Epstein-Barr virus

Shane C. McAllister, MD, PhD Pediatric Infectious Diseases Fellow

Stony Brook Long Island Children’s Hospital

Overview

History of EBV and mononucleosis

EBV structure and gene expression

Pathogenesis/Clinical manifestations

Epidemiology Diagnosis Treatment Cases

History of EBV and mononucleosis

INTRODUCTION

Infectious mononucleosis (IM) was first recognized in1920 however the etiology was unknown

The heterophile test was discovered to be diagnostic for Infectious Mononucleosis in 1932

A viral cause of mononucleosis was suspected in the 1960s when a laboratory worker became ill while working with Burkitt lymphoma tissue samples

INTRODUCTION

In 1968, Epstein-Barr Virus was actually identified as the cause of Infectious Mononucleosis

Since the initial discovery, EBV has been implicated in a wide variety of both benign and malignant diseases

EBV structure and gene expression

Herpesviruses

8 herpesviruses known to infect humans

Strict species specificity

Closely related rodent and non-human primate strainsused as animal models

Herpesviruses

Large double-stranded DNA Viruses

≥ 84 different proteins

Maintenance/replication of genome in host cell nucleus

Herpesviruses

Life-long latency with periodic lytic reactivation

Control of infection requires cellular and humoral immunity

Kinetic Classes of EBV Genes

Latency LMP-1, EBNAs

Immediate Early: initiate lytic cycle Zta, Rta

Early: condition the host cell environment and synthesize viral DNA EA-D

Late: structural components of capsids/mature virions gp350

Pathogenesis/Clinical manifestations

DISEASE ASSOCIATIONS

Infectious Mononucleosis Chronic Infectious

Mononucleosis Burkitt Lymphoma Nasopharyngeal carcinoma Hodgkin Lymphoma Lymphoproliferative disease X-linked Lymphoproliferative

disease Oral Leukoplakia (AIDS)

PATHOGENESIS EBV infection is considered

immunopathologic rather than tissue destructive EBV initially infects and replicates in

the oropharyngeal epithelial cells B-cells are subsequently infected Infected B-cells disseminate

throughout the lymphoreticular system

PATHOGENESIS

EBV infection triggers an impressive but self-limited immune response Infected B-cells are transformed

and secrete a diverse group of antibodies

Heterophile antibodies Antibodies to specific EBV antigens Various auto-antibodies

EBV induced polyclonal activation of B-cells also leads to an increase in serum immunoglobulins

PATHOGENESIS Infected B-Lymphocytes induce T-

Lymphocyte proliferation Manifested as Atypical Lymphocytosis

Proliferation of reactive T-cells and infected B-cells leads to Lymphadenopathy Hepatosplenomegaly

CLINICAL MANIFESTATIONS

SYMPTOM % RANGE (%)

SORE THROAT 82 70 - 88MALAISE 57 43 - 76HEADACHE 51 37 - 55ANOREXIA 21 10 - 27MYALGIAS 20 12 - 22CHILLS 16 9 - 18NAUSEA 12 2 - 17ABDOMINAL DISCOMFORT 9 2 - 14COUGH 5 5VOMITING 5 5ARTHRALGIAS 2 2

CLINICAL MANIFESTATIONS

SIGNS % RANGE (%)

LYMPHADENOPATHY 94 93 - 100PHARYNGITIS 84 69 - 91FEVER 76 63 - 100SPLENOMEGALY 52 50 - 63HEPATOMEGALY 12 6 - 14PALATAL ENANTHEM 11 5 - 13JAUNDICE 9 4 - 10RASH 10 0 - 15

PHYSICAL FINDINGS

EXUDATIVE PHARYNGITIS

PHYSICAL FINDINGS

TONSILLAR HYPERTROPHY

EBV – Physical Findings Rash and Antibiotics

Nonspecific maculopapular eruption associated with administration of Ampicillin/Amoxil (50 – 100%)

May be associated with other -lactam antibiotics (40 – 60%)

Usually develops 7 – 10 days after the first dose

Does not represent Penicillin allergy Mechanism is unclear

Transient hypersensitivity reaction Immune complex production

Complications of Primary EBV

ORGAN/SYSTEM COMPLICATIONSLIVER: Abnormal Liver Function Tests

(80 – 90%)Clinical jaundice (5%)Fulminant hepatitis (rare)

RESPIRATORY: Airway Obstruction (<5%)Interstitial Pneumonitis (Rare)

HEMATOLOGIC: Thrombocytopenia (25-50% Mild/Mod)Neutropenia (50 – 80% -

Mild/Mod)Pancytopenia (Rare)Hemolytic Anemia (3%)Aplastic Anemia (Rare)

