Human Immunodeficiency Virus & Lab Diagnosis
-
Upload
neelam-badruddin -
Category
Documents
-
view
221 -
download
0
Transcript of Human Immunodeficiency Virus & Lab Diagnosis
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
1/12
Human Immunodeficiency Virus
The Virus & The Laboratory Diagnosis
Dr. Sudheer Kher
Prof & Head, Dept ofMicrobiology
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
2/12
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
3/12
HIV Genes
Three basic genes
gag encodes matrix, capsid, nucleic acid
binding proteins
pol encodes reverse transcriptase
env - encodes surface glycoproteins,
transmembrane proteins
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
4/12
Regulatory genes
tat ( transactivator of transcription)
rev (regulator of expression of viral protein)
nef ( negative expression factor)
vif (virion infectivity factor)
vpr (stimulating promoter of virus)
vpu (HIV-1) & vpx (HIV-2) small viral proteinspromoting maturation and release of progeny
virus from cells.
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
5/12
HIV Antigens
Major surface/envelope glycoproteinsgp120
gp41 anchors gp120 to virusMajor capsid proteins
p24
P18Other minor surface & structural proteins
p55
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
6/12
Laboratory Diagnosis
Test
Serology ELISA
Latex Agglutination
Western Blot
Immunofluorescence
Virion
RNA, RT-PCR P24 antigen
Isolation of virus
Lymphocyte CD4:CD8 T cell ratio
Objective
Initial Screening
Initial Screening
Confirmatory test
Confirmatory test
Detection of virus in bloodEarly marker of infection
Test not readily available
Correlate of HIV Disease
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
7/12
Laboratory tests for diagnosis of
HIV infection
Simple tests- Particle agglutination
Rapid tests
- Latex agglutination- Dot blot assay
Western Blot
/Virus isolation
/Immunofluorescence
Detection of viral nucleic
acid- In situ hybridization- PCR
Detection of p24 antigen
ELISA
Confirmatory testsScreening tests
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
8/12
Before you ask for HIV test
Are you asking for the test
because you feel it is
mandatory?
Are you asking for the test
out of fear?
Have you acquired basic
knowledge of HIV/AIDS?
Do you value human rights?
Are you aware that your
patient too has rights?
Are you prepared to docounseling before askingfor the test?
Are you prepared tocounsel the patient afterthe test?
Are you prepared to takeinformed written consentof the patient beforesending the sample?
Are you aware that HIVtest is no substitute for
your precautions?
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
9/12
Strategies for HIV testing in
India
Strategy-I
Serum tested by one of
the E/R/S.
If reactive, sample
considered positive
If not reactive, sample
considered negative
Use Transfusion safety
Highly sensitive &
reliable kits used
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
10/12
Strategy-II
Serum reactive withone E/R/S retestedwith second E/R/Susing different Ag/test
principle. If reactive,reported positive.
Use Unlinkedanonymous HIVSurveillance
Strategies for HIV testing in
India
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
11/12
Strategy III
Serum reactive with two
E/R/S tests is retested
with a third E/R/S.
Or two of the ERS
followed by confirmatory
test.
Use Diagnosis of HIV
infection
Strategies for HIV testing in
India
-
8/14/2019 Human Immunodeficiency Virus & Lab Diagnosis
12/12
-Non-specific tests for HIV
Blood counts Leucopenia
Lymphocyte count less
than 400/cmm Thrombocytopenia
T-cell subset assay CD4 count below
200/cmm
Normal CD4:CD8 ratio2:1. Reversed in AIDS to0.5:1.
Hypergammaglobulinaemia
Diminished CMI Candidial, tuberculin tests.
Lab diagnosis of
opportunistic infections
Malignancies