Morphology, Pathogenesis, Labdiagnosis, Treatment and Prevention of HIV

1. Dr. S. MEENATCHISUNDARAM
ASSOCIATE PROFESSOR
DEPARTMENT OF MICROBIOLOGY
SNMV COLLEGE OF ARTS AND SCIENCE
COIMBATORE
https://orcid.org/0000-0002-8691-449X
95496
https://scholar.google.com/citations?user=IkdZ5XsAAAAJ&hl=en
HIV - The AIDS Virus

2. INTRODUCTION
H - Human (because it infects people)
I - Immunodeficiency (because it affects the immune system and
eventually stops it working properly)
V- Virus (because it is a retrovirus)
- Subgroup – lentiviruses
- etiologic agents of AIDS
- AIDS is one of the most important public health problems
worldwide at the start of the 21st century

3. INTRODUCTION
There are two types of HIV virus
 HIV 1 is most common in sub-Saharan Africa and throughout the world.
 HIV 1 can be divided into groups M, N, and O.
 The pandemic is dominated by Group M, which is composed of subtypes A – J.
 HIV 2 is most often found in West Central Africa, parts of Europe and India.
 Both produce the same patterns of illness. HIV 2 causes a slower progression
of disease than HIV 1. It is important for tests to detect the HIV subtypes that
are present in the region. Otherwise, testing may lead to false negative
results.

4. INTRODUCTION
AIDS stands for
Acquired: To come into possession of something new
Immune Deficiency: Decrease or weakness in the body’s ability to fight off
infections and illnesses
Syndrome: A group of signs and symptoms that occur together and characterize
a particular abnormality
AIDS is the final stage of the disease caused by infection with the virus.

5. MORPHOLOGY
 Virion: Spherical, 80-100 nm diameter, cylinderic
 Genome: SS +RNA (diploid), 9-10kb
 Proteins: Envelope glycol protein (Ag-variation),
RTase, integrase, protease
 Envelope: present, lipid membrane, gp120 & gp41
 Other proteins: P17 matrix protein, P24 Capsule Protein

6. MORPHOLOGY
A. Envelope antigens:
1. Spike antigen—gp120 (Principal envelope antigen)
2. Transmembrane pedicle protein—gp 41
B. Shell antigen
1. Nucleocapsid protein—p18
C. Core antigens
1. Principal core antigen—p24
2. Other core antigens—p15, p55
D. Polymerase antigens—p31, p51, p66
MAJOR ANTIGENS OF HIV

7. VIRAL GENES AND ANTIGENS
 The genome of HIV contains the
three structural genes (gag, pol and
env) characteristic of All retroviruses,
as well as other nonstructural and
regulatory genes specific for the
virus.
 The products of these genes, both
structural and nonstructural, act as
antigens
 Sera of infected persons contain
antibodies to them.
 Detection of these antigens and
antibodies is useful in the diagnosis
of HIV infections
RETROVIRUS GENES AND THEIR FUNCTION

8.  HIV continues to be a major global public health issue
 HIV infection is often diagnosed through rapid diagnostic tests (RDTs), which detect the
presence or absence of HIV antibodies.
 Most often these tests provide same day test results; essential for same day diagnosis and early
treatment and care.
 There is no cure for HIV infection. However, effective antiretroviral (ARV) drugs can control the
virus and help prevent transmission so that people with HIV, and those at substantial risk, can
enjoy healthy and productive lives.
 The Human Immunodeficiency Virus (HIV) targets the immune system and weakens people's
defence systems against infections and some types of cancer.
 As the virus destroys and impairs the function of immune cells, infected individuals gradually
become immunodeficient. Immune function is typically measured by CD4 cell count.
 Immunodeficiency results in increased susceptibility to a wide range of infections and diseases
that people with healthy immune systems can fight off.
 The most advanced stage of HIV infection is Acquired Immunodeficiency Syndrome (AIDS),
which can take from 2 to 15 years to develop depending on the individual.
 AIDS is defined by the development of certain cancers, infections, or other severe clinical
manifestations.
HIV – The AIDS Virus
Key facts

9. VIRAL ENTRY
 HIV Binds to Cell (gp 120 WITH CD4)
 Fuses with cell and injects its core
VIRAL TRANSFER
 Reverse transcriptase makes DNA copy of viral RNA
 DNA Polymerase makes second DNA copy
 Integrates into cellular DNA (integrase)
 Translation of RNA into viral proteins
 Protease cleaves viral enzymes
 Proteins and RNA are assembled into new virions
VIRAL EXIT
 Virus buds from cell surface
HIV – The AIDS Virus
HIV CYCLE

10. HIV – The AIDS Virus
REPLICATION
VIRAL ENTRY
 HIV Binds to Cell (gp 120 WITH CD4)
 Fuses with cell and injects its core
VIRAL TRANSFER
 Reverse transcriptase makes DNA copy of
viral RNA
 DNA Polymerase makes second DNA copy
 Integrates into cellular DNA (integrase)
 Translation of RNA into viral proteins
 Protease cleaves viral enzymes
 Proteins and RNA are assembled into new
virions
VIRAL EXIT
 Virus buds from cell surface

