1. FAMILY RETROVIRUSES

2. Retroviruses possess an enzyme, reverse transcriptase,
that can transcribe ssRNA into double-stranded DNA.
This activity is reflected in the designation
“retroviruses.”
Integration of the DNA thus derived from the viral
genome in the host-cell genome is a precondition for
viral replication.

3. PARTICULAR PROPERTIES OF
RETROVIRUSES
Viruses: have
2 identical RNA
Enzyme reverse transcriptase
are
highly-changeable (because reverse transcriptase is not under control and a lot of mistakes are
present )

4. SUBFAMILY OF RETROVIRIDAE
1. Oncornaviridae – are capable of oncogenic cell transformation, -rna- contain RNA
2. Spumaviridae – CPE - syncytia look like foam, spume
3. Lentiviridae – (from lent, long time)

5. ONCOVIRUSES INCLUDE:
 Oncoviruses D – causative agents of monkey’s
mammary cancer
 Oncoviruses B – causative agents of cancer of mice,
guinea pigs’s mammary
 Oncoviruses C – causative agents of mammalia and
birds leukemia and sarcomas
The term-complex “leukemia-sarcoma” is used for
animals oncogenic viruses (cat, hamsters, monkey,
rats, rabbits,. )
 HTL viruses types I and II - human T-cell
leukemia virus
the bovine leukemia virus.

6. SPUMAVIRUSES
only occur in animals (cattle, monkey,
hamsters, cats…),
two of which are (probably) from humans

7. LENTIVIRIDAE
HIV (human immunodeficiency virus) 1 and 2,
maedi-virus (pneumonia),
visnavirus (encephalo-myelitis) in sheep, viruses
affecting goats and horses,
animal immune deficiency viruses.

8. HUMAN IMMUNE DEFICIENCY
VIRUS (HIV)
Is a causative agent of AIDS (acquired immune deficiency
syndrome). This term used since 1982.
Was developed by R. Hallo (USA) and L.Montanie (France) in 1983
- HIV I.
Two types of HIV are known: HIV I,II (1987).
The types of HIV can be distinguished genetically and antigenically.
HIV-1 is the cause of the current worldwide pandemic while HIV-
2 is found in west Africa but rarely elsewhere.
HIV-2, which is transmitted in the same ways as HIV-1, causes
AIDS much more slowly than HIV-1 but otherwise clinically the
diseases are very similar. Both HIV-1 and HIV-2 are thought to
have arisen from simian immunodeficiency virus (SIV).
HIV-2 is closely related to the SIV found in west Africa.

9. MAIN TYPES HIV
HIV-I HIV-II
virulent high less
widespread Europe, N. America West Africa
genome Homological in 42 %
Near to MIV (monkey)
SIV (simian)
Antigenic structure
(mol. weight in kdt )
gp 120
gp 41
matrix protein 17
p24
gp 125
gp 36
matrix protein 17
p26

10. SUB-GROUPS AND SUB-TYPES
There are three sub-groups of
HIV-1,
M (main or major),
N (new) and
O (outlier).
Type O HIV-1 is mostly found
in Cameroon and Gabon
while the rare N sub-group is
also found in Cameroon. It is
very likely that SIV infected
humans on separate occasions
to give rise to the three sub-
groups.
Based on nucleotide sequence
analyses of the env and gag
genes, it has been found that
there are also at least ten
different HIV-1 subtypes

11. In some countries, mosaics (recombinants) between different
subtypes have been found. These arise when two different subtypes
infect a person at the same time and recombination occurs. The
former subtype I is a circulating recombinant form (or CRF) that is
a recombinant of subtypes A, G, H and K.
There is some evidence from laboratory studies that different
HIV-1 subtypes can be transmitted by different routes.
For example, type B found in western countries, may be
transmitted more effectively by homosexual intercourse and via
blood (as in intra-venous drug use) whereas types C and E may be
transmitted more via a heterosexual route. This is because types C
and E replicate better in Langerhans' cells found in the mucosa of
the cervix, vagina and penis while type B replicates better in the
rectal mucosa. It also appears that type E is more readily
transmitted between sexual partners than type B.
Subtype D seems to be more virulent than subtype A, that is
infected persons progress to overt disease more rapidly. In addition
subtypes D and C seem to be transmitted more effectively from
mother to child than subtype A.

