Micro 2 Test 3

• rabies- pasture
• yellow fever- Reed

• non-living intracellular parasites
• small

in tissue cultures (mainly use bird eggs)

a single viral particle

either RNA or DNA

the nucleic acid surrounded by a capsid (protein coat)

• a lipoprotein coat stolen from the host
• has glycoprotein spikes for host interaction

it has a capsid but no envelope

helical or icosahedral

• no nucleic acid
• self replicating protein
• possibly related to viruses
• causes spongiform encephalopathies

• mad-cow
• creutzfeldt-jacobs
• kuru
• scrapie

• 1. Adsorption
• 2. penetration
• 3. prefabrication
• 4. maturation
• 5. viral release

• adsorbs to receptor site with tail fibers
• (receptor sites are lipopolysaccharide, pili, and flagella)
• beginning of latent period

• tail penetrates bacteria, releases nucleic acids, takes over host
• beginning of eclipse period

• viral genome replicated
• viral mRNA synthesized
• all viral parts are prefabricated

• end of eclipse phase
• virus assembled (dont grow!!)

• end of latent period
• viruses produce lysosome, rupture cell wall, and released

• 1. adsorption
• 2. penetration and uncoating
• 3. synthesis of DNA/RNA viruses
• 4. maturation
• 5. viral release

• naked virus- capsid binds to host cell receptors
• enveloped virus- glycoprotein spikes bind to host cell receptors

• naked- change in capsid structure on adsprtion to plasma membrane, release nucleic acids into cytoplasm
• enveloped
• a. envelope fuses with cytoplasmic membrane and releases nucleocapsid into cytoplasm
• b. endobytosed into cell (endocytic vesicle), lysosomes fuse to vesicle, release nucleic acids

• early synthesis- viral DNA synthesized-> transcription to RNA-> inhibits host (usually occurs in host nucleus, except for pox virus)
• often remain latent
• early viral genes- DNA binding proteins and enzymes
• late viral genes- structural genes

• (+) stranded
• double stranded (ds)
• (-) stranded
• retrovirus

• (+) strand used as giant mRNA
• translated into viral enzymes by host
• RNA polymerase forms (-) strand RNA
• (-) strand forms more (+) strands used as mRNA and for new viruses

• transcriptase copies (-) strand of genome to mRNA
• mRNA translated into enzymes to synthesize new viruses

• viral transcriptase converts (-) strand to (+) strand
• (+) strand acts as mRNA
• viral replicase produces double stranded RNA that assembles new virus

• has single stranded (+) RNA genome
• synthesize mRNA and replicate RNA by converting RNA-> DNA by reverse transcriptase
• (-) DNA copied to create double stranded proviral DNA
• proviral DNA synthesizes (+) RNA for new viruses

• capsid formation
• 1. synthesis directed by late genes
• 2. spontaneously self assembled around nucleic acid
• 3. location of maturation is viral specific
• if enveloped...
• 1. late viral mRNA transcribes glycoproteins-> inserted into host cell membrane
• 2. viral particle enveloped during exocytosis

• naked- infected cell lysed, virons released
• enveloped- possible lysis, otherwise budding from membrane bound organelles then exocytosed

• persistance
• transformation
• immunological escape

virus is not cleared from host followign primary infection, remains associated with specific cells

establish persistanct infections that stimulate uncontrolled cell growth causing transformation or immortalization of cells (CANCER)

virus can evade detection (herpes)

• Poxvirus
• herpes virus
• adenovirus
• Papovaviridae
• parvovirus

• mulluscum contagiosum
• small pox
• cow pox
• monkey pox
• orf

• big, brick shaped
• 1 molecule of linear double stranded DNA

• pearly/flesh colored bumps
• contagious
• not harmful
• impaired immune system= disfiguring

• caused by variola virus (major= more severe)
• highly contagious via respiratory secretions and direct contact
• causes fever, chills, nausea, severe muscle aches, rash
• rash: flat-> papules-> postules->scar
• vaccination= 1967
• last case in somalia in 1977
• erradicated in 1980

• zoonosis
• infected teats of milking cows
• treated with vaccinea virus (no one knows what it is!!)

• rare
• rain forest in west africa
• initially found in lab monkeys

viral pox from sheep and goats

a leading cause of human viral disease, second to influenza. once infected, you are infected for life!

• icosahedral symmetry
• enveloped
• single molecule of ds DNA
• attracted to neurons

• cytomegalovirus
• varicella-zoster virus
• herpes simplex virus
• epstein barr virus
• human herpes virus 6,7, and 8

• in US 15% of college age and 50% of 35 y.o. are infected
• spread in body secretions (sexually)
• transplacental- spreads to fetus (1 in 40)
• most common viral cause of congenital mental retardation
• no symptoms in children, maybe mild in adults
• problematic in immunocomprimised adults (CMV-retinitis in 15% of AIDS)

• chicken pox
• shingles

• respiratory droplet/direct contact transmission
• rate of infection >90%
• spreads from lungs by entering blood (viremia)-> sub-endothelial-> endothelial
• forms papules-> fluid filled vesicles-> postules->scab
• vesicles are found on the scalp
• itchy, can cause bacterial superinfection
• recovery in 2 weeks
• problems in utero if infection during 1st trimester

