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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?
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
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
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
virus bings to host cell
virus enters host cell
viral nucliec acid is exposed for replication machinery
viral nucliec acid is replicated, transcribed, and translated
viral virion components are assembled
mature virions are released to infect the next cell
penetration of animal viruses occur by ______ or ______ between the viral envelope & the host cell membrane
uncoating & synthesis of viruses rely on the....
hosts metabolic systems
a mature virus can obtain a _____ by ________
by budding off the host cell
(envelope virus way)
instead of budding a virus can _________ to _________
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...
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 is...
prevalent in US & Europe
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
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)
intact skin-
low mositure, low pH; oily (sebum) residues inhibit microbes; desquamation (shed dead skin layers
conjuctiva (EYES)-
(lacrimal apparatus) tear dilution & lysozyme
outer ear-
antibacterial activity of waxes
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 ______ & ________
entrap & propel particles out of the respitory tract
white bloods cells =
**** 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
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
involved in specific resistance
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"
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

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