HIV/AIDs by Professor Yusuf Mohammed, Department of Medical Microbiology and Parasitology, Faculty of Basic Clinical Sciences, College of Health Sciences, Bayero University Kano

Presentation on HIV/AIDS

1. HIV/AIDS HIV/AIDS HIV/AIDS HIV/AIDS
Yusuf Mohammed, MBBS, MSc, MHE,PhD
Department of Medical Microbiology and Parasitolog y,
Bayero University, Kano.

2. WHY
HIV/AIDS?

3. Latin
“AIDS’
”

4. What is HIV?
H-uman
Found only in humans Found only in humans
Transmitted among humans Transmitted among humans
Preventable by humans Preventable by humans
I -mmunodefiency
Body lacks ability to fight off infections Body lacks ability to fight off infections
V-irus
Type of germ Type of germ
Lives and reproduces in body cells Lives and reproduces in body cells
3/9/2015
4
Copyright - National HIV/STI Programme

5. AIDS
A-cquired;received, not inherited (does not run received, not inherited (does not run
in families) in families)
I-mmuno; protected from (in this case the protected from (in this case the
system protects the body from disease) system protects the body from disease)
D-eficiency,--a lack of a lack of
S-yndrome;––a group of symptoms or a group of symptoms or
diseases diseases
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6. HISTORY OF HIV AND AIDS
•Human immunodeficiency virus (HIV) is believed to have
originated in non-human primates followed by cross-species
transmissiontohumans.
•Estimates of the time when HIV was introduced into human
populationsvarywidely.
6

7. HISTORY OF HIV AND AID
•One of the earliest known cases of human HIV infection
involved
the
retrospective
identification
of
HIV
antibodies
from
involved
the
retrospective
identification
of
HIV
antibodies
from
stored serumof an individual who died in 1959 in Leopoldville,
Zaire(RepublicofCongoinCentralAfrica)
7

8. HISTORY OF HIV AND AIDS
•First cluster of HIV infected patients were identified in t he
United States in 1981.
•
The patients presented with mysterious illness that kille d its
•
The patients presented with mysterious illness that kille d its
victims by progressively destroying the immune system.
•The result is susceptibility to infections that were rel atively
harmless to immune competent persons
4

9. AIDSASADISEASEENTITY
•AIDS as a disease entity came into lime light when the
morbidity and mortality weekly report of the centre for
Disease control reported presence of severe opportunistic
diseasesinAmericanadultmalehomosexuals.
•The reported opportunistic illnesses were pneumocystis
jiroveci pneumonia, perianal herpes simplex infection,
Kaposis Sarcoma and Non-Hodgkins lymphoma particularly
CNSlymphoma.
9

10. AIDSASADISEASEENTITY
•The disease entity was described occurring in adult males
consisting of opportunistic illnesses and immunosuppression,
and absence of any of the previously known causes of inherited
or
acquired
immune
deficiency
state
.
or
acquired
immune
deficiency
state
.
•As such, a syndrome of opportunistic illnesses with evidence of
immunodeficiency (that is likely to be froman acquired cause)
wasdescribedasAIDS
10

11. DISCOVERY OF HIV
•Previously assigned names to HIV include
-HTLV III (Human T lymphocyte virus III),
-
ARV (AIDS
-
related virus )
-
ARV (AIDS
-
related virus )
-LAV (Lymhadenopathy associated virus).
-GRID (Gay-related immune deficiency disease)
•The disease entities referred to as AIDS was fully describe d
for about 3 years before the causative agent was discovered.
11

12. DISCOVERYOFHIV
-In 1986, the International Committee on Taxonomy of Viruses
notedtwomostimportantpropertiesoftheviruswhichare:
-The virus infects only human beings and it is not pathological t o
non
-
human
primates
that
have
their
own
immunodeficiency
virus
non
-
human
primates
that
have
their
own
immunodeficiency
virus
referredtoas‘SimianImmunodeficiencyVirus’.
-The effect of this virus in human beings is induction of profoun d
immunodeficiencycharacterizedbydepletionof CD+4cells.
For these two properties the virus earned the name“Human
Immunodeficiency
Virus”
.
12

