Immune System Diseases Flashcards
Difference between primary and secondary immunodeficiency syndromes?
- Primary = inherited
- Secondary = acquired
What are the 5 major risk groups of adults at high risk of developing AIDS?
- homosexual/bisexual men (50%)
- IV drug users (not homosexual) (20%)
- Recipients of blood and blood components who are not hemophiliacs (1%)
- Heterosexual contacts of members of other high risk groups (20%)
- HIV infection of the newborn (2% under 13 y/o) =placental transmission
What are the two ways in which HIV viral transmission occurs?
- Direct inoculation into the blood vessels by trauma
- infection of dendritic cells or CD4+ cells within the mucosa
Sexual transmission of HIV is _________ by coexisting sexually transmitted diseases especially those associated with genital ulceration.
Enhanced
HIV is a non-transforming human retrovirus belonging to the lentivirus family, meaning:
-it will not transform normal cells into cancer cells
What is the structure of the HIV virus?
- Spherical
- electron dense core surrounded by a lipid envelope derived from host cell membrane
What is contained within the HIV core?
- The major capsid protein p24
- Nucleocapsid protein p7/p9
- Two copies of viral genomic RNA
- The three viral enzymes protease, reverse transcriptase and integrase
Why is research of HIV so complicated?
-there are a butt load of subtypes
What are the two main targets of HIV infection?
- Immune system
- CNS
Describe the pathogenesis of HIV.
- Profound immune deficiency, primarily cell-mediated immunity
- results from infection and loss of CD4+ T cells and impairments of surviving Th cells
Describe the life cycle of HIV.
Consists of infection of cells, integration of the provirus into the host cell genome, activation of viral replication, and production and release of infectious virus
What does gp120 bind to?
CD4
CCR5 & CXCR4
Describe the process of HIV entering a cell.
- gp 120 binds CD4
- gp120 & CD4 binds CCR-5 receptor (on T cell)
- leads to fusion to host cell
Why are naive T cells difficult for HIV to infect?
- they contain an active form of an enzyme that introduces mutations to the HIV genome
- they don’t express CCR5 & CXCR4
Can macrophages and dendritic cells also be infected by HIV?
-Yes
Why can’t B cells produce antibodies to HIV
-They don’t have the T cells to stimulate them
What are the three phases of the clinical manifestations of HIV?
- An acute retroviral syndrome
- Middle chronic phase
- Clinical AIDS
What is the initial clinical presentation of the initial viremia of HIV?
- Acute retroviral syndrome
- 3-6 weeks after infection
- nonspecific symptoms including sore throat, myalgias, fever, weight loss, and fatigue similar to the flu
Describe the middle chronic phase of HIV infection.
- In the next phase of the disease lymph nodes and spleen are sites of continuous HIV replication
- during this phase of the disease there are little or no clinical symptoms
- However the infection is killing off T cells and over years the CD4+ T cells drop to insufficient numbers
Describe the AIDS stage of HIV infection.
The final progression is to AIDS, characterized by a breakdown of host defense, a dramatic increase in plasma virus, and severe, life threating disease
Why does it take at least 6 months (of age) for a primary immunodeficiency to show up?
-Momma’s antibodies
What is the difference between Type I and Type II leukocyte adhesion defects?
Type I: Defect in synthesis of Beta2 chain shared by integrins
Type II: Defects in selectins
What is Chediak-Higashi syndrome?
- defective fusion of phagosomes and lysosomes, resulting in defective phagocytic function and susceptibility to infection
- main abnormalities: neutropenia, defective degranulation, and delayed microbial killing
Why does Chediak-Higashi syndrome result in neutropenia?
-need to phagocytose bacteria to create cytokine signals to attract neutrophils
