BIO 110 Study Guide - Midterm Guide: Luc Montagnier, Reverse Transcriptase, Envelope Glycoprotein Gp120
Bio Study Guide – Post Exam 3
Immune System
- Innate immunity – nonspecific, used against many organisms
o Barriers, skin, mucugens
o Lysozyme – breaks down bacterial cell walls
o Defensin – binds to bacteria and ruptures their membranes
- Acquired immunity – specific, involves antibodies and memory
o Lymphocytes
o B cells – make antibodies – proteins that bind specifically to antigens identified
by the immune system
▪ Antibodies have two light chanis and two heavy chains held together by
disulfide bonds. Each has a variable region of the heavy chain, which is
where it recognizes the antigen and binds to it
o T cells – can recognize antigens by attaching a signal to the antigen membrane
(Th – general cells, recognize invasion and activate B-cells. Tc – release toxins that
kill pathogens
o Is very specific (1 antibody can recognize 1 antigen)
o Immunological memory
▪ Primary immune response – the lphotes are aïe of the atige
and take a while for a mounted attack or creation of memory cells
▪ Second and later immune response – response is much faster because
immune system recognized the antigen and knew how to kill it
• Recognition – cells discriminates between self and antigen
• Activation – cells move to site
• Effector – mobilized cells destroy invader
- White blood cells
o Phagocytes – engulf pathogens
o Lymphocytes – help with adaptive immunity
o Inflammation gone bad
▪ Allergies, autoimmune diseases, sepsis
- Humoral v. cellular immunity
o Humoral – production of antibodies ending with B-cells
o Cellular Immunity – activation of Tc that bind and destroy infected cells
- Viral diversity
o Either DNA or RNA; single stranded or double stranded; linear or circular
- HIV history
o June 5, 1981 – a report publishes about 5 cases of pneumonia in previously
healthy gay men (2 had died)
o Discovered by Robert Gallo and Luc Montagnier
▪ HIV was at first believed to be HTLV-III, but it is not actually that similar
o Probably occurred through zoonosis – transfer of a virus from animal hosts to
humans under natural conditions
▪ Two strains of HIV: HIVI and HIVII
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▪ HIVI and HIVII are more similar to other viruses than each other, which
likely means that developed individually and there were two cases of
zoonosis
o 1984 – CD4 is HIV receptor
o 1987 – 1st drug
o 1989 – 2nd drug
▪ NOTE: would not give the drugs until one showed symptoms because the
virus could easily develop resistance
o 1996 – more receptors
o 1996 – good antiretroviral therapy
▪ treatment is very expensive
- HIV structure
o Very small genome, overlapping genome (multiple reading frames)
o Has receptor gp120 that binds with CD4
o Capsid protein (p24)
o Within capsid there is RNA genome and reverse transcriptase
- HIV Steps
o HIV must bind to CD4
o Once bound to CD4, gp120 changes shape to be able to bind with another
receptor on the Tc cell
o Membranes fuse
o RNA genome binds to reverse transcriptase, which is a RNA dependent and then
a DNA dependent enzyme
o RNA is transported to the nucleus and is integrated into the host genome
(integrase)
o Viral genome will chill there for a bit
o Under right conditions, viral genome will be expressed and produce RNA
genomes and viral proteins that are all attached to each other
o Products move to cell surface and form an immature HIV cell
o Protease cleaves protein clump into respective proteins and cell is mature
o Virus leaves the host cell
▪ Some people are non-progressors that are not hurt by infection
▪ Could be due to stronger Tc cells or better antibodies
- Testing for HIV
o Elisa – looks for antibodies against HIV by using proteins
o Western Blot – looks for HIV proteins by using antibodies
o PCR – use PCR with HIV primers
- Why is it so devastating?
o Reduces helper T cells
o Immune system kills good cells
o HIV destroys immune system precursor
o High mutation rate
o Most infectious at the beginning and the end
o Latent reservoir
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- Treatment
o Sterilizing cure – eliminating all traces of the virus in body
o Functional cure – a drug that is taken once so they are not infectious or harmed
o Prevention:
▪ TRUVADA
o Treatments for infected individuals
▪ CRISPR – cut out viral genome
▪ Blocking binding of CD4 with gp120
▪ Reverse transcriptase inhibitors (AZT, didanosine, abacauir)
▪ Integrase inhibitors
▪ Protease inhibitors
▪ HAART – combine three or more drugs at a time in order to prevent
evolution of drug resistance
▪ Shock and kill to kill the latent reservoir
▪ Creating the antibodies that resistant people have and making a gene
that a e plaed ito other people’s DNA
• Converts them into a human factory of that antibody
▪ Editing Tc receptor genes
▪ Evolution of cleaver protein that is highly specific for HIVI
Cell to Cell Communication
- Cell signaling – cell to cell communication, usually involving signaling molecules and
specific cell surface receptors
- Signal transduction – all occurrences that occur after receptor is bound to signal ligand
o This is iportat eause the sigal ligads a’t activate anything within the
membrane
o Aids in signal amplification – signal affects more and more things
o Can be used to influence many different kinds of cells
- This is regulated through post-trasitioal proessig, eause the rai a’t afford to
waste time making these proteins
- Rules of signaling
o Cells exist in a changing environment (receive external signals)
o Cells must receive and process external signals
o Cells can send out signals of their own
- Steps to signaling
o Make signal
o Release signal
o Transport signal to target cell
o Target cell detects signal
o Change in the receptor in response to signal, causes the desired response
o Remove the signal
- Types of signaling molecules/ signals
o Protein hormones
o Signaling proteins
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Innate immunity nonspecific, used against many organisms: barriers, skin, mucugens, lysozyme breaks down bacterial cell walls, defensin binds to bacteria and ruptures their membranes. Is very specific (1 antibody can recognize 1 antigen) White blood cells: phagocytes engulf pathogens, lymphocytes help with adaptive immunity. Inflammation gone bad: allergies, autoimmune diseases, sepsis. Humoral v. cellular immunity: humoral production of antibodies ending with b-cells, cellular immunity activation of tc that bind and destroy infected cells. Viral diversity: either dna or rna; single stranded or double stranded; linear or circular. Hiv structure: very small genome, overlapping genome (multiple reading frames, has receptor gp120 that binds with cd4, capsid protein (p24, within capsid there is rna genome and reverse transcriptase. Testing for hiv: elisa looks for antibodies against hiv by using proteins, western blot looks for hiv proteins by using antibodies, pcr use pcr with hiv primers.