13. CULTIVATION HIV
in tissue culture :
H-9 (clone TCD4-lymphocytes from leukemia
TCD4-limphocytes)
in monolayer of astrocytes
CPE: syncytial formation
Lab. Animals - Chimpanzee

14. STRUCTURE OF HIV

15. Electron micrograph of
HIV - Cone-shaped cores
are sectioned in various
orientations.
Viral genomic RNA is
located in the electron-
dense wide end of core.
CDC/Dr. Edwin P. Ewing,
Jr. epe1@cdc.gov

16. OTHER INTERNAL PROTEINS
These are encoded by the pol (polymerase) gene. They are
enzymes that participate in integration and replication:
Reverse transcriptase - copies RNA genome into double
stranded DNA
Integrase - integrates the double stranded DNA into the
host cell chromosome
Protease - cleaves the pol and gag-encoded polyproteins

17. CELLS THAT ARE INFECTED BY HIV
HIV lyses CD4+ T4 cells specifically, causing profound immuno-
suppression.
Other cells tend to harbor and replicate the virus without lysis or, in
the case of dendritic cells, they may concentrate virus at the cell
surface with little or no replication of the virus.
CD4+ T4 helper cells - HIV leads to disease as a result of the
depletion of CD4+ T4 helper cells and the consequent inability to
fight opportunistic infections.
Natural Killer cells -These are also CD4+ T cells and interact with
dendritic cells. In addition to CD4 antigen, they express the co-
receptor CCR5 and are thus infected by those HIV strains that
require CCR5 for entry into the cell.

18. CD8+ Killer T cells- These cells express low levels of CD4 antigen
when they are activated and appear to be infected in small
numbers by HIV in the later stages of disease. Naive CD8 cells do
not express CD4 antigen and do not appear to be infected
(although they do express the co-receptors).
Macrophages- Monocytes/macrophages express CD4 antigen
(although in much lower amounts that T4 cells) and are infected
by HIV. They may provide an important reservoir for the virus
within the host and may be especially important in HAART-
treated patients
Cells of the nervous system- HIV infects oligodendrocytes,
astrocytes, neurones, glial cells and brain macrophages.
Macrophage-tropic forms are found in the cerebro-spinal fluid.
Dendritic cells- Follicular dendritic cells (FDCs) are important in
the biology of HIV. These are antigen-presenting cells that
process antigen and present peptides to T cells. They are not
readily infected by HIV, though they can be productively infected

19. CELLS THAT ARE INFECTED BY HIV

20. ENTRY OF HIV VIA THE MUCOSAL ROUTE
AND TRANSIT VIA DENDRITIC CELLS TO
THE LYMPH NODES
When HIV enters the body
via the mucosal route
(epithelia of the vagina, penis
or rectum), it is bound by
FDCs that migrate to the
lymph nodes; here the FDCs
present HIV to T4 cells,
which become infected.

21. STAGES OF THE HIV REPLICATION
CYCLE
Binding to surface receptors
Fusion of viral and host cell membranes
Uncoating of the nucleocapsid
Reverse transcription of RNA to DNA
Integration of DNA provirus into the host genome
Replication (Host DNA polymerase)
Transcription (Host RNA polymerase II)
RNA splicing in the host cell nucleus (host and viral factors)
Translation of viral proteins
Proteolysis of viral polyproteins (Host protease in the Golgi Body processes gp160,
Viral protease processes GAG,POL)
Glycosylation of gp160
Phosphorylation of viral proteins
Fatty acylation of GAG
Assembly of the virus at the host cell membrane
Budding
Maturation of the virus particle after budding
The stages in italics are likely targets since they are specific to the virus

23. 1. ATTACHMENT OF HIV TO A CD4+ CELL.
The outer domain of
gp120 binds to the CD4
antigen. This leads to a
conformational change in
gp120 and a co-receptor
binding site is exposed.
This region of gp120 binds
to the chemokine
receptor. Binding to the
chemokine receptor allows
another conformational
change to occur so that
regions of the gp41 HIV
protein interact to form a
fusion domain that allows
the viral and cell
membrane to fuse. As a
result the viral core enters

