HIV Flashcards
This HIV protein binds cell surface proteins CD4 and CCR5
p120
What is protein p120?
Protein on HIV that binds cell surface proteins CD4 and CCR5
Both proteins needed for infection to occur
People with this homozygous mutation are resistant to HIV infection
CCR5
Both CD4 and CCR5 are needed for infection to occur
What is the result of HIV infection of a quiescent T cell?
Latent infection
Viral RNA remains linear and cytoplasmic
What is the result of HIV infection of an activated proliferating T cell?
Cell death
Viral RNA integrates into host genome
Type of T cell that Proliferating infected cell sheds virus and is killed
Th cells
2 cells that are not killed by HIV infection, but serve as reservoirs of infection (important when Th count is very low)
Macrophage and Dendritic cell
Probable initial infected cell at mucosal inoculation
Dendritic cell
Cell that Brings infection to other tissue sites (microglia, etc)
Macrophage
Cell that Brings HIV infection to lymph nodes and more CD4+ T cells
Dendritic cell
This begins 3-6 weeks after HIV infection and lasts 2-4 weeks
Acute retroviral syndrome
How do you get loss of barrier function at mucosal sites and microbial invasion often with diarrhea in acute retroviral syndrome?
Infection and death of memory T cells at mucosal site
How do you get generalized lymphadenopathy and viremia in acute retroviral syndrome?
Dendritic cells bring HIV to lymph nodes
Acute retroviral syndrome is characterized by generalized ______ and _______
Lymphadenopathy and Viremia
When does seroconversion (making Abs; humoral response) occur in acute retroviral syndrome?
3-7 weeks
Fever, sore throat, fatigue, rash, and lymphadenopathy are symptoms of this
Acute retroviral syndrome
What affect does the cell-mediated response have on viremia?
Decreased
When does the cell-mediated response (and subsequent decreased viremia) occur in acute retroviral syndrome?
12 weeks
Does the humoral response or cell-mediated response occur 3-7 weeks in acute retroviral syndrome?
Humoral (seroconversion)
Does the humoral response or cell-mediated response occur 12 weeks in Acute retroviral syndrome?
Cell mediated (decrease viremia)
Seroconversion takes 3-7 weeks after infection, and these are detectable a little earlier
Viral particles or p24 capsid protein
Long period of stable viremia and gradual decreased CD4+ T cells
Latency period
CD4 count trend in latency period
Gradually decreases
Viral load count trend in latency period
Gradually increases
Period where HIV is replicating in spleens, lymph nodes
Latency period
Symptoms of HIV during the latency period
Usually asymptomatic
May have minor opportunistic infections (Candida, Tb, Herpes)
Occasionally have autoimmune thrombocytopenia
Level of viremia reaches plateau with onset of this
Cell mediated response
This level predicts the time course to AIDS
Level of viremia that reaches plateau with CMI onset
This count is assessment of current immune deficiency
CD4 count
Viremia level of >36k predicts 62% chance of this at 5 years
AIDS
Viremia level of <4k predicts 5% chance of this at 5 years
AIDS
Viremia level of this predicts 62% chance of AIDS at 5 years
> 36k
Viremia level of this predicts 5% chance of AIDS at 5 years
<4k
When does AIDS occur?
Generally 5-10 years after initial infection
AIDS is defined by a CD4 count of this
<200 cells/ul
AIDS is defined by either of these
CD4 count <200 cells/ul OR
AIDS defining illnesses
This is Often preceded by constitutional SSx, generalized LAD, fever
AIDS
Viral load count trend in AIDS
Dramatically increases slope
CD4 count trend in AIDS
Loss accelerates
6 AIDS defining illnesses
Viral
Pneumocystic pneumonia
Mycobacteria
Recurrent bacterial pneumonia
Fungal infections
Neoplasms
AIDS defining illness:
What cell dysfunction causes bacterial pneumonia?
B cell and neutrophil dysfunction
AIDS defining illness:
In bacterial pneumonia, what type of bacteria are patients most vulnerable to?
