EBV

Question 1

Which cells does EBV infect, and where is the site of latency?

Answer 1

Epithelial cells, B cells, NK and T cells. The main site of latency is the peripheral memory B cells (but also NK and T cells)

During latency the virus is present in the nucleus as a circular episome tethered to host proteins by EBNA1

Question 2

What is the transmission route of EBV, and what is the seroprevalence?

Answer 2

Saliva and respiratory secretions are the main transmission route. Breast milk, bodily fluids and transplant are also routes of transmission.

Seroprevalence of 90% - most infections occur in early childhood or teenage years

Question 3

What is the cell receptor for EBV?

Answer 3

CD21

Question 4

What are the most common symptoms of primary EBV infection in a) young children b) older adults/teens?

Answer 4

a) symptomatic b) IM

Question 5

Name some EBV associated diseases

Answer 5

Oral hairy leukoplakia
Uveitis/retinitis
Encephalitis
Hydroa vacciniforme
Burkitts lympoma
Nasopharyngeal carcinoma
Gastric cancers
Hodkin’s lymphoma
X-linked lymphoproliferative disease
Diffuse large B cell lymphoma
Chronic active EBV
HLH
PTLD

Question 6

What are the causes of infectious mononucleosis?

Answer 6

90% caused by EBV, other causes include CMV, HHV-6, adenovirus, Toxoplasma

Question 7

What is the heterophile antibody test? When would you use it?

Answer 7

Paul Bunnell/monospot.

Latex agglutination test using erythrocytes to test for hetrerophile Abs, positive in up to 90% of patients and with EBV.

Not for use in under 4 y or immunocompromised

If negative, repeat in 5-7 days, if still negative and a diagnosis is required send for EBV and CMV serology (as per SMI)

Question 8

What ophthalmic issues occur due to EBV. What diagnostic tests can be used, and what treatment options are available?

Answer 8

Scleritis, posterior uveitis, retinal vasculopathy, retinitis, PORN

DNA detection in vitreal fluid, however note low PPV. Possibly compare quantitation of vitreous virus to blood VL

Systemic aciclovir (or ganciclovir) and intravitreal foscarnet can be used

Question 9

Treatment options for EBV encephalitis, what patients is the most common in and what does CSF show?

Answer 9

1st line is corticosteroids, if non resolving can use IVIG +/- rituximab

Most common in immunocompromised but can occur in immunocompetent (can be reactivation or primary infection)

CSF would be lymphocytic and a high proportion are EBV DNA positive

Question 10

What are the screening and monitoring rules for EBV in SOT and HSCT?

Answer 10

Pre-transplant screening for donor and recipient in both SOT and HSCT

Weekly EBV DNA for paediatric SOT, no routine screening for adult SOT (test if symptoms of PTLD)

HCST test for EBV DNA weekly from 1-3 months post transplant (longer if delayed T cell reconstitution)

Question 11

What are the risk factors for PTLD?

Answer 11

EBV donor/recipient serostatus
T-cell depletion
HLA mismatch
Second HSCT
Severe GVHD
High or rising EBV VL
Cord blood transplant
Any D/R mismatch

Question 12

What is the incidence and when are the peak(s) of PTLD in a) SOT b) HSCT?

Answer 12

a) Incidence = 1-20%, peaks at 12-24 months and then 5-10 y post transplant

b) Incidence = 1% (but can rise to >10% with T cell depletion), peaks 2-3 months post transplant

Question 13

What are the symptoms of PTLD? And how is it diagnosed?

Answer 13

Symptoms are non-specific - weight loss, sweats, pyrexia. Mostly symptoms specific to the organ involved. Can be rapidly enlarged tonsils/adenoids in children.

CT - chest, abdo, pelvis! PET scan. Diagnosis relies on tissue biopsy, morphological assessment and EBV ISH can be performed (looking for EBV encoded RNAs (EBERS))

Question 14

What causes PTLD?

Answer 14

Lymphomas caused by proliferation of B cells due to unchecked B cell activation because of loss of cytotoxic T-cell control. Most are B cell derived but 15% are from the T cell lineage

Question 15

Why are antivirals not indicated for PTLD?

Answer 15

EBV utilises host DNA pol when lymphocyte divides, proliferation of EBV infected cells causes disease, not lytic EBV infection

Question 16

What does viral load monitoring contribute to diagnosis/monitoring of PTLD?