24. Chemokine receptors are involved, in association with CD4 antigen,
in infection by HIV (left). The chemokine can block attachment of
the virus to its receptors (middle). Mutations in the chemokine
receptor can lead to resistance to HIV infection (right)

25. CHEMOKINES ARE
small secreted proteins that are chemotactic for cells
in the immune system such as leukocytes which move up the
gradient of chemokine secreted by another cell;
thus, they control the temporal and spatial positioning of leukocytes
during an immune response.
Chemokines are divided into two groups according to a conserved
dicysteine motif that they contain.
These are the C-C group and the C-X-C group. They bind to the cell
surface via receptor molecules that are integral membrane
proteins that span the plasma membrane seven times (seven
transmembrane receptors). The receptors are named for the type
of cytokine that they bind (CCR- or CXCR-).

26. 2. ENRTY INTO CELL: PH INDEPENDENT
FUSION WITH PLASMA MEMBRANE
No pH-dependent conformational change in a viral membrane
protein is necessary for fusion between the viral membrane and the
membrane of the cell to be infected. Thus, no entry into endosomes
or lysosomes is required.
As with herpes virus, this sort of fusion of a virus with the plasma
membrane is associated with fusions of infected cells to form
syncytia. Syncytium formation is also a characteristic of HIV
infection.
This has profound significance for spread of infection between cells
without any free virus. This means that virus may spread from cell
to cell so that immune system circulatory antibodies cannot have
any effect (problem for vaccine). Not only will a vaccine have to be
able to destroy the virus, it will also have to be able to destroy
infected cells. Gp41 is the fusogen. Syncytia are most often seen in
brain.

27. 3. REVERSE TRANSCRIPTION AND INTEGRATION
This is similar to other retroviruses. HIV uses reverse transcriptase
imported during infection as part of the virus. The nucleocapsid
enters the cytoplasm and reverse transcription occurs within the
nucleocapsid.
After uncoating and entry into the nucleus, both linear and
circular forms of the viral DNA are found. Linear double strand
viral DNA is inserted into the host cell chromosomes using the viral
integrase protein (translated from the pol gene).
4. After integration, viral RNA is transcribed by host RNA
polymerase II.

28. FORMATION OF POLYPROTEINS AND THEIR
CLEAVAGE
Assembly of new virus takes place at the membrane of the host cell. Three types
of protein make up the virion. These are the membrane protein complex (Gp120
and Gp41 - originally derived from Gp160) plus two internal precursor
proteins, the Gag polyprotein and the Gag/Pol polyprotein (the latter is the
result of a frame shift that allows the ribosome to continue translation from the
Gag gene into the Pol gene)
The proteins aggregate at the cell membrane and the membrane pinches off .
The larger internal precursor (Gag-Pol) draws two strands of the positive
strand RNA into the nascent virion and the protease (part of the Gag-Pol
protein) cuts itself free. The protease completes the cleavage of Gag-Pol to
liberate other enzymes (reverse transcriptase, integrase and more protease).
The protease also cleaves the remainder of Gag-Pol and the smaller Gag into
structural proteins. p24, p7 and p6 form the bullet-shaped core while p24
underlies the membrane. The Gag and Gag/Pol fusion proteins are made in
ratio of about 20:1.
This specific viral protease is vital as the viral proteins are not functional unless
separated. This specificity makes the protease a good candidate inhibition by
anti-HIV drugs (see appendix 3 and anti-viral chemotherapy sections). Gag/Pol
and Gag are attached to the viral membrane via a fatty acid that is covalently

29. PATHOGENESIS
Selective affection of cells with CD4 receptor (T-helpers,
macrophages, monocytes…)
Virus is not detected by immune system because: viral
genome is integrated into DNA of host cell and is
highly-changeable
Virus has high speed of replication (5000 copies per 5 min)
Gp 120 (separately from virion) in blood mark cells with
CD4 receptors and as result these cells will be destroy by
T-killers
Viruses can penetrate into cells by intracellular canals (so
antibody will not find virus)
Virus also infect precursor of T-lymphocytes in tymus and
born marrow (a new T cells will be not differentiated)