Encapsulated bacteria (due to poor opsonization)
Includes pneumococcus, haemophilus, staph aureus
AIDS defining illness:
Occurs early, incidence 10-20x
Due to B cell and neutrophil dysfunction
Bacterial pneumonia
AIDS defining illness:
Occurs anytime, usually early (CD4 ~ 325)
Restricted to lungs if CD4 count relatively high
(Pneumonia, Cavitary disease, Hilar lymph nodes)
Disseminated disease if CD4 count low
(Bone marrow, adrenals, etc)
Tuberculosis
AIDS defining illness:
Tuberculosis trend if CD4 count is relatively high
Restricted to lungs
Pneumonia, cavitary disease, hilar lymph nodes
AIDS defining illness:
Tuberculosis if CD4 count is low
Disseminated disease
Bone marrow, adrenals, etc
AIDS defining illness:
Kaposi Sarcoma is always associated with this
HHV8 (human herpes virus) infection
HHV8 (human herpes virus) infection is always associated with this AIDS defining illness
Kaposi Sarcoma
Blue-violaceous-brown maculopapular skin lesions are characteristic of this AIDS defining illness
Kaposi Sarcoma
AIDS defining illness:
When does bacterial pneumonia occur?
Early
Incidence 10-20x
AIDS defining illness:
When does tuberculosis occur?
Anytime, usually early (CD4 ~ 325)
AIDS defining illness:
When does Kaposi Sarcoma occur?
Anytime
AIDS defining illness:
When does lymphoma occur?
CD4 < 200
AIDS defining illness:
Lymphoma is associated with this coinfection
EBV
AIDS defining illness that is associated with EBV coinfection
Lymphoma
Lymphoma is typically this cell lineage
B cell
AIDS defining illness:
Lymphoma is frequently located
Extra-nodal
AIDS defining illness:
2 common types of lymphoma
Burkitt lymphoma
Diffuse large B-cell lymphoma
AIDS defining illness:
When does Pneumocystis occur?
CD4 < 200
Begin prophylaxis
AIDS defining illness:
Pneumocystis is caused by this
Unicellular fungal organism
AIDS defining illness characterized by:
Non-productive cough, Fever, and bilateral fluffy infiltrates (not always present with low CD4)
Pneumocystis
AIDS defining illness:
Involves bilateral fluffy infiltrates (not always present with low CD4)
Pneumocystis
AIDS defining illness:
Unicellular fungal organism causes this
Pneumocystis
AIDS defining illness:
When does Cryptococcus infection occur?
CD4 < 100
AIDS defining illness:
2 forms of Cryptococcus
Pneumonia or disseminated forms
AIDS defining illness:
Encapsulated yeast; visible with mucicarmine or India ink preparations
Cryptococcus
AIDS defining illness:
Cryptococcus is visible with either of these 2 preparations
Mucicarmine or India Ink preparations
AIDS defining illness:
When does taxoplasmosis occur?
CD4 < 200
AIDS defining illness:
CNS disease producing abscesses
“Ring enhancing lesions” as seen on brain scans
Toxoplasmosis
AIDS defining illness:
“Ring enhancing lesions” as seen on brain scans
Toxoplasmosis
AIDS defining illness:
Toxoplasmosis involves these seen on brain scans
Ring enhancing lesions
AIDS defining illness:
What is taxoplasmosis?
CNS disease producing abscesses
AIDS defining illness:
When does Mycobacterium avium-intracellulare occur?
CD4 < 50
AIDS defining illness:
Fever, weight loss, night sweats
Initial pulmonary infection
Disseminated form
Mycobacterium avium-intracellulare
AIDS defining illness:
When does cytomegalovirus infection occur?
CD4 < 50
AIDS defining illness:
3 characteristics of cytomegalovirus infection
Retinitis (painless vision loss, floaters)
Colitis (diarrhea)
Esophagitis (odynophagia, dysphagia)
AIDS defining illness:
Characterized by retinitis, colitis, esophagitis
Cytomegalovirus
AIDS defining illness:
Neoplasms are often associated with this
Viral associated
(Cervical or anal squamous cell carcinoma, Non-Hodgkin lymphoma, Hodgkin lymphoma, Kaposi sarcoma)
2 tests for initial HIV diagnosis
Antibody test
p24 antigen test
3 confirmatory tests for HIV diagnosis
HIV antibody specific assay
HIV viral RNA
Ab- with RNA+ : recent infection (window period; blood test not positive yet)