HIV P. I Flashcards
In what part of the world is the highest region of AIDs?
South and central Africa
What is the most common form of HIV?
HIV - 1
What group of people(s) are more likely to have HIV?
Gay men, IV drug users, Haitians
What did Luc Montagnier do?
Got t-lymphocytes cultured from an AIDS patient and isolated the virus from their blood, Cultured the virus with patients T-lymphocytes and discovered the Lymphadenopathy associated virus (LAV)
What did Robert Gallo do?
Discovered the human t cell leukaemia virus, HTLV-1 & HTLV-2
What characteristics of HIV led to the discovery that it was the cause of AIDS?
- AIDS characterised by decrease in T cells that have the CD4+ antigen - Causative agent of AIDS is found in swollen lymph nodes - Found that HIV’s high capacity for growth especially in T cell lines was the cause of AIDS
What kind of virus is HIV and what family does it belong to?
It is a retrovirus and is a part of the family Retroviridae
What are the 3 groups of genes in the viral genome? What do they transcribe?
- gag, pol and env.
- gag: p55 - group specific antigen
- pol: p100 - makes viral long proteins needed for processing virus/ host cell machinery
- env: gp160 - viral envelope
What are the proteins that make up the HIV structure?
p55, gp160, p100
What does p55 do in the structure of HIV?
It is a matrix and capsid protein. Encloses nucleic acid virus Histone like nucleoproteins that bind and stabilise viral RNA in genome
What does gp160 do in the structure of HIV?
Its a transmembrane glycoprotein: it anchors between the lipid bilayer
What does p100 do in the structure of HIV?
It is a protease, integrase and reverse transcriptase. The integrase incorporates HIV into the chromosome
What molecule do viral surface proteins mediate the binding of?
T4 lymphocyte binding
Outline the HIV replication cycle.
(5 marks)
- Have initial binding with CD4+ receptor but need a very high affinity with CCR5 which interacts with CD4R and the virus particle to get membrane fusion into the cell
- Viral RNA will enter the cell and reverse transcriptase will make a DNA copy but will use viral integrase to incorporate it into the chromosome
- Virus then triggered for replication by trans activators Tat and Rev, which will activate replication for gene expression and the production of proteins gp41 and gp120
- The viral proteins will get packaged and worked into the membrane and bud off
- Replication will lead to destruction of T4 cells
What other molecules need to be bind along with CD4+ to ensure membrane fusion of HIV into the cell?
CCR5 and CD4R
What are some of the functions and roles of T4 lymphocytes?
Core for immune system function. Stimulate B lymphocytes to make antibodies. Assist in elimination of cancer cells. Stimulate other T cells.
What does active HIV replication cause?
T4 lymphocyte reduction
How is HIV diagnosed?
Recurring bacterial infections, mycobacterial infections, kaposis sarcoma, lymphoma
What test is used to find HIV antibody’s?
ELISA test
What is an ELISA test?
An immunoassay test to determine if you possess certain antibodies to a disease.
What equipment is usually required for an ELISA test?
- 96 well plate - primary or secondary detection antibody - antigen - coating antibody/ antigen - buffer - wash - substrate
How are the primary and secondary antibody’s used n an ELISA test?
Primary detection antibody specifically binds to the protein of interest, while the secondary antibody is a second enzyme conjugated antibody that binds to a primary antibody that isn’t enzyme conjugated
What are the general 4 steps in an ELISA?
- Coating w/ antigen/ antibody
- Blocking (norm w/ additional bovine serum albumin)
- Detection
- Final read
What is the difference between a direct and indirect ELISA?
A direct ELISA will only use a primary antibody, whereas an indirect ELISA will use a primary and secondary antibody