30. Scanning electron micrograph of HIV-1 budding from cultured lymphocyte. Multiple
round bumps on cell surface represent sites of assembly and budding of virions (CDC)

31. DURING THE COURSE OF INFECTION, THERE
IS A PROFOUND LOSS OF THE SPECIFIC
IMMUNE RESPONSE TO HIV BECAUSE:
responding CD4+ cells become infected. Thus, there is clonal
deletion leading to tolerance. The cells that proliferate to
respond to the virus are infected and killed by it
epitope variation can lead to escape of HIV from the immune
response
activated T cells are susceptible to apoptosis. Spontaneous
apoptosis of uninfected CD4+ and CD8+ T cells occurs in HIV-
infected patients. Also there appears to be specific apoptosis of
HIV-specific CD8+ cells
the number of follicular dendritic cells falls over time, resulting in
diminished capacity to stimulate CD4+ cells
T-killers find and destroy all cells with molecules gp120
(uninfected to)
the synthesis of interleukins is destroyed
the functions of complement and macrophages are depressed

32. ONSET OF DISEASE - AIDS
The period of clinical latency varies in length from 1 to 2
years to more than 15 years.
Onset of AIDS is rare in less than 3 years except in
children. But, eventually, the virus can no longer be
controlled as helper CD4+ (T4) cells are destroyed.
Ironically, the killer cells needed to control HIV also
damage the helper T cells that they need to function
efficiently. With the lack of CD4+ cells, new cytotoxic T
cell responses cannot occur as helper cells are lacking and
such new responses are required as the virus mutates. As
the T4 cells fall below 200 per cu mm, virus titers rise
rapidly and immune activity drops precipitously. It is the
loss of immune competence that enables normally benign
opportunistic parasites such as viruses, fungi or protozoa

33. Once AIDS develops, patients rarely survive more than two years
without chemotherapeutic intervention. There is considerable
variability at this stage. Some patients with clinical AIDS do
survive for several years while others who appear relatively
healthy can suddenly succumb to a major opportunistic infection.
It is the onset of HIV-associated cancers and opportunistic
infections that defines AIDS proper. At this stage, also,
syncytium-inducing HIV appear in many (about half) AIDS
patients. These are more CD4+ cell tropic than the initially
infecting HIV and this contributes to the rapid loss of CD4+ cells
in later stages of the disease.
It should be noted that a phase of HIV infection, AIDS-related
complex (ARC), used to be defined. This is now little used. It is the
phase of the disease that lacks the neoplasms and opportunistic
infections that are the definition of AIDS. Patients at this stage of
the disease show weight loss and fatigue together with fungal
infections of the mouth, finger and toe nails.

34. SYMPTOMS OF HIV DISEASE
Incubation period - of some week - to some years
The first symptoms - fever, headache, sore throat, muscle aches,
enlarged lymph nodes and generalized rash (typically subside
abruptly within a few weeks). Many patients are asymptomatic or
experience mild symptoms attributed to «the flu». For the
majority of patients the first concern is persistent enlargement of
lymph nodes.
The disease slowly advances, most people remain unaware of their
infection until the development of AIDS.
AIDS represent the end stage of HIV disease (patients become highly
susceptible to infections) - EB virus, pneumonia, meningitis,
diarrhea,.. Progressive dementia, weight loss, appearance of
malignant tumors often accompany the AIDS, (Kaposi’s sarcoma)

37. METHODS OF LABORATORY
DIAGNOSIS
Material - blood, sperma, other tissue
Molecular biology – PCR – detection viral genome
Serology: 1) detection viral antigens
2) detection antiviral antibodies
by ELISA, Immune blotting (more sensitive)
Microscope examination,
Isolation and identification of virus – for research
(not used in ordinary laboratory)

38. Steps of PCR
1. Isolation DNA (RNA)
2. Amplification
temperature cycles
amount of fragments of
the new copies DNA (RNA)
3. Detection in agarose
gele

39. SHORT SCHEME OF IMMUNE BLOTTING

42. EPIDEMIOLOGY
Source - infected person
routes of transmissions - transffusion (blood trasfusion,
shered drug injection equipment with infected person,
tatoo or pirsing with not steril instrument); sexual
contact; from mather to fetus (during pregnency, at
birth,...)
susceptible - general

43. HIV/AIDS AROUND THE WORLD
The overwhelming majority of people with HIV, some
95% of the global total, live in the developing world. The
proportion is set to grow even further as infection rates
continue to rise in countries where poverty, poor health
care systems and limited resources for prevention and care
fuel the spread of the virus.
The chart on the right shows the distribution of people
living with HIV around the world, according to 2007 data.

