KSHV

Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is a member of the Herpesviridae family, subfamily Gammaherpesvirinae. The genome is a linear double-stranded DNA molecule of roughly 165 kilobases that encodes dozens of genes involved in latency, immune evasion, and signaling. KSHV establishes lifelong latency, primarily in B cells and endothelial cells, with episodic reactivation under conditions of immune suppression.

KSHV was identified in 1994 in tissues from patients with AIDS-related Kaposi's sarcoma. Seroprevalence varies widely, higher in sub-Saharan Africa, the Mediterranean, and parts of Latin America, and among men who have sex with men. Transmission is thought to occur mainly via saliva, with sexual contact and blood exposure contributing in some settings.

The viral life cycle includes latent and lytic phases. Latency-associated nuclear antigen (LANA) helps tether viral episomes to host chromosomes and modulates p53 and Rb pathways; other viral proteins promote cell survival and proliferation (including vFLIP, vCyclin, and K1). KS is a vascular tumor with spindle cells and angiogenesis; primary effusion lymphoma and multicentric Castleman disease are also linked to KSHV; a systemic inflammatory syndrome (KICS) is described in some patients.

Diagnosis relies on serology for KSHV antibodies, detection of viral DNA by PCR, and histopathology. Management depends on disease and immune status: antiretroviral therapy for HIV-associated KS, and chemotherapy such as liposomal doxorubicin or paclitaxel; rituximab-containing regimens for MCD; antiviral therapy may suppress lytic replication but is not curative. No vaccine is available.