Virology/Pneumotrophic diseases

Tobacco mosaic virus

Foot-and-mouth disease

Yellow fever virus

• 1. Helix-tightly wound corkscrew
• 2. Icosahedron (herpes virus)
• 3. Complex- helical and icosahedron

Virion

-fully mature virus body

Lipid membrane w/spikes (peplomers)

• protein subunits that protect nucleic acid
• part of capsid

without envelope

-has nucleocapsid = DNA + capsid

• -part of naked virus
• -DNA + capsid

formation of Tobacco Mosaic Virus

Bacteriophages

-Inject DNA

T4 phage

Head: Protein + DNA

Tail: Protein only

Tail fibers: specificity for different species

Tail pins: have Lysozyme

• 1. Attachment- absoption to host
• 2. Penetration- injection of nucleic acid
• 3. Biosynthesis- nucleic acids and proteins
• 4. Maturation- assembly and packaging
• 5. Release- of virion from cell

Lytic phage- destroys bacterial cell

• -form small pores in peptidoglycan
• -destroys peptidoglycan

Know when to co-exist and when to kill

• -Temperate phage
• -Prophage

• -Smart virus
• -virus genome replicates with host genome
• -follow lysogenic pathway
• -can induce lytic pathway

-genome of temperate phage integrated into host chromosome

Prokaryote containing a prophage

• -virus-mediated lysis
• -plaque-forming units PFU
• -produce clear zones

plaques formed by Lytic bacteriophage

• 1. Attachment- at plasma membrane
• 2. Penetrations- of whole virus
• 3. Uncoating
• 4. a. DNA replication- in nucleus
• b. RNA replication- in cytoplasm
• 5. Envelope aquisition- lipids come from host cell

*RNA replicates FASTER than DNA

Naked viruses

• GP120
• GP41- T helper cells CD-4

• Rhabdovirus
• Coronavirus
• Orthomyxovirus
• Paramyxovirus

Reverse transcriptase- mRNA to dsDNA

• HIV
• HTLV

animal virus genome integrated into host cell genome

HIV

cell lysis with virion

causes cell lysis to host cell death

• CMV = Owl Eyes- intranuclear inculsions
• Rabies = Negri bodies- pyramidal cells, purkinje cells

CPE of rabies encephalitits

• -cellular inclusions
• -pyramidal cells of Ammon's horn
• -Purkinje cells of cerebellum
• -also cells of Medulla and other ganglia

20% of human tumors

• -EBV - linked to Burkitt Lymphoma (tumor of jaw)
• -HPV - cervical cancer

• only in plants
• -small, circular ssRNA
• -no capsid
• -no protein-coding genes

• Coconut cadang viroid
• Citrus exocortis viroid
• Potato spindle tuber viroid

• -Proteinaceous infectious particles
• -very resilient
• -causes nerve cell death--> sponge-like holes in brain
• -Spongiform change
• -dementia, weakened muscles, loss of balance

• Scrapie- goats, sheep
• CJD
• TSE
• BSE- mad cow disease

• PrP^c = normal
• PrP^sc = abnormal; causes folding changes; does not change sequence

PrP^sc kills neurons

• -caused by prions
• -demonstrates abnormal EEG
• -diffuse spongiform changes and coalescent vacuoles

• inactivated- heat/chemical treated (Salk)
• attenuated- virulence decreased; replicate slowly (Sabine)
• genetically engineered- viral subunits synthesized (HepB capsid proteins synthesized in yeasts)

• -CPE
• -Serological tests
• -Plaque formation
• -Electron microscopy
• -cultivating methods

Orthomyxoviridae

• -A, B, C
• -respiratory droplets
• -chills, fatigue, pain, severe cough, congestion
• -Fever

-invasion of trachea and bronchi

Orthomyxoviridae

• Hemagglutinin (H)
• -attach and penetrate host cell

• Neuraminidase (N)
• -helps release virions from host cell

*mutations occur in H and N spikes

Orthomyxoviridae

• -every year
• -causes most epidemics

Orthomyxoviridae

• -every year
• -less common than type A

Orthomyxoviridae

• -mild respiratory illness
• -no epidemics

• -mutations within genome
• -Random

• -different strains infect same host
• -Recombination = new viral genome
• -no mutation

-major cause of Pandemics

-Pneumonia - infants, elderly, immunocompromised

-Guillain-Barre - body damages own peripheral nerves

-Reye - children who take ASA; sudden acute encephalopathy and liver problems

Picornaviridae

• -airborne respiratory droplets and contaminated objects
• -thrive in nose
• -Common Cold

Adenoviridae

• -respiratory droplets
• -Common Cold
• -induce formation of inclusion bodies in host cells

