Recent Developments in AIDS Diagnosis & Treatment

Presented by Joyce Lee, Kobika Thiyagasothy & Stephen Yee

Overview

Introduction to AIDSDiagnosis of HIV-AIDSTreatment of HIV-AIDS Summary

Introduction to AIDS

What Is HIV/AIDS?

Human Immunodeficiency Virus (HIV) causes Acquired Immune Deficiency Syndrome (AIDS)

Origin of HIV HIV-2 from soty mangabeys HIV-1 from chimps

Viral Life Cycle

2 phases: Extracellular & Intracellular Virus targets CD4 Receptor and Co-Receptor

on T-helper cells Reverse transcription of viral genome into a

DNA copy followed by integration into host genome

New virions assembled and bud off from host

How Does HIV Spread?

Transfer of bodily fluids Hetero and homosexual sex Oral Sex Needle Sharing Transfusion of contaminated blood products Childbirth & Breastfeeding

HIV/AIDS Mechanism

Immune system battles with virus Depletion of helper T-cells Host becomes vulnerable to secondary

infections

HIV/AIDS Mechanism

3 Phases of InfectionI. Acute Phase

Initial spike in viral load Followed by host immune response

II. Chronic Phase Immune system remains highly activated Results in depletion of helper T-cells

III. AIDS Phase

AIDS as a Public Health Issue

First case in 1981 13 400 newly infected with HIV every day 8 500 die of AIDS everyday

Methods of Diagnosis

Symptom Diagnosis

Compromised immune system High vulnerability to opportunistic infections Severity of symptoms can encompass multiple

organ systems

Symptom Diagnosis

Pulmonary1. Pneumoncytis Pneumonia (PCP)2. Tuberculosis (TB)

Gastrointestinal1. Esophagitis2. Chronic Diarrhea

Salmonella, Shigella, Listeria, Campylobacter

Symptom Diagnosis

Neurological1. Taxoplasmosis2. Progressive Multifocal Leukoencephalopathy

(PML) Tumors

Epstein-Barr Virus (EBV) Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) Human Papillomavirus (HPV)

Symptom Diagnosis

Antibody Tests

Enzyme Linked Immunosorbent Assay (ELISA) High degree of sensitivity for screening

Western Blot Test Viral proteins are separated first

Rapid Antibody Test Qualitative immunoassays OraQuick, Orasure & UniGold

Antibody Tests

Enzyme Immunoassays (EIA) 3rd Generation Wells contain recombinant proteins or synthetic

peptides Also contains anti-HIV IgG and IgM antibodies Change in colour indicates presence of anti-HIV

IgG and IgM Faster detection of HIV infection than previous 2

generations

Antigen Tests

P24 antigen test for HIV specificity A capsid protein of the virus Very short window of viability

Antibody Tests

Nucleic Acid-Based Tests

Has been used to detect diseases and genetic implications

Detection of target HIV gene sequences PCR is one method used to detect diagnostic

DNA fragments

Nucleic Acid-Based Tests

Polymerase Chain Reaction (PCR) uses heat stable DNA polymerase and 2 primers to amplify a target sequence

Real-time PCR Assays: Quantitative Method to measure PCR product as it is produced Allows quantification of number of pathogens in a

sample

Nucleic Acid-Based Tests

Abbot RealTime HIV-1 Assay Nested set of hybridization probes of various

lengths▪ Fluorescein (FAM) label at the 5’ end▪ Dabcyl or BHQ 1–dT at the 3’ end

Nucleic Acid-Based Tests

• In absence of target sequence, the quencher in close proximity of FAM absorbs the fluorescent signal

In presence of target sequence, the hybridization probe binds to target sequence Quencher separates from FAM resulting in

fluorescent emission

Antibody Tests

Enzyme Immunoassays (EIA) 4th Generation Well coated with HIV antigen and P24 antibody Colour change indicates anti-HIV antibody or P24

antigen Detection of P24 allows for earlier diagnosis of HIV

infection

Algorithm Tests

Future Algorithms Testing algorithm proposed to use the most

sensitive test possible with assays that differentiate HIV-1 from HIV-2 antibodies

If reactive for Ag / Ab but negative for antibodies, then tested for HIV-1 RNA

RNA establishes diagnosis of AHI which alerts doctors for urgent care

SIMBAS

Self-Powered Integrated Microfluidic Blood Analysis System (SIMBAS) Future cell powered chip Works like pregnancy test but checks for HIV or TB Chip separates plasma from blood cells and

detects if Vitamin B7 or Biotin was present Diagnosis in a matter of minutes

Methods of Treating HIV/AIDS Patients

Treatment

Isolated to homosexuals, hemophiliacs and heroin users

No actual cure Prevention based treatment

Sexual Education Drug Awareness

Treatment

AZT Structure similar to normal nucleotide Thymidine Has a –N3 group which interrupts DNA synthesis Proved effective and halted loss of macrophages

and T-cells In 1989 patients stopped responding Mutations were located in active sites of reverse

transcriptase

Antiretrovirals

Delay onset of infections Lifetime commitment drug plan Determined necessity by CD4 test Goal is to keep HIV in the body at a low level

