The Epstein-Barr virus and EB virus infections in childhood

Prevalence of Epstein-Barr virus antibodies in healthy children and adolescents in Vitória, State of Espírito Santo, Brazil

The prevalence and age distribution of Epstein-Barr virus infection varies in different populations and there is little information about the epidemiology of this infection in Brazil. We studied the prevalence of EBV antibodies in a sample of 283 children and adolescents between 1 and 21 years old. The sample was taken from two neighborhoods in Vitória (capital city of Espirito Santo, Brazil). The São Pedro (SP) neighborhood represented an area with lower socioeconomic status and the Praias (P) neighborhood represented an area with higher SES. Anti-VCA (Virus Capsid Antigen) antibodies were detected by ELISA and anti-EBNA (Epstein-Barr Nuclear Antigen) antibodies were detected by an anti-complement immunofluorescence method, both using commercial kits. The results showed an overall prevalence rates of anti-VCA and anti-EBNA of 71% and 54% respectively. The prevalence for both anti-EBV antibodies was higher and probably the infection occurred earlier in the SP neighborhood. Among the various socioeconomic factors studied only low family income and maternal education level were significantly correlated with a higher frequency of positive serology for anti-VCA. These results demonstrate that there is a high prevalence of EBV antibodies in children and adolescents living in Vitória, that occurs more frequently at a younger age in children from families with low socioeconomic status. In addition, the results demonstrate an intermediate age distribution pattern between those reported in developed and underdeveloped countries.

Application of virus-specific immunoglobulin M (IgM), IgG, and IgA antibody detection with a polyantigenic enzyme-linked immunosorbent assay for diagnosis of Epstein-Barr virus infections in childhood

The Enzygnost anti-Epstein-Barr virus enzyme-linked immunosorbent assay (ELISA) system, which is based on a defined antigen mixture and on detection of antibodies of the immunoglobulin G (IgG), IgM, and IgA classes, was evaluated for its reliability in diagnosing Epstein-Barr virus infections in childhood. With samples from 66 children, the Epstein-Barr virus status and the infection phase were defined by indirect immunofluorescence and anticomplement fluorescence assays: 11 children were seronegative, 8 had a primary infection, 20 had a recent primary or past infection, and in 27 a reactivated Epstein-Barr virus infection was diagnosed. When applying the Enzygnost ELISAs, 15 serum samples (22.7%) were not interpretable due to indeterminate results in at least one of the assays used and were therefore excluded from further evaluation. The respective sensitivities and specificities for the diagnosis of seronegativity were 100 and 100%, those for the diagnosis of primary infection were 100 and 97%, those for the diagnosis of recent primary or past infection were 100 and 52%, and those for the diagnosis of reactivated infection were 10 and 100%. This poor performance of the Enzygnost system with reactivated infections is due to the prerequisite of an IgG antibody value of >650 IU/ml for the diagnosis of viral activity, which was fulfilled in only two of the children. Despite the high rate of indeterminate results, the Enzygnost system is useful in diagnosing acute and past Epstein-Barr virus infection in childhood. For serological diagnosis of viral activity in childhood, a supplementary assay is necessary.

Prolonged meningoencephalitis due to Epstein-Barr virus with favorable outcome in a young infant

We present a case of meningoencephalitis due to EBV in a 2-month-old infant, without mononucleosis, which persisted for more than 5 months. Evidence for persistence of the infection was provided by a convulsive disorder and prolonged CSF pleocytosis, combined with persistent moderate anemia. Despite the persistence of the infection, the child continued to develop normally. This case demonstrates that EBV meningoencephalitis occurring in young patients may present with only subtle clinical findings and may have a favorable prognosis.

A case of fatal infectious mononucleosis presenting with fulminant hepatic failure associated with an extensive CD8-positive lymphocyte infiltration in the liver

We describe a fatal case of infectious mononucleosis presenting with fulminant hepatic failure associated with extensive CD8-positive lymphocyte infiltration and diffuse karyorrhexis in the liver. Immunohistochemical analysis of mononuclear cells showed that Leu-2a (CD8)-positive lymphocytes were heavily distributed in the portal areas and the sinusoidal spaces, but Leu-3a (CD4)-, Leu-14 (CD22)-, or My 4 (CD14)-positive cells were undetectable in sections of the liver. Southern blot hybridization studies disclosed the presence of Epstein-Barr virus DNA fragments in the liver tissue. The unusual pathologic and immunologic responses observed in this case could not simply be explained by severe Epstein-Barr virus infection. Some superimposed factors should be considered.