Complications of Primary EBV

ORGAN/SYSTEM COMPLICATIONSSPLEEN: Splenic rupture (0.1 – 0.5%)

Splenic Infarction

RENAL: HematuriaInterstitial nephritisGlomerulonephritis

CARDIAC: MyocarditisPericarditisArrhythmias

Complications of Primary EBV

ORGAN/SYSTEM COMPLICATIONSSECONDARY INFECTION: Streptococcal pharyngitis

Secondary sepsis due to neutropenia

IMMUNOLOGIC: Depressed T-cell immunity

NEUROLOGIC: EncephalitisAseptic MeningitisGuillain-Barre SyndromeCranial nerve palsiesTransverse MyelitisOptic NeuritisCerebellar AtaxiaBrachial Plexus Neuropathy

Neurologic Complications

May be the first or sole manifestation of EBV mononucleosis

Occurs in 1 – 5% of cases Prognosis is generally good with 85%

complete recovery Most frequent cause of death related

to EBV Infectious Mononucleosis Diagnosis is difficult

Heterophile is negative Atypical lymphocytosis is minimal or

absent

Neurologic Complications

“Because EBV may present atypically and has been associated with a myriad of neurologic diseases, EBV should be considered in all acute neurologic illnesses of unknown etiology in the Pediatric population”

Connelly et al., Pediatr Neurol 1994; 10: 181-184

INFECTIOUS MONO IN CHILDREN

Compared with adolescents, young children more commonly had the following features: URI symptoms Rash Splenomegaly and/or Hepatomegaly Higher peak leukocyte counts with fewer

Atypical Lymphocytes More frequent neutropenia

Epidemiology

EPIDEMIOLOGY Antibodies to EBV found in all

populations Lower socioeconomic groups- higher

prevalence By adulthood, 90 - 95% of most

populations have demonstrable antibodies

In the US, EBV seroconversion occurs before age 5 years in 50% of the population

Second wave in the second decade of life No predilection for male or female

EPIDEMIOLOGY In the US - 45.2

cases/100,000/year The incidence is highest in the

15 - 24 year-old age group College and military populations

have the highest morbidity Not a reportable disease No clear seasonal pattern

Diagnosis

DIFFERENTIAL DIAGNOSIS OF MONO-LIKE SYNDROME

Epstein-Barr virus

Cytomegalovirus Toxoplasma

gondii Adenovirus Human

herpesvirus 6/7 Hepatitis A Influenza A and B

Rubella virus

Diphtheria HIV Malignancie

s

DIFFERENTIAL DIAGNOSIS OF MONO-LIKE SYNDROME

CMV mononucleosis is most frequently confused with EBV: Patients are generally older

(Adults) Pharyngitis and lymphadenopathy –

less common Fever and malaise are the major

manifestations Heterophile negative

Atypical Lymphocytes

Activated T cells responding to the EBV-infected B-cells

Features of Atypical Lymphs: Larger than mature Lymphocytes Have vacuolated basophilic

cytoplasm

DIAGNOSIS

ATYPICAL LYMPHOCYTES

Heterophile Antibody Test

Heterophile antibodies comprise a broad class of antibody characterized by ability to agglutinate antigens on RBCs from different mammalian species

IM heterophile Ab (IgM) does not react with EBV- specific antigens characterized by its ability to react with beef, sheep and horse RBCs

The antigen that stimulates this heterophile ab is unknown

Heterophile Antibody Test

Replaced by the monospot slide test (Antigen-coated beads on a slide)

15% of patients with IM may be initially heterophile negative and become positive within 2 – 3 weeks

High false negative rate in children less than 4 years (>50%)

False positive rate - 7% Remains positive for up to 9 months Sensitivity and specificity: 85%/97%

MONOSPOT

NEGATIVE POSITIVE

Sumaya et al., Pediatrics 1985; 75: 1011 - 1019

FALSE – POSITIVE MONOSPOT

Collagen Vascular diseases Leukemia/Lymphoma Malaria Pancreatic Carcinoma Viral Hepatitis Other

EBV SEROLOGY The appearance of antibodies induced

by EBV specific antigens correlates with the phase of replication IgM antibody to VCA appears at the onset

of symptoms and typically disappears within 1 – 3 months

IgG antibody to VCA begins to rise shortly after the onset of symptoms

Peaks at 2 – 3 months Gradually decreases to a steady-state

and persists for life

EBV SEROLOGY Antibodies to EA are not always

detectable IgG to EA begins to rise at the onset of

symptoms Peak concentration occurs at 3 – 4 weeks Subsequently decreases and disappears

Antibodies to EBNA appear during the convalescent period and persist for life along with anti-VCA IgG

