Ch 6 STUDYGUIDE

Survery of Viruses

what are prions

infectious misfolded protein particles that lack a nucleic acid

how do prions cause diseases

they cause transmissible spongiform encephalopathies (TSEs)

how do TSEs work

• Normal brain protein (PrPᶜ) is misfolded into a disease-causing form (PrPˢᶜ)

• Misfolded prions cause other normal proteins to also misfold

• These clump together and damage brain tissue

what are oncoviruses

cancer causing viruses that enter the host genome, disrupting regulatory genes and triggering uncontrolled cell division

what are anti-viral agents (-vir drugs)

antiviral drugs that target specific steps in viral replication

what does a protease inhibitor do

ex: ritonavir

blocks the enzyme that cuts viral polyproteins which prevents maturation

what does an integrase inhibitor do

ex: raltegravir

blocks the enzyme that integrates viral DNA into the host genome

Temperate phage

a bacteriophage that can integrate into the host genome

prophage

the latent form of a bacteriophage inside a bacterial genome

provirus

the latent form of a retrovirus integrated into a eukaryotic host genome

what makes up a viral envelope

lipids and proteins, often from the host cell membrane

how do viruses acquire envelopes

acquired when the virus buds off from the host cell

what is a capsid

a protein shell made out of capsomers that protects the viral genetic material

what is a nucleocapsid

caspid & a nucleic acid

what shape is an Icosahedral

20 sided shape, symmetrical

what is the shape of a Helical

rod shaped, spiral structures around a nucleic acid

list the differences between naked vs. enveloped viruses

naked: no envelope, more resistant to drying and disinfectants

enveloped: has aa lipid membrane, more sensitive to environmental conditions

whaat does “host range” mean

the spectrum of host cells a virus can infect

what is meant by the term “Lysogenic conversation”

when a prophage imparts new traits to the bacterial host

complex vs. enveloped viruses

complex: atypical structure, may have tails and other apparatus

enveloped: have a lipid enveloped with embedded proteins, often icosahedral or helical in shape

lytic vs lysogenic cycles

lytic: virus replicates and kills the host cell

lysogenic: viral DNA integrates into host genome, host lives, virus can later reactivate into lytic cycle

HSV-1 vs. HSV-2

HSV-1: oral herpes (cold sores), latency in trigeminal ganglion

HSV-2: genital herpes, latency in sacral ganglion

BOTH: can cross infect and cuase latent recurrent infections

what are the virluence factors of H (hemagglutinin)

helps virus attach to host cell receptors

what are the virluence factors of N (neuraminidase)

aids in virus release from host cell