MID Test II Viruses and TB Kit Delgado [email protected]
Herpesviruses and Smallpox General Stuff
Common Features of Herpesviruses Replicative Cycle •Morphology 1. Enveloped viral particle invades clss by utilizing receptors on the cell surface (HSV binds to members of Ig, TNF family and • Basic mode of replication VSV to mannose-6 phosphate and heparan sulfate) • Primary infection followed by latency 2. Glycoproteins (B, D, H, I) on virion – enable attachment of virus to cell (also used by the • Ubiquitous 3. Virus uncoats, DNA goes to nucleus and replicates • Ability to cause recurrent infections (reactivation of latent virus), reinfections • Transcription of viral genome and protein synthesis (cascade of gene expression), essential and luxury (with a new virus), persistent infections – 1. immediate early (IE): regulation of gene expression, DNA binding (chronic low grade virus multiplication) – 2. early (E): more transcription factors, enzymes, DNA polymerase immortalizing infections (EBV only). The other form of infection is latent, and there is little viral – 3. late (L): structural proteins gene expression, so the host cell survives. 4. Nuclecaspids are formed there, which extrude into the perinuclear space with an early envelope 5. Fuses with the RER naked nuclecaspid goes into cytosol 6. Nucleocaspid become enveloped by tegument proteins and glycoprotiens in the trans Golgi Network (TGN) 8 Human Herpesviruses, 3 categories 7. Enveloped virion incorporated into endosomes (HSV resists the acidic environment) released extracellularly • Alpha: short reproductive cycle,variable host range, latent in sensory neurons 8. virus in cell to cell spread). They are components of a new HSV2 vaccine. – Herpes simplex virus (HSV 1, 2) 9. Lytic infection cell death – Varicella- zoster virus (VZV) 10. Latency occurs when the cascade is interrupted 11. Latent infection occurs in sensory neurons • Beta: long reproductive cycle, narrow host range, latent in lymphoid cells & others – Latency associated transcripts (LATS) (salivary glands, kidney) – Minimal transcription of DNA, no translation – Cytomegalovirus (CMV) – HHV6, HHV 7 Because of cell cell spread, CMI is crucial in host response; Ab’s usually inefective (except for VSV infection. . • Gamma: narrow host range; latent in lymphoid cells, associated with tumors Herpesviruses can also spread as a free enveloped particle. – Epstein Barr Virus (EBV) – Kaposi Sarcoma Virus (KSH, HHV8) • Encode targets for antiviral therapy – Thymidine kinase (TK), DNA polymerase
Clinical Presentation Pathogenesis Predisposing Factors/ Likely Definitive Diagnosis Complications Treatment / Prevention Epidemiology Pathogens Genital Ulcers: Transmitted via sexual Virus can be shed by symptomatic Herpes Simplex Clinical: Associated with Acyclovir (ACV), famicylovirm, contact and asymptomatic individuals Virus 2 mostly, ulcerate leaving a primary disease: valacylovir Multiple, bilateral grouped umbilicated Invades local cell causes HSV-1 rarely shaggy ulcer Aseptic meningitis vesicles which become postular and local inflammatory Most common STD in higher (from oral lymph node Transverse coalece into large PAINFUL ulcers response socioeconomic groups genital involvement myelitis (“shaggy”) Spreads to other cells locally transmission) Sacral severe painful vulvovaginits or balantis Moves aliong sensory nervers Microscopic: radiculopathy with or without urthritis (Schawn cells) to ganglia Wright-stained or Can be pain, itching, dysuria with or without Becomes latent, reactivates Tzank stained: transmitted to urethral discharge see newborn tender inguinal lymphadenopathy multinucleated resulting in giant cell in serious organ In 1/3 of patients, symptomatic complaints: Herpes damage headache, fever, malaise, and myalgia (cytopathic involvement)
Serology: Rise in anitbody titers
Rule out syphilis, chancroid, LGV.
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Baby with: Saliva transmission Usually transmitted by saliva HSV-I May lead to poor No antiviral therapy Ulcers in oral mucosa nutrition and (gingivostomatatitis) Examiners should wear gloves, dehydration of a Swollen friable gums highly infectious at this point few days Secondary infection on the thumb from sucking on it (whitlow of the finger) Baby may have fever or be irratable Although infection looks severe, it’s self limited