Group case study presentation evaluation 50 points
This presentation is the property of its rightful owner.
Sponsored Links
1 / 32

Group Case Study Presentation Evaluation: 50 points PowerPoint PPT Presentation


  • 26 Views
  • Uploaded on
  • Presentation posted in: General

Group #1 = 49.4 #2 = 49.4 #3 = 49.2 #4 = 49.8 #5 = 49.0 #6 = 48.3 #7 = 48.4 #8 = 49.8. Group #9 = 49.6 #10 = 49.5 #11 = 47.6 #12 = 49.3 #13 = 49.3 #14 = 49.8

Download Presentation

Group Case Study Presentation Evaluation: 50 points

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Group case study presentation evaluation 50 points

Group #1 = 49.4

#2 = 49.4

#3 = 49.2

#4 = 49.8

#5 = 49.0

#6 = 48.3

#7 = 48.4

#8 = 49.8

Group #9 = 49.6

#10 = 49.5

#11 = 47.6

#12 = 49.3

#13 = 49.3

#14 = 49.8

#15 = 48.7

Group Case Study Presentation Evaluation: 50 points


Replication of reverse transcribing virus

Replication of Reverse-Transcribing Virus


Family retroviridae

Family Retroviridae

  • “backward” nucleic acid synthesis

  • Convert genomic viral (+)RNA -> cellular dsDNA (provirus)

  • Uses RT (reverse transcriptase), RNA-dependent, DNA polymerase (also DNA-dependent, DNA polymerase)


Sub family spumavirinae

Sub-Family: Spumavirinae

  • “foamy” vacuoles in cell culture

  • Mammals, primates

  • Human foamy virus – first retrovirus found in humans

  • “orphan virus” - no associated disease


Sub family oncovirinae

Sub-Family: Oncovirinae

  • “tumor”

  • infection leads to cell transformation

  • RNA tumor virus

  • Avian, reptile, mammals, primates

  • Human T-cell leukemia virus (HTLV)


Sub family lentivirinae

Sub-Family: Lentivirinae

  • “slow”

  • Persistent chronic infection

  • Chronic disease of CNS, lung, immune deficiency

  • No cell transformation

  • Mammals, primates

  • Human immunodeficiency virus (HIV)


Lentivirus hiv

Lentivirus: HIV

  • Envelope (env) - 120 nm, glycoprotein spikes

  • Matrix protein (gag)

  • Capsid -icosahedral, wedge-shape

  • Nucleoprotein (gag) – group-specific antigen

  • Genome – two copies (+)RNA

  • Enzymes (prot:pol:int) – protease, polymerase (RT, RNAse-H), integrase


Hiv genome rna

HIV Genome: (+)RNA

  • Two RNA molecules associate by dimer linkage site

  • 10 kb; 5’ cap, 3’ polyA tail

  • Three major genes -(gag, pol, env)

  • Complex overlapping genes found in Lentivirus - regulatory, accesory

    (vif, tat, rev, vpu, vpr)


Hiv genome 5 end region

HIV Genome: 5’ End Region

  • R – terminal repeat, important for reverse transcription

  • U5 – unique 5’ end sequence (becomes 3’end of proviral DNA, signal for poly-A addition to mRNA)

  • PB – primer binding site of cell tRNA

  • Leader – recognition sequence for packaging genome RNA, donor site for all spliced subgenomic mRNAs


Hiv genome major genes

HIV Genome: Major Genes

  • gag (“group-specific antigen”) - code for structual proteins; capsid, matrix, nucleoprotein (RNA-binding)

  • pol (prot:pol:int) – code for enzymes

    • Protease cleaves viral polyprotein

    • RT/RNase for reverse transcription

    • Integrase cuts cell DNA to insert proviral DNA

  • env– code for envelope glycoproteins; surface, transmembrane


Hiv genome 3 end region

HIV Genome: 3’ End Region

  • PP – polypurine (A-G) tract, initiation site for viral (+)DNA synthesis

  • U3 – unique 3’ end sequence (becomes 5’ end of proviral DNA), regulatory sequences for mRNA transcription & DNA replication

  • R – terminal repeat, for reverse transcription


Hiv provirus dsdna replication

HIV Provirus (dsDNA) Replication

  • Uncoat in cytoplasm, viral genome (+)RNA with RT -> (-)DNA -> (±)DNA, transport into nucleus

  • Evidence for viral DNA:

    • Virus replication inhibited by actinomycin-D (blocks DNA->mRNA)

    • Infected cells have DNA complimentary to viral RNA

    • Discovery of viral RT


Reverse transcription ssrna to dsdna

Reverse Transcription (ssRNA to dsDNA)

  • Cell tRNA primer at PB internal site

  • (-)DNA synthesis, simultaneous RNA degradation by RT

  • “strong stop” at end, reinitiate DNA synthesis by “jumping” to other end

  • PP (short RNA sequence of genome) primer for (+)DNA strand synthesis

  • “strong stop” at end, “jumping” to other end

  • Proviral dsDNA with novel ends, Long Terminal Repeat (U3, R, U5)


Reverse transcription 1st jump

Reverse Transcription: “1st Jump”

  • 1. Primer tRNA anneals to PBS (genome RNA); RT makes (-)DNA (R U5) copy of 5’ end; RNase H removes hybridized RNA (R, U5)

  • 2.“(-)DNA strong stop”

  • 3. “First Jump” – (-)DNA R hybridizes to RNA R sequence at 3’end

  • 4.(-)DNA extended and completed (to PBS); most RNA removed, except PP tract


Reverse transcription 2nd jump

Reverse Transcription: “2nd Jump”

