Biology subjects

Phipps, W. T.

Publications and source records attributed to Phipps, W. T..

3 recordsLinked to original sources

bioRxiv2026

Cytotoxic T cells targeting lytic KSHV gene products infiltrate Kaposi sarcoma tumors

Kaposi sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and KSHV-associated multicentric Castlemans disease (MCD), malignancies that predominantly arise in the context of T-cell deficiency. Unlike responses to other human herpesviruses such as EBV and CMV, KSHV-specific T-cell responses detected in blood have been described as heterogeneous and low-intensity. Hypothesizing that KSHV-specific T cells are recruited to KS tumors, we analyzed the T-cell receptor (TCR) repertoire of biopsies from 144 Ugandan adults with KS (106 people living with HIV [PLWH], 38 HIV-seronegative) and identified >4,000 {beta} TCRs with predicted specificity for KSHV- or HIV-encoded peptides presented by specific MHC alleles. We tested 14 putative KSHV- or HIV-specific TCRs for recognition of cells presenting cognate peptides in the predicted MHC context. Three novel HIV-specific TCRs, found only in tumors from PLWH, exhibited high-avidity, MHC-restricted recognition of HIV Vpr and Nef peptides previously identified as CD8+ T-cell targets. Four KSHV-specific TCRs, detected in tumors from both PLWH and HIV-seronegative individuals, recognized peptides encoded by the lytic KSHV genes ORF6, ORF57, and ORF59. The ORF6- and ORF57-specific TCRs were observed in multiple individuals and constitute the first examples of public T-cell responses to KSHV. We then confirmed that these four KSHV-specific TCRs recognized KSHV-infected cells undergoing lytic reactivation. Identification of TCRs specific for KSHV lytic gene products will enable the development of T-cell-based therapies for KS and other KSHV-associated diseases. Author summaryKaposi sarcoma-associated herpesvirus (KSHV) is the only oncogenic human virus for which there is no effective vaccine, antiviral, or immunotherapeutic strategy that directly targets the virus. KSHV is the causative agent of Kaposi sarcoma and primary effusion lymphoma, cancers that primarily affect immunocompromised individuals, most commonly people living with HIV in sub-Saharan Africa, where KSHV is endemic and HIV infection is prevalent. In this study we defined the antigenic specificity of novel, putative KSHV- and HIV-specific T-cell receptors (TCRs) that are carried in T cells commonly infiltrating KS tumor biopsies. We show that T cells engineered to express KSHV-specific TCRs exhibit high-avidity, MHC-restricted recognition of KSHV-infected cells presenting naturally processed peptides encoded by KSHV lytic genes. Our findings provide a blueprint for dissecting KSHV-specific T-cell immunity and advancing the development of immunotherapeutic strategies for the prevention or treatment of KSHV-associated diseases.

immunology↗

bioRxiv2024

The signature of a T-cell response to KSHV persists across space and time in individuals with epidemic and endemic KS from Uganda

