Module 10 Flashcards by Aimee Rodwig

2 types of RNA viruses

Positive and negative stranded

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Which RNA virus strand can immediately be translated?

positive strand

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Which RNA virus strand cannot be immediately translated?

negative strand

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What enzyme is necessary for RNA viruses to transcribe a negative strand virus?

RNA-dependent RNA polymerase

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What enzyme for RNA transcription do humans not possess?

RNA-dependent RNA polymerase

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This RNA virus can incorporate into the host genome

retroviruses (like HIV)

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This is the only virus group with a dsRNA genome

Reoviridae (like rotavirus)

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What type of strand do most DNA viruses have?

both positive and negative strands

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What makes parvoviruses an exception to DNA virus genome rules?

they’re ssDNA

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2 types of viral capsids

icosahedral and helical

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What type of viruses have helical symmetry

RNA viruses

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Capsid shape of rhabdoviruses (like rabies)

bullet shaped

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What type of viruses have icosahedral symmetry?

DNA viruses

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How do viruses acquire a viral envelope

by budding through a host cell nuclear or cytoplasmic membrane and taking a piece with it

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List the DNA viruses

think HHAPPPy: Hepadna, Herpes, Adeno, Papova, Parvo, Pox

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List the RNA viruses

just think it’s everything except HHAPPPy

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4 steps of viral replication

adsorption and penetration, uncoating of the virus, synthesis and assembly of viral products, and release of virions from the host cell by lysis or budding

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passage of virion from surface of the cell across the cell membrane and into the cytoplasm

penetration

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cell membrane invaginating that encloses a virion in an endocytic vesicle

receptor-mediated endocytosis

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How do some enveloped viruses, like HIV, enter a host cell?

membrane fusion of the viral envelope with the host plasma membrane

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stepwise process of disassembly of a virion that enables the expression of viral genes that carry out replication

uncoating

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Where do viral DNA transcription and replication occur?

host cell nucleus

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What form of mRNA codes for capsid structural proteins?

late mRNA

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2 problems RNA viruses encounter

no host cell RNA polymerase to use and usually eukaryotic mRNA only produces one polypeptide

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Type I RNA virus replication

ssRNA with + polarity that replicates via complementary (-) strand intermediate

Type II RNA virus replication

ssRNA with - polarity that replicates via a complementary (+) strand intermediate

Type III RNA virus replication

Viruses with a dsRNA genome- have to have RNA dependent RNA polymerase/transcriptase in order to transcribe

Type IV RNA virus replication

ssRNA of + polarity that is replicated by a DNA intermediate (uses reverse transcriptase, or RNA-dependent DNA polymerase)

Assembly of RNA viral nucleocapsids happens in the:

cytoplasm

Assembly of DNA viral nucleocapsids happens in the:

nucleus

Difference in release of naked virions vs enveloped virions

naked are exocytosed and enveloped virions bud out

4 possible outcomes from viral infection in a cell

non permissive (virus can't replicate or cell dies too fast), permissive (virus replicates but doesn't do anything), latent viral state, host cell death and viral release through lytic cycle

viral family that includes all influenza viruses

orthomyxoviridae

viral family that includes mumps, measles, RSV, and parainfluenza

paramyxoviridae

Flu symptoms that differentiate it from a cold or other viral infection

muscle aches, high fever, and headaches

structure of orthomyxoviridae virions

spherical, with 8 negative stranded RNA with a nucleocapsid with helical symmetry capsid

2 types of glycoprotein spikes on orthomyxoviridae

hemagglutinin activity (HA) and neuraminidase activity (NA)

What does hemagglutinin attach to?

sialic acid receptors on the surface of erythrocytes

What does neuraminidase do?

cleaves neuraminic acid and disrupts the mucin barrier, exposing sialic acid binding sites underneath it

What is critical for the release of newly formed virions from an infected host cell?

neuraminidase

What protein forms a proton channel and depends on host cell nuclear functions to be transcribed?

flu M2 protein

What type of influenza affects humans and animals?

Type A

small changes in HA or NA of influenza that make it slightly different

antigenic drift

When 2 influenza strains co-infect the same cell, what can happen?

