Longitudinal sero‐reactivity to human herpesvirus 8 (KSHV) in the Swiss HIV Cohort 4.7 years before KS

Abstract

The relationship between viral infection with Kaposi sarcoma-associated herpesvirus (KSHV) and the onset of Kaposi sarcoma (KS) in AIDS patients is incompletely understood. This study investigates the use of three serological assays to predict the development of KS in HIV-positive patients. Serially collected serum samples from 36 patients with KS and matched controls in the Swiss HIV Cohort Study (SHCS) were analyzed in a case control study. Three serologic assays to detect antibodies against KSHV (nuclear and membrane antigen immunofluorescence assay, N-IFA, M-IFA and ORF 65.2 ELISA) were used to determine the predictive value of KSHV-seropositivity. Serial samples from the cases were also analyzed to determine longitudinal patterns of seroreactivity and identify cases of seroconversion. Assay sensitivity for detection of KSHV antibodies was highest for M-IFA (83%), followed by N-IFA (74%) and 65.2 ELISA (52%). At the time of initial serum sampling (median 4.7 years before KS), only the N-IFA distinguished case and control sera (61% vs. 32%) and no assay was clearly predictive of subsequent onset of clinical KS. Moreover, an unexpectedly high rate of reversions to seronegativity were observed by N-IFA (27/33) as well as by 65.2 ELISA (11/26) in the longitudinal analysis. Analysis of the ORF65.2 ELISA index indicated that these reversions before the clinical onset of KS were associated with antibody levels that frequently hovered around the level of detectability. A marked increase in ORF 65.2 antibody titer occurred in a third of the patients at the time of KS diagnosis. Only two seroconversions were documented. KSHV infection within the SHCS is likely to have preceded HIV infection. KSHV infection alone is not highly predictive of KS development in this cohort of HIV-infected homosexual men as compared with matched controls. Three KSHV serologic assays, though sensitive at the time of clinical KS are inconsistently positive before the development of AIDS-related KS.

Impact of Kaposi Sarcoma–Associated Herpesvirus (KSHV) Burden and HIV Coinfection on the Detection of T Cell Responses to KSHV ORF73 and ORF65 Proteins

“…The detection of viral DNA in 1 of these subjects by a PCR-based assay demonstrates the presence of the virus and highlights the need for improved assays to more reliably determine KSHV infection. The need for more consistent measures of KSHV infection is also highlighted by the previously reported frequencies of seroreversion [15,27], which may have caused some individuals to appear, at least temporarily, to be seronegative, whereas CTL responses remained detectable [43]. Clearly, more-extensive studies with prolonged follow-up and more repetitive serologic analyses will be needed to resolve the current discordance between cellular and humoral immunity to this virus.…”

Development of an Immunofluorescence Assay Using Recombinant Proteins Expressed in Insect Cells To Screen and Confirm Presence of Human Herpesvirus 8-Specific Antibodies

“…This patient had undergone antiretroviral treatment after the development of KS; the treatment could have suppressed the viral load and led to the complete seroreversion for HHV-8-specific antibodies by the time of the present study. Seroreversion has, in fact, been documented in patients after treatment and the regression of symptoms (25). CD4 ϩ cell count data were not available to help gauge the level of immunosuppression, which may also help explain the unexpected HHV-8 seronegativity.…”

“…By the use of sera from KS patients, several proteins have been identified to be highly reactive antigens. These include open reading frame (ORF) proteins 6,8,9,25,26,39,59, 65, 68, and 73; K8.1A; and K8.1B (5). Of these proteins, ORF59, K8.1A, ORF65, and ORF73 have been used in the development of various enzyme immunoassays (EIAs) and have been reported to be good candidate antigens (5,14,16,19,28,32).…”

Spectrum of Kaposi's Sarcoma-Associated Herpesvirus, or Human Herpesvirus 8, Diseases

“…In Amsterdam, HHV-8 antibodies were most often found in HIV-infected men who had recently seroconverted and could be used to predict risk for KS (119). In the French-speaking part of Switzerland, no cases of classic KS were recorded before 1983; thereafter, most KS was found in HIV patients, but the assays used were unable to predict the incidence of KS by testing for HHV-8 antibody (232). The exception for northern Europe is Sweden, where 20% of blood donors were reported to test positive for HHV-8 antibodies; however, the same report shows a wide variety of results depending on the assay used (86).…”