Epstein Barr Virus (EBV) Serological Diagnosis of Epstein Barr Virus. Epstein Barr Virus (EBV) Epstein Barr Virus (EBV)

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1 Serological Diagnosis of Epstein Barr Virus L Ross Whybin SEALS Serology Epstein Barr Virus () Family Herpesviridiae,, subfamily gammaherpesvirinae,, genus lymphocryptovirus ds DNA enveloped virus Nucleocapsid 00-0nm 0nm in diam; ; with 6 capsomers Aymmetrical material surrounding capsid designated the tegument (structures between the capsid & envelope) Envelope containing viral glycoprotein spikes on its surface Membrane is derived by budding of immature particles through cell membrane and is required for infectivity Genome is linear ds DNA molecule with 7 kbp Viral genome does not normally integrate into cellular DNA but forms f circular episomes which reside in the nucleus Genome is large enough to code for proteins but only a few have been indentified Epstein Barr Virus () Family Herpesviridiae ds DNA enveloped virus Genome is linear with 7 kbp Genome is large enough to code for proteins but only a few have been identified Epstein Barr Virus () peaks of : young pre-school( school(-6) and adolescents/young adults (4-0) Estimated 80-90% of adults are seropositive for Infectious mononucleosis (IM) Chronic active Burkitt s s Lymphoma Nasopharyngeal Carcinoma Lymphoproliferative disorders (immunocompromised( immunocompromised) X-linked lymphoproliferative syndrome Oral hairy leukoplakia, diffuse polyclonal lymphomas, chronic interstitial i pneumonitis in AIDS patients Epstein Barr Virus () Symptoms: Sore throat (80-90%) Lymphadenopathy (cervical) present in majority of cases and may last several weeks Splenomegaly (50-60%) Hepatomegaly (5-5%) Jaundice (5-0%) Pharyngitis & palatal petechiae (grey-white membrane) first week Fever first weeks Immunocompromised: : GI symptoms, renal graft rejection/failure, lymphoproliferative disease, lymphoma History of Serological testing for 93 Paul & Bunnell (sheep RBC s) 975 Monospot (horse RBC s) 966 IgG & IgM IFA; cultivation of infected lymphoid cell lines 985 EIA; antigens from infected cells purified under solid-phase absorption 986 EIA; polypeptides with immunodominant epitopes prepared by recombinant technology

2 Testing for Heterophile Antibodies Paul Bunnell + Monospot IgM class, not specific 90-98% 98% sensitive in adults Negative early in May remain positive for up to 6-6 months 0-0% adults and up to 50% young children never develop heterophile Abs (false negative) 3-7% false positive rate due to long-term persistence of Ab -3% false positive results in patients with autoimmune diseases Detected in other mononucleosis illnesses (primary CMV, Hep A, HIV, H lymphoma) Heterophile Ab detection + atypical lymphocytes support lab diagnosis of Viral capsid antigen Synthesized late in the lytic cycle A complex of at least 7 structural proteins and glycoproteins making up the viral capsid. Incl. gp5 - major capsid protein p8 - minor tegument protein VCA IgG ANTIBODY Appears early in primary 4-77 days after symptoms May precede VCA IgM: uncertainty in diagnosis from a single sample Usually persists for life VCA IgG: acute, convalescent or past phase of High levels in Burkitt s s lymphoma and NPC VCA IgM ANTIBODY Indicator of recent primary VCA IgM usually present from -4 4 months after primary Can be delayed, even absent in a small number of primary in adults May persist for several months (0% for months) after May re-appear in reactivation of Cross-reactivity reactivity with other Herpesviruses (VZV, HSV) False-positive in other acute viral s (HIV, Parvovirus B9) and patients with IgM RF. False-negative with excess IgG/co-specific IgG blocking attachment sites Reactivation in Hepatitis A Epstein Barr Virus Nuclear Antigen (EBNA) Complex of at least 6 proteins (EBNA, -, -3A, -3B, - 3C & -LP) EBNA- thought to be essential for maintenance of episomal state of in infected cells and binds to the origin of replication EBNA- expressed in all known virus carrying cells; expression may be lost when lytic cycle ensues EBNA- IgG ANTIBODY Late (latent phase protein) marker of primary,, although may be present soon after onset of IM Appears months following ; marks transition from acute to convalescence; indicates past or resolving Peaks 3-3 months post, declines but remains detectable indefinitely Up to 6% of s never develop EBNA- IgG antibody (higher in immunocompromised) ) (Bauer 994) In severely immunocompromised patients, EBNA- IgG may decline to low or undetectable levels in response to increase in productive replication