13. DISCOVERYOFHIV
•Up to 1987, it was believed that the AIDS virus is just one
virus.
• InWestAfricantheywerepatientswithclinicaldescriptionof
AIDS,butwhoseHIV-antibodieswerenotreactinginexpected
wayforHTLV-III/LAV(HIV-1).
•ThissecondvirustemporarilyborethenameHTLV-IV/LAV-II.
13

14. DISCOVERY OF HIV
•Bytheendof1986andearly1987,theInternationalCommittee
on Taxonomy of Viruses renamed HTLV-IV/LAV-II as“Human
ImmunodeficiencyVirus2(HIV-2)”.
•HIV-2 is found predominantly in West Africa, Angola and
Mozambique.
•Itrepresents<2% of all HIVinfections. Theprevalenceof HIV-2
inmostpopulationsappeartobedecreasing.
•Fornowitisrarelyfoundinmostpopulations
14

15. HISTORY OF HIV/AIDS IN NIGERIA
•The first description of HIV and AIDS in Nigeria
dated back to 1986 when a sexually active 13 year
old girl with features of HIV and AIDS tested sero-
positive to HIV antibodies. positive to HIV antibodies. •This report led to the establishment of a National Expert Advisory Committee 1997 and subsequently the National AIDS and STDs Control Programme
which had the responsibility for the National
Health response to HIV and AIDS in the country.
15

16. EPIDEMIOLOGY OF HIV AND AIDS
16

17. HIV-1
Group M
(Major)
A B C D E F G H
GroupO
Molecular Epidemiology
(Types and Subtypes)
HIV
I J K ?
GroupO (Outlier)
Group N
(Non-M,Non-O)
HIV-2
A B C D E
17

18. HIV-1 SUBTYPE DISTRIBUTION
SUBTYPEREGION FOUND (predominantly)
BAmericas, Japan, Australia, the Caribbean,
and Europe
A and DSub-Saharan Africa
CSouthern Africa, Brazil, India
ECentral African Republic, Thailand, and
other Southeast Asian countries
FBrazil and Romania
G and HRussia and Central Africa
I Cyprus
OCameroon
18

19. DISTRIBUTION OF HIV-1 SUBTYPES IN AFRICA
North
0.2
A/G
C
Western
Horn
11.0
A/G
Eastern
10.5
A/G
C
A
Western
5.0
Southern
20.0
Central
6.0
19

20. HIV-1 SUBTYPES
•
10 genetically distinct subtypes known
•
These subtypes are unevenly distributed throughout the world throughout the world
•
Nigeria: predominantly subtypes
-A
-G
-A/G
20

21. HIV IS FOUND IN BODY
FLUIDS
•
Semen
•
Breast milk
•
Breast milk
•
Blood
•
Vaginal fluid
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22. MODES OF HIV TRANSMISSION
Sexual contact (80% of transmission)
•Heterosexual (Male-to-female, female-to-male)
•Homosexual (Male-to-male, and female-to-female)
•Oro-genital sex
•Outercourse (kissing, fingering, artificial insemination, etc)
22

23. MODES OF HIV TRANSMISSION
Parenteral (2.8% of transmission)
•Blood transfusion
•Contact with infected sharps
•Intravenous Drug Users(IDU) through needle-sharing,
•Needle stick accidents or infected sharps
•Innocuous (manicure, hair barbing, pedicure etc)
23

24. IMMUNOLOGY AND NATURAL HISTORY
24

25. BIOLOGYANDSTRUCTURE
•HIV-1 and HIV-2, belonging to the Lentivirus group of
Retroviridae
family
.
Retroviridae
family
.
•HIV has a dense cylindrical core whose structural elements
are coded by thegaggene for the protein that encloses the
RNAgenome.
25

