14.CMV_Flashcards
What is HHV-5 (Cytomegalovirus, CMV)?
HHV-5 belongs to the β-Herpesviridae subfamily. It is the largest herpesvirus, encodes over 200 proteins, replicates slowly (~24 hours), grows best in fibroblasts, and establishes latent infection in salivary glands.
How does CMV evade immune responses?
CMV produces proteins that mimic Fc receptors and forms a protective coat using host immunoglobulins (Ig) to evade immune elimination.
What is the cytopathic effect caused by CMV?
CMV causes perinuclear (cytoplasmic) and intranuclear inclusions. Infected cells become enlarged (cytomegalic cells) and form giant cells.
What are the target cells for CMV?
CMV targets monocytes, lymphocytes, and epithelial cells.
Where does CMV establish latency, and how is it reactivated?
CMV establishes latency in monocytes and lymphocytes. Reactivation occurs due to decreased cell-mediated immunity (CMI), inhibiting T-cell function, especially in immunosuppressed individuals.
What is the prevalence of CMV antibodies in adults?
Over 80% of adults have CMV antibodies. Most cases are asymptomatic or subclinical.
How is CMV transmitted?
CMV is transmitted via all physiological fluids:
1. Saliva: Infects salivary glands.
2. Urine.
3. Semen and vaginal secretions (STD).
4. Blood transfusion or organ transplantation.
5. Congenital transmission (transplacental, birth, or breast milk).
What are the diseases caused by congenital CMV infection?
Congenital CMV infections (TORCH) can cause:
- Intrauterine fetal death.
- Cytomegalic inclusion disease (CNS and RES involvement).
- IUGR (intrauterine growth restriction).
- Hepatosplenomegaly.
- Jaundice.
Is CMV symptomatic in most cases?
No, most CMV cases are asymptomatic or subclinical, especially in healthy individuals. Symptomatic infections occur in immunosuppressed patients.
