Microbiology Lecture 7 Review: ADDITIONAL Chpt 27.5 Questions

1.    ADDITIONAL QUESTIONS # 1 (Self Added)
What are the components of the HIV virus?

Proteins	Function
Capsid protein (CA or 24)	Coats proteins
Matrix protein (MA or p17)	Stabilized virion
Transmembrane protein (gp41)	Stalk like portion of spikes, anchors them to viral envelope
Surface glycoprotein (gp120)	Cap like portion of the spikes with which the virus attaches to host receptors
Reverse transcriptase	Enzyme that makes viral RNA into DNA
Integrase	Enzymes that inserts viral cDNA into host genome
Protease	Enzyme involved in viral protein processing.

2.    Draw the graph for Pathogenesis of HIV (Indicate # of T helper cells and amount of viral antigen): Lec 7 – Slide 21

Blue line = # of T helper cells
Orange line = Viral antigens (RNA)
4 stages:
1 – Incubation → NO signs/symptoms, HIV hiding in T helper cells.
2 – Acute HIV infection → Signs & Symptoms: fever, swollen lymph nodes, pharyngitis; HIV replicating in T helper cells, immune system exposed to HIV mounting response to eliminate virus from bloodstream and destroy infected T helper cells. HIV hides in macrophages now.
3 – Latency stage → NO signs/symptoms, macrophages infected, presence of anti-HIV antibody only indication of HIC infections, HIV spread back to T helper cells after budding from marcophages
4 – AIDS → Opportunistic infections, T helper cell count drops below 200 cells/µL.

3.    How can HIV be diagnosed? Lec 7 – Slide 22

·      Genetic analysis – Presence of HIV RNA can be tested at any time because viral genome is present either in cytoplasm/integrated into host cell chromosome, can be seen when amplified by PCR reaction.

·      Serological analysis

o   HIV antigens – Presence can only be tested in serum during 2^nd phase (acute infection) or 4^th phase (AIDS) because HIV antigens must be present in blood stream to be found with Western blot.

o   Antibodies against HIV – Presence can only be tested in serum 2 – 6 weeks after 2^nd phase (acute infection), for phases 3 and 4 (latent, AIDS) because antibodies that are developed to the virus persist for up to 3 months. Can be detected with ELISA.

4.    How can HIV be prevented? Lec 7 – Slide 28

·      Use of condoms: Reduce possibility of trauma to mucous membrane.

·      Use of sterile needles: Needles destroyed before discarded.

·      Healthcare workers use universal precautions: PPE, NO recapping of needles, protective prophylaxis, ART (antiretroviral therapy) upon accidently exposure to HIV.

·      Mandatory screening of blood: Screening of blood supply.

5.    What are the current vaccines for HIV in clinical trials? Lec7 – Slide 28

·      Whole-cell Salmonella with gp120 gene expressed

·      Subunit vaccine using gp120 expressed in Saccharomyces cerevisia

·      Canarypox virus with HIV capsid protein genes

·      Naked DNA consisting of tat (transcription factor) and gag (capsid protein) genes

6.    What are the treatment options for HIV infection? Lec7 – Slide 29
Highly Active Anti-Retroviral Therapy:

·      Reverse transcriptase inhibitors – Prevent conversion of viral ssRNA to dsDNA.

o   Nucleoside analogs – Inhibit reverse transcriptase by competing with nucleotides for enzyme’s active site (Ex: Didanosine). ~ Competitive

o   Non-nucleoside inhibitors – Inhibit reverse transcriptase by binding to site other than nucleoside binding site (Ex: Nevirapine, Delavirdine). ~ Non-competitive

·      Integrase inhibitors – Block HIV from becoming latent virus by stopping viral genome integration with chromosome of infected cell.

·      Protease inhibitors – Block assembly of new viral particles

*** As of 2018 less than 50% of HIV infected people have access to drugs.