herpesviruses

Herpesviruses are a large family of DNA viruses within the order Herpesvirales. Members infect a wide range of vertebrates and are characterized by enveloped, icosahedral virions, large double-stranded DNA genomes, and a tendency to establish lifelong latent infections in host cells. Following primary infection, many herpesviruses establish latency in sensory neurons or lymphoid cells and can reactivate periodically, often during stress or immunosuppression.

Taxonomy and key members: The family is divided into three subfamilies. Alphaherpesvirinae includes rapidly replicating viruses such as herpes simplex viruses 1 and 2 and varicella-zoster virus. Betaherpesvirinae contains cytomegalovirus and related viruses such as HHV-6 and HHV-7. Gammaherpesvirinae includes Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus, which establish latency in B cells and are linked to certain lymphoproliferative diseases.

Clinical spectrum: HSV-1 and HSV-2 commonly cause oral and genital lesions and can involve the eyes or central nervous system. Varicella-zoster virus causes chickenpox in primary infection and shingles upon reactivation. EBV is associated with infectious mononucleosis and certain cancers; CMV can cause congenital disease and opportunistic infections in immunocompromised individuals. HHV-6/7 are major causes of roseola in children, and KSHV is linked to Kaposi sarcoma and related conditions.

Diagnosis and treatment: Diagnosis uses PCR, serology, and, when appropriate, viral culture. Antiviral drugs such as acyclovir, valacyclovir, and famciclovir are active against many alphaherpesviruses; ganciclovir is used for CMV. Resistance can occur, and no therapy cures latent infection.

Prevention and vaccines: Vaccines exist for varicella and herpes zoster (Varicella vaccine and Shingrix), reducing the burden of chickenpox and shingles. Vaccines for HSV and CMV are not yet widely available, though development continues.

Epidemiology: Herpesviruses are globally prevalent; most people acquire primary infection in childhood or early adulthood, with lifelong persistence and intermittent reactivation.