Download MBBS General Medicine PPT 9 Hiv Aids Part I Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) General Medicine 2022 PPT 9 Hiv Aids Part I Lecture Notes

Infectious diseases

4/5th Semester Classes on Infectious Diseases, 8-9AM, Tuesdays (LT-1)



Approach to Infectious Diseases and their prevention


Antibiotic stewardship practices


Community-Acquired Infections


Health Care?Associated Infections


Gram-Positive Bacteria (part-1)


Gram-Positive Bacteria (part-2)


Gram-Negative Bacteria (part-1)


Gram-Negative Bacteria (part-2)


Spirochetal Diseases


Diseases Caused by Atypical/Miscel aneous Bacterial Infections


Revision-cum-exam on bacteria (Must to know type)


Infections Due to DNA Viruses



Infections Due to RNA Viruses (part 1)


Infections Due to RNA Viruses (part 2)


HIV/AIDS ? part 1


HIV/AIDS ? part 2


Fungal Infections


Parasitic Infections (part 1)


Parasitic Infections (part 2)


Revision-cum-exam on Virus, Fungal, and Parasite (Must to know type)


? HIV is a retrovirus which attacks the T-cel s in the immune


? Acquired Immuno deficiency syndrome or AIDS, is a

collection of symptoms due to underlying infections

and malignancies resulting from specific damage to

immune system caused by human immunodeficiency

virus (HIV).

A Global view of HIV Infection

? Approximately > 40 million people are currently living with HIV

infection, and 25 million have already died


? The first indication of this new syndrome came in 1981 in

homosexual drug addict males;

? They had two things in common- Pneumocystis pneumonia and

Kaposi's sarcoma

? In 1983, HIV was isolated from a patient with

lymphadenopathy, and by 1984 it was demonstrated clearly to

be the causative agent of AIDS

? In 1986, The International Committee on virus Nomenclature

decided on the generic name of the causative virus as the Human

Immunodeficiency Virus
Structure of HIV

? It has a diameter of 100-120 nm

with a spherical morphology

? Cone-shaped core surrounded

by lipid matrix containing key

surface antigens and


? Viral core contains 2 copies of

genomic RNA, reverse

transcriptase, integrase and


Based on molecular and antigenic differences, two types of HIV have been recognized



? HIV-1 is more common in

? HIV-2 is found in West Africa,


Mozambique, and Angola.

? Easily transmited.

? Less easily transmitted.

? Pathogenic in nature

? Less pathogenic.

? Duration of infection is

? Duration of infection is shorter

quite long.


? classified in to at least

? Relatively rare and has not

ten subtypes based on

been reported from India.

sequence analysis of

their gag and env genes

(Group M (For major) is


Antigenic variations in HIV

? HIV is a highly mutable virus and exhibits frequent antigenic variations

as wel as dif erences in other features such as nucleotide sequences,
cell tropism, growth characteristics and cytopathology

? Not only are there dif erences between isolates of HIV from different

races or persons but also between sequential isolates from the same
person, and even between those obtained from different sites of the
same person at the same time.

? This great variability is believed to be due to error prone nature of

reverse transcription

Mode of transmission

1. Sexual contact- In 75 % cases , transmission

is by sexual contact.

? People who already have a sexual y

transmit ed disease, such as syphilis, genital
herpes, chlamydial infection, gonorrhea, or
bacterial vaginitis, are more likely to acquire HIV
infection during sex with an infected partner
Mode of transmission

2. Parenteral- In 15 % cases, it is by blood transfusion or blood

product transfusion.

3. Sharing of unsterilized needles or syringes in drug addicts

contaminated with blood from an infected person can spread


4. HIV can be spread in health-care set ings through accidental

needle sticks or contact with contaminated fluids.

5. HIV can also spread through organ transplantation.

6. Mother to child

From mother to child

? 30% of children born to

infected mothers have

the acquired infection

unless virus is treated by

antiviral drugs before


? In nursing mothers

transmission can occur

through breast milk.


CD 4+ cel s are present in- T helper cels, B -lymphocytes ,

macrophages, monocytes , and dendritic cels

Steps of viral entry in to the host cell

o Strains of HIV that utilize

CCR5 as a co-receptor are

referred to as macroph e


tropic viruses (M ?tropic


o Strains of HIV that utilize

CXCR4 are referred to as -


tropic viruses.

o Many virus strains are dual

tropic in that they utilize

both CCR5 and CXCR4.

