HHV8

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is a double-stranded DNA virus in the Herpesviridae family, subfamily Gammaherpesvirinae. It establishes latent infection in B cells and endothelial cells and can reactivate under conditions of immune suppression. The genome encodes latency-associated and lytic genes, including LANA, v-cyclin, and v-FLIP, as well as viral microRNAs that modulate cell survival and immune evasion.

HHV-8 was identified in 1994 by Chang and Moore in Kaposi's sarcoma lesions, establishing a causal link between the virus and KS. Seroprevalence varies by region and population; it is relatively common in sub-Saharan Africa and parts of the Mediterranean and the Middle East, while prevalence is low in many other areas. Transmission occurs mainly via saliva; sexual contact is an important route in high-prevalence populations; parenteral transmission can occur through contaminated blood products or needles.

Clinically, HHV-8 infection is associated with Kaposi's sarcoma, a vascular tumor most common in individuals with HIV/AIDS or other forms of immunosuppression; the virus is also linked to primary effusion lymphoma and multicentric Castleman disease. Other HHV-8–related conditions can occur, especially in immunocompromised hosts.

Diagnosis relies on serology for antibodies to HHV-8 or detection of viral DNA by PCR in blood or tissues; immunohistochemical staining for LANA supports latent infection. There is no licensed vaccine. Management focuses on treating the underlying immunosuppression (such as antiretroviral therapy for HIV infection) and on local or systemic cancer therapies for KS, including liposomal chemotherapy, radiotherapy, or targeted approaches. Research continues into antiviral strategies and vaccines, but no preventive vaccine is available.