Background
Kaposi Sarcoma-Associated Herpesvirus (KSHV) is the causative agent of Kaposi sarcoma (KS) and multiple other diseases that affect people-living-with-HIV-1 (PLWH) and immune suppressed patients. Like HIV-1, KSHV can remain latent in an infected individual and could periodically reactivate to cause diseases upon immunosuppression. While HIV-1 tissue reservoirs in aviremic individuals were recently identified, little is known about KSHV tissue reservoirs, especially whether they exist in KSHV seronegative individuals. Here, our objective is to determine whether KSHV seronegative individuals can harbour KSHV in their tissues. Since tissue sampling of multiple organs from living donors is not feasible, we collected tissues from an extensive list of organs from KSHV seronegative deceased donors through postmortem autopsy. The collected samples were subjected to further analysis. Surprisingly, KSHV DNA were detected in multiple tissues of KSHV seronegative individuals.
Methods
An average of 62 various tissues and organs samples per donor were collected during full-body autopsy of a cohort consisting of 40 PLWH and HIV-1 negative individuals. KSHV serostatus was determined with KSHV-specific immunofluorescence assay and KSHV seronegativity was further confirmed by high-throughput ultra-sensitive serological assay VirScan. The presence of KSHV DNA in the collected tissues were analysed by PCR, Southern blot and tissue viral load determined by digital PCR.
Results
Immunofluorescence assay against KSHV antigens indicates that 32 out of 40 full-body autopsy donors were KSHV seronegative. Seven (6 PLWH and 1 HIV uninfected donors) out of the 32 KSHV seronegative donors were found to contain KSHV DNA in multiple anatomic sites, such as oral cavity, respiratory tract, kidney and lymph nodes. The KSHV seronegativity of these 7 donors was further confirmed with ultra-sensitive serological assay VirScan.
Conclusions
Previous reports of KSHV seroreversion were often dismissed as an issue of low-sensitivity detection methods. However, our study provides compelling evidence to the contrary. We detected KSHV DNA in multiple organs, including the kidney and lungs, in 7 of 32 (22%) seronegative individuals. This finding highlights that antibody testing is inadequate and may underestimate KSHV prevalence. This presents a significant risk in organ transplantation, where donors with a negative antibody test could still transmit the virus, leading to KS in the recipient.