Gammaherpesviruses

Gammaherpesviruses are one of the three subfamilies of the Herpesviridae family. They are enveloped double-stranded DNA viruses with linear genomes and are known for establishing lifelong latent infection in lymphoid cells, particularly B lymphocytes. The subfamily Gammaherpesvirinae includes several genera, such as Lymphocryptovirus, Rhadinovirus, and Macavirus, which collectively infect humans and a variety of mammals and birds.

Among humans, the best-characterized member is Epstein-Barr virus (EBV), a Lymphocryptovirus. EBV is associated with infectious mononucleosis and with several malignancies, including Burkitt lymphoma, nasopharyngeal carcinoma, and Hodgkin lymphoma. Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) belongs to the Rhadinovirus genus and is linked to Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Other gammaherpesviruses infect animals and may contribute to lymphoproliferative disorders or tumors in their hosts.

Biology and latency: Gammaherpesviruses preferentially maintain latent infection in B cells, expressing latency-associated genes to evade immune detection and occasionally reactivating to produce infectious virions. They often have large, complex genomes encoding immunomodulatory proteins and multiple mechanisms to manipulate host cell cycle and apoptosis.

Transmission and diagnosis: EBV is mainly spread by saliva; KSHV is transmitted via saliva, sexual contact, and blood products in certain settings. Diagnosis typically relies on serology and polymerase chain reaction assays to detect viral DNA, supported by histopathology when cancers are suspected.

Clinical relevance: There is no universal vaccine for gammaherpesviruses, though vaccines are in development for EBV in some contexts. Treatment focuses on managing disease and, when needed, antiviral therapy during reactivation or in associated malignancies.