26. BIOLOGYANDSTRUCTURE
•Thegag, polandenvgenes that code for the capsid
proteins, the viral enzymes and the internal and external envelopeproteins.
•HIV genome has at least five other genesTat,Rev, Nef, Vif
andVpu/Vpx.Vpuis present in HIV-1 whileVpxis present in
HIV-2.
26

27. Objectives
•
Reviewthemost commoncutaneous
manifestations of human
immunodeficiencyvirus(HIV)infection.
•
Describethemethods of diagnosis and
treatment foreachcutaneousdisease.

28. •
The
envelope
encloses
the
core
proteins
that
in
nature
•The envelope is made of two glycoproteins gp120 and
gp41 for HIV-1 and gp105 and gp36 for HIV-2. These
trans-membraneproteinsprojectoutofthelipidbarrier.
BIOLOGY AND STRUCTURE
•
The
envelope
encloses
the
core
proteins
that
in
nature
house the virus genome (RNA) and the enzymes (reverse
transcriptase,integraseandprotease).
•The core is made up of two proteins, p18 and p24. Thegag
precursor p55 gives rise to five smaller proteins p25, p17, p9,
p6andp4byproteolyticcleavage.
28

29. •Thepolprecursor protein is cleaved into products consisting
of the reverse transcriptase (RT), the protease (PR), and the
intergrase(IN)proteins.
BIOLOGYANDSTRUCTURE
•The envelope precursor Gp160 is also split into two smaller
glycoproteins,gp120andgp41.
29

30. SIMPLIFIED HIV STRUCTURE
30

31. THENORMALHUMANIMMUNESYSTEM
DEFINITION
The immune systemrefers to the mechanisms by which the
body prevents invasion of the body by pathogenic organisms
as well as those mechanismthat prevent spontaneous
developments
of
neoplasms
.
developments
of
neoplasms
.
Thismechanismsareoftwomajortypes
•Theinnatemechanisms
•Theadaptivemechanisms.
31

32. THE NORMAL HUMAN IMMUNE SYSTEM
THE INNATE MECHANISMS
This refers to those mechanisms that are pre-existing in t he body
and are used to prevent invasion of the body by pathogeni c
organisms. organisms. Components of the innate immune system
•Physical barrier
•Humoral innate mechanisms
•Cellular innate mechanisms
32

33. HUMORALINNATEIMMUNITY
The
body
naturally
produces
some
proteins
that
have
anti
-
viral
PHYSICAL BARRIER
•The Skin
•The Mucousal surfaces.
THE NORMAL HUMAN IMMUNE SYSTEM
CELLULAR INNATE IMMUNITY
The most important cell the is the natural killer cells w hich are
cells that have morphological resemblance to the large g ranular
lymphocyte.
The
body
naturally
produces
some
proteins
that
have
anti
-
viral
activities.
- Interferons
- Complementproteins.
33

34. ADAPTIVE IMMUNITY
This refers to specific immune response developed by the
organism after the organism has been exposed an antigen.
THE NORMAL HUMAN IMMUNE SYSTEM
organism after the organism has been exposed an antigen. There are two major forms of adaptive mechanism
•Humoral adaptive mechanism
•Cellular adaptive immune mechanism
34

35. ADAPTIVE HUMORAL MECHANISM
This refers to the production of a specific antibody to an antigen
expressed by an infectious agent.
HE NORMAL HUMAN IMMUNE SYSTEM
ADAPTIVE CELLULAR IMMUNITY
The T-cell express the equivalence of surface membrane
immunoglobulin which is refered to as T-cell receptor (T cR).
35

