Exam 3-3d (STD Viruses)
Last Modified: 2016-03-08
- Large complex enveloped viruses with dsDNA genome (encodes 50-80 proteins)
- Replication and assembly occurs in cell nucleus, budding thru nuclear and Golgi membranes produces envelope; then “exocytosed”
- prot made in cyto. with ribosomes
- Electron microscopy (EM), similar structure; there are differences in Ag and DNA composition; herpes simplex (HSV) types 1 and 2 share some protein Ag and DNA homology, but people can have infections with both viruses
-% w/ Ab?
- 10 fold (order of magnitude) increase in HSV 2 infections from 1965- 1995
- Many HSV infections are asymptomatic
- Virus is susceptible to drying, heat, detergents, and solvents (because of envelope) - hand sanitizer works well
- Don't survive well on environmental surfaces- need direct inoculation of virus from person to person
- HSV enters thru mucus membranes of mouth, eye, genitals, respiratory tract, anus/rectum;
- unbroken keratinized epidermis (skin) not readily colonized; abraded skin (damaged skin) - herpetic “whitlow”
- Cytomegalovirus (CMV) and Epstein Barr virus (EBV),
- what diseases?
- transmitted by?
- HHV 8 associated with ____________
- Kaposi Sarcoma
- Varicella zoster virus (VZV)
- causes what diseases?
- where does it go?
- HSV 1 dormant in _____________
- HSV 2 in ___________
- HSV 1 dormant in trigeminal ganglion
- HSV 2 in sacral ganglion
- they both can recur by descending from the ganglia to mucus membranes
- Ab does play a role in making recurrences milder
- Sometimes abraded skin can be infected- herpetic whitlows are painful lesions on finger tips from touching HSV lesions
- Inoculation of eye- herpetic keratoconjunctivitis, inflammation and swelling of cornea and conjunctiva; can lead to vision loss
- Virus isolation in cell culture
- Looking for typical cytology (giant cells, or atypical lymphocytes); serology - look at Ab
- Varicella vaccine for chickenpox; Zoster vaccine for shingles
- Acyclovir, gangcyclovir and newer anti-herpetic drugs
- (work on replication of the virus)
- Large group of viruses that infects humans, other primates, mice, cattle, birds, fish, etc.
- DNA virus; no envelope (hand sanitizer useless)
- Cannot culture them in tissue culture
- DNA is cloned and used in hybridization studies to determine what virus is seen
- Encountered by direct contact with lesions from infected individuals
- Ano-genital warts an STD that is increasing in incidence faster than HSV
- Warts of the uterine cervix can be a great problem
- Some of the HPV types that cause cervical warts (HPV 16 and 18)can cause dysplasia (cells look abnormal) or even cervical carcinoma (evidence is that 80% of cervical carcinomas contain HPV DNA)
- Warts of pharynx/ larynx
- oral carcinoma
- Cells are unable to carry out “lytic cycle” to produce more virus
- Then have an “abortive” growth cycle (no new virus made)
- This state persists, and the infected cell transforms into a precursor tumor cell
- HPV DNA is found in the transformed cell genome
- These transformed cells become “immortalized” (don’t die and keep replicating) and ready to develop into tumors
- Need “early” HPV proteins for transformation; one, E7, is an “oncoprotein” a transforming agent
- Binding of E7 to a protein that “normally” suppresses cell division results in loss of suppression, subsequent uncontrolled cell growth, and ultimate tumor formation
Treatment of warts
- Many skin warts regress spontaneously, or can be removed via liquid nitrogen (ablation)
- For cervical warts- colposcopic examination with use of 3% acetic acid to visualize for biopsy followed by liquid nitrogen for ablation
- Laryngeal warts may also be treated with liquid nitrogen for ablation
- atypical cells of uncertain significance (ACUS)
- CIN1 - cervical intraepithelial neoplasia (new growth, not necessarily cancer)
- CIN 3 carcinoma in situ
- Condoms may prevent some transmission, but are not absolute
- Safe monogamous sex
- Pregnant women with cervical warts can deliver by
- Gardasil - highly effective HPV vaccine that has HPV 16, 18, 6, 11
- recommended for young women/girls
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