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Objective: To study the natural history and pathogenesis of human herpesvirus 8 (HHV-8) infection in HHV-8-seropositive, immunosuppressed men., Design: Longitudinal study of 87 HHV-8- and HIV-seropositive men [42 with Kaposi's sarcoma (KS)] during four visits over a 2 month period., Methods: : Patients provided oral fluid and blood. HHV-8 antibody titers were measured with peptide-based enzyme-linked immunosorbent assays (ELISA) for ORF65 and K8.1; HHV-8 DNA was detected with polymerase chain reaction ELISA., Results: HHV-8 DNA was present in oral fluid or peripheral blood mononuclear cells (PBMC) at one or more of the four visits in 71% of men with KS and 56% of men without KS. The strongest correlate of HHV-8 DNA in PBMC was the presence of KS [odds ratio (OR), 8.7; 95% confidence interval (CI), 3.4-22]. Detection of HHV-8 DNA in oral fluid or PBMC was often intermittent, but individuals who shed virus at one time point were more likely to shed at other times. Some men had incomplete epitope recognition in their anti-HHV-8 antibody response. High antibody titers were associated with the absence of circulating HHV-8, particularly for the ORF65 seroassay (OR, 0.16; 95% CI, 0.05-0.51)., Conclusions: Among HHV-8 seropositive men, circulating virus is common even in the absence of disease. The link between KS and HHV-8 DNA in PBMC suggests that anti-herpes drugs may impede KS development or progression. Seroassays should target multiple epitopes to achieve maximal sensitivity. HHV-8 replication may be limited by high antibody titers or other immune function for which antibodies are a marker.

Human herpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma (KS). Several studies indicate horizontal HHV-8 transmission among children in areas where KS is endemic, but few studies have assessed acquisition of HHV-8 by children in low seroprevalence areas. Antibody screening was carried out for HHV-8 and Epstein-Barr virus (EBV) on 787 serum specimens from children living in two areas where HHV-8 is not endemic, the United States (US) and Germany, and on 184 specimens from children living in a KS-endemic area (Nigeria). For children in the US and Germany, the results showed low HHV-8 seroprevalence rates (3-4%). However, US children aged 6 months to 5 years had higher HHV-8 antibody titers than did 6-17-year-old children (P < 0.01), a finding consistent with more recent infections being detected in the younger children. Compared with seroprevalence rates and antibody titers in US and German children, those in Nigerian children were significantly higher, and seroprevalence increased with age. There was no evidence of cross-reactivity between assays for HHV-8 and EBV, despite the genetic similarity of these two herpesviruses. The data indicate that HHV-8 transmission among children where HHV-8 is not endemic occurs, but is uncommon. The findings also suggest that HHV-8 antibodies, as measured by current tests, may not persist for long periods in populations at low risk for KS and that vertical transmission is rare, although longitudinal studies are necessary to address directly these issues., (Copyright 2004 Wiley-Liss, Inc.)

The immunodominant region of the human herpesvirus 8 (HHV-8), the antibody-binding site of glycoprotein K8.1A, was mapped to the N-terminal region by using overlapping peptides and a residue replacement method. The main epitope was located within residues 44 to 56 (GQVYQDWL----C). Based on this information, we developed an enzyme immunoassay to detect HHV-8 antibodies in human sera using a four-branch multiple antigenic peptide as the antigen. The sensitivity and specificity of the assay were 96 and 99.4%, respectively. This assay should be useful for population-based, epidemiological studies of HHV-8 infection.

Improvement of serologic assays for detection of antibodies against human herpesvirus 8 (HHV-8) is critical to better understand its epidemiology and biology. We produced the HHV-8 latent (ORF73) and lytic (ORF65, K8.1, and glycoprotein B) antigens in the Semliki Forest virus system and evaluated their performance in immunofluorescence assays (IFAs) and enzyme-linked immunosorbent assays (ELISAs). These assays were compared with other latent antigen-based assays, including an IFA based on primary effusion lymphoma (PEL) cells and an ELISA based on bacterially expressed ORF73 antigen, as well as with other lytic antigen-based assays, including an IFA based on induced PEL cells, a commercial ELISA based on purified virions, and ELISAs based on K8.1- and ORF65-derived oligopeptides. We used a panel of 180 serum specimens obtained from three groups expected to have high, intermediate, and low HHV-8 prevalences. Using three different evaluation methods, we found that (i) the performances of the lytic antigen-based ELISAs were almost equivalent, (ii) the lytic antigen-based assays were more sensitive than the latent antigen-based assays, and (iii) in general, IFAs were more sensitive than ELISAs based on the same open reading frame. We also found that serum specimens from healthy individuals contained antibodies cross-reactive with HHV-8 glycoprotein B that can potentially cause false-positive reactions in lytic PEL-based IFAs. Although this is not a substantial problem in most epidemiologic studies, it may confound the interpretation of data in studies that require high assay specificity. Because the K8.1-based IFA provides sensitivity similar to that of lytic PEL-based IFAs and improved specificity, it can be a useful alternative to the PEL-based IFAs.

A dominant epitope within the human herpesvirus 8 (HHV8) ORF 65-encoded protein was mapped to an 8-amino-acid (aa) sequence (RKPPSGKK [aa 162 to 169]) by an amino acid replacement method. Using a 14-aa peptide (P4) encompassing this epitope as the antigen, we developed an enzyme immunoassay for HHV8 antibodies. The presence of P4 antibodies in a panel of 61 human serum specimens was highly correlated with biopsy-confirmed Kaposi's sarcoma. The homologous Epstein-Barr virus peptide derived from BFBR3-encoded protein did not interfere with the assay, suggesting that P4 is specific for HHV8.

