Virological and immunological studies on a fatal case of infectious mononucleosis

Mapping of B-cell epitopes on the polypeptide chain of the Epstein-Barr virus major envelope glycoprotein and candidate vaccine molecule gp340

The Epstein-Barr virus (EBV) major envelope glycoprotein gp340 is the subject of current efforts to develop an EBV subunit vaccine. The importance of gp340-specific humoral immunity has been highlighted by studies of natural infection in humans and gp340 immunization of experimental animals. The former studies have demonstrated the presence of gp340-specific serum antibodies which mediate EBV neutralization, complement fixation, and antibody-dependent cellular cytotoxicity. The latter studies have often shown a correlation between the induction of gp340-specific EBV-neutralizing antibodies and protection from virus challenge. We have used a series of bacterial beta-galactosidase-gp340 fusion proteins and overlapping synthetic peptides from the gp340 open reading frame to map the positions of B-cell epitopes within the gp340 primary amino acid sequence. The data reported here indicate the presence of B-cell epitopes within the carboxy-terminal third of the gp340 polypeptide chain. These epitopes could not be detected with a peptide enzyme-linked immunosorbent assay, thereby suggesting that they are discontinuous. Affinity purification of antibodies with a gp340 fusion protein from the carboxy terminus of the gp340 polypeptide chain has been used to show that these antibodies are not EBV neutralizing in vitro. The consequences of these findings for future EBV vaccine development are considered.

Antibody response to Epstein-Barr virus antigens in patients with chronic viral infection

We tested antibody titres against Epstein-Barr virus (EBV) antigens in patients suffering from chronic viral disease and compared them with those determined in sex- and age-matched healthy controls. Patient sera showed signs of active EBV infection [antibodies against early antigen (EA) and/or viral capsid antigen (VCA) in the IgM or IgA classes] significantly more frequently than the control group. Correspondingly, geometric mean titres (GMT) of antibodies against all viral antigens were elevated in the patients. The strongest association with EBV was observed in patients whose clinical symptoms closely resembled infectious mononucleosis: 92% of the subjects in this subgroup possessed anti-EA and 41 and 25% had IgM and IgA anti-VCA antibody, respectively. In patients with signs of lymphoproliferation only and in those suffering from frequent respiratory infections the association with EBV was less marked but still significant. Patients with transient defects in humoral and cellular immunity mounted higher titres against VCA in the IgG class than those without immune defects.

Immunohistological studies of lymphoproliferative lesions in a fatal case of Epstein-Barr virus infection

A fatal case of infectious mononucleosis occurred in a young adult. Abnormal serological features were noted in his mother, although there was no other family history suggesting an inherited defect of immune response to Epstein-Barr virus (EBV). The cellular infiltrate observed in tissues obtained at necropsy was analysed with a range of specific monoclonal and polyclonal antibodies. Polyclonal plasmacytoid B cell proliferation had occurred in many tissues. These cells were positive for EBV nuclear antigen, but viral particles were not seen on ultrastructural examination, and the virus was not isolated, suggesting a non-permissive infection.

Demonstration of Epstein-Barr virus DNA in a previously healthy boy with fulminant hepatic failure

A previously healthy 9-year-old boy died from acute liver failure during an acute Epstein-Barr virus infection. Epstein-Barr virus DNA could be demonstrated in the liver by Southern blot--and by in situ hybridization techniques. The identification of the virus in the liver suggests a causal relation between the Epstein-Barr virus and the acute massive liver cell necrosis.

Infectious mononucleosis mimicking a B cell immunoblastic lymphoma associated with an abnormality in regulatory T cells

An elderly woman is described with infectious mononucleosis in whom cervical node biopsy was interpreted as showing immunoblastic lymphoma. Concomitant reactive lymphocytosis, Epstein-Barr virus serologic results consistent with an acute infection, and demonstration of polyclonal B cell infiltration of other tissues argued against intervention. Defective in vitro T cell responses were demonstrated during the acute phase of Epstein-Barr virus infection. Infectious mononucleosis has rarely been reported as mimicking a non-Hodgkin's lymphoma. At 18 months, our patient's course has been typical for infectious mononucleosis with no evidence of disseminated malignancy.

