This presentation cover the biology of HIV, specifically the virus lifecycle. The different types and sub-types of HIV are also covered

1. HIV BIOLOGY

2. HIV VIRUS
The human immunodeficiency
virus (HIV) is a retrovirus
belonging to the family of
lentiviruses.
Retroviruses can use their
RNA and host DNA to make
viral DNA and are known for
their long incubation periods.

3. Ct……..
 HIV causes severe damage to the
immune system and eventually
destroys it by using the DNA of
CD4+ cells to replicate itself.
 Size: 1/10,000th of a millimeter in
diameter.
 It has a protein capsule containing
two short strands of genetic
material (RNA) and enzymes.

4. HIV Types
HIV type 1 (HIV-1) and HIV-2.
 Both have the same modes of
transmission and are associated
with the same opportunistic
infections, but

5. HIV-1 & HIV-2
HIV-1 exhibits a genetic relation to
viruses indigenous to chimpanzees
and gorillas that inhabit West Africa,
while HIV-2 viruses are affiliated with
viruses present in the sooty
mangabey, a vulnerable West African
primate.[2]

6. HIV-1 viruses
HIV-1 is the most common and most
pathogenic strain of the virus.
As of 2022, approximately 1.3 million such
infections occur annually.[4][5] Scientists
divide HIV-1 into a major group (group M)
and two or more minor groups, namely
groups N, O and possibly a group P.
Each group is believed to represent an
independent transmission of simian
immunodeficiency virus (SIV) into humans,

7. HIV-1 viruses
HIV-1 viruses can be further stratified
into groups M, N, O, and P.
Among these, HIV-1 group M
viruses are the most prevalent,
infecting nearly 90% of people living
with HIV and are responsible for the
global AIDS pandemic.

8. Group M
Group M viruses can be further
subdivided into subtypes based
on genetic sequence data. Certain
subtypes are known for their
increased virulence or drug
resistance to different medications
used to treat HIV.

9. Which HIV-1is most widespread
worldwide.
HIV-1 is further classified
into four groups; M, N, O
and P. Of these, group M is
the most widespread
worldwide.

10. Which is the newest group of
HIV-1 virus?
P group: This is the newest
group of HIV-1. It was given its
own name because of how
different it is from the M, N, and
O strains.

11. Group M subtype
Group M is divided into nine
distinct subtypes; A, B, C, D,
F, G, H, J and K.
NB. Two or more subtypes of
HIV can combine to form a
hybrid.

12. Which is the most common among
Group M nine distinct subtypes?
Subtype C currently
accounts for more than half
of all new HIV infections
worldwide.
Various subtypes of HIV-1
have been found in specific
geographic areas and in

13. SUBTYPES OF HIV-1
Subtype A: common in Central Africa,
sub-Saharan Africa & West Africa
Subtype B: is the dominant form in
Europe, the Americas, Japan, and
Australia.In addition, subtype B is the
most common form in the Middle East
and North Africa.[ South America,
Brazil, United States, Thailand,
Europe, Caribbean, India, Japan

14. Ct…..
Subtype C: is the dominant form in
Southern Africa, Eastern Africa, Brazil
India, Nepal, and parts of China.
Subtype D: is generally only seen in
Eastern and central Africa,
(Subsahara África= East África,
Southern África, West África, Central
África)

15. Ct….
Subtype E: Thailand, Central
African Republic, Southeast Asia
NB: Subtype E was originally used
to describe a strain that is now
accounted for as the combined
strain AE.This means the original,
singular, E strain has disappeared,
but we know it existed, as it is
visible in this combined strain
form.[citation needed]

16. Ct….SUBTYPES OF HIV-1
Subtype F: Brazil, Romania,
Democratic Republic of Congo,
central Africa, South America and
Eastern Europe.[12]
Subtype G: Democratic Republic
of Congo, Gabon, Thailand,
Russia, Central Africa and central
Europe.[12]

17. Ct……
Subtype H: is limited to central
Africa, Democratic Republic of
Congo, Gabon, Russia
Subtype I: is found in Cyprus:
Subtype I was originally used to
describe a strain that is now
accounted for as CRF04_cpx, with
the cpx for a "complex"
recombination of several

18. Ct…….
• Subtype J: is primarily found in
North, Central and West Africa, and
the Caribbean[13]
• Subtype K: is limited to the DRC and
Cameroon.[12]
• Subtype L: is limited to the DRC.[14]

19. HIV-2 viruses
HIV-2 viruses are generally considered to
be less virulent and
less transmissible than HIV-1 M group
viruses, although HIV-2 is also known to
still cause AIDS.
One of the prevailing challenges in the
pursuit of effective management of HIV is
the virus's pronounced genetic
variability and rapid viral evolution.[3]

20. HIV-2 viruses
HIV-2 is mostly only found in Africa,
and therefore less recognized
outside of Africa.
The first identification of HIV-2
occurred in 1985 in Senegal by
microbiologist Souleymane
Mboup and his collaborators.[27]

21. Ct……………..
The first case in the United States was
in 1987.[28] The first confirmed case of
HIV-2 was a Portuguese man who was
treated at the London Hospital for
Tropical Diseases and later died in
1987.
He was believed to have been exposed
to the disease in Guinea-Bissau where
he lived between 1956 and 1966.