Background: If Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma, serologic evidence of infection should be present in patients before the disease develops., Methods: Using an immunoblot assay for two latent nuclear antigens of KSHV, we tested serum samples from homosexual male patients with the acquired immunodeficiency syndrome (AIDS) with and without Kaposi's sarcoma (HIV-infected men with hemophilia), HIV-seronegative blood donors, and HIV-seronegative patients with high titers of antibodies against Epstein-Barr virus (EBV). Serial serum samples obtained from patients with Kaposi's sarcoma before the diagnosis of the disease were tested for evidence of seroconversion., Results: Of 40 patients with Kaposi's sarcoma, 32 (80 percent) were positive for antibodies against KSHV antigens by the immunoblot assay, as compared with only 7 of 40 homosexual men (18 percent) without Kaposi's sarcoma immediately before the onset of AIDS. Of 122 blood donors, 22 EBV-infected patients, and 20 HIV-infected men with hemophilia, none were seropositive. When studied by the immunoblot assay over a period of 13 to 103 months, 21 of the 40 patients with Kaposi's sarcoma (52 percent) seroconverted 6 to 75 months before the clinical appearance of Kaposi's sarcoma. The median duration of antibody seropositivity for KSHV-related latent nuclear antigens before the diagnosis of Kaposi's sarcoma was 33 months., Conclusions: In most patients with kaposi's sarcoma and AIDS, seroconversion to positivity for antibodies against KSHV-related nuclear antigens occurs before the clinical appearance of Kaposi's sarcoma. This supports the hypothesis that Kaposi's sarcoma results from infection with KSHV.

An assay for antibodies to membrane antigens of cells infected by human T-cell leukemia virus was used to examine serum from persons who donated blood to 12 patients with acquired immunodeficiency syndrome (AIDS) associated with blood transfusions. The occurrence of positive results in the assay was significantly greater among donors to the AIDS patients (9 of 117; 7.7 percent) than among random donors (1 of 298; 0.3 percent). Of 12 sets of donors examined, 9 sets included a donor whose serum gave positive results for the presence of the antibodies. In six of these nine sets, the seropositive donor was an individual who was also identified as a possible source of AIDS transmission when epidemiologic and immunologic criteria were used.

The titers and isotypes of antibodies to specific proteins of the human immunodeficiency virus were determined by Western blot analysis of sera from 107 homosexual men. Antibody titers were generally lower in sera from patients with the acquired immunodeficiency syndrome (AIDS) and in sera from men whose condition subsequently progressed to AIDS than in sera from men who had not progressed to AIDS. We found no evidence of isotypic prominence or restriction of the antibody response. In multivariate analysis, lower levels of CD4 helper cells were most highly associated with progression to AIDS. Lower antibody titers to the envelope protein gp110, the core protein p24, and the reverse transcriptase enzyme p51/65 were also predictive of progression to AIDS independent of their association with CD4 cell levels. These data suggest that differences in antibody levels are not simply a consequence of severe immunodeficiency but may be markers for control of infection.

Lymphadenopathy-associated virus ( LAV ), a human T- lymphotrophic retrovirus isolated from a homosexual man with lymphadenopathy, has been causally associated with acquired immunodeficiency syndrome (AIDS). A sensitive and specific radioimmunoprecipitation test was developed for the detection of antibodies to the major core protein of LAV , p25 (molecular weight 25,000). Antibody to LAV p25 was found in the serum of 51 of 125 AIDS patients, 81 of 113 patients with lymphadenopathy syndrome, 0 of 70 workers at the Centers for Disease Control (some of whom had handled specimens from AIDS patients), and 0 of 189 random blood donors. Of a group of 100 homosexual men from San Francisco whose serum was obtained in 1978, only one had antibody to LAV p25; in contrast, of a group of 50 homosexual men in the same community whose serum was obtained in 1984, 12 had antibodies to LAV p25.

Human T cell leukaemia virus (HTLV), HTLV proviral DNA, and antibodies to HTLV or a related agent have recently been detected in patients with acquired immunodeficiency syndrome (AIDS). Antibodies against HTLV-related antigens were assayed by means of indirect living cell immunofluorescence of HTLV-infected cells in sera recently collected from Georgia haemophiliacs and in sera collected between 1976 and 1981 from New York haemophiliacs. 5 of 45 Georgia haemophiliacs and 8 of 48 New York haemophiliacs had antibodies to HTLV-associated cell membrane antigen (HTLV-MA). None of the control Georgia patients on haemodialysis or with chronic hepatitis had detectable antibodies. The 5 haemophiliac patients from Georgia with HTLV-MA had significantly fewer T4 lymphocytes than similar HTLV-MA-negative patients. There were no other significant immunological differences between these groups. These data suggest that transfusions with blood products may expose haemophiliacs to a substantial risk of acquiring HTLV or a related virus.

Immunologic and serologic studies were done in 120 homosexual men who reportedly had no symptoms related to the acquired immunodeficiency syndrome. Forty-nine men (41%) had antibody to the retrovirus human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV), and 37 (31%) had an abnormal T-cell subset ratio and other immunologic abnormalities. These abnormalities were almost exclusively confined to men seropositive for the retrovirus. Multivariate statistical analysis showed that exposure to HTLV-III/LAV was the single best predictor of T-cell (and other) immunologic abnormalities. Sexual practice, particularly receptive anal intercourse, predicted exposure to HTLV-III/LAV but was not independently related to T-cell abnormalities. The association of other microbial serologic findings with HTLV-III/LAV seropositivity or T-cell changes was a coincidental function of sexual activity. Immunologic abnormalities in asymptomatic homosexual men are mostly related to exposure to HTLV-III/LAV.