Epidemiology of herpesvirus papio infection in a large captive baboon colony: similarities to Epstein-Barr virus infection in humans.

The epidemiology of herpesvirus papio, a lymphocryptovirus similar to Epstein-Barr virus (EBV), was studied in a captive colony of >1900 baboons. Herpesvirus papio IgG antibody titers were measured by IFA. In total, 438 specimens from 296 baboons were assessed, including 116 serial specimens from 52 juveniles and 6 infants studied monthly for 1 year following birth and at age 18 months. Maternally derived antibody reached a nadir at 4 months of age. About 75% of animals at 12 months of age and >95% of animals after age 24 months demonstrated serologic evidence of herpesvirus papio infection. After age 3 years, the geometric mean titer was 1:60-75. The epidemiology of herpesvirus papio infection in baboons closely parallels that of EBV infection in humans. An animal model of lymphocryptovirus infection will facilitate investigations of human lymphocryptovirus biology.

Characterization of natural Epstein-Barr virus infection and replication in smooth muscle cells from a leiomyosarcoma.

Cells from a leiomyosarcoma tumor (LMS-1) from a patient with the acquired immunodeficiency syndrome (AIDS) were explanted, cultured in vitro, and studied by phase-contrast microscopy for morphologic and growth characteristics, immunostaining for cell markers, EBER in situ hybridization and polymerase chain reaction for detection of Epstein-Barr virus (EBV), and immunostaining for expression of EBV antigens. The cells exhibited very slow growth in vitro, with unusual elliptical and spindle-shaped morphology and fragmentation of the cytoplasm into long, tapering, cytoplasmic processes. Greater than 90% of cells expressed diffuse distribution of the smooth muscle isoform of actin by immunoperoxidase staining. Approximately 25% of cells expressed very bright fluorescence by immunostaining of the smooth muscle isoforms of calponin and actin. The majority of cells demonstrated a weak signal for CD21; approximately 5-10% of cells showed a strong signal that was confined to cell surfaces. The cultured cells harbored EBV, and infectious EBV continued to be detected by polymerase chain reaction and virus culture through several passages in vitro. Several EBV antigens were expressed, including latent antigen EBNA-1, immediate-early antigen BZLF1, early antigen EA-D, and late antigens, including viral capsid antigen p160, gp125, and membrane antigen gp350. Human umbilical cord lymphocytes that were transformed with virus isolated from cultured cells yielded immortalized cell lines that expressed EBV antigens similar to other EBV-transformed lymphocyte cell lines. These results confirm that EBV is capable of lytic infection of smooth muscle cells with expression of a repertoire of latent and replicative viral products and production of infectious virus. EBV infection of smooth muscle cells may contribute to the oncogenesis of leiomyosarcomas.

Immunofluorescence microscopy and flow cytometry characterization of chemical induction of latent Epstein-Barr virus.

The effects of chemical induction of latent Epstein-Barr virus (EBV) with 12-O-tetradecanoyl phorbol-13-acetate (TPA) and n-butyrate on cell viability and induction of latent EBV in Raji and X50-7 B lymphocytes, indicated by expression of the diffuse component of the EBV early antigen (EA-D), were measured by visual immunofluorescence microscopy (of both viable and nonviable cells) and fluorescence-activated cell sorter (FACS) flow cytometry (of viable cells only). Cell viability at 4 days decreased moderately for treated Raji cells (9 to 37%, compared to 55 to 69% for untreated cells) and markedly for X50-7 cells (1-32% compared to 35-44% in untreated cells). The highest EA-D levels in viable cells occurred in Raji cells treated with both TPA and n-butyrate and untreated X50-7 cells. TPA and n-butyrate acted synergistically to induce latent EBV, resulting in increased levels of EA-D production in Raji cells and cell death in X50-7 cells. Methodological differences including the ability to detect antigen in only viable cells by FACS flow cytometry accounted for the higher levels of EA-D observed by FACS analysis compared to the levels observed by immunofluorescence microscopy. FACS analysis may be more objective and reproducible than immunofluorescence microscopy for the detection of EBV induction and also permits viral protein expression to be distinguished in the subpopulation of viable cells.

Absence of a reservoir of Epstein-Barr virus (EBV) in normal tongue epithelium.

We examined human tongue epithelium and serum samples at autopsy for evidence of latent Epstein-Barr virus (EBV) infection. Although clinical serology revealed anti-EBV antibodies in most sera indicating past EBV infection, we found no Epstein-Barr nuclear antigen (EBNA)-coding sequences in tongue tissue by polymerase chain reaction (PCR), or Epstein-Barr-encoded RNA (EBER1) by in situ hybridization. Tongue epithelium does not appear to be a natural reservoir for latent EBV in immunocompetent hosts.

Epstein-Barr virus infections in families: the role of children with infectious mononucleosis.

We performed a prospective evaluation of Epstein-Barr virus (EBV) infections in 78 families with a childhood index case of EBV-infectious mononucleosis (EBV-IM). During the acute index episode, adult family (household) contacts, compared with control adults, had a greater rate of oropharyngeal EBV excretion and high serum antibody responses, which suggested a recent antecedent reactivation of an old EBV infection. The increased prevalence of oropharyngeal EBV and acute serological responses found in sibling family contacts during the early surveillance period suggested that these contacts had experienced an increased rate of primary-type EBV infections shortly before or concurrent with the index case. Although nonimmune sibling contacts seroconverted at a slow rate, five of nine manifested IM with their eventual documented primary EBV infection. This study noted significant intrafamilial EBV activity surrounding an episode of childhood EBV-IM. Reactivation of an old EBV infection in adults may be an important source of virus for susceptible children within these families. Siblings of a childhood case of EBV-IM appear to be at increased risk for manifesting IM with their primary EBV infection.