Epstein-Barr virus-associated malignancies

The infectious aspects of cancer in humans were epidemiologically pioneered by Dr. David Burkitt through his observations of lymphomatous tumors seen in children in equatorial Africa. Years, later, the Epstein-Barr virus (EBV) was shown to be intimately associated with such tumors and is now recognized as a component of some B-cell lymphomas and nasopharyngeal carcinoma. Still the questions of an active, passive, or accessory role persist. The ability of this virus to cause immunosuppressive hemopoietic disturbances in individuals infected with EBV but not developing cancer raise questions about host susceptibility, host immune response, and possible coconspiring, infectious, oncogenic agents. Recent associations of EBV antibody found in diseases, such as squamous cell carcinoma of the head and neck and acquired immunodeficiency syndromes, point to its possible accessory role as an immunosuppressive agent. The ability of EBV to spread by extracellular and intracellular mechanisms demonstrates its variable infectious potential. Numerous EBV-transformed human cell lines attest to its ability to confer "immortality" with uncontrolled growth patterns. This review critically examines the association of EBV with various malignancies, the type of evidence which links it there, and the implications for further investigations and therapy.

Assessment of serologic markers for Epstein-Barr virus

Antibody responses to early antigen (EA) and viral capsid antigen (VCA) were analyzed in 48 proven cases of Epstein-Barr Virus infection and in 48 age- and sex-matched healthy controls to establish optimal cutoff values for diagnosing EBV infection. Predictive values were determined for individual EA and VCA antibody titers and for EA to VCA antibody ratios and the optimal dilution cutoff values for positivity of EA (1:20), VCA (1:640), and EA to VCA (0:031) were selected. When evaluated on a subset of 10 VCA IgM positive cases and 35 negative controls, the three selected cutoff values identified as infections nine of 10, four of 10, and 10 of 10 of the cases and one of 35, none of 35, and one of 35 of the controls, respectively. When evaluated individually on 22 cases of suspected EBV infection who were heterophile antibody-negative and presented with symptoms compatible with EBV infection, an equal number of VCA IgM-positive and negative cases were identified as EBV infections. Overall, the cutoffs EA, VCA, and ratio identified 19 of 22 (86.4%), 14 of 22 (63.6%), and 18 of 22 (81.8%), respectively, and all cases could be identified using combinations of these values. Although these serologic values may be used with some accuracy, until more definitive markers are described a combination of heterophile responses, lymphocyte analysis, clinical symptoms, and serologic cutoff values should be used to assess the role of EBV in patient evaluation.

Heterogeneity of immune defects in three children with a chronic active Epstein-Barr virus infection

Three children, all girls, showed long-lasting clinical and serologic evidence of chronic active Epstein-Barr virus (EBV) infection. Extremely high serum titers of IgG- and IgA-type VCA antibodies and EA antibodies were present, whereas EBNA antibody titers were in the range of those found in seropositive individuals. All three patients repeatedly showed the presence of nonspecific pokeweed mitogen (PWM)-activatable suppressor cells in the peripheral blood. The analysis of EBV-specific cytotoxic T cells showed that one patient exhibited normal cytotoxicity, whereas a second patient demonstrated no EBV-specific cytotoxicity together with unusually high levels of virus-infected B cells in the blood and lymph node. The third patient repeatedly showed refractoriness of the circulating B cells to EBV infection, probably on the basis of some developmental defect. It was concluded that each patient has his or her own peculiar defect in the virus-host balance, indicating that heterogeneity may underlie the syndrome of chronic active EBV infection in humans.

Studies on chemical carcinogen enhancement of Epstein-Barr virus induced transformation of human neonatal and adult peripheral blood lymphocytes