36. 36

37. HIVLIFECYCLE
•The primary receptor for HIV is the CD4 molecule on the human
T-helpercells.
•Attachment to and fusion with the target cells is determined b y
its
binding
with
CD
4
molecules,
and
secondary
binding
sites
its
binding
with
CD
4
molecules,
and
secondary
binding
sites
knownasb-chemokinesuchasCCR5andCXCR4.
•Replication of the virus particle begins with attachment of gp1 20
totheCD4onthesurfaceofatargetcell.
•Following the gp120-CD4 binding, a structural change allows for
the interaction of the V3 loop region in the gp120 with a
chemokinereceptor,includingCCR5andCXCR4.
37

38. •The reaction with the co-receptor results in conformational
change,whichexposesafusiondomaincontainedwithinthe
envelopetrans-membraneglycoprotein.
HIV LIFECYCLE
•Exposure ofthe fusion domain results in the insertion of the
gp41intothecellularmembrane.
•Subsequent to the fusion event, the viral core is released
intothecytoplasmofthehostcell.
38

39. HIVLIFECYCLE
•Inthe cytoplasm, theviral RNAgenome is uncoated and reverse
transcribed by the virally encoded Reverse Transcriptase (RT)
enzymetogenerateadouble-strandedviralDNA.
•
The
double
stranded
DNA
is
transported
into
the
host
cell
•
The
double
stranded
DNA
is
transported
into
the
host
cell
nucleus and, via catalysis by integrase, becomes integrated into
thehostcellchromosome,whereitresidesasprovirus.
•Once in the host cell genome, it can remain in a latent state for
manyyearsorcanbegintheproductionofnewviralRNA.
•Ifthehostcellisactivated,thehostcellenzymeRNApolymerase
IIwilltranscribetheproviralDNAintomessengerRNA(mRNA).
39

40. •The mRNA is then translated into viral proteins that undergo
extensivepost-translationalmodifications.
•The viral RNA becomes the genetic material for the next
generation
of
viruses
.
Viral
RNA
and
viral
proteins
assemble
HIV LIFECYCLE
generation
of
viruses
.
Viral
RNA
and
viral
proteins
assemble
atthecellmembrane.
•After proper assembly and processing, newinfectious virus
particlesarereleasedbybuddingfromthecellmembrane.
40

41. NATURALHISTORY
•
Typical infection can be divided into three
stages:

Primary infection

Asymptomatic infection

Symptomatic infection, or AIDS

42. PRIMARY INFECTION

Following primary HIV infection, the CD4+ cell coun t decreases,
while HIV RNA rises to high levels.
At this time, diagnostic HIV antibody is not presen t.

The diagnostic characteristic of acute HIV consists of
•
- Symptoms of viraemic illness
•
- High plasma viral load
•
-No diagnostic HIV antibodies.

43. CLINICAL LATENCY
•
About half of newly infected people experience the flu-
likesymptomscharacteristicofacuteHIVinfection. •
With
sufficient
exposure
to
viral
antigens,
cytotoxic
T
-
•
With
sufficient
exposure
to
viral
antigens,
cytotoxic
T
-
lymphocyte responses are generated and the HIV viral
load typically declines to an equilibriumknown as a
virologic “setpoint,” which occurs within 6to 12 monthsof
initialinfection.

44. CLINICAL LATENCY
•
The lower the virolgic set point, the longer the time it
takesforanindividualtodevelopAIDS. •
Once this viral set point is reached, the CD 4+ cell count
may rebound again marginally, although it does not often
returntobaselinevalues.

45. Key Points

Cutaneous lesions areoftenthefirst
manifestationofHIVnotedbypatientsand
healthcareprofessionals.

Cutaneouslesionsoccurfrequentlyinboth
adults andchildreninfectedwithHIV

46. SYMPTOMATIC PHASE

The high viral load during primary infection is usually
sequestered in the follicular dendritic cells of the
lymphnodes.

Later in infection,viruses are no longer retained in the
lymph nodes; thus, the circulating levels of free virus
increase.

