Background: HHV-6 is a ubiquitous virus and its infection usually occurs in childhood and then becomes a latent infection. HHV-6 reactivation has been shown to play a role in the pathogenesis of AIDS and several other diseases. Objectives: To determine what role HHV-6 infection or reactivation plays in the pathogenesis of multiple sclerosis (MS) and chronic fatigue syndrome (CFS). Results: Twenty-one MS and 35 CFS patients were studied and followed clinically. In these patients, we measured HHV-6 IgG and IgM antibody levels and also analyzed their peripheral blood mononuclear cells (PBMCs) for the presence of HHV-6, using a short term culture assay. In both MS and CFS patients, we found higher levels of HHV-6 IgM antibody and elevated levels of IgG antibody when compared to healthy controls. Seventy percent of the MS patients studied contained IgM antibodies for HHV-6 late antigens (capsid), while only 15% of the healthy donors (HD) and 20% of the patients with other neurological disorders (OND) had HHV-6 IgM antibodies. Higher frequency of IgM antibody was also detected in CFS patients (57.1%) compared to HD (16%). Moreover, 54% of CFS patients exhibited antibody to HHV-6 early protein (p41/38) compared to only 8.0% of the HD. Elevated IgG antibody titers were detected in both the MS and the CFS patients. PBMCs from MS, CFS and HD were analyzed in a short term culture assay in order to detect HHV-6 antigen expressing cells and to characterize the viral isolates obtained as either Variant A or B. Fifty-four percent of MS patients contained HHV-6 early and late antigen producing cells and 87% of HHV-6 isolates were Variant B. Isolates from CFS, patients were predominately Variant A (70%) and isolates from HD were predominately Variant B (67%). Moreover, one isolate from OND was also Variant B. Persistent HHV-6 infection was found in two CFS patients over a period of 2.5 years and HHV-6 specific cellular immune responses were detected in PBMCs from ten CFS patients. Conclusions: In both MS and CFS patients, we found increased levels of HHV-6 antibody and HHV-6 DNA. A decrease in cellular immune responses was also detected in CFS patients. These data suggest that HHV-6 reactivation plays a role in the pathogenesis of these disorders. (C) 2000 Elsevier Science B.V. All rights reserved.

We examined cerebral spinal fluid (CSF) from multiple sclerosis (MS) patients and patients with other neurological diseases (OND) for antibody specific for Human Herpesvirus-6 (HHV-6) and for HHV-6 DNA detectable by PCR. CSF from MS patients had a higher frequency of IgG antibody to HHV-6 late antigens (39.4%) compared with CSF from OND (7.4%). In contrast, the frequency of detectable IgG antibody in CSF from MS patients specific for Epstein-Barr Virus (EBV) (12.1%) and Human Cytomegalovirus (HCMV) (6.1%) was much lower. Two of 12 MS CSFs (16.7%) also contained HHV-6 DNA detected by PCR. None of four OND CSF were positive for HHV-6 DNA. Plasma from 16 patients with MS, eight with OND and 72 healthy donors were tested for antibodies by ELISA to HHV-6 early (p41/38) and late (gp110) proteins. Although no differences in anti-gp110 IgG antibody were detected between MS patients, patients with other neurological diseases, and normals, IgG antibody to early protein p41/38 was detected in > 68% of the plasma from MS patients, 12.5% from OND patients and 27.8% of the controls. IgM antibody to p41/38 was present in > 56% of MS patients, 12.5% of OND patients, and 19% of controls. These data suggest that more than half of the MS patients had active, ongoing HHV-6 infections. HHV-6 was also isolated from peripheral blood mononuclear cells (PBMC) from 3/5 MS patients who were in relapse or had progressive disease and was identified as HHV-6 Variant B. These preliminary results support the hypothesis that HHV-6 may be a co-factor in the pathogenesis of some cases of MS.

