BIOL 442- Viruses

Vocabulary flashcards covering fundamental terms, structures, replication strategies, disease associations, laboratory methods, antiviral drugs, and prion concepts from the lecture on viruses.

Virus- size

small, has to be smaller than cell it’s going in

Virus- Obligate parasite

has a living cell

Virus- Host cell specific

if cell does not have correct receptors, then the virus will not bind

Virus- No cellular organelles

no organelles can be targeted, making it harder to defeat

Virus- Capsid

protein coat, protecting nucleic acid

Virus- DNA or RNA

contains either DNA, can be single stranded like human parvovirus, or RNA, can be double stranded like reovirus

Virus- Metabolism

Do not metabolize

Virus- Dormant

they are dormant as they require a host cells to activate and replicate

Capsid

Protein coat surrounding a viral nucleic acid; protects the genome and determines the virus’s overall shape.

Capsid- Polyhedral

round-like; adenovirus

Capsid- Helical

rod-shaped, spiral tube around the nucleic acid; tobacco virus

Capsid- Complex

irregular shape, often possessing additional structures such as tails or fibers; bacteriophage, tadpole like

Naked (non-enveloped) virus

Virus composed only of nucleic acid and capsid; lacks a plasma envelope.

Enveloped Virus

Virus composed of nucleic acid and capsid, with a surrounding envelope

Envelope

plasma membrane derived from the host cell that surrounds the capsid of some viruses.

Spike

Viral glycoprotein projection on the envelope or capsid that mediates attachment to host receptors.

Nucleocapsid

Combined structure of the viral nucleic acid and its surrounding capsid.

Human papilloma virus (HPV)

DNA; genital warts and cervical cancer

Small pox

DNA; small pox

Hepatitis B

DNA; hepatitis B

Herpes simplex 1 &2 (HSV)

DNA; cold sores, chicken pox and genital herpes

Hepatitis A

RNA; hepatitis A

HIV (retrovirus)

RNA; HIV/AIDS

Reovirus

RNA; respiratory infections

Coronavirus

RNA; colds and SARs

Hepatitis C

RNA; hepatitis C

Retrovirus

RNA virus that uses reverse transcriptase to synthesize DNA from its RNA genome (HIV); RNA -> DNA -> RNA -> Proteins

Reverse transcriptase

Enzyme that converts viral RNA into complementary DNA in retroviruses.

Function of Viral NA: Entering cell

strategy for entering a cell as human cells don’t have a cell wall but bacteria cells do have a cell wall

Function of Viral NA: Synethesis

Synthesis of viral nucleic acids and protein

Function of Viral NA: Exiting cell

strategy for exiting the cells as human cells dont have cell wall and bacteria cell do

Virus state of Existence- Extracellular

it’s dormant as far as viral replication is concerned, lays dormant outside

Virus state of Existence- Intracellular

viral replication occurs during this times, active inside

Viral Replication- phases

Lytic and lysogeny; one or the other not both at the same time, determine based on nucleic acid of cells

Viral Replication- Steps

attachment, penetration, biosynthesis, maturation/assembly, and release

Bacteriophage

Virus that infects bacteria; often possesses head, tail, sheath, and tail fibers.

Lytic cycle for phages

attachment of phage, entry of phage DNA and degradation of host DNA, synthesis of viral genome and proteins, assembly of phage, and release

Lysogenic cycle

adsorption of phage into target cells, injection of phage DNA, phage DNA integrate to cells DNA- prophage, replicates with host, dormant until swictehd to lytic growth

Transduction

Phage-mediated transfer of bacterial DNA from one cell to another; regulated by lysogenic bacteriophages

Generalized transduction

Random bacterial genes are transferred between bacteria by a phage; streptococcus pneumoniae

Specialized transduction

specific genes are transferred between bacteria by a phage; Corynebacterium diphtheriae

Lytic Cycle for human viruses

virion attaches to host cell, virion penetrate cell and its DNA is uncoated, early transcription and translation and enzymes are synthesizes; late transcription and DNA is replicated; late translation and capsid proteins are synthesized; virions mature, virions are released

Persistent infection

Long-term infection in which virions are produced continuously or intermittently; genital herpes

Chronic Infection

virus is actively presented and replicating; hepatitis C and HIV

Latent infection

Dormant state of a virus within a host cell; HIV

Bacteriophage Viral replication- Attachment

tail fibers

Bacteriophage Viral replication- Entry

viral DNA only is injected into the cell

Bacteriophage Viral replication- Biosynthesis

in cytoplasm

Bacteriophage Viral replication- Release

host is lysed in lytic phase but may not be in the lysogenic phase

Human Viral replication- Attachment

Spike

Human Viral replication- Uncoating

intracellular

Human Viral replication- Biosynthesis

in the nucleus (DNA viruses) or cytoplasm (RNA viruses)

Human Viral replication- Release

enveloped viruses bud out; non-enveloped or naked viruses lyse the wall

Latent human viruses link to cancer

about 15% of all human cancer are linked to viruses; Epstein-Barr- T/B cell lymphoma; HPV- Cervical cancer; Hepatitis C- Liver cancer

Proto-oncogene

Normal cellular gene that can become an oncogene after mutation or viral insertion (‘first hit’).

Tumor suppressor gene

Gene that restrains cell division; viral damage or mutation constitutes the ‘second hit’ toward cancer.

Plaque assay

Laboratory method to quantify viruses by counting clear zones (plaques) formed on cell monolayers.

Tissue culture

Growth of cells in vitro used for virus isolation and study.

Embryonated egg

Fertilized egg used as a host system for cultivating certain viruses (e.g., influenza vaccine production).

Attachment: Maraviroc

Antiviral drug that blocks the receptor for the HIV virus and Enfurvirtide which block the penetration of HIV

Intracellular uncoating: Amantadine

Antiviral that interferes with uncoating of influenza A viruses inside host cells.

Inhibition of NA synthesis: Acyclovir

zoravirax, valtres; mimics guanosine nucloetides

Inhibition of NA synthesis: AZT

retrovir, zidovudine; inhibits reverse transcriptase enzymes

Inhibition of assembly/maturation: Protease inhibitors

lopinavir, amprenavir, atazanavir

Prion

proteinaceous infectious particles; discovered by Dr. Stanley Prusiner; cause dimentai in hmans and aminals, link to alzheimers

Prion- in sheep

scrapie

Prion- in cows

mad cow disease

Prion- in humans

kuru, creutzfeldt-jakob diesease (CJD)