Past infection: No anti-VCA IgM (Potential for false-

positives) No anti-EA IgG

DIAGNOSIS

Interpretation of EBV Serology

INFECTION ANTI-VCA-IgM ANTI-VCA-IgG ANTI-EA ANTI-EBNA

NONE NEGATIVE NEGATIVE NEGATIVE NEGATIVE

ACUTE POSITIVE POSITIVE POS/NEG NEGATIVE

RECENT POS/NEG POSITIVE POS/NEG POS/NEG

PAST NEGATIVE POSITIVE NEGATIVE

POSITIVE

EBV SEROLOGY Effective lab diagnosis can be

made on single acute phase serum sample

Antibody response appears rapidly (onset of symptoms)

Acute and Convalescent phase serum will not demonstrate a significant change in antibody titer

EBV SEROLOGY Literature supports the general

concern that there is considerable variation in the performance of serological test kits for EBV and other infectious agents

VCA-IgM Cross-reactivity occurs Especially with other herpesviruses

(CMV)

EBV - DIAGNOSIS

The ability of EBV to maintain lifelong latency with low levels of replication and viral shedding results in enduring antigen exposure and continued humoral immune response Variation of EBV antibody titers may

be due to reactivation of latent virus due to infection with another virus and development of cross-reactive antibodies

EBV - DIAGNOSIS

Important to be aware of nuances of serologic testing as well as viral detection for latent viruses such as EBV

Must be cautious with utilization of serologic testing/DNA detection as the sole means for establishing causal relationship between illness and EBV infection

Treatment

TREATMENT

Supportive care Avoid contact sports Corticosteroids for selective

complications Airway obstruction Massive splenomegaly Myocarditis Hemolytic Anemia/ITP

Acyclovir – No clearly documented benefit

ANTIVIRAL TREATMENT

5 randomized clinical trials conducted to evaluate treatment of Infectious Mononucleosis with Acyclovir (339 patients) Studies showed no statistically significant

benefit or clinical effectiveness Met-analysis also showed no significance No evidence that therapy shortens

duration of symptoms or prevents complications

Prognosis and Outcome The majority of cases are

uncomplicated resolving in 1 – 2 months

Minority of patients experience persistent fatigue for up to 6 months

Although EBV remains latent lifelong in a few cells in throat and blood, not thought to be clinically significant

Periodically the virus can reactivate (virus isolated in saliva)

Cases

Case 1

5 year old female with acute febrile illness including URI symptoms and sore throat

Physical exam significant for exudative tonsillitis and cervical adenopathy

Rapid GAS test negative but patient started on Amoxil pending culture.

Patient developed diffuse rash on second day of antibiotic treatment.

Culture negative

Interpretation of EBV Serology

INFECTION ANTI-VCA-IgM ANTI-VCA-IgG ANTI-EA ANTI-EBNA

NONE NEGATIVE NEGATIVE NEGATIVE NEGATIVE

ACUTE POSITIVE POSITIVE POS/NEG NEGATIVE

RECENT POS/NEG POSITIVE POS/NEG POS/NEG

PAST NEGATIVE POSITIVE NEGATIVE

POSITIVE

Case 2

15 year old female with acute febrile illness of 6 days duration including sore throat, malaise, fatigue, and swollen glands

Physical exam significant for no tonsillar tissue, positive cervical adenopathy, no HSM

Lab work demonstrated: elevated WBC with lymphocyte

predominance Heterophile antibody positive, VCA IgM

positive; VCA IgG, EAD IgG, and EBNA IgG negative

DIAGNOSIS

Interpretation of EBV Serology

INFECTION ANTI-VCA-IgM ANTI-VCA-IgG ANTI-EA ANTI-EBNA

NONE NEGATIVE NEGATIVE NEGATIVE NEGATIVE

ACUTE POSITIVE POSITIVE POS/NEG NEGATIVE

RECENT POS/NEG POSITIVE POS/NEG POS/NEG

PAST NEGATIVE POSITIVE NEGATIVE

POSITIVE

Case 3

17 year old male diagnosed with mono one year ago presents with continued fatigue. He sleeps 7 to 8 hours a night and is a long distance runner

Physical exam is normal Lab work demonstrated:

Normal CBC Heterophile antibody, VCA IgM, and

EAD IgG negative; VCA IgG and EBNA IgG positive

DIAGNOSIS

Interpretation of EBV Serology

INFECTION ANTI-VCA-IgM ANTI-VCA-IgG ANTI-EA ANTI-EBNA

NONE NEGATIVE NEGATIVE NEGATIVE NEGATIVE

ACUTE POSITIVE POSITIVE POS/NEG NEGATIVE

RECENT POS/NEG POSITIVE POS/NEG POS/NEG

PAST NEGATIVE POSITIVE NEGATIVE

POSITIVE

THANK YOU !