The document discusses HIV classification, structure, pathogenesis, and modes of transmission. It describes the CDC classification system for HIV based on CD4 cell counts and conditions, with categories A, B, and C. It explains HIV's structure including its envelope, matrix proteins, core, and RNA. HIV pathogenesis involves binding to and fusing with host cells, reverse transcribing its RNA into DNA, and using the host cell to replicate. HIV is typically transmitted via unprotected sex, contaminated needles, or from mother to child during birth or breastfeeding.

1. Dental therapy l 2
oral biology
Reg: 216191912
Isaac NSENGIYAREMYE
WORK 7 : HIV

2. 1. HIV CLASSIFICATION
Classification system of HIV is based on CDC disease staging and assess the severity of
HIV disease by CD4 cells counts and by the presence of specific HIV- related
conditions.
The CDC categorization of HIV/AIDS is based on the lowest documented CD4 cell count
and on previously diagnosed HIV-related conditions.
They are classified in A,B AND C categories
Patients in categories A3, B3, and C1-C3 are considered to have AIDS.

3. CDC Classification System for HIV-Infected
CD4 Cell Count Categories
Clinical Categories
A
Asymptomatic, Acute HIV
B
Symptomatic Conditions,
not A or C
C
AIDS-Indicator Conditions
(1) ≥500 cells/µL A1 B1 C1
(2) 200-499 cells/µL A2 B2 C2
(3) <200 cells/µL A3 B3 C3

4. Category A
Asymptomatic HIV infection
Persistent generalized lymphadenopathy
Acute HIV infection with illness or history of acute HIV infection

5. Category B Symptomatic Conditions
Are defined as symptomatic conditions occurring in an HIV-infected adolescent or
adult that meet at least one of the following criteria:
They are attributed to HIV infection or indicate a defect in cell-mediated immunity.
They are considered to have a clinical course or management that is complicated by
HIV infection.
Examples include the following:
Bacillary angiomatosis

6. Category B CONT’D
Vulvovaginal candidiasis
Oropharyngeal candidiasis (thrush)
Pelvic inflammatory disease
Cervical dysplasia and cervical carcinoma in situ
Hairy leukoplakia
Herpes zoster (shingles
Idiopathic thrombocytopenic purpura
 fever (>38.5°C) or diarrhea lasting >1 month
Peripheral neuropathy

7. Category C
It is associated by the following complications
Bacterial pneumonia
Candidiasis of the bronchi, trachea, or lungs
Candidiasis of esophageal
Cervical carcinoma, invasive, confirmed by biopsy
Coccidioidomycosis, disseminated or extrapulmonary
Cryptococcosis, extra pulmonary
Cryptosporidiosis, chronic intestinal (>1 month in duration)
Cytomegalovirus disease (other than liver, spleen, or nodes)
Encephalopathy, HIV-related

8. Category C CONT’D
Herpes simplex: chronic ulcers (>1 month in duration), or bronchitis, pneumonitis, or
esophagitis
Histoplasmosis, disseminated or extrapulmonary
Isosporiasis, chronic intestinal (>1-month in duration)
Kaposi sarcoma
Lymphoma, immunoblastic, or primary central nervous system
Mycobacterium avium complex or Mycobacterium kansasii, disseminated or
extrapulmonary
Mycobacterium tuberculosis, pulmonary or extrapulmonary

9. Category C CONT’D
Progressive multifocal leukoencephalopathy
Salmonella septicemia
Toxoplasmosis of brain
involuntary weight loss >10% associated with either chronic diarrhea or chronic
weakness and fever.

10. SECOND CLASSIFICATION
Second classification of HIV into HIV 1 and HIV 2 is shown in the table below
SPECIES VIRULENCE INFECTIVITY PREVALENCE
HIV 1 high high global
HIV2 lower low west Africa

11. 2. HIV STRUCTURE
The basic structure of the virus is as follows:
The viral envelope, the outer coat of the virus which consists of two layers of lipids.
different proteins are embedded in the viral envelope, forming "spikes" consisting of
the outer glycoprotein and the transmembrane.
The lipid membrane is borrowed from the host cell during the budding process
(formation of new particles).
The glycoprotein is needed to attach to the host cell, and transmembrane is critical
for the cell fusion process.