Fulminant hepatic failure and fatal encephalopathy associated with Epstein-Barr virus infection

A case of fulminant hepatic failure, associated with infectious mononucleosis, in a previously healthy 14-year-old girl is reported. Despite intensive therapy, which included the use of acyclovir, charcoal haemoperfusion, and measures to control her raised intracranial pressure (guided by serial EEG and auditory brainstem-evoked response recordings), the outcome was fatal.

The Leeuwenhoek lecture, 1983. A prototype vaccine to prevent Epstein-Barr virus-associated tumours

EB virus is a herpesvirus that infects all human communities. The infection is life-long and usually asymptomatic. Excessive reaction to primary infection leads to infectious mononucleosis while immunological failures give fatal lymphoproliferative diseases. The virus is associated with endemic Burkitt's lymphoma and undifferentiated nasopharyngeal carcinoma. In world cancer terms Burkitt's lymphoma is insignificant, but nasopharyngeal carcinoma has a high incidence in certain important populations. By analogy with herpesvirus-induced animal cancers, prevention of infection should greatly reduce subsequent development of tumours. A prototype vaccine has therefore been produced based on the virus-determined antigen (MA gp340) that elicits virus-neutralizing antibodies. A sensitive assay has permitted the elaboration of an efficient antigen preparation method and the product has been rendered highly immunogenic, as tested in mice and rabbits, by incorporation in liposomes. The only animal suitable for experimental EB virus infection is the little-known cottontop tamarin; a breeding colony has been successfully established and protection against virus challenge assessed in immunized tamarins. The overall structure of the antigen has been determined in preparation for future production by synthesis or rDNA technology.

Fatal lymphoproliferation and acute monocytic leukemia-like disease following infectious mononucleosis in the elderly

Three elderly patients are reported, in whom serologically confirmed recent infectious mononucleosis is followed by fatal lymphoproliferation (case 1), by acute monocytic leukemia (case 2), and by acute probably monocytic leukemia (case 3).

Epstein-Barr-virus-induced lymphoproliferative disorder converting to fatal Burkitt-like lymphoma in a boy with interferon-inducible chromosomal defect

A 6-year-old boy presenting with swelling of cervical and axillary lymph-nodes was diagnosed as having an Epstein-Barr virus infection because of EBV-nuclear-antigen-positive B-lymphocytes in blood and lymph nodes and high antibody titres to EBV antigens. The natural killer activity of blood-lymphocytes was low, and so was the percentage of T-lymphocytes with Fc receptors for IgG (T-gamma cells). Chromosomal studies revealed a defect in the long arms of one of the chromosomes in pair no. 16 (16q22). The defect only appeared after addition of interferon to the lymphocyte cultures and preferentially in T-gamma lymphocytes. The disease progressed despite attempts to restore the patient's immune reactivity by interferon, transfer factor, and blood transfusions. Necropsy showed that the severe hyperplasia of lymph nodes found during life had become a Burkitt-like lymphoma. The possible connection between an interferon-induced chromosomal defect (break at 16q22) and reduced level of natural killer activity, reduced T-gamma lymphocytes, and proliferation of EBV-positive B-lymphocytes is discussed.

A fatal case of Epstein-Barr virus infection with jaundice and renal failure

A fatal case of Epstein-Barr virus infection in a 17-year-old male is described. The patient presented with an illness clinically typical of infectious mononucleosis but death followed development of renal failure, jaundice and pulmonary failure. There was no absolute lymphocytosis nor a significant number of atypical mononuclear cells in his peripheral blood. However, heterophile antibody and Epstein-Barr virus-specific IgM were present.

Herpesviruses

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