Viral Exanthemas + HSV1/2 + VZV Flashcards

Question

Picornavirus • what tissues does it invade? • How long does transmission remain and issue? • Structure?

Answer 1

* *_Picornavirus_** * *General: 4 groups Poliovirus, Coxsackievirus, Echovirus, Enterovirus** _Structure_ **Non-enveloped positive sense ssRNA** _Pathogenic Mechanism_ Initially enteroviruses replicate in **lymph of URT** (tonsils, lymph nodes) and gut (**Peyer’s patches**). Eventually its spreads to **blood (viremia) and infection of spinal cord, brain, meninges, myocardium**, and skin. *Persistence of this infection may be related to its ability to cause asymptomatic infection and its persistence in the stool for several weeks after infection resolves*.

Answer 2

* *_Picornavirus_** * *General: 4 groups Poliovirus, Coxsackievirus, Echovirus, Enterovirus** _Structure_ **Non-enveloped positive sense ssRNA** _Mortality_ Hand, Foot, and Mouth: **Self-limiting disease** that requires only symptomatic management (highly contagious)

Answer 3

* *_Picornavirus_** * *General: 4 groups Poliovirus, Coxsackievirus, Echovirus, Enterovirus** _Structure_ **Non-enveloped positive sense ssRNA** _Mortality_ Hand, Foot, and Mouth: **Self-limiting disease** that requires only symptomatic management (highly contagious)

Answer 4

**_MUMPS (Paramyxovirus)_** _Structure_ Helical, negative sense ssRNA, nonsegmented _Transmission_ Less infectious than measles (aerosol) Virus shed in saliva ~6 days *before onset of clinical disease* (key to it spreading)

Answer 5

**_MUMPS (Paramyxovirus)_** _Structure_ Helical, negative sense ssRNA, nonsegmented _Disease Presentation_ Incubation typically is **18 days** before you start to see the **first clinical sign of swelling in the parotid** (chipmunk). **Aseptic meningitis** may result in the 50% of pts that have viral replication in CNS. This may result in **deafness.** **Gonadal involvement** may occur in post-pubertal men.

Answer 6

**_MUMPS (Paramyxovirus)_** _Structure_ Helical, negative sense ssRNA, nonsegmented _Mortality_ Deafness is an important morbidity, as is Testicular enlargement (3-4x normal size)

Answer 7

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus

Answer 8

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus

Answer 9

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Replication Cycle_ Like all herpes viruses can replicate in ¹epithelial cells then ²lymph node then in they can move into ³neurons and establish latency. Neurotropism for **HSV-1 = Trigeminal** N; **HSV-2 = Sacral and Lumbar**; **VZV = dorsal root**

Answer 10

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus **LYTIC CYCLE** ¹Herpes virus *electrostatically* binds **heparin sulfate** (on host cell surface proteoglycans). *²Lock and key* interactions between the HV and host cell surface proteins leads to fusion of the envelope and host membranes. **³Nucleocapsid is then transported to the nucleus**. ⁴HV uses **Immediate Early transcription factors** to *redirect host RNA polymerase* read the viral DNA and **transcribe RNA for the early proteins** (**DNA polymerase, and Thymidine kinase** etc.). ⁵Early protein RNA is made by ribosomes and imported BACK INTO the host nucleus. The **HERPES DNA pols and thymidine kinase are then used to make more copies of the HV.** ⁶At this point the RNA for **late proteins** starts getting synthesized and **LATE PROTEINS (structural proteins) are produced** and *imported back into the host nucleus*. ⁸**Assembly** of virions can now occur and **exocytosis** happens the usual way (ER à Golgi à Membrane fusion). ⁹As virions fuse with the membrane they **leave behind HV membrane proteins** that are on their outer envelope. **¹⁰Giant cells can now be created by one endothelial cell grabbing onto the next with herpes proteins.**

Answer 11

the entire herpes life cycle occurs in the **nucleus** and the only thing that occurs outside is protein synthesis b/c no ribosomes in nuc.

Answer 12

We assume the same happens in Neuronal virus transmission but in this case the **PROGENY ARE TRANS SYNPATICALLY TRASPORTED IN A RETROGRADE FASHION TOWARD CNS** (but don’t actually get there)

Answer 13

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus **LATENT CYCLE** This occurs soon after the initial infection. The latent cycle consists of 3 phases: *Establishment, Maintenance, and Reactivation.* To maintain latency the virus must: prevent lytic phase, prevent neuronal apoptosis, and evade immune surveillance. HSV does all of this by the **LAT protein** that has **NO PROTEIN PRODUCT,** but **makes micro-RNA** that: ¹**represses viral gene expression, ²prevents apoptosis, ³impairs CD8+ function.** NOTE: VZV does NOT encode LAT protein (we don’t know how it lays latent)

Answer 14

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Transmission_ Saliva and Genital Secretions

Answer 15

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Disease Presentation_ *Primary infections are often not observed*, but when they are they are *more severe* than subsequent secondary infections. Recurrent infections often occur *5-8 times per year* and produce blisters on an erythematous background. For HSV-1 these may be located on **skin**, **eyes**, or **cause encephalitis (via opthic n. involvement)**. For HSV-2 urogenital and meningitis involvement is most common. Stress and Sunburn are often causes of relapse due to **reductions in cell mediated immune surveillance. When these do recur they stay local due to high levels of HV ANTIBODIES.**

Answer 16

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Epidemiology_ 55% of adults have HSV-1 20% of females have HSV-2; 10% of males have HSV-2

Answer 17

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Mortality_ **Neonates and Immunocompromised** patients are at greatest risk of getting **CNS involvement** that can be **fatal.**

Answer 18

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Key findings/Diagnosis_ Dx: Clinical; serology is ONLY USEFUL for Primary Infections; **CONTRETE DX** is need in suspected HV **meningitis** à Use **PCR** (culture rare); **Tzank Smear** à taken from vesicle shows multinucleated giant cells

Answer 19

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus **_Varicella-Zoster Virus_** _Transmission_ AEROSOL

Answer 20

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Disease Presentation_ * *Primary infection** usually occurs in the Late winter/Early Spring and sits latent for about 14 days before you see Chickenpox presentation (Fever + Itchy rash on scalp and trunk). Adult primary infections are more severe and may result in pneumonia. * *Reactivated infections** cause shingles that results in pain and rash (different from primary rash – not the case in HSV) along a thoracic dermatome or forehead (dangerous). 2 to 4 weeks later rash resolves but pain often persists à Postherpetic neuralgia.

Answer 21

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Pathogenic Mechanism_ Conjunctiva or URT get infected (day 0) à Viral replication in regional lymph nodes à Primary Viremia (day 4-6)à viral replication in liver and spleen à secondary viremia à Chickenpox (day 14)

Answer 22

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Epidemiology_ 99% of people have antibodies to it

Answer 23

**_Herpes Simplex 1 and 2 (HSV 1 & 2) + VZV_** _Structure_ Herpesvirus so…Enveloped large linear dsDNA virus _Key findings/Diagnosis_ Dx: **Clinical**; **Tzanck Smear** can be used