The effects of a wide range of selected chemical carcinogens on the frequency of Epstein-Barr virus (EBV)-induced transformation have been investigated. The carcinogens tested included direct-acting chemicals and chemicals requiring either activation via reactions with nucleophiles, or cell-mediated enzyme activation. Treatment with some but not all chemicals suspected of being carcinogens resulted in enhanced EBV-induced transformation of neonatal or adult peripheral blood lymphocytes (PBLs). The temporal relationship between carcinogen exposure and EBV infection could dramatically influence the results of the chemical carcinogen-cellular interaction as measured by the cells' ability to subsequently undergo morphologic transformation. This relationship was particularly evident when cells were treated with alkylating agents such as dimethylsulfonate (DMS) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Beginning at 24 h, and at later times following EBV-infection, cellular transformation became more resistant to the cytotoxic effects of DMS and, in contrast, more sensitive to the cytotoxic effects of MNNG. These diametrically opposed results clearly demonstrate the ability of EBV infection to alter the response of lymphocytes to chemical carcinogens as measured by transformation. The lymphoblastoid cell lines (LCLs) established from carcinogen-treated PBLs had increased cloning efficiency. Furthermore, using radiolabelled, molecularly cloned subgenomic fragments of EBV DNA and DNA-DNA hybridization, we have been able to detect an increased number of EBV genome equivalents in whole-cell and high-molecular-weight cellular DNA extracted from LCLs established from MNNG as well as DMS-treated PBLs. We propose that carcinogen enhancement of EBV-induced transformation is an example of a two-step mechanism of oncogenic transformation in primary human lymphoid cells. The possible significance of these findings in relation to potential development of lymphomas following EBV exposure will be discussed.

Long lasting lymphadenopathy in childhood as an expression of a severe hyperimmune B lymphocyte disorder

On the basis of the 6 cases reported here and scattered published cases, the existence of a childhood chronic immunoblastic lymphadenopathy syndrome is proposed. It is characterized by the following features: A systemic immunoblastic proliferation with varying degrees of maturation resembling the B lymphocyte hyperimmune disorder observed in angioimmunoblastic lymphadenopathy but with no deposits of interstitial amorphous material or vascular proliferation. Disseminated superficial and deep lymphadenopathy. Chronic, pronounced splenomegaly. A constant thrombocytopenia. A polyclonal hypergammaglobulinemia, with markedly elevated antibody titers to various agents. An early onset and a course of several years (up to 20), interrupted in half the cases by the occurrence of a virus-associated (EBV, Papova) neoplastic process or a fatal viral infection. Low natural killer (NK) cell activity in 2 cases.

Changes in T-lymphocyte subsets during childhood Epstein-Barr virus infectious mononucleosis

Lymphocyte subsets were measured using monoclonal antibodies in 11 children with Epstein-Barr virus-induced infectious mononucleosis and compared with those of 10 normal children. In acute infectious mononucleosis the percentage of T8+ lymphocytes was greater while the percentage of T4+ lymphocytes and the T4+ to T8+ ratio were less than those measured in normal children. The percentage and absolute number of T lymphocytes, as enumerated by E rosetting, did not differ from the values for normal children. The children with acute infectious mononucleosis had a somewhat lower T8+ response than that observed in four adult infectious mononucleosis patients. With clinical recovery, the T lymphocyte-subset values returned toward normal. T8+ lymphocytes, a phenotype subset with predominantly suppressor activity, presumably reduce normal cellular immune functions transiently and may limit the continued proliferation of Epstein-Barr virus-infected B lymphocytes.

The child with a stiff neck

The child with a stiff neck can be a challenging diagnostic exercise. Four unusual examples of acute neck stiffness, not associated with meningitis, are presented to illustrate the various pathologic conditions which may produce this symptom. A differential diagnostic schema is suggested on the basis of pathologic and physiologic alterations of cervical and paracervical anatomic structures.

Acyclovir treatment of herpes simplex virus infections in immunocompromised humans. An overview

As reflected in the preclinical and early clinical data, acyclovir seems destined to have a very useful role in the treatment and/or prophylaxis of herpes virus (HSV) infections in immunosuppressed humans. If the preclinical predictions can be extrapolated to varicella-zoster (V-Z) infections, acyclovir could well also play a meaningful role in therapy of V-Z infections in the immunosuppressed host; however, this conjecture awaits proof of controlled studies in humans. Clearly the usefulness of acyclovir for treatment of V-Z infections should be compared with that of adenine arabinoside (ara-A) to put into proper perspective the relative efficacies of the two drugs for future therapeutic regimens. The need for comparative studies is most important at this early stage of antiviral drug development, to avoid ethical problems that will cloud the knowledge needed to move forward in a positive way. In any event, the development of acyclovir, with its targeted approach, represents a real fundamental advance in antiviral drug development. Together with the development and deployment of ara-A, it should provide the needed impetus for a surge in the creation of new antiviral compounds for tomorrow.

