keywords:
Bookmark and Share



Front Back
Virus Properties
- Capsid (always)
- Envelope vs Non-capsid (nucleocapsid) 
- obligate intracellular parasites
Virus Structure
- DNA or RNA
- Helical or Spherical (Icosahedral)
Capsomeres
- clustering of capsid proteins
- defined morphologic subunits
Tropism
- what types of cells a virus can infect.
(ie. envelope viruses need envelope to be infectious)
DS DNA
- enveloped (2) vs non-enveloped (2)
Enveloped
- circular = hepadna (HBV)
- linear = Herpes (HSV, CMV)  
Non-enveloped
- circular = papova (HPV)
- linear = adenovirus
ALL DNA Viruses

- Icosahedral (except pox)
- Nuclear Replication (except pox) Herpesviridae (HSV), Hepadnaviridae (HBV), Papovavirida (HPV), Adenonviridae, Parvoviridae, Poxviridae (smallpox)
Antibodies
- nonenvelope vs envelope viruses
- nonenvelope = capside proteins
- envelope = glycoproteins
Helical Viruses
- ALL helical viruses possess nuclear envelopes.
Icosahedral Viruses
- 20 triangular faces.
- w/ different axises of rotational symmetry (2,3,5)
SS DNA Viruses
Non-enveloped
- parvo virus
Complex DNA Viruses
Enveloped
- Pox Virus
RNA Viruses
2 PCs for Barter (E = ebola = Filo)
- P = Pico RNA (Polio + HepA)
- P = Paramyxo (Measles + Mumps)
- C = Corona (SARS)
- C = Calici (Noro, Hep E)
- F = Flavi (HCV, West Nile, Dengue)
- O = Orthomyxo (Influenza)
- R = Retro (HIV)
- B = Bunya (Hanta)
- A = Arena (Lasa Fever)
- R = Reo (Rota)
- T = Toga (Rubella)
- E = Filoviridae (Ebola)
- R = Rhabdo (Rabies)
ss RNA (+)
- enveloped + non-enveloped
Enveloped
- Toga (Rubella)
- Corona (SARS)
- Flavi (HCV, West Nile, Dengue)
- Retro (HIV)
Non-Enveloped
- Pico RNA (Polio, Hep A)
- Calici (Noro)
DS RNA
Non-Enveloped
- Reoviridae (Rota)
SS RNA (-)
Enveloped
- Arena (Lasa Fever)
- Bunya (Hanta)
- Filo (Ebola)
- Orthomyxo (Influenza)
- Paramyxo (Mumps, Measles)
- Rhabdo (Rabies)
Hemegglutinin (HA)
- binds sialic acid
- attachment + entry of influenza
Neuraminidase
- Cleaves Sialic Acid from terminal oligosaccharide.
Initiation Phase
1) Attachment (HA + N)
2) Fusion (Enveloped)
3) Receptor Mediated Endocytosis (Both)
4) Uncoating


Replication Phase
1) Gene Expression (Late + Early)
2) Gene Replication
Release Phase
1) Assembly (Capsid, Genome, Proteins)
2) Release / Egress
- Envelope = Fusion or Budding
- Non-Envelope = Cell Lysis
Site of Replication
DNA = Nucleus except Pox
RNA = Cytoplasm except Influenza
Early vs Late Viral Gene Expression
Early = Polymerases
Late = Structural
Gamma = Herpes
DNA Virus Life Cycle
1) Code mRNAs -> Viral Proteins
2) DNA Replication w/ DdDP
3) Code Structural Proteins
4) Assembly

Only DNA Required
+ Sense RNA Life Cycle
1) + Sense RNA -> Viral Proteins
2) Code - Sense RNA
3) Code + Sense RNA
4) Assembly w/ Structural Proteins
- Sense RNA Life Cycle
1) - Sense RNA (equipped with RdRP) -> + Sense RNA
2) + Sense RNA -> Viral Proteins and - Sense RNA w/ RdRP
3) Assembly w/ RdRP

Segmented RNA Life Cycle
- Influenza virus
- Occurs like other - sense
- reassortment w/ multiple infections
Retroviruses Life Cycle
1) RNA/DNA synthesis with RdDP
2) production of dsDNA w/ RdDP
3) integration to host genome w/ integrase
4) replication + transcription of + mRNA
5) translation + assembly of retrovirus
Hepatitis B Life Cycle
1) Incomplete Circular DNA into Nucleus
2) Correction w/ host DdDP
3) mRNA coding -> Viral Proteins
4) RdDP (RT) codes mRNA into dsDNA
5) RdDP packaged w/ virus (but not necessary)
Poliovirus Entry
- Poliovirus Receptor (PVR)
- VP1 + VP4 = cause fusion (acidic stomach environment)
- oral-fecal route
Poliovirus
- Pico RNA virus family
- Entero virus genus
- nonenveloped, positive stranded
Polio Virulence
- infect + spread to CNS (numbness + paralysis)