12. CONT’D
The HIV matrix proteins which lie between the envelope and core.
The viral core, contains the viral capsule protein which surrounds two single strands
of HIV RNA and the enzymes needed for HIV replication, such as:
•Reverse transcriptase
•Protease
•Ribonuclease
•Integrase

13. CONT’D
HIV belongs to a group of retroviruses called lentiviruses.
The genome of retroviruses is made of RNA (ribonucleic acid), and each virus has
two single chains of RNA for replication.
the virus needs a host cell, and the RNA must first be transcribed into DNA
(deoxyribonucleic acid), which is done with the enzyme reverse transcriptase

14. HIV STRUCTURE CONT’D

15. HIV STRUCTURE CONT’D
HIV is different in structure from other retroviruses.
It is around 120 nm in diameter (around 60 times smaller than a red blood cell) and
roughly spherical.
HIV-1 is composed of two copies of noncovalently linked, unspliced, positive-sense
single-stranded RNA enclosed by a conical capsid composed of the viral protein,
typical of lentiviruses.
The RNA component is 9749 nucleotides long
.

16. 3. HIV PATHOGENESIS
When HIV infects a cell, it first attaches to and fuses with host cell.
Then the viral RNA is converted into DNA and virus uses the host cell’s machinery to
replicate itself during a process called reverse transcription.
The new copies of HIV then leave the host cell and move on to infect cells.kli

17. factors contribute to the risk of acquisition of
infection include
:
The nature of the exposure (eg, the route, the size of the microbial inoculum)
The "virulence" of the microbe
The nature of the host susceptibility to infection
HIV infects mainly the CD4+ lymphocytes (T cells), but also to a lesser degree
monocytes, macrophages, and dendritic cells (these cells are also CD4+ cells). Once
infected, the cell turns into an HIV-replicating cell and loses its function in the human
immune system

18. These are stages of HIV pathogenesis
Binding to CD4
With the cells
HIV use reverse transcriptase to convert it genetic from HIV RNA TO HIV DNA WHICH
help virus to inter in the cell 'nucleus and change the genetic materials of the cell
DNA
HIV use it viral integrase enzymes to insert it DNA into cell’ DNA
Start to replicate and build more block of HIV
HIV protease and HIV RNA start to assembly as non-infectious
Start budding

20. 4. HIV MODE OF TRANSMISSION
HIV virus can be transmitted from one person to another in the following ways:
Person to person transmission through unprotected (heterosexual or homosexual)
intercourse.
Contact of abraded skin or mucosa with body secretions such as blood, CSF or
semen.
The use of HIV-contaminated needles and syringes, including sharing by intravenous
drug users; transfusion of infected blood or its components.

21. CONT’D
Transplantation of HIV-infected tissues or organs.
The presence of a concurrent sexually transmitted disease, especially an ulcerative
one, can facilitate HIV transmission.

22. CONT’D
HIV can be transmitted from mother to child (MTCT or vertical transmission).
 From 15% to 35% of infants born to HIV-positive mothers are infected through
placental processes at birth.
 HIV-infected women can transmit infection to their infants through breastfeeding
and this can account for up to half of mother-to-child HIV transmission.
 Giving pregnant women antiretroviral such as zidovudine results in a marked
reduction of MTCT.

23. CONT’D
After direct exposure of health care workers to HIV-infected blood through injury with
needles and other sharp objects, the rate of seroconversion is less than 0.5%, much
lower than the risk of hepatitis B virus infection after similar exposures (about 25%).
Unsafe injections may account for up to 5% of transmission.

24. REFERENCE
http://www.itg.be/internet/e-learning/written_lecture_eng/1_hiv_structure.html
https://en.wikipedia.org/wiki/Structure_HIV
www.boundles.com
www.thelancet.com
Hivinsite.ucsf.ed
www.cdc.gov
www.itg.be