Serology of Viral Infections (Exam 3-5a) Flashcards
How does the immune system respond to viral infection?
Cell mediated: presentation to cytotoxic and helper Ts by MHC I.
Humoral: Neutralization by Abs, Ab-dependent cell-mediated cytotoxicity (ADCC), and complement activation
How do viruses evade the immune system?
Frequent genetic mutation (antigenic shift), Specific mechanisms (such as interferons and complement), direct suppression of immune system (down-regulation of MHC), or by remaining latent (ex. CMV, VZV, HIV).
What are the common immunological tests to diagnose viral infections?
Antibody tests for IgG and IgM
Antigen tests using EIA
What are the common molecular tests to diagnose viral infections?
Nucleic Acid Test (NAAT or NAT) and syndrome specific multiplex PCR
What are two forms of testing that are not so commonly used for detection of viruses?
Culture and electron microscopy
What does elevated IgG tell you about an adult?
They may have a current infection, past infection or immunity
What does elevated IgM tell you about an adult?
Current or recent infection
What does elevated IgM tell you about a newborn?
Indicates congenital infection
What does elevated IgG tell you about a newborn?
Maternal antibodies have crossed the placenta
What sort of test is best to detect active infection, monitor therapy, and is sometimes used a confirmatory test?
Molecular tests
What is the standard for care of sterile fluids?
PCR
What are some of the other viral causes of Hepatitis?
CMV, EBV, HSV, and West Nile
What stage if hepatitis is described below?
Fatigue, fever, myalgia, loss of appetite, nausea, vomiting, diarrhea or constipation, and mild pain in the abdomen (RUQ).
Early/acute phase
What stage if hepatitis is described below?
Liver enlargement, tenderness, jaundice, dark urine, light or clay-colored feces
Progression
What stage if hepatitis is described below?
Liver failure and death
Fulminant
What are the main complications of chronic hepatitis?
Cirrhosis, liver failure, liver cancer, and kidney disease
What is considered chronic hepatitis?
Persistence of hepatitis virus in the body for 6 months or more
Which two types of hepatitis are known for coinfection?
Hep B and Hep D
Which type of hepatitis is not able to replicate without the help of another HV?
Hep D
When a person simultaneously acquires two types of hepatitis what is this called?
Coinfection
When a chronic HBV carrier acquires HDV this is called what?
Superinfection
Is someone with a coinfection of HBV and HDV likely to develop a chronic state?
No
Is someone with a superinfection of HBV and HDV likely to develop a chronic state?
Yes
Picornaviridae is responsible for which type of hepatitis?
Hep A
Hepadnaviridae is responsible for which type of hepatitis?
Hep B
Flaviviridae is responsible for which type of hepatitis?
Hep C
Deltavirus is responsible for which type of hepatitis?
Hep D
Hepeviridae is responsible for which type of hepatitis?
Hep E
What family of virus causes localized skin infection that disseminates to numerous organs?
Herpesviridae
Does herpesviridae have a latent phase?
Yes
What family of viruses can cause cardiac and neurological involvement if left untreated?
Herpesviridae
What are the clinical syndromes of EBV?
Teenagers and adults will show symptoms, but get better within 2-4 weeks; EBV can cause infectious mononucleosis, lymphoproliferative disorders and malignancies (Burkitt lymphoma) - usually in immunocompromised
How is EBV transmitted?
Spread by contact with body fluids, especially saliva.
What is a heterophile antibody and what is its diagnostic significance?
Antibodies induced by external antigens (heterophile antigens). Some cross-react with self-antigens
What do the following lab findings describe?
Absolute lymphocytosis, 20% or more atypical lymphocytes, heterophile antibodies (monospot +)
Infectious mononucleosis (IM)
IgM produced as a result of polyclonal B-cell activation, capable of reacting with horse RBCs, sheep RBCs, and bovine RBCs
Heterophile Ab associated w/ IM
Tests the ability of serum absorbed with guinea pig kidney or beef erythrocyte antigens to agglutinate horse RBCs
Classic lab test “monospot”
Incubate serial dilutions of the patient’s serum w/ sheep RBC’s to determine antibody titer
Paul Bunnell test
Version of the Paul Bunnell test where the beef RBC antigens are bound to latex particles (aka solid phase EIA)
Is the current heterophile antibody test for IM; also called latex agglutination
What may bring a false positive in heterophile ab testing for EBV/IM?
lymphoma, viral hepatitis, malaria, and autoimmune disorder
For whom may false positive positives be the result of heterophile ab testing for EBV/IM?
10% of adults, up to 50% in children under 12, and immunocompromised patients
Is heterophile or monospot the preferred method by the CDC?
No
What is VCA?
The viral capsid antigens found in EBV
What is EA?
Early antigen found in EBV
What is EBNA
EBV nuclear antigen
Which EBV Ab declines after peaking, but persists?
anti-VCA IgG
Which EBV Ab declines to undetectable after the acute phase?
anti-EA IgG
Which EBV Ab is absent during the acute phase then appears and persists for life?
anti-EBNA
What are the three routes of transmission for HIV?
Sexual, parenteral (blood and other body fluids), and perinatal
Can HIV be transmitted via saliva, urine, feces, sputum, sweat, vomit, or tears?
No
