MICRO CH9 VIROLOGY
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- Viruses are
- obligate intracellular parasites
- Viruses require:
- living hose cell in order to replicate (must invade & take over host cells functions & resources
- how many viruses have a complete mechanism for nucliec acid?
- none
- viruses usually have no mchanism for __________
- expression of their genes
- What facilitates transfer of viral nucliec acid to the host?
- a protien coat & additional specialized structures &/or enzymes
- a complete virus particle is called _________
- a virion (the product released)
- 2 Major Structures of viruses
-
1. naked nucleocapsid
2. enveloped virus - if a virus is naked it is just....
- protien & nucliec acid
- Capsid is a...
- protective outer chell that surrounds viral nucliec acid
- capsids are composed of
- capsomer subunits
- 3 types of Capsid structure
-
1.Helical
2. Icosahedral
3. Complex - Helical Capsids have...
- rod-shaped capsomers that form hollow discs that resemble a braclet
- a naked helical virus is..
- rigid & tightly wound into a cylinder shaped package
- In a enveloped helical virus the nuclio capsid is...
- more flexible
- Icosahedron Capsid is...
- 3 deminsional, 20 sided w/ 12 evenly spaced corners
- variation in capsomer number
-
polio virus 32 capsomer
adenovirus 240 capsomer - 1 cosahdral virus can be
- naked OR envelope
- during the release of animal virus (envelope)...
- a part of the host membrane is taken (lipid & host proteins)
- envelope enables __________ of the virus
- pleomorphic shape
- Function of the capsid/envelope
-
1.protect nucliec acid from hosts nucliec acid & protein digesting enzymes
2.assist in binding & penetrating host cell
3.avoids the stimulation of the hosts immune system - complex virus structures are...
- more intricate than helical & icosahedral viruses
- complex virues have...
- several layers of lipoprotein & course surface fibrils
- bacteriophage has...
- polyhedral head, helical tail, fibers for attachment
- tail fibers & pins-
- attach virus to specific sites on the cell surface of the bacterium
- viruses contain either
- DNA OR RNA
- viruses possess only the genes to-
- invade & regulate the metabolic activity of the host cell
- there are no viral metabolic genes;
- as the virus uses the hosts metabolic resouces
-
VR-
adsorption - virus bings to host cell
-
VR-
penetration - virus enters host cell
-
VR-
uncoating - viral nucliec acid is exposed for replication machinery
-
VR-
synthesis - viral nucliec acid is replicated, transcribed, and translated
-
VR-
assembly - viral virion components are assembled
-
VR-
release - mature virions are released to infect the next cell
- penetration of animal viruses occur by ______ or ______ between the viral envelope & the host cell membrane
-
endocytosis
fusion - uncoating & synthesis of viruses rely on the....
- hosts metabolic systems
- a mature virus can obtain a _____ by ________
-
envelope,
by budding off the host cell
(envelope virus way) - instead of budding a virus can _________ to _________
-
lyse,
release the viral progeny aka "popping the cell"
(naked viruses) - scaffolding proteins-
- help assembly of the capsid & then removed; other viral protiens are involved in final maturation
- release involves pahge ________ & ____________ to form holes in it
- endolysin & holin
- virulent phage only have a....
- lytic life cycle
- after viral multiplication inside the host cell, viral enzymes will......
- weaken the host cell membrane, rupture the cell (lyses), and release numerous virions
- lysogeny is when....
- the bacteriophage can insert its DNA into the bacterial host genome
- prophage =
- inovated its genome into it's host genome
- WHO estimates _______ people are infected w/ HIV
- 45 million
- AIDS is not a disease, but a...
- syndrome
- AIDS syndrome is....
- any of certain oppurtunistic or rare infections that occur in the presence of antibodies agaist the human immundoefiecny virus (HIV)
- HIV likely arouse from...
- mutation of the simian immunodeficency virus (SIV) found in African monkeys
- HIV only replicates....
- in humans & destroys the human immune system
- 2 major types of HIV
- HIV1 & HIV2
- HIV1 is...
- prevalent in US & Europe
- HIV2
- prevalen in west Africa
- AIDS first recognized in...
- young homosexual males in the US
- HIV is found in...
- sufficient concentrations to cause infections in blood, semen, saliva, vaginal secretions, & breast milk
- most infectious secretions of HIV:
- blood & semen
- immunology
- study of the development of resistance in infectious agents by the body
- remember 3 immunology things:
- surveillance of the body, recognition of forgien material, & destruction of forgien material of agents
- host defenses can be divided into two distinct branches:
- 1.innate immunity & 2. adaptive response
- innate immunity-
- NONspecific host defenses to infection
- adaptive response-
- host response to specific microbial infection (also to anything else that happens to enter the body)
-
1stLofD
intact skin- - low mositure, low pH; oily (sebum) residues inhibit microbes; desquamation (shed dead skin layers
-
1stLofD
conjuctiva (EYES)- - (lacrimal apparatus) tear dilution & lysozyme
-
1stLofD
outer ear- - antibacterial activity of waxes
-
1stLofD
mucus membranes-(gastroentestinal, genitournary, resptitory) -
gastro- saliva,(swalling, lysozymes, antibodies), stomach acids, intestinal mucis w/ antibacterial substances & antibodies
genitour- low pH levevl & high salt or urine flush urinary tract, acid vagina, lysozymes in seminal fluids
respitory- nasal hairs, nasal passages, cilited spithelium, clearing/coughing, alveoli macrophage - normal flora (bacterial antagonsim)-
- harmless bacteria compete w/ pathogens & may produce bacteriocins
- the trachea contain ______ that ______ & ________
-
cilia
entrap & propel particles out of the respitory tract -
2ndLofD
white bloods cells = - leukocytes
- **** phagocytosis-
- endocytosis of a microbe or "agent" & it's subsequent destruction. It is enhanced in neutrophilis & macrophge by OPSONIZATRON
- 8888 opsonizatron
- phagocyte adhesion to antibodies &/or compliment protein 3cb bound to microbes
- WBC recognize....
-
self markers on the host cell
&
nonself markers on the invading microbe - WBC do not attack or respond to....
- hosts cell
- WBC don't destroy....
- self cells while noself cells are recognized & destroyed
- every cell comes from...
- bone marrow
- produce ________ blood cells per second
- 8 million
- macrophage-
- highly produced phageocytic; high surface area of pseudopods, maybe "wandering in blood or "fixed" in assocation w/ mucosal membranes in healthy tissue
- dendritic cells-
- molecular pattern associated receptors for detecting microorganism, present antigens to T-cells. Located throughout lymph system, skin, and other tissues
- lymphocytes
- involved in specific resistance
- B CELLS-
- lymph sysyem associated w/ specific clones recognize ANTIGEN & stimulate multiplication, some mature to antibody releasing plasma cells, others become a long living dormant population of "memory cells"
- T CELLS-
- lymph system associated, involved in chemical communication & stimulation of B cell antibody production & may become cytotoxic to kill infected cells
- natural killer cells-
- granular kill viral infected & tumor cells
- systemic surveilance
-
1. lymphatic system
2. circulatory system (heart, veins & artiries)
3. tissue specific