BMS Viruses

RNA vs. DNA Viruses

• RNA viruses generally exhibit higher mutation rates than DNA viruses.

Viral Diseases

• The provided text mentions several viruses and their associated diseases, but the specific pairings were to be completed in a workbook. Examples of virus families include: Picornaviridae, Astroviridae, Caliciviridae, Togaviridae, Retroviridae, Orthomyxoviridae, Paramyxoviridae, Papillomaviridae, Adenoviridae, and Coronaviridae.

Key Virus Features (HIV, Hepatitis B, Varicella Zoster, Herpes, Influenza)

• Details on the symmetry and nucleic acid classification of these viruses were to be completed in a workbook.

Dentally Relevant Viruses

• Information on this topic requires completion of a workbook activity.

Viral Tropism

• Viral tropism describes a virus's ability to infect specific cells, tissues, or host species. Selectivity is achieved through interactions with host cell receptors.

Viral Replication Stages

• Adsorption: Attachment of the virus to host cell receptors.
• Penetration: Viral entry into the host cell (endocytosis, fusion, or translocation).
• Uncoating/Eclipse: Removal of the viral capsid, releasing the viral genome; a period where the virus isn't detectable.
• Transcription: Production of viral mRNA using host cell machinery.
• Synthesis of Viral Components: Production of viral proteins and nucleic acids.
• Assembly: Formation of new virions.
• Release: Release of new virions from the host cell (lytic or lysogenic).

Virus Structure

• Viruses consist of a genome (DNA or RNA, but never both), a protein capsid, and sometimes an envelope. They may also contain enzymes. Sizes range from 10-100nm. Viruses are obligate intracellular parasites, requiring a host cell for replication.

Virus Classification

• Viruses are classified based on their symmetry (icosahedral, filamentous, head-tail) and their nucleic acid type (dsDNA, ssDNA, dsRNA, ssRNA).

Viral Persistence and Latency

• Viral Persistence: The virus remains in the host without being cleared, potentially exhibiting periods of both active and inactive infection. Examples include HIV, Epstein-Barr virus, human cytomegalovirus, human herpesviruses 6 & 7, varicella-zoster virus, human papovaviruses, and hepatitis B virus.
• Viral Latency: The virus remains dormant within a cell. This is a type of persistent infection.

Prions

• The text mentions prions, but additional information regarding their structural features and relevance was not provided in this section.