Study Guide: Animal Virus Replication and Key Virology Terms

Animal Virus Replication and Key Virology Terms

Overview

This study guide summarizes essential terminology and concepts related to animal virus replication, as well as providing resources for further study. Understanding these terms and processes is fundamental for students of microbiology, especially in the context of viral structure, classification, and replication cycles.

Key Terms in Virology

The following terms are central to the study of animal viruses and their replication:

Term	Definition
Acellular	Not composed of cells; viruses are acellular infectious agents.
Bacteriophage, phage	Viruses that infect bacteria.
Capsid, nucleocapsid	The protein shell (capsid) that encloses the viral genome; nucleocapsid includes the genome and capsid together.
Complex, helical, polyhedral (icosahedral)	Shapes of viral capsids: complex (irregular), helical (rod-shaped), and polyhedral/icosahedral (20-sided).
Cytopathic effect (CPE)	Visible changes in host cells due to viral infection.
DNA virus	Virus with DNA as its genetic material.
Envelope	Lipid membrane surrounding some viruses, derived from host cell membranes.
Genome	The complete set of genetic material in a virus.
Segmented	Viral genome divided into separate pieces.
Herpesviridae	Family of DNA viruses causing diseases like herpes simplex.
Immunogenic	Capable of inducing an immune response.
Latency	Ability of a virus to remain dormant within a host cell.
Lytic	Viral replication cycle resulting in host cell lysis and release of new virions.
Nucleic acid	Genetic material of viruses (DNA or RNA).
Oncogenic, neoplastic	Viruses that can cause cancer (oncogenic) or abnormal tissue growth (neoplastic).
Papillomaviridae	Family of DNA viruses, including human papillomavirus (HPV).
Paramyxoviridae	Family of RNA viruses, e.g., measles virus.
Picornaviridae	Family of small RNA viruses, e.g., poliovirus.
Polio	Disease caused by poliovirus, a member of Picornaviridae.
Polymerase	Enzyme that synthesizes nucleic acids.
Prion, prion disease	Infectious protein particles causing diseases like Creutzfeldt-Jakob disease.
Protein folding, denaturing	Process by which proteins achieve their functional shape; denaturing disrupts this structure.
Retrovirus	RNA viruses that reverse transcribe their genome into DNA (e.g., HIV).
Rhabdoviridae	Family of RNA viruses, e.g., rabies virus.
RNA virus	Virus with RNA as its genetic material.
Virion	Complete, infectious virus particle.
Viral life cycle: entry, attachment, entry, synthesis, assembly, release	Major steps in viral replication.
Virus taxonomy	Classification of viruses based on characteristics such as genome type, structure, and replication method.

Animal Virus Replication: Key Concepts

General Steps in Animal Virus Replication

• Attachment: Virus binds to specific receptors on the host cell surface.

• Entry: Virus or its genetic material enters the host cell, often via endocytosis or membrane fusion.

• Uncoating: Viral capsid is removed, releasing the genome into the host cell.

• Synthesis: Host machinery is used to replicate viral nucleic acids and synthesize viral proteins.

• Assembly: New viral particles are assembled from synthesized components.

• Release: New virions exit the host cell, often by lysis or budding (in enveloped viruses).

Example: The influenza virus (an enveloped RNA virus) enters host cells via endocytosis, replicates its RNA genome, assembles new virions, and exits by budding from the plasma membrane.

Major Virus Families and Their Characteristics

Family	Genome Type	Example Virus	Associated Disease
Herpesviridae	Double-stranded DNA	Herpes simplex virus	Herpes
Papillomaviridae	Double-stranded DNA	Human papillomavirus (HPV)	Warts, cervical cancer
Paramyxoviridae	Single-stranded RNA (−)	Measles virus	Measles
Picornaviridae	Single-stranded RNA (+)	Poliovirus	Polio
Rhabdoviridae	Single-stranded RNA (−)	Rabies virus	Rabies
Retroviridae	Single-stranded RNA (+), reverse transcriptase	HIV	AIDS

Resources for Further Study

• Mastering Microbiology Animations:

  • Viral Replication: Animal Viruses: Link

  • Animation of Animal Virus Replication: Link

  • Concept Map: Link

• Other Resource: Viral Replication YouTube: https://www.youtube.com/watch?v=EqK1CYYQlug

Checklist for Study

• Read chapter 13

• View Mastering Microbiology animation "Viral Replication: Animal Viruses"

• Complete animal virus replication concept map

• Complete Unit 2 quiz

Additional info:

• Understanding the differences between DNA and RNA viruses, as well as enveloped and non-enveloped viruses, is crucial for grasping viral replication strategies and pathogenesis.

• Terms like "oncogenic" and "neoplastic" highlight the role of some viruses in cancer development.

• Prions are unique infectious agents composed only of protein, lacking nucleic acids.