Herpesvirus Flashcards
1
Q
General features of herpesviruses (HV)
A
- Enveloped viruses 120-300nm in diameter
- dsDNA genome of 120-220kb, wrapped round a proteinaceous core + forming a toroid
- The DNA is surrounded by an icosahedral nucelocapsid 95-105nm in diameter
- Between the nucelocapsid the envelope is an amorphous layer of protein called the tegument
2
Q
Herpesvirus genomes structures
A
- UL = Unique Long region
- US = Unique Short region
- The UL + US regions have inverted repeats out either end, enabling the genomes to exist in 4 isomeric forms
3
Q
Human Herpesvirus subtypes
A
- HHV-1: Herpes Simplex Virus Type-1 (HSV-1)
- HHV-2: HSV2
- HHV-3: Varicella-Zoster Virus (VZV), most prevalent within the human population
- HHV-4: Epstein-Barr Virus (EBV)
- HHV-5: Cytomegalovirus (CMV)
- HHV-6: Human Herpesvirus 6
- HHV-7: Human Herpesvirus 7
- HHV-8: Kaposi’s sarcoma Herpesvirus (KSHV)
4
Q
Classification
A
- Herpesviridae family
- The HV are divided into 3 groups with each group ale to establish latency in a different cell type
+ Alpha HV
+ Beta HV
+ Gamma HV
5
Q
Alpha HV
A
- Establishes latency in nerve cells, mainly targets the trigeminal nerves + facial ganglia, occurring in 64% of cases, with HHV-6 being the most common
- Includes: HSV-1, HSV-2, VZV
- HSV-2 is associated with genital herpetic lesions + is latent in sacral ganglia sensory cells. It can occasionally cause cold sores
6
Q
Beta HV
A
- Establishes latency in monocytes
- Includes: CMV, HHV-6, HHV-7
7
Q
Gamma HV
A
- Establishes latency in lymphocytes
- Includes: EBV, KSHV
8
Q
Varicella-Zoster Virus (VZV)
A
- The primary disease caused by VZV is chicken pox
- Initially enters via respiratory tract then spreads systemically via bloodstream, infecting epidermidis + causing vesicle formation
- VZV then travels to the dorsal root ganglia where it remains latent
- In latent life the virus can be reactivated + travels down the sensory ganglia to the epithelium to then cause shingles
- Vaccine contains lyophilised gE antigen + AS01B adjuvant suspension
9
Q
Human cytomegalovirus
A
- Causes enlargement of the infected cells (cytomegaly)
- Normally asymptomatic
- The virus has been linked to infectious mononucelosis
- Normally HMCV is only actively producing virus in patients with immune disorders
10
Q
Signs of CMV infection that may be present at birth
A
- Premature birth
- Liver, lung + spleen problems
- Small size at birth
- Small head size
- Seizures
11
Q
HHV-6 + HHV-7 (Orphan viruses)
A
- Causes roseola infantum, baby measles, 3-day fever
- Like HIV, infect + destroys T4 lymhocytes
- Infects nearly all humans out the age of 2
- Primary infection in adults can cause monoculeosis
- In transplant + HIV positive patients the virus has been linked with hepatitis, encephalitis + pneumonitis
12
Q
Epstein-Barr Virus
A
- Causes lymphoadenopathy, infectious mononucleosis can also occur in the elderly
- Affects B-lymphocytes
- Mostly asymptomatic in young people
- Symptoms:
+ Fever
+ Sore throat
+ Muscle soreness
+ Fatigue
+ Lymph node - Associated with several lymphoproliferative diseases
13
Q
Main symptoms of mono
A
- Not highly contagious as it is only transmitted by saliva
- Central: Fatigue, malaise, loss of appetite, headache
- Systemic: Chills, fever, aches
- Viual: Photophobia
- Tonsiles: Reddening, swelling + white patches
- Soreness + redding of throat
- Swollen lymph nodes
- Coughing
- Splenomegaly + abdomnial pain
- Nausea
14
Q
EBV associated lymphoproliferative diseases examples
A
- Burkitt’s lymphoma
- Nasopharyngeal carcinoma
- Potenitally Hodgkin’s disease + Chronic Fatigue Syndrome + MS
- EBV alone cannot cause these conditions and is often in the case that another environmental factor or disease is required ie Burkitt’s lymphoma + malaria
15
Q
Kaposi’s Sarcoma (KS)
A
- Originally identified as a virus that causes rare disease of Mediterranean men
- Can be seen in tranplant patients + was particularly noticeable in gay men who were HIV positiive
- Characterised by highly pigemented lesions on the skin + lesions on the mucous membranes of the mouse, nose + anus, which contain KSHV DNA
- Can infect epithelial cells + lymphocytes
- Thought to be sexually transmitted by semen + vertically
- Has many genes homologous with human genes involved in immune response that may allow evasion