Enhanced serological and virological findings of Epstein-Barr virus in patients with AIDS and AIDS-related complex.

The potential involvement of Epstein-Barr virus (EBV) in AIDS was examined by determining the type of EBV-specific antibody responses and the EBV content or lymphoproliferative ability present in selected body fluids of patients with AIDS or AIDS-related complex. The results were compared with two control groups. An enhanced antibody response to a broad spectrum of EBV antigens was found in patients with AIDS or AIDS-related complex. The pattern of virus-specific antibody responses resembled that associated with a persistent or reactivated infection. The content of EBV in oropharyngeal secretions and the lymphoproliferative ability in peripheral blood from patients with AIDS or AIDS-related complex was significantly greater than that from healthy controls and approached levels detected in the control group with infectious mononucleosis. These findings, together with recent reports of cellular-level interaction between EBV and human T lymphotropic virus type III, suggest that EBV may have a contributory role in these disorders.

Epstein-Barr virus infectious mononucleosis in children. I. Clinical and general laboratory findings.

Between 1976 and 1982, 113 children aged 6 months to 16 years with documented Epstein-Barr virus-induced infectious mononucleosis were studied prospectively, and in most instances serially. An unexpected finding was the large number of young children, less than 4 years old, with this disease. Children with infectious mononucleosis, in particular the very young, tended to have more rashes, significant neutropenia, abdominal pain (older children only), and possible hepatosplenomegaly than have been reported in adult patients. The intensity of the characteristic relative atypical lymphocytosis found in peripheral blood was age-related; it was less in the very young. Findings of failure to thrive, otitis media, and episodes of recurrent tonsillopharyngitis appeared to be unique or more closely associated with childhood disease. Complications such as thrombocytopenia with hemorrhagic manifestations, significant airway obstruction, and neurologic problems occurred more frequently whereas jaundice occurred less frequently than noted in adult patients. Six children, all less than 4 years old, developed pneumonia during the disease course. The increased availability of Epstein-Barr virus-specific testing should continue to expand our knowledge of this disease in children of all ages.

Epstein-Barr virus infectious mononucleosis in children. II. Heterophil antibody and viral-specific responses.

An investigation was performed to address the need to establish the rate of positive heterophil antibody responses, oropharyngeal isolation of Epstein-Barr virus (EBV), and the evolving pattern of EBV-specific antibody responses among children with documented EBV-infectious mononucleosis. Findings showed that the rate of heterophil antibody responses appeared to increase progressively with advancing age from infancy up to 4 years, after which the rates approached values similar to that reported in young adult patients. The rapid slide test detected a heterophil antibody response as frequently as the Paul-Bunnell-Davidsohn horse cell test, except in children less than 4 years old. The decreased sensitivity found with the rapid slide test in the very young was associated with their less intense heterophil response. The younger group of children also developed a lower acute mean titer and, as a result, a decreased persistence of immunoglobulin M antibody to EBV-capsid antigen, whereas they had more frequent responses to EBV-early antigen directed to restricted component than both the older subjects and adults reported elsewhere. Antibodies to EBV-nuclear antigen, characteristically a late-onset antibody, tended to develop earlier than noted in adult patients. In contrast, the prevalence and continued excretion of EBV from oropharyngeal secretions was similar to that reported in adult patients. It is speculated that these age-related differences in host responses are associated with the ontogeny of the immunologic system.

Increased prevalence and titer of Epstein-Barr virus antibodies in patients with multiple sclerosis.

The prevalence and titer of serum antibodies to several Epstein-Barr virus (EBV) antigens were compared among patients with multiple sclerosis, healthy siblings of multiple sclerosis patients, patients with other neurological diseases, and healthy non-blood-related subjects. Serum-cerebrospinal fluid (serum-CSF) pairs were available on a selected number of multiple sclerosis and control subjects. An increased antibody response to EBV antigens was noted rather consistently in the sera of the multiple sclerosis group in comparison with the control groups. A greater number of reduced ratios of serum:CSF IgG antibody to EBV-capsid antigen and antibody to EBV-early antigen components than to adenovirus, a reference or control virus, were found in the multiple sclerosis group. Reduced ratios of these EBV antibodies were detected more frequently or showed a trend in this direction in multiple sclerosis patients compared with the group with other neurological diseases. Our findings extend the results of an earlier report and strengthen the association between EBV and multiple sclerosis.

Use of a simple separation column in detection of immunoglobulin M antibody to Epstein-Barr virus.

The use of a new commercial separation column on whole test serum improved the method for detecting immunoglobulin M antibody to Epstein-Barr virus. The efficiency of this product in absorbing interfering immunoglobulin G was similar to that of another absorption product, staphylococcal protein A, but it has the advantage of being stable without refrigeration.

Improved test for IgM antibody to Epstein-Barr virus using an absorption step with Staphylococcus aureus.

The determination of levels of IgM antibody to Epstein-Barr virus (EBV) capsid antigen was improved by absorbing unfractionated test serum with Staphylococcus aureus cells containing protein A. Nonspecific background fluorescence was significantly decreased, thus facilitating the reading of slides and the detection of specific fluorescent reactions in serum with low levels of this IgM antibody. Moreover, the inclusion of the absorption step eliminated false-positive reactions caused by the presence of rheumatoid factor in serum and shortened the time needed for the incubation of test serum with the EBV-infected cell smear. This improved antibody test should facilitate the laboratory diagnosis of acute EBV infections, including unaccompanied by a heterophil antibody response.