JOHNS HOPKINS
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Department of Pathology
600 N. Wolfe Street / Baltimore MD 21287-7093
(410) 955-5077 / FAX (410) 614-8087
Division of Medical Microbiology
THE JOHNS HOPKINS MICROBIOLOGY NEWSLETTER Vol. 26, No. 08
Tuesday, April 17, 2007
A. Provided by Emily Luckman, Division of Outbreak Investigation, Maryland Department
of Health and Mental Hygiene.
8 outbreaks were reported to DHMH during MMWR Week 15 (April 8-14, 2007):
5 Gastroenteritis outbreaks
5 outbreaks of GASTROENTERITIS associated with Nursing Homes (2 Washington
Co., Baltimore City, Frederick Co., Anne Arundel Co.)
2 Respiratory illness outbreaks
1 outbreak of INFLUENZA-LIKE ILLNESS associated with an Institution (Howard Co.)
1 outbreak of ILI/PNUEMONIA associated with a Nursing Home (Anne Arundel Co.)
1 Rash illness outbreak
1 outbreak of CHICKENPOX associated with a School (Harford Co.)
B. The Johns Hopkins Hospital, Department of Pathology, Information provided by,
Alexandra C. Hristov, M.D.
Case Summary:
The patient is a 60-year-old Caucasian male with past medical history significant for COPD status post
bilateral lung transplant (1998) and ESRD status post renal transplant (2005). The patient also has a history of a
post-transplant lymphoproliferative disorder (PTLD) of the larynx, diagnosed and treated with radiotherapy at an
outside hospital. The patient was recently admitted with nausea, vomiting and low-grade fevers and was found to
have mild gastroparesis on a gastric emptying study. He subsequently developed aspiration pneumonia and was
successfully treated with antibiotic therapy. An Epstein-Barr virus (EBV) Quantitative Lymphocyte PCR was
performed and demonstrated 12,308 copies of the EBV viral genome (range 50-700, log value 4.09) increased from
133 copies (log value 2.12) in March 2007. An EBV Quantitative Plasma PCR demonstrated 2, 100 copies of the
EBV viral genome per milliliter of plasma (range 50-700 copies/mL, log value 3.32) increased from 410 copies per
mL (log value 2.61) in March 2007.
Organism:
The Epstein-Barr virus was first discovered in 1964 by Epstein, Achong and Barr who visualized viral
particles via EM in cells cultured from Burkitt lymphoma tissue. In 1968, EBV was identified as the etiologic agent
of heterophile-positive infectious mononucleosis. EBV is a member of the herpes virus family. The viral genome is
encased within a nucleocapsid and encodes nearly 100 viral proteins that serve viral replication and allow
modification of the host immune response. A viral envelope surrounds the nucleocapsid. The viral envelope
includes the glycoprotein gp350, which interacts with the B-cell surface protein CD21 and allows the virus to gain
entry into B-cells.
Clinical Significance:
Successful EBV infection requires a delicate balance of the host immune system. EBV requires normal Bcell development for initial and latent infection. The host cytotoxic T-cell response is required to prevent
uncontrolled proliferation of virus and of infected B-cells. For unclear reasons, EBV infection in young children is
likely to be asymptomatic or lead to a mild, brief illness. In adolescents and adults, however, EBV is much more
likely to result in infectious mononucleosis. In some patients, EBV infection is associated with the development of
cancer, including nasopharyngeal carcinoma, Burkitt lymphoma, and diffuse large B-cell lymphoma. In patients who
are status post solid organ or bone marrow transplant, EBV can result in post-transplant lymphoproliferative disorder
(PTLD).
PTLD is a lymphoid proliferation occurring in immunosuppressed transplant recipients, presumably because
of reduced T-cell immunity. PTLD is EBV-driven in the majority of cases (80%). The WHO recognizes three
categories of PTLD, early lesions including reactive plasmacytic hyperplasia and infectious mononucleosis-like
lesions, polymorphic PTLD, and monomorphic PTLD. Early lesions have some preservation of lymphoid architecture
and have an excellent prognosis, if they respond to reducing the patient’s immunosuppression. Polymorphic PTLD
displays architectural destruction, but also displays a full range of B-cell maturation. Monomorphic PTLD has
architectural and cellular features diagnostic of lymphoma. The mortality in patients with PTLD is high and varies
with the type of transplant. In patients receiving bone marrow allograft (BMA), the mortality of PTLD is 80%. In solid
organ transplant (SOT) patients, the mortality of PTLD is 60%. Although PTLD may resemble infection or rejection
clinically in its early stages, recognition is important as PTLD responds better to treatment in its early stages.
