DNA: Herpesviruses Flashcards
Describe the structure of Herpesviridae?
Herpesviridae have an enveloped, icosahedral capsid
Linear double stranded DNA
How do Herpes viruses enter host cells?
Herpes viruses attach to a host cells receptor
Enter the cell through the fusion of its envelope with the host cell membrane
True or False: Herpes viruses can establish a latent infection.
True; Herpes virus can remain inactive inside of infected cells
The viruses may reactivate and cause a recurrence of manifestations of the disease
What are the pathogenic members of the Herpesvirus family?
Simplexvirus
Varicellovirus
Lymphocryptovirus
Cytomegalovirus
Roseolovirus
What is the other way to designate Herpesvirus?
HHV (Human Herpesvirus) followed by a number
The number indicates the order that the virus was discovered in
How does Herpesvirus replicate in the host cell?
After fusion and uncoating in the cytoplasm, the DNA is transcribed in the nucleus
The resulting viral mRNA is translated and the viral DNA is replicated
The resultant viral proteins (That are made in the cytoplasm) move into the nucleus where the viron is assembled
How does the Herepesvirus acquire its envelope and leave the cell?
The viral nucleocapsid buds through the inner nuclear membrane to form an enveloped virus
The now enveloped virus buds though the outter nuclear membrane
The virus then fuses with the plasma membrane and leaves the cell with a portion of the host derived nuclear membrane intact
What is the nomenclature of some of the pathogenic Herpesviruses?
HHV1 = HSV1
HHV2 = HSV2
HHV3 = VZV
HHV4 = EBV
HHV5 = CMV
HHV6 = roseola infantum (major)
HHV7 = roseola infantum (minor)
HHV8 = KS
What are the characteristics of Herpes Simplex infection?
Herpes simplex infection results in slowly spreading skin lesions
These viruses are commonly known as herpes simplex virus (HSV)
Two species of this virus cause disease: HSV-1 and HSV-2
Lesions are usually the source of infection
Asymptomatic carriers can shed HSV-2 genitally!!!
Transmission via close body contact and the virus enters the body through cracks or cuts in the mucous membrane
Skin lesions are the result of inflammation and cell death at the site of infection
Herpes virions can spread from cell to cell through the formation of syncytia
Discuss the epidemiology and pathogenesis of HSV infection.
HSV-1 infection typically occur via cacusal contact in children
HSV-2 infection typically occurs via sexual activity between the ages of 15-29
Herpes infections are often result in the recurrence of lesions
Up to 2/3 of patients experience recurrence due to activation of the latent virus
What are some of the diseases caused by Herpes simplex viurs?
Oral herpes (Mouth)
Keratitis (Eyes)
Whitlow (Fingers / Toes)
Gladiatorum (Face / Neck)
How is Herpes diagnosed, treated, and prevented?
Diagnosis - Characteristic lesions in genital region and on lips
Treatment - HSV infections can be controlled with chemotherapeutic agents
Topical applications of drug limit the duration of the lesions and reduce viral shedding
These drugs DO NOT cure the disease or free nerve cells of latent virus infections
What are the characteristics of Varicella-Zoster virus infections?
Commonly referred to as VZV
Causes Varicella (Chicken pox) - Typically occurs in children
Herpes zoster (Shingles) - Usually occurs in adults
Discuss the epidemiology and pathogenesis of VZV infections?
Chickenpox is highly infectious in children
Virus enters the skin through the resp. tract and the eyes
Virus replicates at site of infection and then travels via blood throughout the body
Chickenpox in adults is more severe than the childhood illness
Latent virus can reactivate producing a rash called shingles
The rash occurs along a dermatome - dorsal roots from the spine
Describe the pathogenesis of Epstein-Barr Virus infection.
Referred to as EBV or HHV-4
Can cause a number of different diseases depending on cellular immunity status
Transmission via salivia
Virus infects the epithelial cells of the pharynx and parotid salivary glands
Virus then enters the bloodstream where it invades B lymphocytes
Virus can become latent in B cells and immortalize them by suppressing apoptosis
Sympotoms arise from immune response - Cytotoxic T cells kill infected B cells
The development of cancer depends on various co-factors working in concert with EBV
