IMMUNODEFICIENCIES Flashcards
what is the example of immunodeficiency caused by infection?
AIDS caused by HIV
what is HIV?
a lentivirus that causes HIV infection and over time acquired immunodeficiency syndrome (AIDS)
what is the structure of HIV?
- roughly spherical
- diameter abt 120 nm
- composed of two copies of positive-sense single-stranded RNA
- a lipid viral envelope is present that composed of proteins.
what are the pathology of HIV infection?
it consist of three phases:
- acute phases
- asymptomatic phases
- symptomatic phases
explain acute phases.
- virus is produced in large quantities by infected lymphocyte
- This initial viremia (blood that contained virus) is greatly reduced - actions of Tcytotoxic (Tc) cells, which kill infected targets.
explain asymptomatic phases.
- Begins 3-4 months after the initial infection
- Memory T cells and dormant macrophages that contain HIV provirus serve as reservoirs for the
infecton. - HIV is latent and does not make any new virions.
- Population of CD4 T helper declines at a steady rate.
- Also known as clinical latency (last for years)
explain symptomatic phases.
- End stage of infection, the infected individual develops the clinical symptoms of AIDS.
- Th and Tc cells count drops
- When Th counts drop below 200 per microliter, the patients is said to have AIDS
- Increased susceptibility to opportunistic infections
- Cancers such as Kaposi’s sarcoma and B-cell lymphoma also develop in some patients
what is pathogenesis?
refers to the biological mechanisms that lead to the development of a disease. It describes how a disease starts, progresses, and causes damage in the body.
what is the pathogenesis of HIV?
- HIV can infect immune cells such as CD4+ T cells, macrophages, and microglial cells.
- HIV-1 entry to macrophages and CD4+ T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 mo;ecule on the target cells ‘ membrane
- also with chemokine co-receptors - CCR5
what is the multiplication steps in HIV
- Binding & Entry - HIV binds to CD4 receptors on T cells and fuses with the cell membrane.
- Reverse Transcription - The viral RNA is converted into DNA by reverse transcriptase.
- Integration - The viral DNA is inserted into the host genome using integrase.
- Replication - The host cell machinery produces viral proteins and RNA.
- Assembly - New viral particles are assembled inside the host cell.
- Budding - New HIV virions exit the host cell and mature, ready to infect more cells.
what is the effect of HIV infection?
HIV infection leads to a weakened immune system. This makes a person with HIV vulnerable to a group of illness, e.g., opportunistic infections, that would not as easily affect a healthy person.
how does HIV resulted in AIDS?
AIDS results when HIV infection progresses to an advanced stage, damaging the immune system to a point at which the body can no longer fight illness.
AIDS is a syndrome because it is characterized by a group of illnesses.
what are the drugs used to control HIV?
antiretrovirals. only prevent the virus from replicating and slow the progress of the disease
what are the symptoms of AIDS in acute phase?
Fever
Swollen lymph nodes
Sore throat
Rash
Muscle and joint pain
Headache
what are the symptoms of AIDS in asymptomatic phase?
No major symptoms, but slow depletion of CD4+ T cells occurs.
Symptomatic Phase (AIDS Stage)
Persistent fever
Chronic diarrhea
Rapid weight loss
Opportunistic infections (e.g., tuberculosis, pneumonia)
Neurological disorders
Cancers (Kaposi’s sarcoma, B-cell lymphoma)
what are the symptoms of AIDS in symptomatic phase?
Persistent fever
Chronic diarrhea
Rapid weight loss
Opportunistic infections (e.g., tuberculosis, pneumonia)
Neurological disorders
Cancers (Kaposi’s sarcoma, B-cell lymphoma)
how does HIV get transmitted?
HIV Transmission
Sexual Transmission - Unprotected sexual contact with an infected partner.
Bloodborne Transmission - Sharing of needles, blood transfusions with infected blood.
Mother-to-Child Transmission - During childbirth or breastfeeding.
Occupational Exposure - Accidental needle sticks in healthcare settings.
what is primary immunodeficiency diseases?
- Result from genetic abnormalities present in the affected individual at
birth - Characterized by an immune system that does not function properly
- Can be caused by mutations in immune response genes
- Inherited immunodeficiency diseases are caused by genetic defects and these diseases can affect both the development and function of T cells ad B cells. There can also be defects in phagocytic cells, complement, or cytokine receptors 🡪 will result in a lack of proper host defense.
what is T cell defects in primary immunodeficiency diseases?
- Defects in T-cell function can result in severe combined
immunodeficiency syndrome (SCID) - There is no T-cell function and therefore no cellular adaptive immune
response
what is B cell defects in primary immunodeficiency diseases?
- Defects in Ab production 🡪 can result in severe and repeated
infection with bacteria - Defects in the development of B cells or to defects in the activation of
the humoral response
what are some common primary immunodeficiency syndromes?
- SCID
- DiGeorge Syndrome
- MHC Class II deficiency
- wiskott-Aldrich syndrome
- x-linked agammaglobulinemia
- phagocyte deficiencies
- complement deficiencies
- ataxia telangiectasia
what is accessory cells defects in primary immunodeficiency diseases?
- Defects in complement cascade 🡪 can lead to an increase in the
occurance of infectious disease - Defects in phagocytic cells can cause widespread bacterial infections
what are the type of defects in acessory cell and the associated infection?
- leukocyte adhesion deficiency - widespread pyogenic bacterial infections
- chronic granulomatous disease - intracellular and extracellular infections
- myeloperoxidase deficiency - defective intracellular killing of pathogens
- chediak-higashi syndrome - intracellular and extracellukar infection
