- Replicate in the nucleus - Use standard mechanism for DNA viruses
What is the term used for transcription of herpesviruses?
What is it?
Cascade control (expression of a first set of genes is necessary for a second set, which is needed for the expression of a third set of genes)
How does the virus get into the host cell?
1) Adsorbs to the host cell 2) Viral envelope glycoprotein allows fusion of the envelope with the cell's plasma membrane
What happens to the host cell when a herpesvirus enters?
1) Tegument protein gets the host cell's RNase to degrade mRNA 2) Host cell protein synthesis is halted
How do herpesviruses replicate?
1) Nucleocapsid transported to nuclear pore 2) Viral DNA released into nucleus 3) Tegument protein activates cellular RNA polymerase 4) Transcription of viral IMMEDIATE EARLY GENES 5) Expression of DELAYED EARLY GENES 6) Expression of LATE GENES
What are immediate early genes needed for?
Coding of a variety of regulatory functions
What do delayed early genes code for?
Enzymes needed for replication of viral DNA - DNA polymerase - Helicase - Thymidine kinase
What do late genes code for?
Structural proteins of the virion
How do herpesvirus acquire the viral envelope? ***
- Virus buds through the nuclear membrane - Newly formed envelope proteins accumulate on the nuclear membrane
Fill in the blank: The latent virus hides in a ___________ than the type it infects.
The latent virus hides in a DIFFERENT TYPE OF CELL than the type it infects
How are HSV1 and HSV2 transmitted?
By direct contact with MUCOSAL or CUTANEOUS surfaces infected with virus
Where is HSV1 present?
Because HSV1 is present in the saliva, in which region do infections occur?
Where is HSV2 present?
In genital secretions
Because HSV2 is present in the genital secretions, how is HSV2 transmitted?
- Sexual intercourse - Newborn leaving birth canal
Where do HSV1 and 2 multiply?
In the epithelial tissue
Because HSV1 and 2 replicate in the epithelial tissue, what do they cause?
Shallow ulcers containing the virus
What other types of cells can HSV1 and 2 infect?
- Macrophages - Lymphocytes
Who is vulnerable to HSV1 and 2?
Anyone coming into contact with bodily secretions
TRUE or FALSE: Shedding may occur in the absence of visible lesions. ***
What host cell kills cells infected with HSV1 and 2 to contain the infection?
Cytotoxic T cells
What is an HSV disease that occursi n healthcare workers?
Which HSV cause it?
- Herpetic whitlow - Caused by either HSV1 or HSV2
What are the signs and symptoms of herpetic whitlow?
Lesions on the fingers or wrist
How long do HSV1 and HSV2 infections last?
Can HSV1 and HSV2 infected patients infect others when the virus reactivates after a latent stage?
- Herpes labialis (cold sorse) -Can occur several times a year
Describe the formation and healing of a cold sore
What is the phrase used to describe its appearance?
- Clear vesicle formed containing infectious virus with a red lesion at the base - Pus-containing ulcers develop - Ulcer heals without scarring in 8-10 days
Referred to as "dewdrop on a rose petal"
What can cause reactivation of HSV1?
- Cold - Trauma - Stress
Who has HSV1?
Describe HSV2 genital infection reactivation - frequency - symptoms - result / infectiousness - healing
- May occur monthly - With no symptoms OR - With genital herpes sores - Results in viral shedding - Increases risk of infecting a sexual partner - Sores heal within 2-3 weeks
What are other symptoms of HSV2 reactivation?
- Flu-like symptoms - Fever - Swollen glands
Who more commonly get HSV2 infections?
What do primary VSV infections cause?
What do latent VSV infections cause?
How is VSV transmitted? ***
Describe the steps of multiplication and distribution of VSV
1) Infection begins in respiratory mucosa 2) Spreads to regional lymph nodes 3) Multiplies 4) Progeny virus enter bloodstream 5) Second round of multiplication occurs in liver/spleen 6) Second progeny distributed in body by MONONUCLEAR LEUKOCYTES
What cells infected by VSV cause the trademark symptoms?
- Endothelial cells of capillaries - Skin epithelial cells
When do virus-containing vesicles of chickenpox appear after exposure?
Within 14-21 days after exposure
When is an individual with VSV contagious?
1-2 days before the rash appears
TRUE or FALSE: Contact with the fluid inside vesicles of chickenpox is a common mode of transmission ***
FALSE Contact with the fluid inside vesicles of chickenpox do NOT seem to be a common mode of transmission
Describe the normal course of a VSV primary infection in a normal healthy child
What other symptoms aside from the rash may appear?
1) First appearance is a rash on scalp, face, or trunk 2) Rash involves into a virus-containing vesicle that crusts over in 48 hours 3) Itching most severe during early stages
Other (later) symptoms include - Fever - Headache - Malaise - Abdominal pain 3)
Do VSV primary infections leave a scar?
Where do the VSV lesions appear in primary infections in older adults and immune-compromised aptients?
On mucous membranes
What are the potential complications of VSV primary infections in adults and the immune-compromised?