers permanent immunity 6) continues production of low levels of viral particles

1) persistant chronic 2) acute 3) latent 4) latent 5) acute 6) persistent

lysogenic conversion

a change in the properties of a bacterium, conferred by a prophage

temperate (or lysogenic) phage

a phage that can initiate a lytic or lysogenic infection in a host cell

lysogenic immunity

a prophage will produce a viral repressor protein that binds to any incoming viral genome of the same type as the prophage, preventing a second infection

bacteriophage

a virus that infects bacteria (often shortened to phage)

three categories of animal virus infections

a) acute infection b) chronic: persistant c) chronic: latent

list the four groups into which viruses can be classified according to transmission route

a) enteric viruses b) respiratory viruses c) zoonotic viruses d) sexually transmitted virus

virus

acellular or non-living infectious agent composed of nucleic acid, surrounded by a protein coat

animal viral replication vs. bacteriophage replication

animal viruses bind to glycoprotein receptors in the cell membrane of the host cell bacteriophages bind to the receptors in the cell wall, or fimbriae, or flagella of the host cell

list the steps in the lytic bacteriophage cycle

attachment, genome entry, synthesis, assembly, release

Picornaviridiae is the name of a: a) viral genera b) viral family c) viral species

b) viral family

restriction enzymes

bacteria carry specialized enzymes called restriction enzymes. these enzymes break down viral DNA. cell's DNA is not broken down by these enzymes because bacterial DNA is methylated, the methyl groups protect the cell's DNA from degradation by these enzymes. In return, one of the first actions of the virus upon invading the bacteria will be to methylate its DNA in order to avoid being degraded by restriction enzymes. Viral infection will result if the virus successfully methylates its DNA before restriction enzymes can get to it. Conversely, a viral infection will be avoided if restriction enzymes get to the viral DNA before it is methylated.

genome entry

bacteriophage injects its nucleic acid into the host cell leaving capsid behind

List 3 types of cancers cause by viruses

leukemia, liver cancer, cervical cancer, lymphatic system cancer

what type of tumors does the Epstein Barr virus (HSV 4) cause?

hodgkins lymphomas, nasopharyngeal carcinomas

papilloma virus

human papilloma viruses cause warts

UV damage of the host cell causes phage _________ which initiates the lytic cycle

induction

lysogenic infection

infection by a temperate phage that results in a prophage residing in the host (viral DNA enters the host cell after attachment, but instead of taking over the cell, and initiating viral replication, transcription and translation, the virus will insert itself into the host's DNA and remain their indefinitely)

E. coli phage that was used to study lysogenic was _______ _______?

lambda phage

herpesviridiae family

the herpes virus are a family of DNA latent viruses that cause a variety of latent infections and cancers in humans

burst size

the number of viral particles released from the host cell after a lytic infection (ex: 200 phages)

Viruses are classified into families, genera, and species

the suffix: virus indicates genera and species the suffix: viridae indicates families

burst time

the time it takes for the lytic cycle to be completed and the new viral particles released

prophage

the viral genome integrated in the host DNA (is replicated along with the host cell chromosome, when the cell divides the prophage is passed onto the cell's progeny, later the prophage can begin the process that leads to a productive infection)

synthesis of proteins and genome

there are two types of viral protein transcribed and translated by the host cell within the first few minutes of infection, these two types of proteins are proteins that will help the virus take over its host

how do viruses replicate?

they are metabolically inactive, so in order to replicate they have to use replicating, transcription, and translation machinery of the cell

bacteriophages are bacteria that infects viruses

true

coronaviridae is the name of the viral family

true

west nile virus is an arbovirus

true

zoonotic viruses are often transmitted via a vector transmission

true

lytic infection

viral infection of a host cell with a subsequent production of more viral particles and lysis of the cell