HIV fragments detected in Kaposi sarcoma tumor cells in HIV-infected patients

Kaposi sarcoma (KS) is a malignant vascular neoplasm caused by KS-associated herpesvirus (KSHV) infection. HIV plays a major role in KS pathogenesis. KS in HIV usually produces more malignant features than classic KS. Despite the close KS–HIV relationship, no study has reported the existence of HIV in KS tissue. We used ddPCR to detect HIV and KSHV in HIV(+) KS samples and classic KS control. We verified KS cell types through immunohistochemistry and applied hypersensitive in situ hybridization (ISH) to detect HIV and KSHV in tumor cells. Furthermore, we co-stained samples with ISH and immunohistochemistry to identify HIV and KSHV in specific cell types. Regarding pathological stages, the KS were nodular (58.3%), plaque (33.3%), and patch (8.3%) tumors. Moreover, ddPCR revealed HIV in 58.3% of the KS samples. ISH revealed positive Pol/Gag mRNA signals in CD34 (+) tumor cells from HIV (+) patients (95.8%). HIV signals were absent in macrophages and other inflammatory cells. Most HIV (+) KS cells showed scattered reactive particles of HIV and KSHV. We demonstrated that HIV could infect CD34 (+) tumor cells and coexist with KSHV in KS, constituting a novel finding. We hypothesized that the direct KSHV–HIV interaction at the cellular level contributes to KS oncogenesis.