This document is a report from medical microbiology students at the University of Gondar on immunity against HIV infection. It outlines the HIV lifecycle and the components of the antiviral response. It reviews literature showing that both humoral and cellular immunity are ineffective at controlling HIV over time as the virus mutates. It concludes that HIV depletes immune cells and blunts the immune response, establishing a latent reservoir early in infection. Further research is needed to better understand the immune response mechanisms against HIV.

1. UNIVERSITY OF GONDAR
COLLEGE OF MEDCINE & HEALTH SCIENCES
SCHOOL OF BIOMEDICAL & LABORATORY
SCIENCES
DEPARTMENT OF IMMUNOLOGY & MOLECULAR
BIOLOGY
TOPIC: IMMUNITY AGAINST HIV INFECTION
3/9/2013 Med.Micro students 1

2. Prepared by:
 Abebe Bekele  Seble Worku
 Alembanch Tsega  Setegn Eshetie
 Amele work Yilma  Tesfaye Andualem
 Feleke Mekonen
 Tigist Engda
 Melkamu Getnet
 Wondossen
 Emebet Sahlie
3/9/2013 Med.Micro students 2

3. Acknowledgment
 We would like to extend our gratitude
to Mr. Biniyam Matheous; for his
interactive and participatory teaching
learning style.
3/9/2013 Med.Micro students 3

4. Out line
 Introduction
 HIV life cycle
 Components of antiviral response
 Immune pathogenesis of HIV
 Literature review
 Conclusion
 Recommendation
 Reference
3/9/2013 Med.Micro students 4

5. INTRODUCTION
Family : Retroviridae
Subfamily : Lentivirus
 RNA virus, 120nm in
diameter
 Envelope gp160; gp120 &
gp41
 Icosahedral symmetry
 Nucelocapsid
 Outer matrix protein (p17)
 Major capsid protein (p24)
 Nuclear protein (p7)
 Diploid RNA with several
copies of reverse
transcriptase
3/9/2013 Med.Micro students 5

6. Retroviral Genes
 gag (group-specific antigen): makes the cone shape
viral capsid.
 pol (polymerase): codes for viral enzymes reverse
transcriptase, integrase, and viral protease.
 env (envelope): makes surface protein gp120 and trans
membrane gp41, enabling HIV to fuse to CD4 cells.
3/9/2013 Med.Micro students 6

7. con…
3/9/2013 Med.Micro students 7

8. HIV life cycle
3/9/2013 Med.Micro students 8

9. Component of antiviral response
 Both humoral and cell-mediated immune responses
partially control the viral production but in this
process they destroy the infected CD4+T cells,
leading to a gradual decline of CD4+ T cells
Innate Immunity
 Antigen presenting cells: Macrophage and Dendritic cells
 Other cell types: NK, gamma- delta , NKT cells
 Soluble factors: Chemokines
Adaptive Immunity
 CD4 T helper cells
 CD8 T cells (CTL)
 B cells: Neutralizing antibodies
3/9/2013 Med.Micro students 9

10. Cont…
3/9/2013 Med.Micro students 10

11. Pathogenesis of HIV / AIDS
Infected T-Cell
HIV HIV Infected New HIV
T-Cell T-Cell Virus
Virus
3/9/2013 Med.Micro students 11

12. Immune pathogenesis of HIV
 Mechanisms
syncytium formation
Apoptosis
Auto immunity
3/9/2013 Med.Micro students 12

13. Literature review
 HIV will mount an effective immune
response to the virus during the first few
months of infection. However, over time this
response will prove ineffective.
Humeral immunity
Cell
mediated immunity
 Both are ineffective
3/9/2013 Med.Micro students 13

14. Cont…
 Mucosal immunity Vs HIV infection
 The study demonstrated that commercial
sex workers were HIV negative after 5 yrs
active prostitutions
 Associated with the integrity of mucosal
immunity.
3/9/2013 Med.Micro students 14

15. Cont..
 Study indicated that intranasal
administration of DNA vaccine and IL-15
expression plasmid is capable of enhancing
the T helper type 1 (Th1) dependent HIV-1-
specific cell-mediated immunity, but
 It decrease humoral immunity
3/9/2013 Med.Micro students 15

16. Cont…
 DCs are key regulators of both adaptive and
innate immune responses
 According the study, it revealed that the
plasma from patients with HIV specifically
inhibited DC function.
 mediated by elevated apoptotic micro
particles.
3/9/2013 Med.Micro students 16

17. Cont…
 The study confirmed that HIV infection causes
 NK cells apoptosis (increase expression of ki67 and
Fas markers in course of infection)
 Macrophage and monocyte phenotype change (
alteration of TLR)
 Causes defect in microbial killing
3/9/2013 Med.Micro students 17

18. Cont..
 Depot medroxyprogesterone acetate
(DMPA) usage relation to HIV immunity.
 Decrease both arms of immunity(interferon
(IFN)-gamma, IL-2, IL-4, IL-6, IL-12, TNF
alpha and other cytokines)
 Mediate up regulation of co-
receptors(CXCR4, CCR5)
3/9/2013 Med.Micro students 18

19. Con…
 In contrast: PA-MSHA activates both
natural and specific immunity
 NK cells, APCs activates through TLR
 More over: serve as adjuvant for HIV-1 DNA
vaccine. Increase Humeral and Cell mediate
response
3/9/2013 Med.Micro students 19

20. Cont…
 cholesterol-25-hydroxylase (CH25H)
recognized that a broadly antiviral
interferon stimulated genes
 Converts cholesterol in to soluble antiviral
agents; inhibits viral replication
(attachment)
 Animal model shows: CH25H deficient mice
more susceptible to HIV-1 infection.
3/9/2013 Med.Micro students 20

21. Conclusion
 HIV establishes a latent reservoir early in infection
 HIV develops mutations to escape immune
responses,
 HIV depletes functional cells of innate immune
system
 HIV depletes CD4 T cells: the “conductor of the
immune orchestra” and blunts immune responses
 HIV causes deleterious effects on the entire immune
system resulting in aberrant immune activation
3/9/2013 Med.Micro students 21

22. Recommendation
 The mechanism of immune response
against HIV infection remains
incompletely understood, so that
 It needs further investigation.
 So that we post graduate students
should take emphasis in this particular
researchable area.
3/9/2013 Med.Micro students 22

23. References
 Hou J, Liu Y, Shao Y. The MSHA strain of
Pseudomonas aeruginosa activated TLR pathway and
enhanced HIV-1 DNA vaccine immunoreactivity. PloS
one. 2012;7(10):e47724. Epub 2012/10/19.
 Poudrier J, Thibodeau V, Roger M. Natural Immunity
to HIV: A Delicate Balance between Strength and
Control. Clinical & developmental immunology.
2012;2012:875821. Epub 2013/01/11.
 And more
3/9/2013 Med.Micro students 23

24. 3/9/2013 Med.Micro students 24