Events that transpire from primary HIV infection

Summary of early events in HIV infection

? Lymphoid tissues are the major anatomic sites for the establishment and propagation of

HIV infection

? Immune activation and inflammation contribute substantially to:

(1) the replication of HIV,
(2) the induction of immune dysfunction, and
(3) the increased incidence of chronic conditions associated with persistent immune
activation and inflammation

? Accelerated aging syndrome
? Bone fragility
? Cancers
? Cardiovascular disease
? Diabetes
? Kidney disease
? Liver disease
? Neurocognitive dysfunction
Increased occurrence and/or exacerbation of certain autoimmune diseases like:

? Psoriasis,
? Idiopathic thrombocytopenic purpura,
? Graves' disease,
? Antiphospholipid syndrome, and
? Primary biliary cirrhosis

Immune reconstitution inflammatory syndrome (IRIS) is an autoimmune-like phenomenon
characterized by a paradoxical deterioration of clinical condition, which is usually
compartmentalized to a particular organ system, in individuals in whom cART has recently been

? It is associated with a decrease in viral load and at least partial recovery of immune

competence, which is usually associated with increases in CD4+ T cell counts.

? Commonly seen with underlying Mycobacterium tuberculosis and cryptococcosis

Immune deficiency in HIV Infection

Typical course of an untreated HIV-infected individual

(The combination of viral pathogenic and immunopathogenic events decides the disease)

? Long-term nonprogressors are by definition long-term

survivors; however, the reverse is not always true

? Long-term nonprogressors were first described in the

1990s, defined if

? They had been infected with HIV for a long period (10


? Their CD4+ T cell counts were in the normal range, and

? They remained stable over years without receiving Cart
Laboratory Diagnosis of HIV infection

1) Non Specific Tests- The fol owing tests help to establish the

immunodeficiency in HIV infection.

? Total Leukocyte and lymphocyte count- to demonstrate leucopenia

and lymphopenia. The lymphocytic count is usual y below


? T cell subset Assays- Absolute CD4+ cell count is reduced with T4 :

T8 ratio is reversed

? Platelet count-shows Thrombocytopenia.

? IgA and Ig G levels are raised

? Diminished cell mediated Immunity as indicated by skin tests

? Lymph node biopsy shows profound abnormalities

Laboratory Diagnosis of HIV infection

2.Specific Tests for HIV infection- Diagnosis depends on the

demonstration of antibodies to HIV and/or the direct detection of HIV or one of its


Detection of antigen - p24 Capture ELISA assay, is positive in about

30% of the infected persons.

? In the first few weeks after infection and in the terminal

phase, the test is uniformly positive

Detection of antibodies - It takes 2-8 weeks to months for the

antibodies to appear in circulation

Recently, the interval between infection and detection (window period) has decreased from

22 days for antibody testing to 16 days with p24 antigen testing and subsequently to 12 days

with NAT
Laboratory Diagnosis of HIV infection

ELISA (most frequently used method for

screening for HIV antibody)
1)First generation - whole viral lysates
2)Second generation - recombinant antigen
3)Third generation - synthetic peptide
4)Fourth generation - antigen + antibody

(Simultaneous detection of HIV antigen and

antibody) - HIV duo

Laboratory Diagnosis of HIV infection

Supplemental Tests
? Western Blot Test (gold standard)
? Indirect Immunoflorescence test
? Radio ImmunoPrecipitaion Assay
Rapid Tests
a) Dot Blot assay
b) Particle Agglutination tests
c) HIV spot and comb test
d) Flurimetric microparticle techn

Laboratory Diagnosis of HIV infection

Demonstration of viral Nucleic


? Three different PCR techniques


? RT- PCR,

? Nucleic acid sequence based

amplification (NASBA) and

? branched-DNA (b-DNA) assay

have been employed to

Extremely high sensitivity

develop commercial kits
Clinical Manifestations

The center for disease control (CDC) has classified the
clinical course of HIV infection under various groups.

1. Acute HIV infection
2. Asymptomatic or Latent infection
3. Persistent generalized lymphadenopathy (PGL)
4. AIDS related complex
5. Full blown AIDS (Last stage)

Thank you

This post was last modified on 05 April 2022