In order to investigate the levels of HHV-6 infection and elevated antibodies to HHV-6 in HIV-1-infected asymptomatic and symptomatic patients, peripheral blood mononuclear cells were (PBMC) cultured. As patients progressed from asymptomatic HIV infection to AIDS, there was a concurrent increase in replicating HHV-6. Plasma obtained from several of these patients showed the presence of IgM antibody and a significantly elevated level of HHV-6 IgG antibody. Serial samples of plasma from 10 AIDS patients collected over a period of 4 years were assayed for the detection of HHV-6 core protein (gp116/64/54) by antigen capture ELISA. The results demonstrated that either a persistent infection or reactivation can occur based on the degree of fluctuation in HHV-6 antigen detected. ELISA to HHV-6 purified viral proteins, i.e., early (p41/38) and late (gp110), demonstrated that IgG antibody to gp110 did not differentiate between HIV-1-infected and healthy donors. IgG and IgM antibody to p41/38, however, showed a significantly higher prevalence in HIV-1-infected individuals (56.7-85.3%) than in normal healthy donors (19.0%), suggesting virus activation. PBMC culture from the AIDS patients expressing significant peaks of HHV-6 core antigen (gp116/64/54) in their plasma showed that in most cases, HHV-6 early and late antigens were detectable; however, those patients with consistently low antigen peaks had no detectable antigens in their PBMC. Only 55% of PBMC cultures established from IgM antibody-positive HIV-1-infected asymptomatic and AIDS patients expressed HHV-6 antigens in the short-term cultures, but HHV-6 antigens could not be demonstrated in PBMC culture from 4 IgM-antibody-positive healthy donors. HHV-6 isolates obtained from the HIV-1-positive patients were predominantly HHV-6 variant A, compared to healthy donors. Based on the data presented here, it is evident that the levels of HHV-6 infection increased in HIV-1-infected asymptomatic individuals as they progressed to AIDS. Our immunovirological data on HHV-6-infected individuals with HIV infection support a role for HHV-6 in the pathogenesis of AIDS. We believe that simultaneous active infection with HIV-1 and HHV-6 may contribute to enhanced immune suppression perhaps leading to disease manifestations.

Transfer Factor (TF) was used in a placebo controlled pilot study of 20 patients with chronic fatigue syndrome (CFS). Efficacy of the treatment was evaluated by clinical monitoring and testing for antibodies to Epstein-Barr virus (EBV) and human herpes virus-6 (HHV-6). Of the 20 patients in the placebo-controlled trial, improvement was observed in 12 patients, generally within 3-6 weeks of beginning treatment. Herpes virus serology seldom correlated with clinical response. This study provided experience with oral TF, useful in designing a larger placebo-controlled clinical trial.

Because of the sudden onset of "flu-like" symptoms in he vast majority of cases, followed by persistent illness and fatigue over several years, bolh RNA (retroviruses) and DNA (herpesviruses and enteroviruses) viruses have been suspected to be implicated in the pathogenesis of CFS. In recent years, evidence of the association of some viruses wilh CFS has progressed, whereas, with some others it has weakened considerably. Thus far, no single virus has been found to be the causative agent of CFS. Reactivation, however, of latent virus or viruses could contribute to the symptomatology of CFS by damaging the immune system either directly or indirectly. In this report we have provided a comprehensive review of the status of research on viral agents which have been investigated for their role in the pathogenesis of CFS.