11. HIV – The AIDS Virus - REPLICATION

12. TRANSMISSION
HIV is transmitted through:
 Unprotected sexual contact with an infected partner
 Exposure of broken skin or wound to infected blood or body fluids
 Transfusion with HIV-infected blood
 Injection with contaminated objects
 Mother to child during pregnancy, birth or breastfeeding

13. RESISTANCE
1. Temperature: HIV is inactivated by heat, in the autoclave or hot air oven. HIV is thermolabile,
being inactivated in 10 minutes at 60°C and in seconds at 100°C.
2. Lyophilization: It withstands lyophilization.
3. Disinfectants: HIV is completely inactivated by treatment for 10 minutes at room temperature
with any of the following: 10% household bleach, 50% ethanol, 35% isopropanol,
0.5% Lysol, 0.5% paraformaldehyde, or 0.3% hydrogen peroxide.
4. pH: The virus is also inactivated by extremes of pH (pH 1.0, pH 13.0).
For treatment of contaminated medical instruments, a 2% solution of glutaraldehyde is useful.
The virus is not inactivated by 2.5% Tween 20.

14. TRANSMISSION
Blood products
Semen
Vaginal fluids
Breast Milk
THROUGH BODY FLUIDS

15. PATHOGENESIS
Virus – entry
Attacks or is captured by dendritic cells in mucous
membrane & Skin (4-11 days)
Viremia (8-12 weeks)
Lymph nodes - CD4 T cells (3-6 weeks & last 10 yrs)
Peripheral blood - CD4 T cells

16. PATHOGENESIS
 Host cells infected with HIV have a very short lifespan (6hrs)
 HIV continuously uses new host cells to replicate itself.
 Up to 10 million individual viruses are produced daily.
 3-6 weeks after primary infection – CD4 t cells drops.
 1 week – 3 months: CD4 T cells rebound
 Lifecycle (HIV) : 2.6 days

17. This stage of infection lasts for a few weeks and is often accompanied
by a short flu-like illness.
 In up to about 20 percent of people the HIV symptoms are serious
enough to consult a doctor, but the diagnosis of HIV infection is
frequently missed.
During this stage there is a large amount of HIV in the peripheral blood
and the immune system begins to respond to the virus by producing
HIV antibodies and cytotoxic lymphocytes. This process is known as
seroconversion. If an HIV antibody test is done before seroconversion is
complete then it may not be positive.
STAGE 1: ACUTE PRIMARY INFECTION
SYMPTOMS AND STAGES OF HIV INFECTION

18. Symptoms can include:
 Fever (raised temperature)
 Body rash
 Sore throat
 Swollen glands
 Headache
 Upset stomach
 Joint aches and pains
 Muscle pain.
STAGE 1: ACUTE PRIMARY INFECTION
SYMPTOMS AND STAGES OF HIV INFECTION

19. STAGE 2: THE ASYMPTOMATIC STAGE
SYMPTOMS AND STAGES OF HIV INFECTION
 Lasts for an average of ten years
 This stage is free from symptoms
 There may be swollen glands
 The level of HIV in the blood drops to very low levels
 HIV antibodies are detectable in the blood So antibody tests will
show a positive result.

20. STAGE 3: SYMPTOMATIC HIV INFECTION
SYMPTOMS AND STAGES OF HIV INFECTION
The symptoms are mild
The immune system deteriorates
Emergence of opportunistic infections and cancers
Symptoms can include:
 Weight loss
 Chronic diarrhoea
 Night sweats
 Fever
 Persistent cough
 Mouth and skin problems
 Regular infections
 Serious illness or disease

21. STAGE 4: HIV AIDS
SYMPTOMS AND STAGES OF HIV INFECTION
The immune system weakens
The illnesses become more severe leading to an AIDS diagnosis

22. SYMPTOMS AND STAGES OF HIV INFECTION

23. SYMPTOMS

24. OPPOURTUNISTIC
INFECTIONS
I. BACTERIAL
1. Mycobacterium tuberculosis
2. Salmonella
II. VIRAL
1. Cytomegalovirus
2. Herpes simplex virus
3. Varicella-zoster virus
4. Epstein-Barr virus
5. Human herpesvirus 6
6. Human herpesvirus 8
III. FUNGAL
1. Candidiasis
2. Cryptococcosis
3. Aspergillosis
4. Pneumocystis carinii pneumonia
5. Histoplasmosis
6. Coccidioidomycosis
IV. PARASITIC
1. Toxoplasomosis
2. Cryptosporidiosis
3. lsosporiasis
4. Microsporidiosis
5. Generalized strongyloidiasis
V. MALIGNANCIES
1. Kaposi’s sarcoma
2. B cell lymphoma or non-Hodgkin’s lymphoma

