micro ch 9 virus replication

naked viruses always exit a cell by _______ the host cell

lysing (pop/crack it) apoptosis

DNA viruses use our genome to make __RNA and RNA _______

mRNA and RNA polymerase

HIV enters the host cell via fusion to the host cell _____

membrane

_____ sense viral RNA may be directly translated into viral proteins

+ sense

RNA has to be ____ sense for ribosomes to bind to it

+ sense (5'->3')

all viruses must get their genome to some form of ____sense mRNA to be translated on host ribosomes

+ to be translated on host ribosomes

there are ___#__ DNA virus groups and ____#____ RNA virus groups

- 3 DNA virus: DS, SS and DS using reverse transcriptase - 4 RNA virus groups DS RNA SSRNA+ SSRNA- SSRNA using reverse trancriptase

for viral entry HIV: - the fusion protein is exposed via _______ interactions with CD4 and CCR5 - envelope fuses with membrane of _____ cell

- fusion protein is exposed from gp120 interacting with CD4 and CCR5 - envelope fuses with membrane of host cell influ: - gets endocytosed - pH changes, exposing fusion protein - viral envelope fuses with endosome membrane

for viral entry influenza: - gets ___________ - ______ changes to expose fusion protein -the viral envelope fuses with _____ membrane

- gets endocytosed - pH changes, exposing fusion protein - viral envelope fuses with endosome membrane hiv - fusion protein is exposed from gp120 interacting with CD4 and CCR5 - envelope fuses with membrane of host cell

what sense of RNA is used as a template

- sense is ued as a template to make more + sense

tamiflu, a flu medicine blocks ______ from working because it allows new virons to be released and for infection to spread

neuraminidase

where does assembly (capsid formation and genome packaging) occur in animal cells - in ____ or _____ of cytoplasm

nucelus or organelles of cytoplasm

if the viruses host does not have the enzyme needed for transcription, it must pack it in its _______

nucleocapsid

(3i) once the pH drops and the fusion protein is exposed, the fusion peptide inserts itself into the host endosomal (inside) membrane - this causes the contents of the ______ to be released into the _____

nucleocapsid contents are released into cytosol

when glycoprotein (gp120) from HIV binds to the host's CD4 it causes a _____ change that expose ____-receptors for the host cell membrane to bind to (CCR5 AND CXCR4)

causes a conformational change and exposes co-receptors

Plant viruses may move from cell to cell within one plant by specific _______ connections or disruption of ____ wall structures (maybe by insects)

cytoplasmic connections or injured cell walls

After attachment, mechanisms of viral ______ vary depending on the type of virus and the host cell/organism.

entry

_____ is a method of viral entry and uncoating where the viral envelope fuses with host membrane and the nucelocapsid enters

fusion

once GP41 is finally exposed after conformational changes it allows for _____ of viral envelope with that of host

fusion

(3i) once the low pH exposes the fusion protein, the fusion _____ inserts inteself into the host ______ membrane causing the contents of the viral nucelocapsid to be released into the cytosol

fusion peptide inserts itself into the host endosomal (inside) membrane - releases viral nucleocapsid into cytosol

(2i) once the endosome has entered the cell, the pH level drops (acidification) and the previously hidden ____ protein is exposed

fusion protein is exposed when pH drops

the strategy a virus uses to replicate depends on their _____ type

genome

____________ (______) on HIV's envelope bind to CD4 receptors on host cells and allow conformational change to expose co-recpetors - cd4 is found on T helper cells and macrophages

glycoproteins (gp 120)

due to gp120 AND CD4 binding 's conformational change and exposing of coreceptors: - _______ is exposed on the virus which induces fusion of viral envelope with that of host

gp 41

for viral attachment HIV uses ______ and _____

gp120 and gp41

for viral attachment influeneza uses _______ (___)

hemagglutinin (HA)

to block replication of hiv many HAART ( highly active antiretroviral therapy) include HIV inhibits including _______ analogs (____)

nucleotide analogs (AZT)

most eukaryal DNA viruses replicate in the ______ because that is where eukaryotic polymerases are found

nucleus (pox is in cytoplasm)

influenza viruses exit the cell by the ______ binding to the cell membrane's sialic acid and neuraminidase cleaves the viron to release new particles

hemmaglutin binds to host membrane silaic acid and then neuraminidase allows release of new particles

range of cell types that can serve as host for viral infection

host range

what cells a virus can infect is determined by viral attachment proteins and host receptor molecules but... which is often critical for cellular function and are not easily eliminated to prevent infections

host receptor molecules are often used for other processes in the host and thus will kill host if targeted

bacteriophages do not actually enter the cell but ____ their genomes

inject

_____ is a method of viral entry and uncoating where the nucleic acid of the virus is injected into the host cell

injection

each virus may use a different method of viral uncoating however in the end they just need to insert their viral _____ into host cell

insert viral genome

3 methods of viral entry and uncoating - - -

endocytosis fusion injection

influenza enters the host cell via fusion to the _______

endosome (endocytosis)

the general virus replication cycle 1. __________ (________) of the virus to a susceptible host cell 2. entry of the _____ or its _____ acid 3. synthesis of virus nucleic acid and protein by cell ________ as redirected by virus 4. assembly of _____ and packaging of viral _____ into new virons (maturation) 5. release of mature _____ from host cell

1. Attachment (adsorption) of the virus to a susceptible host cell 2. Entry (penetration) of the virion or its nucleic acid 3. Synthesis of virus nucleic acid and protein by cell metabolism as redirected by virus 4. Assembly of capsids and packaging of viral genomes into new virions (maturation) 5.. Release of mature virions from host cell

the general virus replication cycle 1. 2. 3. 4. 5.

