Herpesvirus 6 & 8 Flashcards
What are all herpesvirus?
- DNA viruses
- immediate, early, and late replication
- all enveloped so can be killed by detergents, heat, during, and acids
How is Epstein-Barr Virus (EBV) transmitted?
- through saliva
- mono= known as “kissing disease”
What are the characteristics of EBV?
- by 35-40 years, almost all people in the US are infected
- establishes latency in memory B cells
- shed virus in saliva throughout life after they are infected
- young adults: 50% of infected will get infectious mononucleosis
What are the characteristics of infectious mononucleosis?
- virus initially divides in oropharynx causing sore throat through lytic infection.. then infects its main target: B cells
- primary cause of symptoms: massive expansion of cytotoxic T lymphocytes
- LONG incubation time: 4-6 weeks and virus can shed in saliva before symptoms start
What is the cycle of EBV mononucleosis?
- causes generalized activation of B cells
- leads to heterophiles antibody production
- heterophiles antibodies are non-specific antibodies that react with certain animals, horses, sheep RBC’s
- test via monospot test
- once acute infection is over, some memory B cells have latent EBV genome without production proteins
- when B cells divide, they express a viral protein to make sure viral genome goes into both cells
- EBV can reactivation from memory B cell pool and make new infectious virus
- virus will go back to oropharynx and infect epithelial cells to now produce virus that can be detected in saliva
What are complications of mononucleosis?
- spleen enlargement (avoid sports for 3-4 weeks)
- mild hepatitis (avoid alcohol)
- airway obstruction due to enlarged tonsils
What is oral hairy leukoplakia caused by?
- EBV but increased risk with smoking
What are the characteristics of oral hairy leukoplakia?
- benign, non-painful lesion on lateral border of tongue
- can NOT be scraped off tongue (unlike oral candidiasis)
- can be the first sign of someone with an HIV infection or occur in people taking immunosuppressive drugs
- best tx: antiviral drugs to increase CD4 count
What are the cancers involved with EBV?
- oral hairy leukoplakia
- nasopharyngeal carcinoma
- burkitt lymphoma
What are the characteristics of Burkitt Lymphoma?
- very fast growing, aggressive
- also correlated with malaria infection
- endemic BL: starts as tumor of face and more likely in young children
- caused by chromosomal translation of c-myc gene to a chromosome that has immunoglobulin locus that causes unregulated c-myc expression giving uncontrolled cell growth
- sporadic BL: starts in abdomen and not highly ass
T/F: CMV infections are mostly asymptomatic
True!
- except CMV mono-like syndrome, congenital infections, and immunocompromised
How is CMV transmitted?
- saliva, urine, blood, breast milk, semen, cervical secretions
- spread through sexual contact, infected salvia, urine, and breastfeeding
T/F: CMV infects a wide range of cells. It is not possible to be infected with more than one strain
False.
CMV does infect a wide range of cells but it is very much possible to be infected with more than one strain
When is CMV most severe?
- in people with AIDS: retinitis
- big problem in transplant recipients
Where is latency established in CMV disease?
- myeloid precursors cells in bone marrow
In mononucleosis like syndrome of CMV, what cells do they infect?
- T cells… does NOT infect B cells
- no activation/production of heterophiles antibodies
- so it is antibody negative and mono spot negative
What is the #1 congenital infection in the US?
CMV
- due to primary CMV infection having a high risk of transferring to fetus
- but only 10% of babies are symptomatic
What is the difference between asymptomatic and symptomatic CMV diseased in congenital CMV?
Asymptomatic:
- only 10% risk of hearing loss which is delayed and progressive
Symptomatic:
- can have motor, cognitive deficits, hearing loss, or vision impairment
Why are children a major cause of adult infection of CMV?
- they can secrete CMV in saliva and urine for over a year
- most infections are asymptomatic
Who is HHV6 common in?
children
(very common childhood infection)
What does HH6 cause?
- roseola
- febrile seizures
Which is Kaposi sarcoma-associated herpesvirus associated with?
HH8
Who is HHV8 common in?
Men who have sex with men
What are the symptoms and transmission of HH8?
- usually no symptoms unless co-infected with HIV and/or lower CD4 count
- symptoms: oral lesions and lesions on other parts of body that often violet
- transmitted through sex/saliva/kissing
