Ch 13: Viral Infections of the Immune System

What is a pathogen?

Any microorganism that can cause disease (bacteria, viruses, fungi, etc.)

What percentage of mononucleosis cases are caused by Epstein–Barr Virus?

90%

What percentage of mononucleosis cases are caused by Cytomegalovirus?

10%

What diseases does the Epstein-Barr Virus cause?

Mononucleosis and Burkitt Lymphoma

A majority of Epstein-Barr cases are ____________, but if symptoms DO appear, they are usually from _____________:

Asymptomatic; Mononucleosis

What is the hallmark symptom of mononucleosis?

Extreme fatigue 

Which two types of cells does EBV infect?

Epithelial cells and B-cells

Why does EBV spread easily through saliva?

Because it first infects epithelial cells that line the mouth and throat

What are B-cells?

A type of white blood cell that produces antibodies (immune cell)

The cytomegalovirus is a beta herpesvirus meaning it’s latent in WBC’s.

Which specific White blood cells does it infect?

Macrophages and Monocytes

In which cells does the cytomegalovirus often become latent in first?

Monocytes

When does reactivation usually happen?

When the immune system weakens

Cytomegalovirus can reactivate when _______ mature into _______:

Monocytes; Macrophages

How is mononucleosis diagnosed if caused by Epstein-Barr Virus?

With an Anti-EBV antibody test

How is mononucleosis diagnosed if caused by cytomegalovirus?

With a PCR test

What does the Anti-EBV antibody test detect?

Antibodies in your blood that your immune system made in response to EBV infection

What type of disease is Burkitt Lymphoma?

A cancer of B cells

What virus causes Burkitt Lymphoma?

Epstein-Barr Virus

What happens to B cells in Burkitt Lymphoma?

They become cancerous after EBV infection

If someone has oral hairy leukoplakia, what disease do they most likely have?

Burkitt Lymphoma 

How is burkitt lymphoma transmitted?

Through contact with bodily fluids of an infected individual

What ways can you use to diagnose burkitt lymphoma?

CT scan or a biopsy

What is the purpose of a CT scan in diagnosing Burkitt Lymphoma?

To get detailed images of soft tissues, locate tumors, and see if the cancer has spread

What is a biopsy used for in Burkitt Lymphoma diagnosis?

To remove a small piece of the tumor or lymph node for microscopic examination.

What is the main treatment for Burkitt Lymphoma?

Chemotherapy

When reading a EBV antibody test, the timing of when you were exposed to EBV depends on…

Which antibodies are present

Which cells does EBV first infect in mononucleosis?

Epithelial cells

Why is mononucleosis considered an infection of the skin and respiratory systems?

Because EBV first infects the epithelial cells in those areas

What happens if EBV stays only in epithelial cells?

The immune system doesn’t mount a strong response, which is why most infections are asymptomatic

Which immune cells does EBV infect after epithelial cells?

B cells

Why is mononucleosis also considered an infection of the immune system?

Because EBV also infects B cells, which are part of the immune system

Do all EBV infections progress into B cells?

No

Mononucleosis symptoms only appear when EBV…

Moves into the B cells

What is Pre-Exposure Prophylaxis (PrEP)?

A daily medication for people who do not have HIV but are high risk

What is the goal of PrEP?

To prevent HIV

Can PrEP treat HIV in someone who already has it? Why or why not?

No. PrEP only prevents infection, it does not treat existing HIV

What type of virus is HIV?

HIV is an RNA retrovirus 

What is a retrovirus?

A virus that carries RNA but converts it into DNA inside the host cell

What enzyme does RNA use to convert back into DNA?

Reverse transcriptase

What happens once the viral DNA is integrated into the host’s DNA?

It can stay there permanently

Why is HIV called a “moving target”?

It is an RNA virus so each generation of the virus can be slightly different, making it hard for the immune system and treatments to recognize it

Why is HIV hard to cure?

Because once the viral DNA integrates into host cells, it cannot be fully removed

What are the two brands of PrEP medications called?

Truvada and Descovy

Are PrEP drugs safe?

Yes, side effects are rare

When should you avoid using PrEP medications?

If someone has serious kidney problems

How is HIV transmitted?

Through exposure to infected bodily fluids

How can HIV be transmitted through Sexual/ genital fluids?

Through unprotected vaginal or anal sex 

How can HIV be transmitted through blood?

By sharing needles (IV drug use), Perinatally, and transfusions (rare)

How can HIV be transmitted through breast milk?

Mother to baby

Can HIV be spread through casual contact like saliva, sweat, or touching objects?

No

Which population is disproportionately affected by HIV?

African Americans

How has HIV treatment changed life expectancy today?

By taking daily antiretroviral medications, people with HIV can now live a normal, full life expectancy

What type of screening test can first be used to detect if someone has HIV?

A rapid antibody test

What does the The rapid antibody test detect?

Antibiotics made against HIV

How quickly can a rapid HIV antibody test give results and what might the results read?

Within about 20 minutes- may read negative or preliminary positive

What bodily fluids can be tested during rapid antibody tests?

Saliva or Blood

Why might a rapid HIV test show a false negative?

Because antibodies can take weeks to months to form after infection- the window period

Can a person still have HIV during the window period even if they test negative?

Yes

What does a preliminary positive HIV test mean?

It means the person might be positive and needs confirmatory testing by a doctor

What type of confirmatory diagnosis test is used for HIV?

A blood draw and PCR testing 

What is used to treat HIV?

HAART: Highly active antiretroviral treatment

What does HAART do?

It combines multiple drugs that target different steps of the HIV life cycle

Does HAART cure HIV? What does it do?

No, it only controls the virus, prevents progression to AIDS, and reduces transmission risk

What is AIDS?

AIDS is the final and most severe stage of a HIV infection

What happens if HIV isn’t treated?

It progresses to AIDS

How do doctors diagnose AIDS?

By checking the CD4+ T-cell count or identifying an AIDS-defining illness

What is the normal CD4+ T-cell count range in a healthy immune system?

500-1,600 cells

What CD4+ T-cell count indicates AIDS?

Fewer than 200 cells

What is an AIDS-defining illness?

A serious infection or cancer that occurs only when the immune system is severely weakened by HIV

What are the four AIDS-defining illnesses?

Pneumocystis pneumonia, Crytococcus Pneumonia, Burkitt Lymphoma and Kaposi’s Sarcoma

What are opportunistic infections?

Infections caused by microbes that are usually harmless but take advantage of a weakened immune system

How many main stages does HIV infection have? What are they?

Three — Acute HIV infection, Chronic HIV infection, and AIDS

When do symptoms of acute HIV infection usually appear?

About 2–4 weeks after exposure

If someone has a fever, fatigue/body aches, sore throat, swollen lymph nodes, headache, possible mouth ulcers, and a rash, what infection might they have?

HIV (acute HIV)

If a person experiences a rash, night sweats, and weight loss, what infection might they have?

HIV

If a person is experiencing rapid weight loss, chronic diarrhea, constant fatigue, sores on the mouth, genitals, or anus, skin lesions, what infection might they have?

AIDS