Biology Exam 1

Is a virus alive?
no, no cells or cellular complexity
Functional anert material
– live off other animal
– don’t grow, metabolism, produce outside living cell
– don’t move on own
obligate, intracellular, infectious agent
Virus components
– genetic material- DNA/RNA
– inter core
– outer covering- capsid
Genes packaged in a protein coat
philomot virus little body surround by tube
– capsomere make up capsid
Membranous Envelope
picks up cell membrane that surrounds capsid
More complex virus infect simple cells: Bacteria
Simple virus infect complicated cells
a sugar is attached to capsomere
– attach to surface receptor on cell
Surface Receptor
bind to specific receptor sight to get in system
What all viruses do…
stop cell growth and proper cell production uses cell energy to make more virus products (viral progeny)
Viral Classification
placed into “families” and “genera”
– don’t have common ancestor and are independent (not alive and coming from each other)
Viral Groups
based on type of genetic material
1) DNA
2) RNA
Viral Genome
– can be
double stranded DNA
single stranded DNA
single stranded RNA
double stranded RNA
-single linear molecule or circular molecule (two ends joined)
– between 4 genes to several hundred genes
Where virus come from?
1. virus degenart type of cell lost cell like just didn’t need it any more, dependent on host
2. independently form, happened along side when life forms, just not cellular life
3. breaking off of pieces of DNA/RNA and escape from life form
Viruses are considered host cell specific/tissue specific
– many times species specific
– most only exert effect on one species and specific tissue
– molecular receptor site it recognize will be specific and attach and get into that
Small Viruses
20- 40 nanometers
EX: papovaviruses, paroviruses, picornaviruses
Complex Viruses
40- 90 nanometers
EX: adenoviruses (sore throats), retroviruses (aids), bunyaviruses
Large Viruses
over 100s of nm
EX: poxviruses, rhabdoviruses
Giant Viruses
can be >400
EX: megavirus, pandoravirus, pithovirus
Viruses are considered colorless because they are outside the color spectrum
Virus Size range
range from 17-1500 nanometers
-1 nanometer = 1×10^-9 m
(look at comparison sizes in notes)
1796 Edward Jenner
– researched the effects of smallpox
– injected boy with cowpox from a milkmaid’s sore
– created first vaccine (vacca= cow)
Vaccination = immunization
when get pathegine the body recognized the proteins that isn’t self made or matches it will fight it to get out of system, white blood cells, which become memory cells that are left so body doesn’t take so long to make them
Types of Vaccinations
1) attenuated “live” virus (weakened. could readopt)
2) killed “dead” virus (chemical or heat)
3) destroyed capsid pieces (exposing proteins from virus for body to recognize if get it)
1883 Aldof Mayer
– research Tobacco Mosaic Virus (TMV)
– discovered that disease agent was infectious (present in sap and could be passed on to other plants)
1885 Louis Pasteur
– developed rabies vaccine with attenuated viruses
1893 Dimitri Ivanowsky
– passed infected TMV sap through a filter designed to trap bacteria (discovered it was smaller then bacteria)
1897 Marinus Beijerinck
– discovered TMV could reproduce (no dilution of infection when passed from one plant to another)
1935 Wendell Stanely
– crystalized TMV; revealed that viruses were noncellular and nonliving
Gene Therapy
“healthy” alleles are inserted into a virus; virus transports them into a cell it infects that formerly had “diseased” alleles
– these modified cells can now make the “healthy” products and are inserted back into the patient
Oncolytic Viruses
engineered to specifically kill certain cancer cells; patients show improved response rate when used in conjunction with chemotherapy (EX adenovirus H101)
only effect bacteria (attach to outside of bacteria) engulf it and explode to have viruses release it
Phage Therapy
bacteriophages used to specifically kill pathogenic bacteria (EX listeria spp.)
