Virology/Mycology/Parasitology

What are the 3 basic properties that virus classification is based on?

viral morphological characteristics, method of replication, and presence or absence of an envelope

Can a virus be both DNA and RNA simultaneously?

No

What are virions?

virus particles

What is the function of the capsid?

protects the viral genome and is responsible for the tropism to specific cell types in naked viruses

What is the function of the matrix protein?

It has enzymatic activities or biological functions related to infection

What is the function of the envelope?

Responsible for viral entry into the host cell

What is a nucleocapsid?

the nucleic acid genome surrounded by a symmetric protein coat

What is the function of glycoprotein spikes?

Assist with stabilization of attachment for the lipid envelope and for attachment to the host cell to facilitate viral entry

How is a naked capsid released?

Cell lysis

Can a naked capsid survive in the gut?

Yes

Can an envelope survive in the gut?

No

How is an envelope released?

Budding or cell lysis

How is a naked capsid transmitted?

Fomites

How is an envelope transmitted?

Close contact, droplets

What are the 2 most common capsid structures?

Icosahedral and helical

What are the 4 PHASES of viral replication?

Early phase, late phase, eclipse period, and latent period

What happens during the early phase of viral replication?

The virus recognizes a target cell, attaches, penetrates, uncoats its genome, and releases it to the nucleus

What happens during the late phase of viral replication?

The genome replicates, viral macromolecular synthesis, and initiating the eclipse period

What happens during the eclipse period of viral replication?

The virus lives undetected in the cell and ends with the appearance of new virions after virus assembly

What happens during the latent period of viral replication?

Extracellular infectious virus is not detected and ends with the release of new viruses

What are the 9 STEPS of the replication cycle?

Recognition of target cell, attachment, virus entry, uncoating, transcription, protein synthesis, replication of genome, assembly of the virus, budding of enveloped virus and release

What is viral tropism?

Each virus has a limited number of hosts it can infect

What does it mean when a virus group is polythetic?

members of the group share common characteristics but may not have a single defining characteristic

What is a pandemic?

the emergence of a new viral disease worldwide with prolonged human to human transmission

What does being a obligate intracellular parasite mean?

It is incapable of replication without a living host

What do virions consist of?

Nucleic acid, capsid, and/ or a lipid-containing envelope

What is genetic shift?

reassortment of genes

What is an antigenic shift?

MAJOR changes that result in novel virus antigens

What is an antigenic drift?

MINOR changes that occur continuously overtime as the virus replicates

What is the capsid made up of?

Capsomeres

What are characteristics of an icosahedral capsid structure?

cubical with 20 flat sides

What shape is the helical capsid structure?

Spiral

What is the nucleic acid genome?

Functions to encode the proteins required for viral penetration, transmission, and replication

What are the 6 steps of the infectious cycle?

Attachment, penetration, uncoating, macromolecular synthesis, viral assembly, and release

What does a susceptible cell have?

Viral receptors

What does a permissive cell do?

Supports viral replication and production of progeny virus

What are the 3 mechanisms of penetration?

Fusion of the viral membrane with the host cell membrane, phagocytosis by host cells, and injection of the viral nucleic acids into the host cell

How does an enveloped virus penetrate a host cell?

By fusing with the host cell membrane

How does a naked cell penetrate a host cell?

By endocytosis (phagocytosis)

What cen fusion lead to?

Syncytia

What is syncytia?

fusion between the infected host cell and additional nearby host cells, forming multinucleated cells

Are viruses motile?

No

Does attachment require energy?

No

What is the protein shell that surrounds the viral genome?

What is the lipid membrane that surrounds the nucleocapsid of some virus particles?

What method is used to view viruses?

Electron microscopy

What are the size ranges for viruses?

What type of immunity is needed for lysis of the cells infected with a non-cytolytic virus and envelope viruses?

What step of the replication cycle is endocytosis necessary for?

Attachment

What are the different typed of change in a viral genome?

Recombination, reassortment, mutations, and transcapsidation

What are some characteristics of the antigen-nonspecific host defense?

What stage in viral replication does the genome uncoated and is delivered to the nucleus?

early phase

What step in replication causes the genome to fold and be packaged?

What surrounds a virion that makes it an enveloped virus?

Most viruses that use a spherical shaped capsid arrange their capsid proteins with which symmetries?

What part of the replication cycle relies on the host receptor or co-receptor in determining if the virus can attach and infect the cell?

Attachment

The word “phage” is a shortened version of the name of a virus that can affect what type of organism?

What are some prime exposure sites for viruses?