Review Question - QID 106737

Herpesviruses are unique in that, unlike most other viruses that acquire their envelope from budding through the host cell plasma membrane, herpesviruses gain their envelope in budding through the nuclear membrane of the host cell.

The herpesvirus life cycle first begins with the viral envelope incorporation into the host cell plasma membrane and uncoating of the nucleocapsid to release DNA into the nucleus. The viral DNA then is transcribed to mRNA, which then undergoes translation to produce proteins needed for DNA replication, capsid components, and envelope proteins that are produced in the endoplasmic reticulum and become incorporated into the nuclear membrane. The viral DNA is replicated in the host cell nucleus and packaged into capsids. The viral capsid and enclosed DNA then bud off through the host cell nuclear membrane (with the previously embedded viral envelope proteins). The enveloped virus passes through the endoplasmic reticulum then out of the host cell through the plasma membrane for its final release.

Usatine et al. discusses the management of cold sores and HSV-1 infections. For primary HSV-1 gingivostomatitis in children, an oral acyclovir suspension is helpful. For cold sore treatment, oral acyclovir, valacyclovir, and famciclovir are effective. Note that these treatments do not 'cure', as HSV-1 is a life-long infection; rather, they limit the severity and duration of the patient's symptoms. Daily oral acyclovir or valacyclovir can reduce the recurrence of herpes labialis.

Arain et al. investigate the efficacy of topical corticosteroids in addition to antiviral treatment for the management of recurrent herpes labialis. A systematic review and meta-analysis revealed lower recurrence rates and shorter healing times for patients treated with combination antivirals (acyclovir, famciclovir, or valacyclovir) and topical corticosteroids (1% hydrocortisone and 0.05% fluocinonide) as opposed to antivirals alone.

Figure A shows herpes labialis (cold sores) in a patient with latent HSV-1 infection. Illustration A summarizes herpes virus replication; note the presence of the nuclear membrane as the viral capsid and DNA bud off first from the nucleus and then from the cell itself.

Incorrect Answers:
Answers 1,2: Herpesviruses are double-stranded, linear DNA viruses.
Answer 3: Herpesviruses are enveloped viruses.
Answer 5: Herpesviruses are the only viruses to acquire their envelope by budding from the nuclear membrane, not the plasma membrane.