Parasitic wasps: Polydnavirus
– eggs in capitulary, wasp eat out catipellar
– catipellar is paralyzed and immune system is paralyzed
– wasp has virus gene- derive from virus
– 17,500 species
– 100 million years ago mutation occurred
thing derive from ancestry and passed down and are now for all in group
Molecular Clock
mutation rate is constant and is negative and number of times takes to change
-time that it takes to mutate the way it currently is
– single strand mutate faster then double strand
Horizontal Gene Transfer
– getting genes from one species to another- things that aren’t related
– common between bacteria and viruses
– completely outside group/ species
– Human HIV (get into DNA and have it forever)
Skin Warts
– Human Papilloma Virus
– over hundred subtypes
– contagious- especially when cuts on the skin
– most are cosmetic problems
– common in children and persistent in adults
– child 50% disappear w/out treatment within 6 months; 90% in 2 years
Skin Wart Treatments
1) Chemical- 70% wart paint
2) Cryotherapy- 70% freeze it
3) Electrosurgery (80%) electrocute to death
4) Injections (82%) bleomycin or candida extract
5) Occlusion (85%) duct tape- completely covered
Wart Subtypes
1) Common Warts- hand/fingers/knees
2) plane warts- spread by shaving- low profile
3) planter warts- bottom of feet, isolated
4) mosaic warts- bottom of feet, strong together
5) periungual warts- around nails
6) cauliflower warts- anywhere- boldness, black marks dead tissue
7) filiform warts- grow like a stock
8) oral warts- in mouth
9) genital warts
– low risk- cause warts and spread rapidly
– high risk- cause cancer or lead to it
– 66% exposed will contract
– 52 subtypes
– first found in adenoids- tonsils
– cause 10% of kids respiratory infection
– 50% of all human virus common cold are actually this
– spread by fluid droplets
– causes gastroenteritis
– 90 nm- largest non-envelope virus
Herpes Viruses
– over 100 different subtypes
– most prolific and successful group of viruses
– growth hormone receptor site
– most are species specific
– human 8 types; horse 5 types
– herpein: to creep or serpent
– strike and then hide- become latent in CNS
– HSV 1- oral/face HSV 2 genital
HSV 1 and HSV 2
– virtually identical in structures
– 50% identical in genes
– both infect mucosal surfaces then lie latent
– hide from immune system; permanent
– primary difference is site of preference
– HSV 1 lies latent in trigeminal ganglion
– HSV 2 lies latent in sacral ganglion
– both can reside and infect both areas
– 66% of people have subclinical or no symptoms
– 50% of U.S. teens and 90% have by age 50
Herpes Simplex Virus: Outbreaks
– outbreak when first exposed
– chanare- open skin leisure
– induce to recur (outbreak) by:
1) UV light
2) extreme cold or wind
3) emotional or physical stress
4) weakened immune system
– frequency and severity of outbreaks:
1) difference in immune response
2) time (longer had more it occurs)
3) in site of preference
4) viral type 2- genitally 1- orally 1 genitally 2 orally
Herpes Simplex Virus: Transmission
– most contagious during outbreak
– viral particles are always spread even with no symptoms
– HSV 1- in saliva 5% of the time
– HSV 2- shed from genitals 6-10% of days
– can get either type after have the other (change is reduced 40%)
– in absence of prior oral infection HSV-1 easily spreads to genitals
“cold sores” or “fever blister”
– herpes labialis
– neonatal herpes
– herpes keratitis (eyes) “ocular herpes”
– herpes whitlow (fingers/hands)
– herpes gladiatorum (skin lesions) “wrestler head”
herpes genitalis
-herpes zoster “chicken pox”
– Varicell zoster (VZV)
– is a vaccine 1995- 85% effective, lasts 20 years
– mild and severe form
– 4 million cases/year; 90% < 10 years old 5% >20
– 11,000 severe cases; 140 deaths in U.S. (adults)
– symptoms: fever, head aches, back aches, sore throat, skin rash, fluid filled blisters
– highly contagious- transferred through air- 2 days before rash until scabs
– enters lungs, carried by blood to skin
– incubation period 10-20 days
Epstein-Barr Virus
HHV 4 (EBV) “Mononucleosis”
– named because thought monocytes but is lymphnic
– very common
– 95% of U.S. adults have had
– cause mild or few symptoms in kids
– symptoms: fever, sore throat, fatigue, swollen lymph glands
– last 1-2 months
– can cause cancers
– poxvirus
– red skin blister, transmitted by touch through broken skin
– found only in Europe, rare human cases (one class)
– “self-limiting” disease in humans
– reservoir host: voles (rodents)
– usually contracted via cats or cows
– exposure to cowpox produces antibodies that fight small pox
– typically in children
– red skin blister
– transmitted by direct contact, inhalation, or insect bites
– worldwide disease, 1977- last wild case 1979- declared eradicated
– die from other complications: pneumonia, encephalitis, kidney failure
– 2 variants: variola major and minor
– named small pox to distinguish from great pox 1400s
– evolved from a rodent virus 68 to 16,000 yrs ago
– 500 million death in 20c
– 2 million death in 1967
-1947 last major outbreak 1949 last person died
Smallpox Conditions
– incubation 3-10 days
– rash starts on face, forearms, chest
– first emerge as “merciless” (skin blisters)
– 2nd day become raised “papules”
– 3rd-4th day become “fluid filled vesicles”
– max between 7-10 days, then scab over
– leave permanent scars
– vaccine= attenuated live virus- 1982-stopped vaccinating (1 in 1million died from vaccine)
Eradication of a disease
1) severe disease
2) no subclinical cases
3) infectivity accompanies rash
4) no known recurrent infectivity
5) only one subtype
6) seasonlity of disease
7) no animal reservoir
8) vaccines
Picornavirus- poliomyelitis
– damage the nervous system – paralysis
– 3 subtype of virus produce similar disease (PV 1,2,3)
– enter body through mouth via hands
– usually from stool of infected person
– virus lives in throat for 7 days and intestine for 6+ weeks
– symptoms begin after 1-14 days
– no effective treatment ( emily start doing physical therapy- put heat on area and constantly work those muscle to get nerves still alive to work)
– in U.S. last case of “wild polio” was in 1979
– 1994 was eradicated in U.S.
– 2 vaccines IPV- killed; OPV- attenuated
– community health- getting people to be immune without getting vaccine sometimes
– 1,000 cases per year
Why is polio still around?
– 4 countries in 2010
– India (water system isn’t the best)
– Political problems/views
+ don’t trust us with vaccine
+ taliban and extremest won’t allow vaccines
Polio Timeline
– 1890’s- early 1900s: major outbreaks
– ancient virus
– 1907: virus identified
– 1952 (1955): Salk Vaccine (killed Virus)
*Cutter Incident: 120,000 doses of live virus sent out (40,000 caught polio, 56 paralysis, 5 died)
Polio Vaccine
Jonas Salk- IPV (killed virus)
Alber Sabin- OPV (live virus)

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