A prospective study on infectious mononucleosis in childhood--symptoms, serology, Epstein-Barr-Virus specific leukocyte migration inhibition

The clinical course, serological changes and the development of the specific cell-mediated immune response to Epstein-Barr-Virus (EBV), measured in terms of leukocyte migration inhibition, were followed in 40 children suffering from an EBV infection. The patients were followed for between six and 24 months. Although the majority of the children were under six years of age, they presented a typical clinical course; heterophil antibodies could only be demonstrated in 60% of the cases. Anti-VAC-IgM and IgG antibodies were found in all patients during the acute phase, but no anti-EBNA could be demonstrated. In children under three years of age, no antibodies against the D component of the early antigen were found; this antibody was found in 50% of the adolescents. An antibody against the R component of the early antigen could be demonstrated in 73% of the children five to six months after the onset of the disease. Specific leukocyte migration inhibition was present only during convalescence or later. A relationship between the appearance of anti-EBNA and the development of specific leukocyte migration inhibition has been established.

Reactivation of Epstein-Barr virus in pregnant women: social factors, and immune competence as determinants of lymphoproliferative diseases-a hypothesis

In normal pregnant women, reactivation of Epstein-Barr virus (EBV) frequently occurs. Cellular immune responses are apparently suppressed, but high titer EBV-specific antibodies of IgG class may compensate. The antibodies cross the placenta and protect the infant against primary infection for many months. Reactivation of EBV in pregnancy and oral excretion of virus by normal pregnant women could be one explanation why young children in large sibships (among families of low social classes) become infected early in life. Infants are likely infected by EBV from their pregnant mothers who shed virus in saliva. Moreover, the natural protection for several months in the perinatal period against Burkitt lymphoma and fatal EBV-induced lymphoproliferative diseases in congenitally immune deficient children is explained. The maturity and immunocompetence of the immune system at the time of primary infection by EBV and the size of the sibship seem to determine whether infectious mononucleosis occurs. Gammaglobulin derived from human cord blood may be a valuable source of viral-specific antibodies for serotherapy in immune deficient patients.

Core (2'-5')oligoadenylate and the cordycepin analog: inhibitors of Epstein--Barr virus-induced transformation of human lymphocytes in the absence of interferon

The 3'-deoxyadenosine (cordycepin) analog of (2'-5')oligo(A) [(2'-5')oligoadenylate with a triphosphate at the 5' end], synthesized enzymatically from cordycepin 5'-triphosphate in lysed rabbit reticulocytes or L-cell extracts was (i) inhibitory to translation in lysed rabbit reticulocytes and (ii) metabolically stable in extracts of either L cells or C85-5C lymphoblasts. The 5' dephosphorylated (core) (2'-5')oligo(A) and the core cordycepin analog can replace human fibroblast interferon in preventing the transformation of human lymphocytes after infection with Epstein--Barr virus B95-8 (EBV) as determined by the decreased incorporation of [3H]thymidine into cellular DNA and the inhibition of morphological transformation of EBV-infected lymphocytes. Whereas the naturally occurring core (2'-5')oligo(A) was cytotoxic to uninfected lymphocytes and proliferating lymphoblasts, the core cordycepin analog was not. Human leukocyte interferon was more effective than human fibroblast interferon in the inhibition of EBV-induced transformation of human umbilical cord lymphocytes and adult peripheral blood lymphocytes.

Treatment of childhood combined Epstein-Barr virus/cytomegalovirus infection with oral bovine transfer factor

An illness lasting for two years, with recurrent fever, rash, abdominal pain, and arthralgia, developed in a four year old boy. He was found to have a combined Epstein-Barr virus and cytomegalovirus (CMV) infection. His symptoms, CMV in his urine, and an absent in vitro lymphocyte response to CMV antigen persisted for two years. After treatment with orally administered bovine transfer factor clinical symptoms and viruria disappeared and specific immunity to CMV developed. Evaluation of this treatment in chronic virus infections is warranted.

Demonstration of IgG EA (early antigen) and IgM MA (membrane antigen) antibodies in CMV infection of healthy infants and in those with liver disease

The sequence of antibody production to various virus-specific antigens in CMV infection in infancy was studied. In healthy infants, IgG EA antibody was demonstrated in 18% of cord sera, and disappeared within two months after birth in all cases not shedding virus. The nonmaternal EA antibody was produced following virus excretion and decreased rapidly following cessation of virus excretion. Thus, demonstration of EA antibody in infants after 2 months of age was found to indicate acquired CMV infection, even when CMV could not be isolated. IgM MA antibody did not persist as long as EA antibody, disappearing before cessation of virus excretion. Both IgG EA and IgM MA antibodies were more frequently demonstrated in infants with hepatitis than in healthy infants. These findings suggest the possible association of CMV with hepatitis in infants.