  • 5.PP primer for (+)DNA (5’ end U3RU5) synthesis; RNase H degrades PP tract

  • 6.“(+)DNA strong stop”

  • 7. “2nd Jump” – (+)DNA binds to PBS near 3’ end of (-)DNA

  • 7a. RNase H degrades PBS/tRNA of (-)DNA

  • 8. Both strands extended & Provirus completed:

    • dsDNA

    • LTR at ends


Hiv provirus integration into cell dna

HIV Provirus Integration Into Cell DNA

  • Requires viral LTR on ends of DNA

  • Viral integrase (endonuclease) nicks cell DNA at random sites

  • Viral DNA ligated into cell DNA

  • Integration required for retrovirus infection

  • Free viral RNA / DNA degraded by host cell


Hiv provius gene expression

HIV Provius Gene Expression

  • Uses host cell RNA pol II

  • Genome length mRNA:

    • Translates for gag or gag-pol proteins (by translational frame shift)

    • Genome for progeny virus

    • Multiple splicing for subgenomic mRNAs


Hiv spliced mrnas

HIV Spliced mRNAs

  • Translates for env proteins

  • Translates for regulatory & accessory proteins

    • Switch for subgenomic, genomic mRNAs

    • Down-regulate (nef)

    • Activate (tat)

    • Infectivity (vif)


Hiv genomic sub genomic mrnas

HIV Genomic/Sub-genomic mRNAs


Hiv assembly release

HIV Assembly/Release

  • Viral genome mRNA in cytoplasm associates with viral nucleoprotein and viral pol proteins

  • Capsid formation, insert genome RNA, migrate to matrix protein at cell plasma membrane

  • Capsid picks up envelope by budding through plasma membrane, exits cell


Hiv pathogenesis

HIV Pathogenesis

  • Infects macrophage (phagocytic defense) & helper T cell (regulates both humoral & cell-mediated immunity)

  • Persistent chronic infection in lymphoid tissue (clinical symptom of PGL = persistent generalized lymphadenopathy)

  • Virus held in low level by host defense

  • Over time, virus replicates to high level, destroys T cells, host immunity impaired

  • Clinical AIDS disease, opportunistic infections, and death

  • Follow course of infection by: CD4+T cells, HIV (RNA), clinical disease in patient


Natural history of hiv infection

Natural History of HIV Infection


Retrovirus oncogene

Retrovirus Oncogene

  • Oncogene: gene encoding the proteins originally identified as the transforming agents of oncogenic viruses, some of which were shown to be normal components of cells (growth control proteins)

  • v-onc is viral version of an oncogene

  • c-onc is cellular version of same gene

  • Most likely v-onc subverted from cell


Oncornavirus three mechanisms for cell transformation

Oncornavirus: Three Mechanisms for Cell Transformation

  • 1. Oncogene Transforming Protein

  • 2. Alter Host Cell Regulation

  • 3. Stimulate Host Cell Growth

  • Useful models in study of cell regulation and cell transformation

  • Most human cell cancers due to chemical carcinogens


Oncornavirus 1 oncogene transforming protein

Oncornavirus: 1. Oncogene Transforming Protein

  • Rapid transforming

  • Rous sarcoma virus in chickens

  • “src” (v-onc)

  • Gene product - tyrosine kinase, up-regulates cell metabolism

  • Leads to rapid cell transformation


Oncornavirus 2 alter host cell growth regulation

Oncornavirus: 2. Alter Host Cell Growth Regulation

  • Slow transforming

  • Virus does not have oncogene

  • Murine leukemia virus integrates into cell DNA

  • Turns on c-onc, up-regulates host cell

  • Continued cell activation, over period of time, leads to cell transformation


Oncornavirus 3 stimulate host cell growth

Oncornavirus: 3. Stimulate Host Cell Growth

  • Slow transforming

  • Virus does not have oncogene

  • Human T-cell leukemia virus (HTLV)

  • Infects T lymphocyte, release of cytokines, stimulates growth of neighboring T cells

  • Continued T cell activation, over time leads to cell transformation


Cellular retrovirus like genetic elements

Cellular Retrovirus-Like Genetic Elements

  • 1940’s - Barbara McClintock propose “moveable genes” by genetic studies of maize

  • Remove & insert circular genetic elements

  • Allow for genetic diversity

    • Bacterial transponsons: drug resistance

    • Retrotransposons: yeast, drosophila

    • Retroposons: humans


Reading questions

Reading & Questions

  • Chapter 19: Retroviruses: Converting RNA to DNA

  • Omit Chapter 20: Human Immunodeficiency Virus Type 1 (HIV-1) and Related Lentiviruses

  • Questions: 1, 2, 8, 9


Questions

QUESTIONS???


Class discussion chapter 12

Class Discussion – Chapter 12

  • 1. How does reverse transcriptase (RT) synthesize RNA into DNA utilizing three different enzyme activities?

  • 2. Why must the retrovirus DNA replication complex make two “jumps”? How is it able to “jump”? Seriously, does DNA really “jump”?

  • 3. Is reverse transcription unique to viruses?


Micr 401 final exam

MICR 401 Final Exam

  • Tuesday, Dec. 4, 2012

  • 1:30 – 3:00pm

  • Papovavirus thru Hepadnavirus

  • Case Study and Questions #9-15

  • Lecture & Discussion Questions, Reading & Chapter Questions

  • Exam:

    • Objective Questions (MC, T/F, ID)

    • Short Essay Questions


  • Login