Virions, Prions - Introduction to Biology - Lecture Slides, Slides of Biology

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Chapter 14:

Virions, Prions, and Viroids

Infectious Agents of

Animals and Plants

Routes of Transmission

Some viruses are acquired via a respiratory route but cause symptoms elsewhere so aren’t considered “respiratory” viruses; example: measles virus

Entry of Enveloped Viruses

Note that viral proteins remain on outside of cell and therefore exposed to host immunity.

Entry of Enveloped Viruses

Note that viral proteins don’t remain on outside of cell.

Fusion occurs with vesicle membrane rather than plasma membrane

Budding of Enveloped Viruses

Not all enveloped viruses bud through the plasma membrane.

Note though that naked animal viruses generally lyse their host cell to effect virion release.

Cytopathic Effects

Cytopathic Effects are changes virus infection makes on host-cell morphologies.

Cells infected with adenovirus.

Cells infected with HSV.

Uninfected cells.

But note that “the diversity of influenza sequences worldwide in any given year appears to be roughly comparable to the diversity of HIV sequences found within a single individual at one time point.” (Bette Korder as cited

How the Flu Changes its “Spots”in Microbe , 2006 1(3):111-

E.g., swapping of coat proteins between avian and human strains of influenza virus.

Particularly important is the protein virus protein, hemagglutinin.