22. Ct………..
 HIV-2 is closely related to SIV endemic
in sooty mangabeys (Cercocebus atys atys)
(SIVsmm), a monkey species inhabiting the
forests of Littoral West Africa.
 Phylogenetic analyses show that the virus
most closely related to the two strains of HIV-
2 which spread considerably in humans (HIV-
2 groups A and B) is the SIVsmm found in the
sooty mangabeys of the Tai forest, in
western Ivory Coast.[31]

23. Ct……………
As of 2010, there are eight known HIV-2
groups (A to H), Of these, only groups A
and B are pandemic.
Group A is found mainly in West Africa, but
has also spread globally to Angola,
Mozambique, Brazil, India, Europe, and
the US.
Despite the presence of HIV-2 globally,
Group B is mainly confined to West
Africa.[31][32]

24. HIV-2
HIV-2 appears to progress more
slowly.
Most HIV-2 cases are found in
western Africa and in countries
related to western Africa in some
way such as Portugal, France,
Angola, Mozambique, Brazil, and
India.

25. HIV STRUCTURE OF HIV VIRUS

27. HIV is an enveloped RNA virus: As
HIV buds out of the host cell
during replication, it acquires a
phospholipid envelope.
Protruding from the envelope are
peg-like structures that the viral
RNA encodes.
Each peg consists of three or four
gp41 glycoproteins (the stem),
capped with three or four gp120
glycoproteins.

28. Ct……..
 Inside the envelope the bullet-
shaped nucleocapsid of the virus is
composed of protein and
surrounds two single strands of
RNA.
Three enzymes important to the
virus’s life cycle — reverse
transcriptase, integrase, and
protease — are also
within the nucleocapsid

29. CT..
Although helper T cells seem to
be the main target for HIV, other
cells can become infected as well.
These include monocytes and
macrophages, which can hold
large numbers of viruses within
themselves without being killed.
Some T cells harbor similar
reservoirs of the virus.

30. CT….
Entry of HIV into the host cell
requires the binding of one or more
gp120 molecules on the virus to
CD4 molecules on the host cell’s
surface.
Binding to a second receptor is
also required.

31. HIV’S LIFE CYCLE
1 & 2. Binding And Fusion
The envelope proteins gp120 and
gp41 bind to CD4+ cell receptors
and coreceptors on the outside of
CD4+ cells and macrophages.
The chemokine receptors CCR5
and CXCR4 facilitate viral entry.

32.  The joining of the proteins and the receptors
and coreceptors fuses the HIV membrane with
the CD4+ cell membrane, and the virus enters
the CD4+ cell and macrophage.
 The HIV membrane and the envelope proteins
remain outside of the CD4+ cell, whereas the
core of the virus enters the CD4+ cell.
 CD4+ cell enzymes interact with the viral core
and stimulate the release of viral RNA and the
viral enzymes reverse transcriptase, integrase,
and protease.
Binding And Fusion Ct,

33. Binding and FUSION ct,

34. 3. Reverse Transcription
 The HIV RNA must be converted to DNA before it can be
incorporated into the DNA of the CD4+ cell.
 This incorporation must occur for the virus to multiply.
 HIV RNA is converted to single strand of HIV DNA by the
help of HIV enzyme reverse transcriptase.
 The single strand of this new DNA then undergoes
replication into double-stranded HIV DNA.

35. 4. Integration
Once reverse transcription has occurred:
 The viral DNA enters the nucleus of the CD4+ cell and
finally its inserted into the CD4+ cell’s DNA ( a process
called integration) by the viral enzyme integrase
 At this level ,the CD4+ cell has now been changed into a
factory used to produce more HIV.

37. Hiv Life Cycle Ct,
5. Replication
 Once integrated into the CD4 DNA, the
HIV begin to use the machinery of the CD4
cell make long chains of HIV proteins
which are the building blocks for more
HIV.
 Provirus (HIV DNA) is replicated along
with the chromosome when the cell
divides.
 The integration of provirus into the host
DNA provides the latency that enables the

38. Hiv Life Cycle Ct,
6. Assembly
 The HIV proteins and viral RNA, all the
components needed to make a new virus,
gather /assemble at the CD4+ cell membrane
to form new viruses.
 Production of viral proteins and RNA takes
place when the provirus is transcribed. Viral
proteins are then assembled using the host
cell’s protein-making machinery.
 The virus’s protease enzyme allows for the
processing of newly translated polypeptides
into the proteins, which are then ultimately
assembled into viral particles.

39. Hiv Life Cycle Ct,
These new viruses leave the CD4+
cell and contain all the components
necessary to infect other CD4+ cells
but cannot do so until it has matured.
During this process, the HIV protease
enzyme cuts the long HIV proteins of
the virus into smaller functional units
that then reassemble to form a mature

40. 7. Budding and Maturation
These new immature viruses push through the
different parts of the cell wall by budding.
Many viruses can push through the wall of one
CD4+ cell. The virus eventually buds out of the
cell.
A cell infected with a retrovirus does not
necessarily lyse the cell when viral replication
takes place; rather, many viral particles can bud
out of a cell over the course of time.