47. SYMPTOMATIC PHASE

Eventually, the circulating CD4+ T cell levels fall to
less than 500/mm
3
and opportunistic infections may
occasionallyoccur.

Later stage of infection, the CD4+ cell count declines
to below200/mm
3
, the infected individual have
developedimmunologicalAIDS.

48. 1200
1100
1000
900
800
700
1:512
1:256
1:128
CD4 T Cells/mm
3
Titer
Primary
infectionPossible acute HIV syndrome
Wide dissemination of virus
Seeding of lymphoid organs
Clinical latency
Death
Opportunistic
diseases
Constitutional
)
Natural History of HIV Infection
600
500
400
300
200
100
0
1:64
1:32
1:16
1.8
1.4
1.2
0
WeeksYears
0 369 1 2 3 4 5 6 7 8 9 10 11 12
CD4 T Cells/mm
Plasma Viremia Titer
Constitutional
symptoms
(
( )
48

49. Stageofdisease CD4cellcount
Acute sero-conversion
syndrome
> 1000/mm
3
(Value sometimes drops
atthis stage)
Earlydisease >500/mm
3
CD4 COUNT AT VARYING STAGE OF HIV DISEASE
PROGRESSION
Middle-stagedisease 200–500/mm
3
Latedisease 50–200/mm
3
Advanceddisease <50/mm
3
49

50. LABORATORY DIAGNOSIS OF HIV LABORATORY DIAGNOSIS OF HIV
INFECTION
50

51. CONFIRMATORY ASSAY
•WESTERN BLOT
Western blot is the standard confirmatory test for HIV an tibody
assays.
ASSAY METHODS TO DIAGNOSE HIV INFECTION
•INDIRECT IMMUNOFLUORESCENT ANTIBODY ASSAY (IFA)
IFA employs HIV-infected cells (lymphocytes) fixed to the
microscope slide. IFA has been used to confirm diagnosis in
sera producing indeterminate results in Western blot.
51

52. ASSAY METHODS TO DIAGNOSE HIV INFECTION
NUCLEIC ACID-BASE TEST
•Consist of DNA Polymerase Chain Reaction ( DNA PCR) and
reverse transcriptase Polymerase Chain Reaction (RT-PCR).
•These tests are not routinely used valuable in:
-Infant diagnosis
-In situations when it is desirable to exclude serologic l atency
period such as artificial insemination and other tissue or organ
transplant procedures.
52

53. TYPESOFTESTINGALGORITHMS
SERIALTESTING
•Refers to the use of 2 screening tests employed
sequentiallytotestforHIVantibody.
•If the initial screening is negative, no further testing is
required.
•Iftheinitialtestispositive,itisfollowedbyonemoretest.
•Samplesthatproducediscordantresultsinthetwotestsare
subjectedtothethirdtest calledtie-breaker.
53

54. PARALLELTESTING
•Involves the use of two screening tests performed
simultaneously
.
TYPESOFTESTINGALGORITHMS
simultaneously
.
•Samplesreactivetobothtestsareregardedaspositive.
•Thosewithdiscordantresultsrequirefurthertesting.
•The WHOin 2004 recommended either a Serial or Parallel
double rapid testing protocol in order to scale up VCT and
enhance access to ARV in resource-limited countries as
illustratedbelow.
54

55. NATIONAL TESTINGALGORITHM
•Government has approved the use of the serial HIV Testing
AlgorithmtoreplacetheinterimParallelTestingAlgorithm.
TESTINGALGORITHMSUSINGRAPIDTESTS
•To support testing in the country government has approved a
combination of non-cold chain dependent HIV rapid test kits to
beusedintheNationalAlgorithm.
•ThekitsareStatPak,Determine,BundiandUniGold
55

56. Determine HIV
HIV TESTING ALGORITHM FOR
STATE CENTRAL LABS
First Test
Reactive:
Report as POS
Non –Reactive: Report as NEG
56
Stat-Pak
Second Test
Reactive
Report as: POS
Non –Reactive:
Report as NEG (Status will be determined
at QC Retesting Lab)

