Cytomegalovirus

One-Sentence Definition

Cytomegalovirus (CMV) is a beta-herpesvirus with lifelong latency that causes significant disease in immunocompromised hosts (transplant, HIV) and congenital infection when acquired in pregnancy.

Taxonomy & Morphology

• Human herpesvirus 5; dsDNA; envelope; infects many cell types
• Large genome; slow replication compared to alpha-herpesviruses

Virulence Highlights

• Latency in myeloid lineage cells
• Immunoevasion — modulates MHC, innate sensing
• Congenital CMV — leading infectious cause of birth defects (hearing loss, neuro)

Clinical Syndromes

• Immunocompetent: often mononucleosis-like or asymptomatic
• Transplant: pneumonitis, retinitis, colitis, hepatitis
• HIV with low CD4: retinitis, GI disease
• Congenital: microcephaly, hearing loss, chorioretinitis

Diagnosis

• Quantitative CMV DNA PCR (viral load) — transplant monitoring
• pp65 antigenemia (historical)
• Shell vial / culture (slower)
• Congenital: urine/saliva PCR within 3 weeks of life

Treatment / Prevention

• Antivirals (ganciclovir/valganciclovir, foscarnet, cidofovir) — toxicity monitoring
• Preemptive vs prophylactic strategies in transplant
• No routine vaccine in widespread use (research ongoing)

Related Notes

• HIV · Adaptive Immunity · MOC - Virology
• Vaccination (limited for CMV)

Active Recall

1. Why use quantitative PCR in transplant?
2. Major congenital CMV sequel?
3. Classic AIDS-era CMV syndrome organ?