DENGUE Flashcards
DENGUE Family (same as Hep C)
Flaviviridae
DENGUE Structure
Envelope RNA virus
DENGUE Serotypes
4 sero types (DENV-1,2,3,4)
DENGUE Geographic distribution
Tropical and sub tropical countries
DENGUE Vector
Aedes aegypti
DENGUE MOT
Via vector
EPSTEIN-BARR VIRUS (EBV) Family
Herpesviridae
EPSTEIN-BARR VIRUS (EBV) Structure
Double stranded DNA
EPSTEIN-BARR VIRUS (EBV) MOT
Saliva, blood transfusion, transplacental
Gold standard for dengue
Viral Isolation
• 6-10 days to replicate viral cell culture
Viral Isolation
• Molecular detection of dengue genomic RNA; Testing of ribonucleic acid
RT-PCR
• NS1 is a highly conserved glycoprotein for virus viability
Dengue NS1
• Detects acute phase infection
Dengue NS1
First to become (+) prior to IgM as long as infected
Dengue NS1
• First detectable IgM only appears 4- 5 days
IgM-capture ELISA (MACELISA)
• Diagnosis of acute infection
IgM-capture ELISA (MACELISA)
IgM-capture ELISA (MACELISA) Presence of line in IgG only indicates
chronic infection or recovery
• SD BIOLINE Dengue Duo
Rapid test combo kit
• Detects Dengue NS1 Ag and IgG/IgM in a single test
Rapid test combo kit
: High viral load but declines at day 5
Acute Illness
• As the viral load decreases, the antibodies [?]
increase
• First increase [?]
IgM
→ past dengue infection
• IgG persists
→ already high in acute illness
• NS1 Ag
DIAGNOSTIC MARKERS FOR DENGUE
Acute illness:[?]
6 to 14 days: [?]
NS1
IgM followed by IgG
EBV DISEASES
- Infectious mononucleosis (IM)
- Other disease
• Burkitt’s lymphoma
• Nasopharyngeal CA
• Neoplasms of thymuns, parotid gland (salivary gland) and larynx
• Kissing disease
Infectious mononucleosis (IM)
• Young adults affects the mononuclear phagocyte system
Infectious mononucleosis (IM)
• Signs and symptoms: Fever, malaise, lethargy, sorethroat, and enlarged lymph nodes
Infectious mononucleosis (IM)
Same as HIV
Infectious mononucleosis (IM)
EBV Primary target cells
B cells
EBV Hallmark
Downey cells
Entry gained following attachement to the complement receptor 2 (CR2)
B cells
Virus infected B cells which has T cells characteristics
Downey cells
Enlarged lymphocytes with atypical nuclei
Downey cells
Specific EBV antigens
- Viral capsid antigens (VCA)
- EBV nuclear protein (EBNA)
- Early antigen (EA)
Found in patients with acute phase IM
- Viral capsid antigens (VCA)
Found in cases of IM but they disappear early after recovery
Early antigen (EA)
Early antigen (EA) Diagnostic procedure:
EA-Diffuse
EA-Restricted
EA-Diffuse:
Nucleus and Cytoplasm of B cells
EA-Restricted:
Cytoplasm only of B cells
SEROLOGIC TESTS FOR EBV
• Most specific: EBV DNA PCR
• Heterophile antibody tests
• EBV specific serology
Heterophile antibody tests Ex
- Monospot
- Paul Bunnel test
- Davidsohn Differential
Detects the presence of IgM and IgG
• EBV specific serology
• EBV specific serology types
- EBV VCA IgM and EBV VCA IgG
- EBNA IgG
Principle: Direct immune agglutination
Monospot test
Reagent: Horse RBCs agglutinate with the heterophile Ab present in EBV
Monospot test
• Principle: Direct immune agglutination
Paul-Bunnel test
• Reagent: Sheep RBCs agglutinate with the heterophile Ab
Paul-Bunnel test
• Titer of 1:56 is positive presumption test of IM
Paul-Bunnel test
• Principle: Absorption test
Davidsohn Differential Test
Davidsohn Differential Test
Reagent:
Unknown:
Reagent: Sheep RBCs
Unknown: Serum (heterophile Abs)
Davidsohn Differential Test
1. Perform [?]
2. Allow to be absorbed by [?]
3. Distinguish whether [?] based whether the agglutinins were absorbed.
Paul Bunnel test (Serum +Sheep RBC = heterophile sheep agglutinins)
guinea pig kidney cells and beef erythrocytes
Forssman Ag (Guinea pig kidney), serum sickness and IM
Absorbed by Guinea pig Kidney cells
FORSSMAN
SERUM SICKNESS
Absorbed by Beef (Ox) Erythrocytes
IM
SERUM SICKNESS
Mnenomic: GF BI SS (GirlFriend Believes In Safe Sex)
• G- guinea pig (+) →
Forssman
• B- beef erythrocyte (+) →
IM
• SS-serum sickness (
both +)
Not a virus, but an acute phase reactant; rises in inflammation
C-REACTIVE PROTEIN
Abnormal Protein that appears in the acute stages of various
C-REACTIVE PROTEIN
Non-specific indicator of the ff. disorders:
Bacterial infections
Acute rheumatic fever
Malignant diseases
Viral infections
TB
MI
Burn
CRP
Name is derived from the formation of precipitate when reacted with
somatic C polysaccharide of pneumococcus
CRP Electrophoretic mobility:
gamma region
CRP Synthesized:
Liver
CRP Thermolabile :
70C for 30 minutes
Rapid slide test Principle:
reverse passive agglutination
Rapid slide test
Unknown:
Reagent:
Unknown: Antigen (CRP)
Reagent: Anti-CRP Antibody
Rapid slide test
(+) Result:
Agglutination (presence of CRP)
Patient Serum (Ag) is mixed with latex particles coated with anti-CRP antibody
Rapid slide test
CRP Serologic Assay
Rapid slide test
Advantage of CRP Assay
More sensitive indicator inflammatory process than:
Erythrocyte Sedimentation Rate (ESR)
WBC count
Disadvantage of CRP Assay
Non-specific (positive for ALL inflammatory diseases)
Lack of correlation between positivity of the test and severity