RNA segments can be mispackaged into the wrong virus and makes a new viral serotype. Called Antigenic Shift

Trading of RNA segments between animal and human flu strains

antigenic shift

most common cause of human flu

H1N1

Oseltamivir, zanamivir, and peramivir are what kind of drugs?

antivirals to treat type A flu that are NA inhibitors

Serotype of bird flu

H5N1

Differences between paramyxoviridae and orthomyxoviridae structure

for para, NA and HA are on the same glycoprotein spike, not two separate ones

What protein of paramyxoviridae causes infected host cells to fuse into giant multinucleated cells?

fusion protein

What protein causes the formation of syncytial cells?

F-protein

What does RSV lack compared to other paramyxoviridae

lacks both HA and NA

What virus most frequently affects the parotid glad and testes?

mumps

What virus has a prodrome period?

measles

small red lesions with blue-white centers found in the mouth due to Measles infection

Koplik's spots

rash that spreads across the entire body with high fever is characteristic of what virus?

measles

treatments for measles

post-exposure vaccination and immune serum globulin

Acute viral hepatitis types

HAV, HBV, HCV, and HDV

Chronic viral hepatitis types

HBC, HCV, and HDV

Hepatitis type with positive single stranded RNA

HAV

Diagnosis of hepatitis

IgM shows acute infection, igG shows old infection and protective abs

structure of HBV

hepadnavirus- DNA | big virus with enveloped capsid and circular dsDNA

marker for active HBV infection

HBeAg

methods of transmission of HBV

mother to baby, sexual, and parenteral

Severe acute hepatitis w rapid liver destruction

fulminant hepatitis

Disease states caused by HBV

acute, fulminant, and chronic

leading cause of chronic hepatitis

HCV

Which hepatitis form needs another hepatitis form in order to infect?

HDV

What does HDV need in order to infect?

HBV

3 main concepts of retroviridae

retro, grow, and blow

capsid proteins of HIV

p24, p17, p9 and p7

2 HIV lipid membrane proteins

gp120 and gp41

3 HIV viral proteins essential for replication

RT, protease, and integrase

Diagnostic tests for HDV infection

delta antigen and anti-HDV ab

Antibodies against HBsAg is protective against what?

HBV and HDV

Asymptomatic carriers of HBV never develop what antibodies?

anti-HBsAg

IgM anti-HBcAg is used to detect what?

new HBV infection

IgG anti-HBcAg is used to detect what?

old HBV infection

HbeAg is used to detect what?

High infectivity of HBV

anti-HBeAg is used to detect what?

low infectivity of HBV

Genome across all RNA retroviruses

2 LTRs, gag, pol, and env genes

Genes that flank whole viral genome

Long terminal repeat sequences (LTRs)

2 functions of retrovirus LTRs

Sticky ends (insert into host DNA) and promoter/enhancer (bind to LTRs and modify viral DNA transcription)

What does gp120 bind to on cell surface?

CD4 molecule on surface of T cells, macrophages, and microglia

What does gp41 do?

mediates fusion of the HIV viral envelope with the cell plasma membrane allowing viral contents to enter

What are CXCR4 (fusin) and CCR5 required for?

they're cofactors required for HIV entry into T cells and macrophages

this HIV cofactor enhances the entry of T cell line-tropic HIV isolates

CXCR4 (fusin)

This HIV cofactor is specific for macrophage line-tropic HIV isolates

CCR5

Immune response where an infected person first exhibiting detectable levels of anti-HIV abs in their blood serum

seroconversion

Clinical significance of HIV infection

T-cell death, multinucleated giant T cells, hypergammaglobulinemia from B lymphocytes, monocytes and macrophages span BBB

Individuals infected with HIV but show no signs of disease progression for 12+ years

long term non progressors

individuals repeatedly exposed to HIV but never become infected

highly exposed persistently seronegatives

Therapies under HAART

AZT, non-nucleoside RT inhibitors (NNRTIs), protease inhibitors

Transmission route of Ebola

person-to-person contact

What does SARS-CoV-2 bind to?

ACE2 receptors