1. attachment (adsorption) 2. entry (penetration) 3. synthesis 4. assembly 5. release

in reverse transcriptase (retrovirus/hiv replication) the +SSRNA viral genome enters and uses _______ dep ______ poly to make -SSDNA and that then uses _____ dep _____ poly to make a hybrid DSDNA with + and -

1. uses RNA dep DNA poly 2. uses DNA dep DNA poly

what cellular receptor: - immune cell interactions - found in HIV (retroviridae)

CD4

glycoproteins (gp 120) on HIV's envelope bind to ______ receptors on host cells (they are found on t helper cells and macrophages) - gives conformation change to expose co-receptors (CCR5 AND CXCR4)

CD4 receptors

______ dependent _____ polymerase uses DNA for a template to make DNA

DNA dep DNA poly

______ dependent _____ polymerase uses DNA as a template to make RNA

DNA dependent RNA polymerase

when host DNA is used as a template for viral DNA this is called - host DNA dependent ______ polymerase

DNA polymerase - DNA is the template for making viral DNA

drugs have been developed to target ____ since it fuses HIV to the cell membrane - Fuzeon = HIV cocktail

GP41

(1i) __________ (____) on the influenza in the viral envelope binds to the host cell's sialic acid receptor to induce receptor mediated endocytosis

Hemagglutinin (HA)

what cellular receptor: - cell adhesion - found in rhinovirus (picornaviridae)

ICAM-1

most eukaryal DNA viruses replicate in the nucleus (where DNA polymerases r found) - besides ________ viruses which are two large and replicate in the _____

Pox replicate in cytoplasm

RNA viruses have to use RNA dependent RNA polymerase that bind to ____ sense RNA to transcribe it into ____ sense RNA

RNA dep RNA pol binds to - sense (3->5) to trancribe it into + sense (5->3)

for replication of negative sense (3-5) RNA viruses: - they must bring the ____ dep ____ poly with them to make + sense RNA that can be translated into proteins (and more - sense to leave )

RNA dep RNA poly

RNA virus's RNA dependent RNA polymerase acts as both a _______ to transcribe mRNA as well as a _____ to replicate RNA

RNA depend. RNA pol acts as a transcriptase and replicase

RNA viruses have to convert RNA into the other sense during viral replication - thus they need a ______ dependent _____ polymerase

RNA dependent RNA polymerase

______ dependent _____ polymerase uses RNA as a template to make RNA

RNA dependent RNA polymerase

when host DNA is used as a template of for viral RNA this is called: - Host DNA dependent ______ polymerase

RNA polymerase - dna is used as template for making viral RNA

what cellular receptor: - various cellular functions - found in influenza virus (orthomyxoviridae)

Sialic acid

during animal virus assembly the ______ forms for the genome and enzymes to be packaged

capsid

to egress (exit) from host cells enveloped viruses, plant viral proteins in host plasma membrane and then "___" out of cell taking part of the membrane with them

bud out taking part of plasma membrane with them

most animal viruses release/exit via _______

budding

nonenveloped/naked viruses use mediated ________ for entry into host cell (reovirus)

endocytosis

Receptor engagement and membrane fusion can be blocked by specific ______

drugs

(1i) Hemagglutinin (HA) on the influenza in the viral envelope binds to the host cell's sialic acid - this binding induces recptor-mediated _______

endocytosis

_____ is a method of viral entry and uncoating where the endosome aids in viral uncoating

endocytosis

when does HIV get replicated

only when HOST CELL is being replictaed

Host range is determined by interactions between viral and cellular proteins such as phage _____ proteins

phage attachment proteins

retroviruses (HIV) use ______ transcriptase to replicate

reverse transcriptase

______ ______ uses RNA as a template to make DNA

reverse transcriptase dna to rna is dna dep dna poly

many viral components are ______ assembling making the assembly process fast and energetically 'cheap"

self assembling

RNA viruses have to convert RNA into the other ____ strand during viral replication - thus they need an RNA dependent RNA polymerase

sense strand

Each virus has a ______ range/type of cells that it can infect

specific

enveloped viruses like influenza attach to cells using ______ embedded in the viral _____

spikes embedded in the viral envelope

non-enveloped viruses like adenovirus attach to cells using _____ extending from the viral _____ - polio (a non enveloped virus) uses ______ proteins as well

spikes extending from viral capsid polio uses attachment proteins

bacteriophages attach to cells using ____ _____

tail fibers (with attachment proteins)

if the viruses host does not have the enzyme needed for ________, it must pack it in its nucleocapsid

transcription

egress/exit strategys of viruses depend on their virus and host cell ____

type

the possible range a virus can infect is dictated by the interaction between the viral _____ proteins and host ______ molecules

viral attachment proteins and host receptor molecules (think like spikes only fit in certain places)