Answer 16

Routine VL monitoring allows early detection of EBV DNAemia, as usually a high VL precedes EBV-related PTLD

A negative VL has a 100% NPV

Question 17

First, second and third line therapy for EBV-PTLD is HSCT

Answer 17

1) Rituximab and reduction of immunosuppression (+/- EBV CTLs) 2) EBV specific CTLs or donor lymphocyte infusion 3) Chemo +/- rituximab

Question 18

Pre-emptive therapy for EBV PTLD in a) SOT b) HSCT

Answer 18

a) Reduction of immunosuppression b) rituximab and reduction of immunosuppression

Question 19

Treatment of EBV-PTLD in paediatric SOT

Answer 19

1) Reduction of immunosuppression 2) Rituximab monotherapy 3) Rituximab + low dose chemo 4) Traditional high dose chemo

Question 20

What is chronic active EBV? What are the symptoms? What cell lines are involved?

Answer 20

Lymphoproliferative disease not linked to immunodeficiency, systemic inflammation and clonal proliferation of EBV infected T/NK cells (not B cells!). Symptoms include chronic/recurrent IM like symptoms persisting for a long time, marked elevation of EBV-specific antibodies and high viral loads

Question 21

What are the diagnostic criteria for caEBV?

Answer 21

1) Persistent or recurrent IM-like symptoms for >3 months 2) High EBV viral load in blood or affected tissues 3) Detection of EBV infected T or NK cells 4) No other diagnosis

Question 22

What is the treatment of chronic active EBV?

Answer 22

Chemotherapy (poor prognosis) HSCT is the only curative approach

Question 23

What is secondary HLH? Which patients are most at risk? What are the viral triggers? Which is the most common?

Answer 23

Haemophagocytic lymphohistiocytosis caused by external trigger. Uncontrolled immune activation resulting in cytokine storm which causes cell damage and leads to organ dysfunction

Most common in children, immunosuppressed and those with underlying malignancies

EBV is most common (and exclusive cause in X-linked lymphoproliferative disorder) also CMV, influenza and HIV

Question 24

What are the symptoms of HLH and what are the lab findings?

Answer 24

Persistent fever, rash, toxic looking, hepatosplenomegaly

Profound cytopenias (usually >1 lineage)
Very high ferritin (eg >500) (seen in most cases but is not specific)
Low fibrinogen
High triglycerides
Low or absent NK activity
High soluble CD25
Haemophagocytosis in bone marrow, spleen or lymph nodes

H-score can be used to measure likelihood, H-score >169 is specific in 90% cases

Question 25

Treatment for EBV HLH

Answer 25

Main treatment principles: 1) suppress hyperinflammation 2) eliminate EBV 3) replace defective immune system

Mainstay is dexamethasone and etoposide. Rituximab is used but will only work on those with EBV infected B cells (not T/NK cells)

Checkpoint inhibitors may be used for refractory disease and HSCT may be required

Question 26

When does EBNA become positive?

Answer 26

3-4 weeks post infection in up to 95% of people

Question 27

In primary EBV when would you expect to detect DNA?

Answer 27

Always positive until day 12 and negative by 3 weeks of illness

Question 28

What are we measuring when we test EBV viral load in plasma? What rise is considered significant?

Answer 28

EBV DNA is predominantly found within circulating EBV infected B cells so VL measured from plasma does not represent viremia but rather fragments of cell-free DNA (DNAameia)

For measurements done at the same lab, results of VL that differ by at least 0.5 log10 IU/ml (3-fold) should be considered significantly different

Question 29

What would you do if you had an immunosuppressed patient with a high EBV VL?

Answer 29

CT chest, adbo, pelvis > should not show any involvement

LDH should be normal

Monitor these patients carefully to ensure does not progress to HLH/PTLD

Question 30

Antiviral choices for EBV infection

Answer 30

None are approved for treatment

Aciclovir is drug of choice, ganciclovir can also be used and intravitreal foscarnet can also be used

Question 31

What therapeutic antibodies would you use to treat/prevent EBV induced lymphoproliferative disease?

Answer 31

anti-CD20/CD19 mAbs - these not only kill lymphoma cells but also eliminate the normal memory B cell reservoir for EBV latency