1. attachment: GP120 on virus attaches to CD4 receptor on host cell

2. coreceptor binding: after confirmational change, GP 120 bings to coreceptor

3. fusion: structural changes in GP41, HIV fuses and enters cell

-produce too much and host will:

1. die and stop spreading

2. immunity will develop if too common

-must be stable and spread 

1. small, obligatory parasites to cells

2. have either DNA or RNA

3. extracellular and intracellular state

virion a.k.a. protein coat (capsid)

covers the nucleic acid of virus

capsid+nucleic acid=nucleocapsid

give protection and recognizes entry sites

1. type of nucleic acid

2. size, shape, capsid

3. enveloped vs. naked

4. cell types they invade

DNA or RNA (not both)

dsDNA, ssDNA, dsRNA, ssRNA

segmented & linear or single & circular

smaller than genome of a cell

1. most viruses have host cell specificity

2. some infect different cells in a variety of hosts (flu)

protein coat that protects and attaches

made of capsomeres (proteinaceous material) 

can have single or multiple types

1. helical or polyhedral

2. acquired from host cell

3. phospholipid & protein glycoprotein spikes- play a role in binding

needs host's organelles & enzymes

uses lytic replication: host cell dies after replicaiton

1. attachment and entry

2. synthesis

3. assembly and release

Attachment & Entry

In Viral Reproduction (3)

1. chemical attraction

2. glycoprotein spikes attach

3. enter and uncoat

1. DNA viral genome enters nucleus

2. RNA viral genome enters cytoplasm

1. DNA viral genome: nucleus to cytosol

2. RNA viral genome: solely in cytoplasm

3. naked released by exocytosis or lysis

virus stays dorment

can hide for years

once incorporated in DNA, becomes a part of the chromosome

1. viral conjunctivitis

2. SARS

3. foot and mouth disease

4. oral herpes

5. chicken pox/shingles

6. rabies

7. polio

1. respiratory droplets

2. blood

3. semen

4. food or water infected with feces

1. latency

2. cell damage/death

3. immune mediated

fuses cells: HSV, CMV

forms malignant transfromation: EBV, papilloma

cell death: rabies, polio

cell damage: cytotoxic t-cells (kills infected cells- hepititis a, b, c)

immune complex: depletes cartiledge (arthritis from hepititis b)

1. some carry copy of oncogene

2. some stimulate oncogene

3. some interfere with tumor suppression

1. burkitt's lymphoma

2. hodgkin's disease

3. kaposi sarcoma

4. cervical cancer

normal: alpha helices: cellular PrP

disease causing: beta helices: prion PrP

normally, polysaccharides and proteins push PrP into cellular form

extra/mutated PrP may make prion

when present, prion makes new PrP fold that way

swiss cheese/spongy looking brain

1. bovine sponigform encephalopathy

2. creutzfelat jacob disease

3. scrapie, kuru

Bacteriophage Reproduction 

Compared to Viral Reproduction in Mammals (5)

1. protein on tail attaches to proteins on cell wall

2. genome injected or diffuses in 

3. synthesis and assembled in cytoplasm

4. released with lysis

5. held in body with lysogeny

Viral Pneumonia in Kids

Caused By (4)

1. respiratory syncytial virus

2. infuenza

3. para influenza virus 1-3

4. adenovirus

1. constant exposure (in the air)

2. respiratory tract is a favorable environment (warm, moist, dark, 25 cell types)

3. easy transmision (sneeze, cough, contact)

1. tissue tropism

2. stability of virus

3. dosage

1. occupation

2. day care

3. public transport

1. age

2. immue status

3. underlying disease

1. acute (2 weeks)

2. pesistant

3. systemic

genome: 8 - strand, segmented

enveloped

spikes: hemagglutin & neuraminidase (H&N)

attachtment: through H

replicate in the nucleus

H&N go through minor mutations in winter:

H1N1 1918 Spanish Flu

H2N2 1957 Asian Flu

H1N2 1968 Hong Kong Flu

H1N1 1977 Swine Flu

Now: H1N1, H1N2, H3N2

hospitalizes 200,000/year

kills 36,000/year

mostly affects people under 25

sometimes reflects underlyig conditions

1. infect upper respiratory cells

2. viral reproduction & budding

3. cells die, slough, pieces go to blood, becomes systemic

4. secondary bacterial infection kills

cel culture- monkey kidney

hemagglutintion

IFA

ELISA 

serology

amantadine & rimantadine

zanamivir & oseltamivir

vaccine

1. parainfluenza viruses

2. respiratory syncytial virus (RSV)

single strand - RNA virus

enveloped with spikes 

replication in cytoplasm

only in humans

transmitted via aerosole

kids: croup/barking cough

adults: mild

usually in the fall

mostly upper respiratory

no systemic symptoms 

cold symptoms

bronchitis/croup

- sense single stranded RNA

enveloped

most acute LRI in infants, young, elderly, immunocompromised

virus infuses with cells, fusion, syncytium

infancts

incubate 4-7 days

URI with low fever that progresses to LRI

multinucleic giant cells

pink staining inclusion bodies

inflammatory cells

slough epithiliam

picornavirus

over 100 serotypes

+ sense RNA

naked, likes it 33 degrees C

1/2 of all URI

transmit via aerosol

usually early fall, late spring

upper to lower respiratory

binds to ICAM1

immunity is serotype specific

usually by symptoms

nasal washing

decongestant

antiviral

hand washing

corona RNA virus 

suspected if within 10 days of contact with SARS patient or SARS area

acute respiratory distress