25. LAB DIAGNOSIS
Laboratory procedures for the diagnosis of HIV infection include specific
tests for HIV and tests for immunodeficiency as well as. Evidence of
infection by HIV can be detected in three ways
1. Specific tests for HIV infection
2. Nonspecific tests
3. Tests for opportunistic infections and tumor

26. LAB DIAGNOSIS
A. SPECIFIC TESTS FOR HIV INFECTION
1. Antigen Detection
2. Virus Isolation
3. Detection of Viral Nucleic Acid
4. Antibody Detection
A. Screening Tests
a. Enzyme-linked immunosorbent assays (ELISA)
b. Rapid tests: These tests take less than 30 minutes and do not require expensive
equipment.
1. Dot blot assays
2. Particle agglutination (gelatin, RBC, latex,microbeads)
3. HIV spot and comb tests
4. Fluorometric microparticle technologies
Tests using finger-prick blood, saliva and urine have also been developed.
B. Confirmatory Tests
a. Western blot test
b. Immunofluorescence test

27. LAB DIAGNOSIS
A. SPECIFIC TESTS FOR HIV INFECTION
1. Antigen Detection
 The major core antigen p24 is the earliest virus marker to appear in blood and is the one tested
for IgM antibodies appear in about 4–6 weeks, to be followed by IgG antibodies.
 Afterwards, free p24 antigen disappears from circulation and remains absent during the long
asymptomatic phase, to reappear only when severe clinical disease sets in.
 The p24 antigen capture assay (ELISA) which uses anti-p24 antibody as the solid phase can be
used for this antigen
2. Virus Isolation
 The virus is present in circulation and body fluids, within lymphocytes or cell-free.
 It can be isolated from CD4 lymphocytes of peripheral blood, bone marrow and serum.
 The technique of isolation is by cocultivation of the patient’s lymphocytes with uninfected
lymphocytes in the presence of interleukin-2.
 Virus presence is detected by assays for reverse transcriptase and p24 antigen in the culture
fluids.
3. Detection of Viral Nucleic Acid - PCR has become the gold standard for diagnosis in
all stages of HIV infection
4. Antibody Detection
 Most individuals will have detectable antibodies within 6–12 weeks after infection, whereas
virtually all will be positive within 6 months.
 Serological tests for anti-HIV antibodies are of two type-screening and confirmatory tests

28. LAB DIAGNOSIS
B. NONSPECIFIC TESTS
Immunological Tests
The following parameters help to establish the immunodeficiency in HIV infection.
a. Total leukocyte and lymphocyte count to demonstrate leukopenia and a lymphocyte
count usually below 2000/mm3.
b. T cell subset assays. Absolute CD4+ T cell count will be usually less than 200/mm3.
T4:T8 cell ratio is reversed.
c. Platelet count will show thrombocytopenia.
d. Raised IgG and IgA levels.
e. Diminished CMI as indicated by skin tests.
f. Lymph node biopsy showing profound abnormalities.

29. Blood
Urine
Oral
DIAGNOSIS
HIV infection can be measured in terms of
 The amount of virus circulating in the body –called the viral load
 The amount of antigen – p24 antigen – circulating in the body
 Proteins or cells that protect the body against infection – IgG and IgM
antibodies, and CD4 cells

30. • Enzyme-Linked Immunosorbent Assay (ELISA)
• Enzyme Immunoassay (EIA)
• Indirect Fluorescent Antibody Assay (IFA)
• Polymerase Chain Reaction (PCR)
• Western Blot Confirmatory test
BLOOD DETECTION TESTS

31. URINE WESTERN BLOT
As sensitive as testing blood
Safe way to screen for HIV
Can cause false positives in certain
people at high risk for HIV
URINE TESTING

32. ORASURE
The only FDA approved HIV
antibody.
As accurate as blood testing
Draws blood-derived fluids
from the gum tissue.
NOT A SALIVA TEST!
ORAL TESTING

33. NUCLEOSIDE ANALOG REVERSE TRANSCRIPTASE INHIBITORS
 Azidothymidine (AZT) (Zidovudine)
 Dideoxycytidine (ddC) (Zalcitabine)
 Dideoxyinosine (ddI) (Didanosine)
 d4T (Stavudine)
 3TC (Lamivudine)
 ABC (Abacavir)
TREATMENT
NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS
 Nevirapine (Viranune)
 Delavirdine (Rescriptor)
 Efavirenz (Sustiva)

34. PROTEASE INHIBITORS
 Saquinavir (Invirase/Fortovase)
 Ritonavir (Norvir)
 Indinavir (Crixivan)
 Nelfinavir (Viracept)
 Amprenavir (Agenerase)
TREATMENT
HIGHLY ACTIVE ANTIRETROVIRAL THERAPY (HAART) (COMBINATION)
 Indinavir/AZT/3TC
 Ritonavir/AZT/3TC
 Nelfinavir/AZT/3TC
 Nevirapine/AZT/ddI
 Nevirapine/indinavir/3TC