Antiretrovirals

5 Major ClassesI. Protease InhibitorsII. Fusion or Entry InhibitorsIII. Integrase InhibitorsIV. Nucleoside/Nucleotide RT InhibitorsV. Non-Nucleoside RT Inhibitors

Combination Therapy

AIDS is virus with high fidelity Capable of developing resistance quickly

Cross Resistance Salvage Treatment

Side-Effects

Drug Specific Side-Effects Efavirenz causes psychiatric symptoms Protease inhibitors raise cholesterol and

triglyceride levels High Blood Pressure Susceptibility to Hepatitis infections

Side-Effects

Common antiretroviral symptoms Diarrhea Nausea & Vomiting Rashes Lipidystrophy with Loss or Gain of Fat Lipid Abnormalities

Maturation Inhibitors

Immature HIV particles composed of Gag precursor proteins

Mature infectious particle contains dense nucleoprotein Nucleocapsid and RNA

Bevirimat delays or blocks mature infectious particles from forming

Maturation Inhibitors

Maturation Inhibitors

Integrase Inhibitors

Raltegravir Dolutegravir Successful HIV replication requires 3 enzymes

Reverse Transcriptase, Integrase & Protease Inhibiting integrase blocks integration of HIV-1

DNA to host genome Prevents HIV replication and infection of new

cells

Treatments

CCR5 ∆32/ ∆32 Stem Cell Transplantation Patient remains without any sign of HIV infection

after successful transplantation Size of viral reservoir was reduced over time Cells of persons homozygous for the CCR5 gene

variant ∆32 are naturally resistant to R5 HIV strain

Treatments

Immunotherapy HIV infection results in CD4+ T-cell deficiency Correlation between a low CD4+ T cell count with

higher morbidity Helps maintain high level of CD4+ T-helper cells

Treatments

The Thai Trial $105 million, 6 year trial in Thailand Experimental Vaccine 31% effective in preventing

HIV infection RV144 a combination of ALVAC and AIDSVAX Study group includes low-risk heterosexual adults

Time to Go Home

Conclusion

Permanent cure unlikely because of rapidly reproductive nature of HIV

New combinatorial drug therapies are on the horizon

Still an importance on preventative measures

References

“AIDS & HIV Information from AVERT.org” AIDS & HIV Information. 10 January 2011. AVERT. 12 January 2011 http://www.avert.org/.

Nettleman, Mary. “HIV/AIDS Symptom, Treatment, History, Transmission, Diagnosis, Prevention” eMedicineHealth. 02 January 2011. eMedicineHealth. 12 January 2011 <http://www.emedicinehealth.com/hivaids/article_em.htm>.

Harrell, Eben. "Trial: AIDS Vaccine Reduces Risk of HIV Infection - TIME." TIME Magazine. 25 Sep 2009: n. page. Web. 29 Jan. 2012. <http://www.time.com/time/health/article/0,8599,1925957,00.html 

Levy, Yves, Christine Lacabaratz, Laurence Weiss, Jean-Paul Viard, Cecile Goujard, Jean-Daniel Lelièvre, François Boué, Jean-Michel Molina, et al. "Enhanced T cell recovery in HIV-1–infected adults through IL-7 treatment." American Society for Clinical Investigation. 119:4 (2009): pp 997-1007.

Bernard M, Branson. "The Future of HIV Testing." Journal of Acquired Immune Deficiency Syndromes. 55. (2010): pp 102-105. Print.

Evering, Teresa H., and Martin Markowitz. "HIV-1 Integrase Inhibitors." PRN Notebook. 13. (2008): pp 1-9.

Yang, Sarah. "New blood analysis chip could lead to disease diagnosis in minutes." UC Berkeley News Center. N.p., 16 Mar 2011. Web. 15 Jan 2012. <http://newscenter.berkeley.edu/2011/03/16/standalone-lab-on-a-chip/>.

Freeman, Scott, and Jon Herron. Evolutionary Analysis . 4th. Upper Saddle Riber: Pearson Education, 2007. 3-37. Print.

Huang, Shihai, John Salituro, Ning Tang, Ka-Cheung Luk, John Jr Hackett, Priscilla Swanson, Gavin Cloherty, Wai-Bing Mak, John Robinson, and Klara Abravaya. "Thermodynamically modulated partially double-stranded linear DNA probe design for homogeneous real-time PCR." Nucleic Acids Research. 35.16 (2007): 1-12. Print.

NIAID. "Classes of HIV/AIDS Antiretroviral Drugs." 26 03 2009: n. page. Web. 29 Jan. 2012. <http://www.niaid.nih.gov/TOPICS/HIVAIDS/UNDERSTANDING/TREATMENT/Pages/arvDrugClasses.asp&xgt;.

Salzwedel, Karl, David Martin, and Michael Sakalian. "Maturation Inhibitors: a New Therapeutic Class Targets the Virus Structure." AIDS. 9. (2007): 162-72. Print.