The Kaposi sarcoma associated herpesvirus (KSHV) genome encodes more than 85 open reading frames (ORFs). Serological evaluation of KSHV infection now generally relies on reactivity to just one latent and/or one lytic protein (commonly ORF73 and K8.1). Most of the other polypeptides encoded by the virus have unknown antigenic profiles. We have systematically expressed and purified products from 72 KSHV ORFs in recombinant systems and analyzed seroreactivity in US patients with KSHV-associated malignancies, and US blood donors (low KSHV seroprevalence population). We identified several KSHV proteins (ORF38, ORF61, ORF59 and K5) that elicited significant responses in individuals with KSHV-associated diseases. In these patients, patterns of reactivity were heterogeneous; however, HIV infection appeared to be associated with breadth and intensity of serological responses. Improved antigenic characterization of additional ORFs may increase the sensitivity of serologic assays, lead to more rapid progresses in understanding immune responses to KSHV, and allow for better comprehension of the natural history of KSHV infection. To this end, we have developed a bead-based multiplex assay detecting antibodies to six KSHV antigens. Kaposi sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi sarcoma, primary effusion lymphoma and a form of multicentric Castleman's disease, affecting mainly persons with HIV, other immunosuppressed patients and elderly men. Such diseases are most common where KSHV prevalence is high, in sub-Saharan Africa and the Mediterranean, and amongst men who have sex with men. Various assays for the serodiagnosis of KSHV have been developed to investigate global KSHV epidemiology. ELISAs utilizing one lytic (K8.1) and one latent antigen (ORF73) are often used. However, a more complete characterization of immune responses to all KSHV antigens may have important epidemiologic and clinical applications. We systematically expressed and purified 73 of the 85 proteins encoded by KSHV and analysed serologic responses in patients with KSHV-associated malignancies compared to healthy subjects. We identified significant reactivity to ORF38, ORF61, ORF59 and K5, in addition to the known K8.1, ORF73 and ORF65. Reactivity patterns were varied; however, HIV infected individuals were reactive to more antigens, with greater intensity. Next, we developed a bead-based assay that can test a small sample simultaneously for six KSHV antigens. The new tool can improve the detection of KSHV and the characterization of asymptomatic infection and KSHV associated diseases.

Objective: To determine the effect of the introduction of combination antiretroviral treatment (cART) in the HIV-1-infected US population on the epidemiology of Kaposi's sarcoma-associated herpesvirus (KSHV). Design, setting and participants: We investigated the epidemiology of KSHV in 5022 HIV-1-infected, antiretroviral-naive US persons participating in six AIDS Clinical Trials Group (ACTG)-randomized clinical trials, and followed in a long-term cohort study. We tested the first and last available sera of each participant for antibodies to KSHV K8.1 and ORF73. Main outcome measures: We studied prevalence and incidence of KSHV infection, incidence of Kaposi's sarcoma, and overall survival. Results: KSHV prevalence was 38.1% [95% confidence interval (CI) 36.8–39.5%]. Male sex, Caucasian race, age between 30 and 49 years, residence in north-eastern or western United States, and enrolment after 2001 were independently associated with prevalent infection. KSHV incidence was 4.07/100 person-years (95% CI 3.70–4.47). Male sex, Caucasian race, age below 30, and enrolment after 2001 were associated with incident infection. CD4⁺ cell count increase following cART was associated with lower risk. Kaposi's sarcoma incidence was 104.05/100 000 person-years (95% CI 71.17–146.89). Higher baseline CD4⁺ cell count, but not increase in CD4⁺ cell count after cART, was associated with lower hazard of Kaposi's sarcoma. Randomized assignment of protease inhibitors was not associated with better KSHV outcomes. Conclusions: HIV-1-infected individuals, in particular Caucasian men, remain at a significant risk for KSHV co-infection and Kaposi's sarcoma. Thus, optimal management of HIV-1 infection should continue to include vigilance for manifestations of KSHV co-infection, including Kaposi's sarcoma. Video https://vimeo.com/126172348

T-cell responses to KSHV infection: a systematic approach T-cell responses to KSHV infection: a systematic approach

Immune modulation by parasites may influence susceptibility to bacteria and viruses. We examined the association between current parasite infections, HIV and syphilis (measured in blood or stool samples using standard methods) and antibodies against Kaposi's sarcoma herpesvirus (KSHV), measured by ELISA, in 1915 stored plasma samples from pregnant women in Entebbe, Uganda. Seroprevalence of KSHV was higher in women with malaria parasitaemia (73% vs 60% p = 0.01), hookworm (67% vs 56% p = 0.001) and Mansonella perstans (69% vs 59% p = 0.05); seroprevalence increased with increasing intensity of hookworm infection (p < 0.001[trend]). No associations were found for HIV, five other parasites or active syphilis. These effects were not explained by socioeconomic status or education. Specific parasite infections are associated with presence of antibodies against KSHV, perhaps mediated via their effect on immune function.