Epidemiology:
EBV is considered by some experts to be the most successful human pathogen. It infects more than 90% of
humans and persists for the lifetime of the individual. Nearly all seropositive persons shed virus through their saliva.
Infection is thought to occur via the oropharynx, when virus in the saliva of an infected individual contacts the
oropharyngeal mucosa and B-lymphocytes of a naive host. EBV is also shed in genital secretions and may be
transmitted through sexual contact. Infants become susceptible as soon as maternal antibody declines.
EBV-associated neoplasms increase in frequency in immunosuppressed patients. PTLD, by definition, is
exclusively seen in patients post transplant. In recipients of SOT, the frequency of PTLD ranges from <2% in renal
transplants to 5-10% in heart-lung or liver-bowel transplant patients. In BMA patients, the frequency of PTLD is 1%,
but the mortality is higher (80% BMA, 60% SOT). Risk factors for PTLD in transplant patients include severe
immunosuppression and primary EBV infection.
Laboratory Diagnosis:
Several recent studies have demonstrated that EBV load in plasma, mononuclear cells, or whole blood is
predictive of PTLD. At several centers, including JHH, EBV load is monitored in transplant patients. At JHH, EBV
load is determined in lymphocytes and plasma using Artus ® Real-Time PCR EBV quantitation. A 97 base pair region
of the EBNA gene is amplified and detected via a fluorescently labeled oligonucleotide probe. Patient values are
compared to a standard curve created using standards with a known EBV load. Unfortunately, a universally accepted
reference range or cut-off value has not been determined. At JHH, an 8-fold increase in the 100 copy range or a 3 fold
increase in the 1000 copy range indicates a significant change in viral load, and the patient’s physician is contacted
with this information.
Treatment:
In addition to decreasing immunosuppression, PTLD can be treated with surgery, radiotherapy, chemotherapy
including anti-CD20, and cytotoxic lymphocyte therapy. Cytotoxic lymphocytes that target EBV can be infused from
the transplant donor, from the patient, or from a healthy blood donor. Early lesions are most likely to completely
respond to decreased immunosuppression, but all PTLD categories including polymorphic and monomorphic PTLD
may completely respond to decreased immunosuppression. The prognosis for patients with early lesions who
completely respond to decreased immunosuppression is excellent.
Patients with an elevated EBV load, but without diagnostic evidence of PTLD may also prophylactically
undergo reduction of their immunosuppression. BMA patients with a high viral load may be treated with anti-CD20,
which rapidly lowers viral load by lowering circulating B-cells and may reduce the incidence of PTLD. Many SOT
recipients have an elevated baseline EBV load. In these patients, a rapid rise in viral load is more significant than a
single elevated value.
References:
1. Cohen, J.I. Epstein-Barr virus infection. NEJM 2000; 343(7): 481-492.
2. Jaffe ES, Harris NL, Stein H et al. eds., Pathology and Genetics of Tumours of Haematopoietic and Lymphoid
Tissues. WHO Classification of Tumours. Lyon: ARC Press; 2001.
3. Muti, G. et al. Significance of Epstein-Barr virus (EBV) load and Interleukin-10 in post-transplant
lymphoproliferative disorders. Leukemia & Lymphoma, 2005; 46(10):1397-1407.
4. Razonable RR and CV Paya. Herpesvirus infections in transplant recipients: current challenges in the clinical
management of cytomegalovirus and Epstein-Barr virus infections. Herpes 2003; 10:60-65.
5. Stevens SJC et al. Frequent monitoring of Epstein-Barr virus DNA load in unfractionated whole blood is essential
for early detection of posttransplant lymphoproliferative disease in high-risk patients. Blood 2001; 97(5):11651169.
6. Thorley-Lawson, D.A. et al. Persistence of the Epstein-Barr virus and the origins of associated lymphomas. NEJM
2004; 350(13): 1328-1337.
7. Williams H and DH Crawford. Epstein-Barr virus: the impact of scientific advances on clinical practice. Blood
2006; 107(3):862-869.