Host Metabolism Inhibition
- 2A -> translation
- 2BC + 3A -> secretory pathway
- 3C -> transcription
Polio pathgenesis
Infection (100%)
Asymptomatic (90%)
GI Symptoms (10%)
CNS Infection (1%)
Poliomyelitis (1/20k)
Poliomyelitis (Post Polio syndrome)
- flaccid paralysis due to motor neuron dmg.
- muscle wasting + neuromuscular dmg (anterior horn + muscle cells)
Noro Virus
- Calci
- ssRNA, +, non-enveloped
- acute gastroenteritis
- Koch's Postulates - Feed Filtered Feces to People.
- Cruise ships (resistant to detergents)
- Oral / Airborne
SARS
- Corona
- ssRNA, +, enveloped
- respiratory illness
- China -> 1st global response
- Fruitbats -> adapted human transmission
West Nile Virus
- Flavi
- ssRNA, +, enveloped
- Queens, Dead crowns NYC Parks
- birds -> mosquito
- 1:5 symptomatic, 1:150 w/ meningo-encephalitis
Avian Influenza
- orthomyxo
- ssRNA, (-), enveloped
- no efficient human transmission
- high mortality (no pre-existing immunity)
- Low Path (LPAI) and High Path (HPAI) strains.
- Illegal Bird Trading = Problem (anti-virals in bird feed = resistance)
Rota Virus
- intense diarrhea w/ vomiting (<2 yrs old + day cares)
- ingestion pathogen
- NSP4 - enterotoxin-like
- dsRNA, non-enveloped
- icosahedral capsid (2 layers)
- "spoke wheel" appearance
- serologic tests
- fecal-oral / winter season
- vaccine = intestinal blocakage w/ reduction in disease.
Hepatitis A
- Picorna (ssRNA, +, Nonenveloped)
- fecal-contaminated food. (humans only)
- ingestion pathogen
- flu, suppressed by HAV antibodies
- Liver -> jaundice (acute)
- diagnosis on serology
- vaccine (<12 mths)
Hanta Virus
- Bunya viruses (Sin Nobre). <15 yrs old
- ssRNA, -, enveloped
- Zoonotic Disease: Rodents
3 Diseases: Hemorrhagic Fever (HF), Hemorrhagic Fever w/ Renal Syndrome (HFRS), Hanta Pulmonary Syndrome (HPS)
- Clinical + Exposure History
- Supportive Therapy (Fluids + Dialysis)
Rabies Virus
- Rhabdovirus
- ssRNA, -, envelope
- bullet-shaped
- Zoonoses: Bats, Dogs, Racoons -> bite = muscle access
- Neural Tropism - Acth Receptor (retrograde transport)
- Behavior: Aggressive, hydrophobia, fetal encephalitis
- Vaccination + IVIG
Small Pox
- Variola Major
- Complete Envelope DNA virus
- maculopapular rash (esp on face),  vesciles, pustuls, crusts, scarring
- aerosols or droplets
- Vaccine: Dryvax (old, from calf leg), ACAM (new)
Ebola / Lassa
- Filo, Arena
- ssRNA, -, enveloped
- hemorrhagic fever
- unexplained bleeding w/ no treatment.
Hepatitis B
- Hepadna Virus
- Circular, incomplete dsDNA
- Large % are Asymptomatic (HBsAG negative)
- Carriers -> chronic hepatitis, cirrhosis, hepatocellular carcinoma
- Liver enzymes, PCR, Serology
- Virulence: HBsAG + HBV X protein
- Treatment: HBIG + Lamivudine (nucleoside analogue)
Hepatitis B Serology
HBsAG - surface. acute + persistant = chronic infection. Anti-HBsAG = Immunity (resolved or vaccine)
HBcAG - core. acute + persistant
HBeAG - pre-core. acute + maybe persistant.
NO AntiHB antibodies during window.
Hepatitis D
Defective RNA virus: requires HBV co-infection/super-infection
- Chronic + More severe chronic hepatitis.
- Hep B Vaccine Prevents Hep D
Hep C Virus
Flavi
- ssRNA, +, enveloped
- high error -> quasispecies (hypervariable genome)
- genotype 1 is bad.
- 50% w/ cirrhosis (higher than HBV)
- Ribavirin (hemolytic anemia) + INFa (pegylated)
- no IVIG or Vaccine
Epstein-Barr Virus
- Herpes Virus Family
- DNA Virus
- Infectious Mononucleosis: Fever, Pharyngitis, Lymphadenopathy, atypical lymphocytosis
- Immunosuppressed patients
- Cancers (chronic): Burkitt's, Lymphoma
- Immortalized B Cells
- Mono = LARGE CTL response to infected B cells
- EBNA-1 (antigen that evades MHC1)
- Monospot test + Atypical lymphocytes
- Acyclovir + Gancyclovir (HSV, VZV) + Decrease Immunosuppressants
Post-transplant Lymphoproliferative Disease (PTLD)
- Epstein-Barr Virus causes immortalized B Cells -> lymphoma
Adeno Virus Characteristics
- Case: Respiratory distress epidemic w/ HIV
- dsDNA, non-enveloped
- fiber = serotype + tissue specificity (Coxsackievirus/ adenovirus receptor)
- serotypes correlate w/ disease manifestation.
- human resevoir
- URI followed by LRI
x of y cards Next >|