• reoccurence of latent varicella infection
• virus from nerves to epidermis
• reactivated by stress, injury, disease
• severe radicular pain in infected nerves
• chicken pox-like lesions in dermatomal pattern

• culture from lesions
• giant cells with inclusions

• live attenuated vaccine leads to antibodies and cell mediated immunity
• chemotherapy- various nucleotide analogs

• 1st infect mucoepithelial or enter thru wounds-> latnent infection in neuronal cells
• HSV-1 usually above the waist
• HSV-2 usually below the waist

• herpes labialis: fever blisters/ cold sores
• eczema herpeticum: widespread cutaneous HSV if have pre-existing eczema
• keratoconjunctivitis: infection of cornea. leading cause of corneal blindness in industrealized countries

• Genital herpes
• herpetic whitlow: on fingers or hands
• herpetic grandiatorum: skin lesions mainly on wrestlers from direct contact

• prodome (pre infection) 1-2 days of buring sensation
• primary infection: viremia, fever, swollen lymph nodes, pain on urination
• secondary episodes: caused by reactivation of virus, less severe and shorter
• triggers: fever, menstration, stress, UV light
• person is infectous even when not in active rash

• paitent counseling
• drugs (Acyclovir)
• nucleotide analog, inhibits DNA polymersae
• no action on latent infection
• doesnt reduece symptoms
• oral and topical

• infectous mononucleosis
• african-burkitts lymphoma
• nasopharyngeal cancer
• hairy oral leukoplakia

• occurs worldwide in humans, usually in childhood
• aquired thru contact with cervical or oral secretions
• multiplies B cells in oralpharyngeal epithelium
• asymptomatic in children
• T cell # increases to 80% of WBCs causing enlarged liver, spleen, and lymph nodes
• activation of T cells limits proliferation of B cells
• lasts 8-10 days

• tumor in jaw and face in children
• tumor shows EBV DNA and tumor antigens
• patients have an increased level of anti-EBV antibodies

• epithelial tumor
• tumor contains EBV-DNA
• possible genetic predisposition or environmental factors

• EBV associated
• lesions in the mouth
• opportunistic infection in HIV patients

• elecated white count
• downy cells

• causes roseola infantum
• -sudden rash, 3 day fever, rose rash, 6th disease

causes no known disease

• found in saliva of AIDS patients
• associated with karposis sarcoma
• colorful blotches, usually painless

• no envelope
• ds DNA
• icosahedral caapside with 12 penton fibers to bind to host
• attacks mucoepithelial cells of conjunctiva, respiratory tract, GI and gastrourinary tracts

• acute respiratory infection- common cold
• pharyngitis- like strep
• gastroenteritis
• epidemic keratoconjunctivitis

• HPV
• polymvirus

• wart causing virus
• naked double stranded DNA
• icosahedral cpsid
• replicate in suamous epithelium of skin and mucous membranes
• different serotypes determins warts

• common warts
• plantar warts- painful, deep, bottom of feet
• laryngeal papillomas- benign epithelial warts
• genital warts- common STI. 30 different types. many people are asymptomatic. associated with penile, uterine, and cervical cancers

• naked ds DNA
• icosahedral symmetry
• history unknown, no syndromes

• smallest naked, icosahedral DNA
• very resistant
• infects dogs, cats, mice, and humans

• B19 found in respiratory secretions
• Fifth disease
• -1st stage: fever/cold symptoms 8 days after infection
• -2nd stage: slapped cheek rash on face- erythema infectiosum. resolves in 1-2 weeks

• paramyxovirus
• Togaviridae

• enveloped
• (-) stranded RNA
• helical symmetry
• causes: Rubeola (measles) mumps, parainfluenza

• attaches via hemmagglutinin
• lacks neuraminidase activity
• caused by inhilation of respiratory secretions
• symptomatic
• highly contagious, especially 2-3 days before rash

• fever, runny nose, cough, conjunctivitis, Koplik's spots on mucosal membranes (white with blue halo)
• maculopapular rash from face to extremities

• impaired cell mediated immune response (giant cell pneumonea)
• otitis media and bacterial pneumonia
• encephalitis
• sum-acute sclerosing pan encephalitis (1-10 years after infection, progressing, very rare)

• life long immunity
• MMR attenuated live virus

• there are 4 types
• infect the upper and lower respiratory tracts
• causes 40-50% of croup cases

• parotid gland swelling
• transmitted via respiratory secretions and saliva
• highly contagious
• infects respiratory tract-> lymphoid tissue-> viremia

• orchitis
• aseptic meningitis

• MMR vaccine
• single serotype, life long immunity

• (+) strand RNA
• enveloped
• icosahedral symmetry
• member of rubrivirus genus

german measles (rubella)

• respiratory secretions
• upper respiratory tract infection-> lymph-> viremia-> elsewhere
• possible rash after 2 week inhibation period

• highest risk in early pregnancy
• infects placenta-> fetus
• neonate defects: hearing loss, mental retardation, congenital heart defects, neurologic problems, opthalmic problems, infectous of 1 year!