Human CytomegaloVirus

Human CytomegaloVirus - Characteristics
* ubiquitous among HerpesViruses
* lymphotrophic
* largest genome of all Herpes Viruses
* replicates only in human cells
+ permissive cells include fibroblasts, epithelial cells, and macrophages
+ semipermissive cells include mononuclear lymphocytes, the stromal cells of the bone marrow, and others = basis of latency
+ Infected cells become significantly enlarged = cytomegaly
* Highly species-specific
+ Only infected humans
+ There are cytomegaloviruses specific for other animals

CytomegaloVirus - Pathogenesis

* Replicative Cycle is the same as other herpeviruses
+ replication occurs in epithelial cells and virus is shed into most body fluids
+ virus then infects cells like lymphocytes and macrophages
# virus is highly cell-associated and is transmitted by these cells
# Envelope glycoprotein protects virus from host antibody
* Binds Fc portion of immunoglobulins
* Virus establishes latent infection in monouclear cells and in organs such as kidney, liver, heart; fibroblasts and mononuclear cells in these organs
+ reactivation due to various factors including imunosuppression
+ reactivation sheds virus into body fluid including semen, breast milk, and urine
+ also reactivation often follows blood transfusion and organ transplants

Human CytomegaloVirus – Clinical Diseases

* asymptomtic infection
+ in most healthy individuals infection may occur without symptoms
+ however, virus is shed; these people are healthy carriers
+ if symptoms develops they appear as mononucleosis or hepatitis
* Mononucleosis-like syndrome
+ much like EBV with atypical lymphocytosis
+ mild pharyngitis and variable lymphadenopathy
+ heterophile antibody negative
* Hepatitis = liver dysfunction similar to hepatitis, but no evidence of classical hepatitis viruses
* Cytomegalic Inclusion Disease
+ Congenital
+ Perinatal

CMV– Cytomegalic Inclusion Disease
Human CytomegaloVirus – Risk Factors
CytomegaloVirus - Epidemiology

* Cytology
+ hallmark of CMV infection is the “cytomegalic cell” ; an enlarged cell in which the nucleus contains a dense, central, basophilic intranuclear inclusion body; often looks like an “owls eye”
+ infected cells may be found in any tissue and in urine
+ Papaicolaou or hematoxylin-eosin stains
* Antigen Detection Rapid and Sensitive Tests
+ Antigen detection using enzyme or fluorescent labeled monoclonal antibody
+ Nucleic acid detection using similarly labeled DNA probes
* Serology
+ Seroconversion,(antibody response) in an excellent marker for primary infection(IgM) or recurrent infection(IgG)
* Culture
+ CMV grows in diploid-fibroblast cell cultures
+ characteristic CPE observed in 4 - 6 weeks
+ not routinely used for diagnosis; much used epidemiologically

Human Herpes Virus, Type 6
Human Herpes Virus, type 6 – Roseola
Human Herpes Virus, type 6 - Epidemiology
ParvoViruses - Characteristics
ParvoViruses- Virus Cycle
ParvoViruses - Pathogenesis
Human Parvovirus, B19 – Erythrema infectiousm
Erythrema infectiosum; Fifth’s Disease
ParvoViruses – Other Clinical Diseases
ParvoVirus, B19 - Diagnosis
ParvoVirus, B19 - Epidemiology
ParvoVirus- Control
PoxViruses - Characteristics
PoxViruses – Clinical Diseases
Molluscum contagiosum – Clinical Disease
Small Poxvirus - Epidemiology
* Human Reservoir
o Respiratory droplets
o Scabs from lesions
* Most common mode of transmission
o Person-to-Person, direct, respiratory droplet

Smallpox - Control
* Active Attenuated Vaccine – chemically stabilized
o Vaccinia Virus– naturally attenuated zoonotic strain
+ Obtained from vesicular lesion of calves
+ Later virus were grown in chicken embryos
o From early experiment conducted by Edward Jenner -1796
* First microbial disease to be eradicated via herd immunity from a vaccine
o Routine vaccination in the U.S ceased in 1971
o Routine vaccination in the World ceased in 1978
* Epidemiology/Control
o The importance of smallpox today is that it is and example of the disease which was eradicated by producing “herd immunity” through the process of vaccination( use of active vaccinia virus)


Human CytomegaloVirus.ppt