ANTIVIRAL AGENTS

capsid

protein shell, or coat, that encloses the nucleic acid genome

envelope

a lipid-containing membrane that surrounds some virus particles; it is acquired during viral maturation by a budding process through cellular membrane

nucleocapsid

the protein-nucleic acid complex representing the packaged form of the viral genome

virion

complete virus particle, which serves to transfer the viral nucleic acid from one cells to another

transcription

process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)t

translation

process of translating the sequence of an mRNA molecule to a sequence of amino acids during protein synthesis

reverse transcription

process by which an enzyme makes a copy of DNA from RNA

mutations

errors in the replication process causes amino acid substitutions, which may result in changes to protein structure (leading to possible change in function)

viral load

a measurement of the amount of a virus in an organism, typically in the bloodstream, usually states in virus particles per milliliter

resistance

loss of viral susceptibility to single drugs or groups of drugs due to mutations in the viral genomere

reservoir

a cell type or anatomical site in the association with which a replication-competent form of the virus accumulates and persists with more stable kinetic properties than the main pool of actively replicating virus

genotyping

genetic sequence of viral nucleic acid; allows a prediction of drug susceptibility; a way to determine whether certain viruses are genetically susceptible to certain drugs

phenotyping

interesting, but no need to know details; allows a direct observation of drug susceptibility

virus characteristics

• smallest infectious agent (~20-300 nm in diameter)

• contain only one kind of nucleic acid (RNA or DNA)

• they are parasites at the genetic level

• spectrum is rich in diversity

what makes viruses parasites at the genetic level

• replicate only in living cells

• inert in the environment

what makes viruses rich in diversity

• vary greatly in structure, genome organization and expression, and strategies of replication and transmission

• host range for a given virus may be broad or extremely limited

can viruses act on their own?

no, they hijack cellular machinery

how do viruses hijack cellular machinery 

• viral nucleic acid contains information necessary to cause the infected host cell to synthesize virus-specific macromolecules required for the production of viral progeny

• some viruses use only host machinery, others use a combination 

ways viruses kill host cells

• cell lysis

• alterations to the cell’s surface membrane

• various modes of programmed cell death