57. PHENOMENONOFSEROLOGICLATENCY
(WINDOWPERIOD)
Definition A
time
lag
from
the
point
that
a
person
is
exposed
to
the
virus
to
A
time
lag
from
the
point
that
a
person
is
exposed
to
the
virus
to
the point at which a diagnostic antibody becomes detectable in
theblood.
57

58. Window Period
•
When a person gets infected it may take 6 weeks or up to
3 months before antibodies to HIV are detected in the
blood
•
The HIV test looks for antibodies. When these antibodies
are detected the person is diagnosed HIV positive •
A person can be positive and the test shows negative
because the test was done during the window period
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59. CAUSEOFFALSENEGATIVEHIVTESTING
•Unexplained Atypical host Response •Agammaglobulinaemia
•Seroreversion-Certain phase of the disease when B cell
function is completely paralysed
•Excessive Antigen production mopping up all the antibody
formed uncommon strains of HIV such as HIV 1 TypeN, O strain
•Technical Error
59

60. CLINICAL DIAGNOSIS OF HIV INFECTION
60

61. HIV DISEASE STAGING

62. WHO IMPROVED CLINICAL STAGING
Lab Axis
Clinical Axis (Clinical stages
WHO IMPROVED CLINICAL STAGING
Lab Axis Clinical Axis (Clinical stages Lymphocyte count/
m
l
CD4+
count/ml
1.
Asymptom
atic PGL
2. Early
HIV
3.
Intermedi
ate ARC
4. Late
HIV
Lab Axis
Clinical Axis (Clinical stages
Lymphocyte
count/ml
CD4+
count/ml
1.
Asymptom
atic PGL
2. Early
HIV
3.
Intermedi
ate ARC
4. Late
HIV
A
>2000 >500
1A 2A 3A 4A
B
1000-2000 200-500
1B 2B 3B 4B
C
<1000 <200
1C 2C 3C 4C
count/
m
l
atic PGL
ate ARC
A
>2000 >500
1A2A3A4A
B
1000-2000 200-500
1B 2B 3B 4B
C
<1000 <200
1C 2C 3C 4C
62

63. LABORATORY INVESTIGATIONS TO
DIAGNOSIS OF HIV ASSOCIATED ILLNESS
•Investigation for TB
-Chest x-ray
-Sputum for AFB
-
Culture for AFB
-
Culture for AFB
-Tuberculin skin test
•Investigating for diarrhoea agents
-Stool microscopy, culture and sensitivity
63

64. LABORATORY INVESTIGATIONS TO
DIAGNOSIS OF HIV ASSOCIATED ILLNESS •Investigating for renal functions
-Serum electrolytes,ureaand creatinine
-Creatinine clearance.
Estimated from the
Cockroft
-
Gault
formula:
Estimated from the
Cockroft
-
Gault
formula:
(140 -age in year )wt(kg
) x 72
Plasma creatinine(mg/dl)
(Above formula is multiplied by 0.85 for females)
•Investigating for bone marrow functions
-Full blood count ,recticulocytescount and red cell indices for
the anaemic patients
-Bone Marrow Aspirate
64

65. •Investigating for HBV
-HbSAg
-HBe antigen
-AntiHbe
-
HBV DNALABORATORY INVESTIGATIONS TO DIAGNOSIS
OF HIV ASSOCIATED ILLNESS
-
HBV DNA
-Prothrombin Time
-LFT
•Investigating for HCV
-HCV antibody
-HCV DNA
-Prothrombin Time
-LFT
65

66. OTHER LABORATORY INVESTIGATIONS
•Blood culture
•Malaria Parasites
•
VDRL
•
VDRL
•Lipid profile
•Plasma lactic acid
•Fasting blood sugar
66

67. What have we learnt?
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