The Epstein-Barr virus (EBV) has been studied for over 25 years as a probable cause of certain human cancers, including nasopharyngeal carcinoma (NPC). This is a low-incidence head and neck cancer in Western countries (including the USA), but is the third-leading cancer in males in Southeast Asia. Evidence supporting an etiologic relation between this virus and NPC includes the fact that there is a 100% infection rate in patients with this cancer and that EBV DNA and antigens have been demonstrated in all biopsies examined to date. The determination that EBV is at least a major co-factor in the etiology of NPC has led to the development of new diagnostic and prognostic tests for this disease using anti-viral markers. Of particular importance to the diagnosis of NPC were the findings, initially reported by the Henles [Int J Cancer 17:1-7, 1976], that the serum of patients with NPC contain IgA antibodies to EBV at a high frequency. In general, 80-90% of patients with this disease contain serum IgA antibodies to EBV as opposed to 10-30% of the normal population. This finding has resulted in the development and successful employment of tests measuring this antibody as adjuncts to pathology in the diagnosis of NPC including the occult form. In addition, this finding has resulted in the development of tests for the early detection of this disease. The IgA test for antibodies to EBV is currently employed in large screening programs in Southeast Asia designed to identify those individuals at risk for the development of NPC. Results from these screening programs that have now been ongoing for over 5 years indicate that the incidence of NPC is 100-1000-fold higher in IgA antibody-positive individuals as opposed to IgA anti-EBV antibody-negative individuals, demonstrating the value of this IgA test for identifying individuals at high risk for NPC. The fact that this antibody test can be used reliably for the detection of early NPC should lead to earlier and more successful treatment of this disease. (C) 1993 Wiley-Uss, Inc.

The Epstein-Barr virus (EBV), isolated in 1966, continues to draw worldwide attention as an important human pathogen. Its impor tance is largely related to the continuing accumulation of evidence that

Epstein-Barr virus (EBV) is one of the most widespread human viruses, with over 80% of the general population exposed by young adulthood, as determined by antibody studies. Initial infection usu ally

Infectious mononucleosis (IM) is characterized as an acute, usually self-limited, lymphoproliferative disorder caused by the Epstein-Barr virus (EBV) (Henle, Henle, and Diehl 1968; Henle and Henle 1978). During the course of this disease, antibodies are produced against a variety of antigens, some of which are synthesized during the virus replication cycle, while others are related to normal cellular elements. The antibodies produced against this latter category of antigens often have the characteristics of autoantibodies. Some of the antibodies produced during the course of IM are of significant diagnostic value for this disease, and others are produced probably as a consequence of EBV infection of B lymphocytes, the target cells for this virus (Pattengale, Smith, and Gerber 1974), and are of no apparent diagnostic or prognostic importance. They may, however, contribute to the development of the various complications frequently noted following the active disease.

While reliable tests are available to diagnose acute herpesvirus infections, this does not apply equally well to the identification of chronic active or recurrent infections. Common serology in most cases is not very reliable, unless the antibody response is carefully dissected to determine the response to some early antigens related to viral replication, such as against EA complex in Epstein-Barr virus infections. There are a number of techniques that hold some promise for the future: antigen demonstration by monoclonal antibodies such as in the shell vial assay or in tissue culture cells exposed to body fluids; in situ hybridization for viral DNA and polymerase chain reaction; and antigen assays by combined blotting/monoclonal antibody techniques. In developing meaningful parameters for defining persistent active or reactivated herpesvirus infections, techniques for quantitating virus and/or antigen should be helpful.

The Epstein-Barr virus (EBV) major surface membrane antigen, gp350/220, was expressed in recombinant yeast cells and in several recombinant mammalian cell lines. Each of the expressed proteins was analyzed for its ability to bind to a panel of anti-gp350/220 monoclonal antibodies and to a series of anti-EBV positive human sera. The antigens also were used as immunogens for the immunization of rabbits. Each expressed protein was found to be unique both in its pattern of reactivity to the various antibodies and in the spectrum of antibody induced following animal immunization. These results suggest that cell-specific post-translational modifications critically influence the antigenic presentation of the expressed proteins. Nonetheless, all of the mammalian cell-derived versions of the membrane antigen were found capable of inducing EBV-specific neutralizing antibodies.

Monoclonal antibodies have now been prepared against a number of the major polypeptides associated with the different EBV-induced antigenic complexes. These antibodies have made it possible to purify and characterize most of these polypeptides and to identify the viral genes encoding for these proteins. In addition, new ELISA tests have been developed which measure antibodies in different immunoglobulin classes against the purified polypeptides. These assays have been useful in the diagnosis of EBV-associated diseases in clinical laboratories. The development of these antibodies and their application to the development of the new ELISA tests will be reviewed in this paper.