46. GLOBAL HIV/AIDS ESTIMATES, END OF 2007
THE LATEST STATISTICS ON THE WORLD EPIDEMIC OF AIDS &
HIV WERE PUBLISHED BY UNAIDS/WHO IN JULY 2008, AND
REFER TO THE END OF 2007.
Estimate Range
People living with HIV/AIDS in 2007 33.0 million 30.3-36.1 million
Adults living with HIV/AIDS in 2007 30.8 million 28.2-34.0 million
Women living with HIV/AIDS in 2007 15.5 million 14.2-16.9 million
Children living with HIV/AIDS in 2007 2.0 million 1.9-2.3 million
People newly infected with HIV in 2007 2.7 million 2.2-3.2 million
Children newly infected with HIV in 2007 0.37 million 0.33-0.41 million
AIDS deaths in 2007 2.0 million 1.8-2.3 million
Child AIDS deaths in 2007 0.27 million 0.25-0.29 million

47. More than 25 million people have died of AIDS since 1981.
Africa has 11.6 million AIDS orphans.
At the end of 2007, women accounted for 50% of all adults
living with HIV worldwide, and for 59% in sub-Saharan
Africa.
Young people (under 25 years old) account for half of all
new HIV infections worldwide.
In developing and transitional countries, 9.7 million people
are in immediate need of life-saving AIDS drugs; of
these, only 2.99 million (31%) are receiving the drugs.

48. REGIONAL STATISTICS FOR HIV & AIDS, END
OF 2007
Region
Adults &
children
living with
HIV/AIDS
Adults &
children
newly infected
Adult
prevalence*
Deaths of
adults &
children
Sub-Saharan Africa 22.0 million 1.9 million 5.0% 1.5 million
North Africa & Middle East 380,000 40,000 0.3% 27,000
Asia 5 million 380,000 0.3% 380,000
Oceania 74,000 13,000 0.4% 1,000
Latin America 1.7 million 140,000 0.5% 63,000
Caribbean 230,000 20,000 1.1% 14,000
Eastern Europe & Central
Asia
1.5 million 110,000 0.8% 58,000
North America, Western &
Central Europe
2.0 million 81,000 0.4% 31,000
Global Total 33.0 million 2.7 million 0.8% 2.0 million

49. During 2007 more than two and a half million adults and
children became infected with HIV (Human
Immunodeficiency Virus), the virus that causes AIDS.
By the end of the year, an estimated 33 million people
worldwide were living with HIV/AIDS. The year also
saw two million deaths from AIDS, despite recent
improvements in access to antiretroviral treatment.
Notes
Adults are defined as men and women aged 15 or above,
unless specified otherwise.
Children orphaned by AIDS are defined as people aged
under 18 who are alive and have lost one or both parents
to AIDS.

50. Summury
Before the appearance of HIV, AIDS-like syndromes were rare, today they are
common in HIV-infected people
The main risk factors for AIDS are sexual contact, transfusions, IV drugs,
hemophilia. These have existed for years but only after the appearance of HIV,
has AIDS been observed in these populations
Infection by HIV is the ONLY factor that predicts that a person will develop
AIDS
Numerous serosurveys show that AIDS is common in populations with anti-HIV
antibodies but is rare in populations with a low seroprevalence of anti-HIV
antibodies
New-born infants with no behavioral risks develop AIDS if infected as a result of
the mother being HIV-infected
Since the appearance of HIV, mortality has increased dramatically among
hemophiliacs
Studies of transfusion-acquired AIDS has repeatedly led to discovery of HIV in
recipient as well as donor
Sex partners of HIV-infected hemophiliacs and transfusion patients acquire the
virus and AIDS without other risk factors
HIV infects and kills CD4+ T cells in vitro and in vivo

51. PREVENTION
Non speciphic
Caution in handling blood. Safe sex. Screen blood and organ
donors.