Molecular Analysis of the ORFK73 Gene and Cellular Morphometry in Kaposi’s Sarcoma in the Democratic Republic of the Congo

Background: Kaposi’s Sarcoma (KS) is an angioproliferative tumor caused by human herpesvirus 8 (HHV-8), prevalent in sub-Saharan Africa and strongly associated with HIV infection. Data on the molecular characteristics and immune microenvironment of KS in the Democratic Republic of the Congo (DRC) are limited. Objective: To characterize HHV-8 ORF73 viral load and immune cell infiltration patterns in KS lesions from eastern and western DRC. Methods: This case series included 43 histologically confirmed KS patients from 2015 to 2024. DNA was extracted from formalin-fixed, paraffin-embedded biopsies, and HHV-8 ORF73 copy number was quantified by qPCR. Immunohistochemistry for HHV-8 LANA-1, CD3, CD4, CD8, CD20, and CD68 was performed, followed by digital morphometric quantification using HALO software. Viral load and immune infiltration percentages were compared between regions. Results: HHV-8 ORF73 copy numbers ranged from 11.26 to 2.7 × 10？ copies/μL DNA, with higher values observed in samples from eastern DRC. LANA-1 expression ranged from 2% to 69% positive cells. CD4⁺ T cells were the predominant infiltrate (mean 32.96%), followed by CD8⁺ T cells (18.97%) and macrophages (17.14%). B cells were sparse (2.64%). Positive correlations were observed between viral load and LANA-1 expression, as well as between viral load and T-cell infiltration. Conclusion: KS lesions in the DRC exhibit considerable heterogeneity in viral load and immune composition, with higher viral activity in the eastern region. Integrating molecular analysis with digital morphometric assessment can enhance diagnostic precision and inform therapeutic strategies, particularly in resource-limited settings.