Introduction to HIV

Question 1

What are the joint united nations for ending aids

Answer 1

• AIMS TO BRING HIV TESTING AND TREATMENT TO THE VAST MAJORITY OF PEOPLE LIVING WITH HIV BY THE END OF 2020
• To reduce the amount of HIV viral load to undetectable levels, prevent the onset of opportunistic infections and further transmission of HIV

Question 2

What is the 90-90-90 target?

Answer 2

90%vof people to be diagnosed
90%v of people who are diagnosed to be on treatment
90%of people on treatment are virally suppressed

Question 3

Discuss the structure of HIV

Answer 3

• Hiv has a spherical morphology
• Cone-shaped core surrounded by a lipid matrix containing key surface antigens and glycoproteins
• Viral core contains 2 genomic copies of rna ,reverse transcriptase ,intergrase and protease

Question 4

Discuss the viral genome( 9 genes and what they encode )

Answer 4

> the viral genome has 9 genes :
1.Encoding 3 structural:
GAG = group-specific antigens (structural proteins -capsid and matrix)

ENV =Envolope ( The gene product is the transmembrane and surface glycoproteins,gp 120 binds to CD4 and coreceptors CCR5 and CXCR4 ); gp41 is required for virus fusion and internalization (3 structural )

2. Functional enzymes encoding 1 functional enzyme
   POL =Polymerase ( Reverse transcriptase, protease, and intergrase enzymes and RNaseH )
   (3 enzymes)
3. Accessory proteins (6 regulatory proteins )

> Consist os ssRNA ( + sense ) and a homodimer of linear

Question 5

What are the groups and subgroups of HIV

Answer 5

There are 2 groups of HIV: HIV 1 and HIV 2
HIV 1 is then subdivided into Group MNOP

The subgroup M is then also subdivided into ABCDEFGHIJK CRF

The subtypes C is dominant in SA

Question 6

How is HIV transmitted?

Answer 6

• Sexually ( 70-80% of transmissions)
• Paranatal
• Vertical

Question 7

Discuss the life cycle of HIV

Answer 7

1. HIV attaches to CD4 T cell: gp120 attaches to the CCR5(chemokine receptor ) or CXCR4 on the CD4 cell to allow the virus to enter
2. Once inside the CD4cell, the capsid is removed, exposing the RNA, integrase, protease, and reverse transcriptase
3. The ssRNA is converted into dsDNA by reverse transcriptase
4. The viral dsDNA is then incorporated into the host genome by intergrase
5. Provial DNA is transcribed and translated into a polyprotein, the enzyme protease then cuts the polyprotein into functional proteins which then forms virons and leaves the host cell

Question 8

Which group of the world population is immune to HIV-1

Answer 8

• Those with Northern European orgins
• Those with No CCR5 receptors but can rarely get infected with HIV-1 because of the CXCR4 receptor which is not commonly found in healthy individuals but common in some types of cancer cells. In order to have a T cell without these receptors = it is a recessive homogenous trait
• Those with the CCR532 mutation ( deletion of both segment of genes that codes for the CCR5 receptor)

Question 9

Which individuals may not be on treatment for HIV

Answer 9

1. Elite controllers: Someone who can keep a nearly undetectable level of the virus without treatment
2. Long-term nonprogressors: Someone who can maintain a normal level of CD4 and CD8 count for a minimum of 10 years without the aid of ART . They normally test pos for HV but have a CCR5 mutation

Question 10

How is HIV diagnosed?

There are 2 types of approaches to testing :
> Antibody-based eg HIV ELISA ( Ag/AB combo)

> Nuclei Acid testing eg HIV DNA PCR

Answer 10

1. Rapid point of care
   Measures antibodies and antigens
   results; 20 min
2. At home test
   Measures antibodies
   Results; 20 - a day
3. Standard Point of care
   Measures antibodies
   results 5- 1o days
4. Nucleic Acid Test
   Measures HIV Rna
   results in a few days

Question 11

What are the HIV diagnostic challenges

Answer 11

*Maternal antibodies from infected pregnant mother will interfere with HIV testing of children less than 18 months

Children > 18 months are tested using HIV ELISA ( AG/AB combo)

Children <18 months will be tested using HIV DNA PCR

Question 12

What are the HIV tests that can be used 2-3 weeks after infection

Answer 12

• ELISA
• Rapid Hiv test
• Western Blot

Question 13

When can an HIV infection emerge or be detected?

Answer 13

The presence of Hiv infection can only be detected as early as 1-2 weeks after infections

Question 14

Monitoring tests performed before and after being placed on ARV?

Answer 14

• CD4 count
• Hiv viral load
• HIV drug levels
• Hiv drug resistance (genotype)
• Safety pane : LFT ,Uand E and Hb

Question 15

What is the goal of ART therapy?

Answer 15

1. Viral suppression ( viral load to be below the limit o detection 3-4 months after HAART initiation)
2. Immunological CD4 reconstitution ( CD4 count to increase by 50-100 cells / mm3 in the first month and therefore increase is mich slower thereafter