83. HUMAN IMMUNODEFICIENCY VIRUS (HIV) Flashcards
- When was HIV discovered?
- in 1981
- it was isolated in 1983
- What are the two types of HIV?
- HIV-1
- HIV-2
- What cell in the body does HIV infect?
- it affects the T-helped Lymphocytes (Th-cells)
- it only affects them because they carry the CD4
Receptor
- How does HIV attach itself onto the Host Cell?
- the Viral HIV Glycoprotein attaches itself to the CD4
Receptor - this is found on the surface of the Host’s T-Helper
Lymphocytes
THE GLYCOPROTEIN OF HIV IS:
- 120 glycoproteins long
- What does HIV cause?
- it causes AIDS
- this is an Acquired Immuno Deficiency Virus
- What do the T-helper Cells do?
- they activate the B cells to produce antibodies
- Cytotoxic C-Cells will attack the target cells
IT THE T-HELPER CELLS ARE NOT ACTIVE:
- only pathogens will exist in the host cell’s body
- What are the steps of the HIV Replication Cycle?
- Attachment
- Reverse Transcriptase
- Integrase
- Translation
- Protease
- Assembly
- New Virus leaves the Host Cell
- What happens during: Attachment?
- the virus attached itself the CD4 receptor of the host
cell - this is found on the cell membrane
- a single RNA genome from the Virus will enter the cell
- What happens during: Reverse Transcriptase?
- this enzyme will synthesise the virus RNA into DNA
- What happens during: Intergrase?
- the virus DNA will integrate into the genome of the
Host Cell - Transcription will take place
THIS CONVERTS THE VIRAL DNA AND HOST DNA:
- into a new strand of pathogenic RNA
- this viral RNA leaves the nucleus of the Host Cell
- What happens during: Protease?
- Translation will take place
- a Virus Protein is formed
PROTEASE:
- is an enzyme
- it cuts up the protein
- What happens during: Assembly?
- the viral protein fragments will reconstruct
- they do this by themselves
- this forms a new virus
- Which enzymes does the Anti-Retroviral Therapy target?
- Reverse Transcriptase
- Integrase
- Translation
- Protease
- What is the most serious pandemic of the 21st Century?
- AIDS
- 25 million people died
- 40 million people are infected
- What is the infection rate of AIDS?
- 6 million people are killed per year
- How long after someone contracts HIV, do they develop AIDS?
- 10 to 15 years after the infection
- they can be asymptomatic during this period of time
- this allows them to transmit the disease
PEOPLE WITH HIV WILL START TO DEVELOP AIDS SYMPTOMS:
- when the number of their T-helper cells falls under 200
cells per mm³ of blood
- How much has Anti-retroviral therapy helped to increase life expectancy?
- it has increased it by 5 to 20 years
- it allows people to live a life as normal as possible
- What kind of infections do people with AIDS suffer from?
- they suffer from opportunistic infections
- this is because they are severely immuno
compromised
- What are the main two categories of diseases that AIDS patients will experience?
- Opportunistic Infections
- Malignant Tumours
- What are some examples of Opportunistic infections?
- CANDIDIASIS
- this is a type of yeast - TOXOPLASMOSIS
- this is a type of protist - PNEUMONIA
- this is a type of bacteria
- What are some Malignant Tumours associated with AIDS?
- KAPOSI SARCOMA
- this is a malignant tumour
- it effects the endothelial cells
- these are found in blood vessels - BURKITT’S LYMPHOMA:
- this cancer affects the B-cells
- it results in swollen lymph nodes
- What are the three ways in which HIV is transmitted?
- Sexual Intercourse
- Blood
- Mother to Child
- How is HIV transmitted through Sexual Intercourse?
- it is transmitted through sperm
- it is transmitted through vaginal fluids
- How is HIV transmitted through Blood?
- it is transmitted by sharing infected needles
- it is transmitted by sharing infected syringes
- it is transmitted through blood transfusions
WHEN IT COMES TO BLOOD TRANSFUSIONS:
- there is a window period
- where the virus is present in the blood
- but cannot be detected
- it is present in very low levels in the blood
- this is how it is transmitted to other people
- How is HIV transmitted from Mother to Child?
- it is transmitted during pregnancy
- it is transmitted during birth
- it is transmitted through breast feeding
BREAST MILK:
- carries a large amount of then virus in it
- this can infect the child
INFECTED MOTHERS:
- will often have C-sections
- Can HIV be transmitted through Saliva or Tears?
- no
- the viral count is far too low for any transmission to
occur
- How is HIV detected?
- the virus can be detected in the Blood
- this happens 3-6 weeks after the suspected infection
date - the detection depends on the method used
- What are the Diagnostic Methods used for HIV?
- ELISA
- this detects anti-HIV antibodies in the blood
- it can be done 6-8 weeks after infection
- it is a slower technique - RT-PCR
- this detects the viral HIV RNA in the blood
- this can be done 3 weeks after the infection
- Is there a cure for an HIV Infection?
- no there is not
- there is no vaccine available
- this is because HIV mutates at a very high rate
- What are the Treatment strategies for HIV?
- HAART
- this is a High Active Anti-Retroviral Therapy
- it is a combination of many types of anti-retroviral
drugs
- What are the common problems that we find when we use Anti-retroviral therapy?
- toxicity resistance
- this is because the components of the virus are
mutating - this interferes with the replication cycle of the healthy
cells in the body and the infected cells
- What are the three main types of Anti-retroviral Drugs?
- NUCLEOTIDE ANALOGUES
- NON-NUCLEOTIDE ANALOGUES
- PROTEASE INHIBITORS
- What are Nucleotide Analogues?
- they are drugs
- they inhibit the replication of the RNA in the virus
- the RNA is incorporated into a growing cDNA chain
EXAMPLE:
- AZT
- What are Non-nucleotide Analogues?
- they are drugs
- they inhibit Reverse Transcriptase
- this enzyme no longer has activity
EXAMPLE:
- SUSTIVA
- NEVIRAPINE
- What are Protease Inhibitors ?
- they are drugs
- they inhibit HIV protease
HIV PROTEASE:
- is responsible for the polypeptide cleavage of the virus
- it allows for new virus particles to mature
EXAMPLE:
- SAQUINAVIR
- RITONAVIR
WHEN TREATING HIV:
- it is encouraged to give one medication from each
category
- What is AZT?
- it is Azido-deoxy-thymidine
- it is a Nucleotide Analogue Anti-retroviral drug
HOW IT WORKS:
- the next nucleotide cannot be incorporated into the
growing DNA chain
- this is because of the presence of Nitrogen (N₃) instead
of -OH
- this inhibits the replication of the viral RNA
- Define: HIV Polymorphism.
- HIV has a high rate of mutation
- new strains will continue to emerge
THE RNA OF THE HIV VIRUS:
- is exposed to the enzyme : Reverse Transcriptase
- this will form copies of HIV DNA (cDNA)
THE REVERSE TRANSCRIPTASE:
- will allow for 1 mutation per HIV genome
- per replicative cycle