Kaposi sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi sarcoma (KS), which causes significant morbidity and mortality worldwide, particularly in people living with HIV (PLWH) and in sub-Saharan Africa where KSHV seroprevalence is high. Postulating that T-cells specific for KSHV and HIV would be attracted to KS tumors, we performed transcriptional profiling and T-cell receptor (TCR) repertoire analysis of tumor biopsies from 144 Ugandan adults with KS, 106 of whom were also living with HIV. We show that CD8+ T-cells and M2-polarized macrophages are the most common immune cells in KS tumors. The TCR repertoire of T-cells associated with KS tumors is shared across spatially and temporally distinct tumors from the same individual. Clusters of T-cells with predicted shared specificity for uncharacterized antigens, potentially encoded by KSHV or HIV, comprise [~]25% of the T-cells in KS tumors. Single-cell RNA-sequencing of blood from a subset of 9 adults captured 4,283 unique {beta} TCRs carried in 14,698 putative KSHV- or HIV-specific T-cells, which carried an antigen-experienced effector phenotype. T-cells engineered to express a representative sample of these TCRs showed high-avidity recognition of KSHV- or HIV-encoded antigens. These results suggest that a polyspecific, high-avidity KSHV- and HIV-specific T-cell response, potentially inhibited by M2 macrophages, migrates to and localizes with KS tumors. Further analysis of KSHV- and HIV-specific T-cells in KS tumors will provide insight into the pathogenesis of KS and could guide the development of specific immune therapy based on adoptive transfer or vaccination. Author SummaryIn this work, we set out to examine Kaposi Sarcoma (KS) tumor tissue, as well as peripheral blood cells from individuals with KS, both living with and without HIV. Our goal was to identify T-cells that specifically recognize antigens encoded by Kaposi sarcoma-associated herpesvirus (KSHV) or HIV. By analyzing the T-cell repertoire in KS tumor biopsies from people in Uganda with different types of KS, we uncovered clusters of T-cells with previously unknown ability to recognize these viruses. Through single-cell sequencing of peripheral blood cells, we also observed that many of these T-cells had cell-killing properties. Notably, they often coexisted with a subset of macrophages with immunosuppressive properties, which we suspect may be suppressing the function of virus-targeting T-cells. Our findings suggest that additional studies of these virus-targeting T-cells and their interaction with immunosuppressive macrophages could significantly advance the development of effective therapeutics against KS.

immunology↗

bioRxiv2020

Tumor-specific changes in Kaposi sarcoma-associated herpesvirus genomes in Ugandan adults with Kaposi sarcoma

Intra-host evolved tumor virus variants have provided insights into the risk, pathogenesis and treatment responses of associated cancers. However, the intra-host variability of Kaposi sarcoma-associated herpesvirus (KSHV), the etiologic agent of Kaposi sarcoma (KS), has not been explored at the whole viral genome level. An accurate and detailed description of KSHV intra-host diversity in whole KSHV genomes from matching tumors and oral swabs from Ugandan adults with HIV-associated KS was obtained by deep, short read sequencing, using duplex unique molecular identifiers (dUMI) - random double-stranded oligonucleotides that barcode individual DNA molecules before library amplification. This allowed suppression of PCR and sequencing errors down to [~]10-9/base. KSHV genomes were assembled de novo, and identified rearrangements were confirmed by PCR. 131-kb KSHV genome sequences, excluding major repeat regions and averaging 2.3 x 104 reads/base, were successfully obtained from 23 specimens from 9 individuals, including 7 tumor-oral pairs. Sampling more than 100 viral genomes in at least one specimen per individual showed that KSHV genomes were virtually homogeneous within samples and within individuals at the point mutational level. Heterogeneity, if present, was due to point mutations and genomic rearrangements in tumors. In 2 individuals, the same mutations were found in distinct KS tumors. The K8.1 gene was inactivated in tumors from 3 individuals, and all KSHV genomic aberrations retained the region surrounding the first major internal repeat (IR1). These findings suggest that lytic gene alterations may contribute to KS tumorigenesis or persistence. Author summaryKaposi sarcoma (KS) is a leading cancer in sub-Saharan Africa and in those with HIV co-infection. Infection by Kaposi sarcoma-associated herpesvirus (KSHV) is necessary for KS, yet why only few KSHV infections develop into KS is largely unknown. While strain differences or mutations in other tumor viruses are known to affect the risk and progression of their associated cancers, whether KSHV genetic variation is important to the natural history of KS is unclear. Most studies of KSHV diversity have characterized only [~]4% of its 165-kb genome and may have been impacted by PCR or cloning artifacts. Here, we performed highly sensitive, single-molecule sequencing of whole KSHV genomes in paired KS tumors and oral swabs from 9 individuals with KS. We found that KSHV genomes were virtually identical within individuals, with no evidence of quasispecies formation nor multistrain infection. However, KSHV genome aberrations and inactivating mutations appeared to be a common, tumor-associated phenomenon, with some mutations shared by distinct tumors within an individual. Certain regions of the KSHV genome featured prominently among tumor-associated mutations, suggesting that they are important contributors to the pathogenesis or persistence of KS.

microbiology↗