3 EBNA- IgG ANTIBODY EBNA- IgG antibodies appear early in May be present in up to 30% of individuals at time of onset of disease Presence of EBNA- IgG and absence of EBNA- IgG excludes primary Ratio of EBNA- Abs vs EBNA- Abs used for the serodiagnosis of reactivation No commercial assays for EBNA- Ab available EBNA IgM ANTIBODY Indicator of recent primary EBNA IgM usually present from -4 4 months after primary May persist for several after May re-appear in reactivation of Cross-reactivity reactivity with other Herpesviruses (VZV, HSV) False-positive in other acute viral s (HIV, Parvovirus B9) and patients with IgM RF. False-negative with excess IgG/co-specific IgG blocking attachment sites EA (Early Antigen) ANTIBODY EA is a complex of proteins only expressed in infected cells undergoing lytic cycle Early antigen/diffuse (EA/D) & Early antigen/restricted (EA/R) EA/D Abs rise during acute and fall to undetectable levels within months EA/R remain elevated for up to years 30-70% of patients with acute develop EA/R and EA/D Abs High levels of EA/R detected in Burkitt s s lymphoma High levels of EA/D IgG and EA/D IgA in NPC VCA IgA & EA/D IgA Abs Induced during acute primary Persistent high levels in NPC Negative predictive value/sensitivity approx. 97% Positive predictive value 0.5-% VCA IgA in NPC (high risk populations) Positive predictive value VCA IgA + EA/D IgA in NPC rises to 0% Used for screening in very selected groups (middle aged to elderly Southern Chinese with family history of NPC) Rising titres indicate progression or relapse VCA IgG Avidity Index Can distinguish recent from past or reactivated particularly where VCA IgM persists long-term B cells switch from IgM to IgG isotype in vivo; the first IgG Abs produced are of low avidity Later IgG Abs mature through somatic hypermutation in the IgG DNA-encoded region and B cell clones end up producing relative higher avidities AI: ratio between urea-treated and non-urea treated sample Improved sensitivity for diagnosis from 93% to 00% AI: 54% at 6 weeks AI: 8% at 8 weeks Western Blot Classical lysate blot assays with transformed cells Line blot assays with recombinant antigens incl. p7 (EBNA-) p8 (VCA) p3 (VCA) p54 (EA) p38 (EA) Detects specific antibodies to multiple -specific antigens simultaneously Useful confirmatory method

4 OTHER SEROLOGY VCA IgA: BL, NPC EA (D/R) IgG, IgA: BL,NPC Western Blot: Confirmatory method EBNA- IgG: Primary, Reactivation serology Dubbo study: 8 well characterised cases Specificity: 30 cases previous & recent HIV, CMV or Hepatitis A (FP serology) The Dubbo Cohort Study The Dubbo Cohort Study Serological responses Serological responses (IgG VCA avidity) Proportion (%) of the group positive % of the group positive Weeks post onset of symptoms 8 VCA IgM VCA IgG EBNA IgM EBNA IgG Percentage avidity Avidity Weeks post onset of symptoms Number of samples from cases tested: n = CMV HIV Hepatitis A The Dubbo Cohort Study Serological responses (IgG VCA avidity) Number (%) of group with positive serology VCA EBNA Sample IgG IgM IgG IgM IgG VCA avidity size (n) (mean % and SD) Hep A 5 5 (00) (80) 5 (00) (80) 95 (5.7) HIV 4 4 (00) 5 (36) 4 (00) 0 (7) 98 (.8) CMV 6 6 (00) (6) 6 (00) 6 (00) 96 (3.) Combined (00) 8 (5) 35 (00) 8 (80) 96.3 (4.4) VCA IgG (gp5) & EBNA- IgG Age - 50 yrs (n=337) VCA IgG + - EBNA + 59% 6% IgG - % 4%

5 VCA IgG(gp5) & EBNA- IgG Age 0-0yrs (n=55) VCA IgG + - EBNA + 53% 6% IgG - 5% 6% VCA IgG (gp5) & EBNA- IgG Age > 50 yrs (n=747) VCA IgG + - EBNA + 76% % IgG - 8% 5% VCA p8 IgG ANTIBODY Highly immunogenic in humans Recognised by healthy -seropositive persons worldwide Found in most carriers-(wout 993) A late marker of.(hinderer 999) Not lost during immunosuppression (Bauer 00) Does not appear to have sequence homologues to other human herpesviruses Previous Infection 53 Samples VCA gp5 IgG Negative / EBNA- IgG Positive gp5 IgG p8 IgG No Neg Pos 5 Neg Neg Anti VCA p8 in recent VCA IgM pos / EBNA IgG neg (n=3) /3 anti p8 neg. VCA IgM pos / EBNA IgG neg/avidity<60%. (n=) 5/ anti p8 neg. VCA p8 IgG ANTIBODY CONCLUSIONS VCA p8 IgG EIA appears more sensitive than VCA gp5 IgG EIA (except early acute ) VCA p8 IgG EIA agrees better than VCA gp5 IgG EIA with EBNA IgG EIA (5/53) VCA p8 useful to assist in the determination of immune status

6 summary VCA-IgM antibody appears in both primary & reactivation of. RCPA QAP L:005:A,B VCA IgG antibody appears early in primary and should last for life. TESTS VCA IgM EIA PARTICIPANTS 70 MANUFACTURERS Low avidity IgG antibody only appears in primary & increases to approx 80% by 6 months. VCA IgG EIA Heterophile Screen * EBNA IgG antibody appears after about 3 months & should last for life. EBNA IgG EIA EA IgG EIA 5 7 The combination of low VCA IgG avidity with positive VCA IgM & negative EBNA IgG is 00% specific for the diagnosis of primary. EA & EBNA IgA EIA EBNA IgM EIA Avidity Index RCPA QAP L:005:A,B VCA IgG EIA: 6 participants PanBio VCA gp5 IgG: 6/6 PanBio VCA p8 IgG: /6 Trinity Biotech VCA p8 IgG: 9/6 VCA IgG: Negative AI: N/A No evidence of past. If early in course of illness, repeat blood. Suggest VCA p8 IgG. VCA IgG: Negative VCA IgM: Positive AI: N/A Early or False Positive Suggest VCA p8 IgG Ab Suggest repeat blood AI:<60% Probable acute, suggest repeat

7 AI:>60% Probable past EBNA IgG: Positive AI: >60% Past VCA IgG: Negative EBNA IgG: Positive AI: N/A Probable past VCA IgM: Positive EBNA IgG: Positive AI: >60% Past (>=3 months) VCA IgM: Positive AI: <60% Acute