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31 Cards in this Set
- Front
- Back
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Virus
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ametobolic, obligate, intracellular parasites, no metabolism, some cells involved in viral infection
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Virion
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complete virus particle intact infectious form
virion=virus |
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genome (nucleic acid)
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virus genome-composed of DNA or RNA, but never both, encode virus specific proteins
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Capsid
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protein structure that surrounds and protects genome
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Nucleocapsid
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genome + capsid, property of all viruses, many constitute virion
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Spikes
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glycoproteins that extend out from capsid, promotes attachment to specific cell surface molecules, allows viral entry into cell
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Envelope
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external to nucleocapsid, essentially is lipid bilayer acquired from previous cell (stolen cell MB), is non fnxal MB
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Host range
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spectrum of species or genera that support virus replication
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Narrow host range
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viruses that can infect 1 or few closely related species
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Broad host range
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capable of infecting many different species, beyond class designation (kingdom, etc.)
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Viral specificity
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cell types that a specific virus can infect
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Varicella Zoster Virus (VZV)
chicken pox, shingles |
can infect multiple cell types, respiratory and skin epithelium, neurons - stays in spinal chord
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Viral classification
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based on genome-starts w/ type of nucleic acids, NOT based on type of disease-symptoms produced
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Hepatitis A
Infectious hepatitis, epidemic hepatitis, short-term hepatitis |
Agent: HAV, ssRNA virus-Picornaviridae
Transmisison: Fecal/Oral Severity: usually mild Carrier: No CLD: No, Vaccines: Yes |
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Hepatitis B
Serum Hepatitis |
Agent: HBV, dsDNA virus-Hepadnaviridae
Transmisison: Blood, body fluids Severity: can be severe, most recover Carrier: Yes, associated w/ 80% of liver cancer CLD: Yes, Vaccines: Yes |
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Hepatitis C
non-A,non-B hepatitis |
Agent: HCV, ssRNA virus-flavivirus
Transmisison: Blood & blood products, sometimes crosses placenta Severity: subclinical to severe, most resolve spontaneously Carrier: Yes, possible assoc. w/ liver cancer CLD: Yes, Vaccines: No |
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Adsorption
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virus binds to target (host) cell using spike protein, dictates host range and tissue tropism
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Penetration
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entry of virus into cell, enveloped virus-fusion of envelope and cell MB, non-enveloped virus-attached virion becomes trapped in cell MB (pits)
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Synthesis
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viral-directed synthesis of viral genome & viral proteins
DNA virsus-replicate in nucleus of Eukaryotes, RNA viruses-replicate in cytoplasm |
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Maturation
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assembly of viral genome & proteins into a complete nucleocapsid
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Release
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release of virion from cell
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Lytic release
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virus destroys cell
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Budding
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virus passes through cell MB, acquires envelope, may not directly kill host cell-if rate of budding slow
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Lytic infections
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viral replication leads to cell death, leads to organ/host dysfnx (illness)
classified as acute infections |
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Respiratory syncytial virus (RSV)
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pediatric infections/disease
destruction of pulmonary epithelial cells, leads to respiratory distress |
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Persistent infections (3 types-chronic, latent, transforming)
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continued production of viruses over many months or years - Hepatitis B
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Chronic viral infections
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long term, continuous production of virus by host tissues, long term survival of cell w/ dysfnx
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Latent viral infections
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3 steps-causes primary lytic infection, inserts into host chromosome, viral reactivation (subsequent episode of primary disease)
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Transforming virus
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integrates into host chromosome (NO latency), causes loss of cell cycle control (mitosis), changes gene expression of host cell
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Anti-viral drugs
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must target specific viral activity or structure, like viral replication
acyclovir-blocks HSV replication AZT-blocks reverse transcription of HIV |
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HAART (highly active anti-retroviral therapy)
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2 reverse transcriptase inhibitors (blocks HIV biosynthesis)
protease inhibitors (blocks HIV maturation) |