• -Acute febrile pharyngitis
• -Pharyngoconjunctival fever
• -Acute respiratory disease

-Anhy of these can progress to pneumonia

• -Measles (Rubeola)
• -Mumps
• -Parainfluenza
• -RSV

Paramyxoviridae

• -children <1 y/o
• -cells fuse together into syncytia

Coronaviridae

• -severe respiratory illness and pneumonia
• -close person-to-person contact
• -natural host may be bats
• -10 day isolation
• -forms multi-nucleated cells in lung

• -HSV-1 above
• -HSV-2 below
• -VZV
• -EBV
• -HHV6 infants
• -HHV8 Kaposi's sarcoma

*total of 8 species infect humans

Herpesviridae

• -above the waist
• -cold sores

• -latent viruses in sensory ganglia
• -reactivate and move to epithelium

Herpesviridae

• -below the waist
• -genital sores/blisters
• -cervical cancers

• -latent virus in nerve cells
• -recurrence 8-10 times a year

• -cervical cancer
• -encephalitis
• -herpes keratitis -scars cornea; blindness

• -neonatal herpes -life-threatening
• -passed to newborns during birth
• -delayed mental development
• -blindness and seizures

• Herpesviridae
• Varicella-zoster virus VZV

• -skin contact
• -respiratory droplets
• -red, itchy rash
• -fluid-filled vesicles

Hemorrhagic chickenpox complication

#1 = bacterial skin infections

• Reye's syndrome- convulsions, fever, brain/liver
• Shingles

• VZV
• Influzenza (Orthomyxoviridae)

• Herpesviridae
• human herpesvirus 6

• -Infants 6mo-3yr
• Roseola infantum
• -high fever
• -red rash

• -respiratory secretions
• -saliva

• -common with bone morrow transplant recipients
• -may be associated with MS

• Herpesviridae
• VZV

• -reactivated as adults
• -blisters and red patches on body trunk
• -facial paralysis
• -ice-pick pains
• -Postherpetic neuralgia- pain after blisters disappear

HHV-6

• -high fever
• -red rash

Herpesviridae

• Kaposi's sarcoma- dark, purple skin lesions
• -angiogenic tumor of blood vessel walls

Oncogenic

Herpesvirus simiae

-acute encephalitis in humans

Paramyxoviridae

-respiratory droplets

• -Koplik spots- red patches with white grain centers along gum line and mouth
• -appear 2-4 days after onset of symptoms

-Maculopapules-at hairline, spread to face, trunk, extremities

Paramyxoviridae

• -enlarged jaw tissues from swollen salivary glands
• -blocked ducts from parotid glands
• Orchitis- swelling and damage of testis

• Measels/Rubeola
• paramyxoviridae

-red patches w/white grain centers in mouth and gum line

Togaviridae

• Maculopapular rash- similar to Rubeola
• Congenital rubella- fetus infected through placenta
• -destroys fetal capillaries and hypoxia

Parvoviridae

• -respiratory droplets
• -mild rash
• -fiery red rash on cheeks, ears, trunk

-in adults, symptoms similar to rheumatoid arthritis

• Papillomavirus
• -non-enveloped
• -icosahedral particles
• -capsid of 2 proteins: major (L1), minor (L2)
• -DNA viruses
• -oncogenic

• 6
• 16
• 18
• 11

• -lead to neoplasia
• Polyoma and Papilloma viruses

protects against HPV types 6, 11, 16, 18

-vaccine made from non-infectious HPV-like particles

• Papillomavirus
• -infects basal cells of dermal layer
• -Condylomata- genital warts; some strains of HPV
• -Cervical cancer- 2nd cause of cancer death in women

named for 3 main members:

• PApillomavirus
• POlyomavirus
• Vacuolating Agent

HPV type 16

• E6 and E7 - genes expressed early
• -interact with cellular proteins
• -called oncogenes - promote cancers

• E6 -binds p53 in host cell
• -promotes degredation of cellular p53 via ubiquitin dependent pathway--> apoptosis and cancer

E7 -binds pRb, inactivates it

p53 and pRb = tumor suppressors involved in DNA repair and cell death

• -tumor suppressor protein
• -arrests cell cycle when DNA is damaged via apoptosis

E6 binds and degregates p53

Poxviridae

Macules-->papules-->fluid-filled vesicles-->pustules-->pox

-eradicated in 1979

Poxviridae

• -mildly contagious
• -wart-like skin lesions
• -lesions: firm, waxy, elevated, flesh-tones, emit milky substance

transmitted by sexual contact

• -facial skin in children
• -genitals in adult