PATHOGENS

• HIV-associated multicentric Castleman disease (MCD) always associated with HHV-8, aka Kaposi sarcoma-associated herpesvirus (KSHV). HHV-8 is present in 40% or less (depending on location) of non-HIV cases. Other categories of CD: unicentric (UCD) and non-KS MCD.
• HHV-8 is a double-stranded DNA gamma-herpesvirus.
• MCD is likely the result of uncontrolled lytic infection with all viral genes expressed and viral replication as opposed to a very small proportion of HHV-8 cells (1%) having lytic infection in Kaposi sarcoma. KS viral loads are also markedly elevated (2 log higher) in MCD than in KS.
• HHV-8 infects B cells (B cell proliferation plays a central role in MCD) and plasmablasts
• HHV-8 is secreted in saliva; a possible reason for high MSM prevalence of HHV-8 infection in the U.S. is through oral anal infection, unclear reasons for high general population infection in Africa.