Viral DEI
This universal virion component consists of a protein shell that encloses and protects the viral nucleic acid genome from physical and enzymatic degradation.
capsid
This specific term describes the host cell types, tissues, or species a virus can infect, dictated entirely by lock-and-key surface interactions.
viral tropism
Group 5 viruses possess a single-stranded RNA genome of this orientation, meaning host ribosomes cannot translate it directly upon entry.
negative-sense single-stranded RNA
Group 4 +ssRNA viruses can begin this biochemical process immediately upon entering the host cytoplasm.
translation
Group 6 retrovirus replication uniquely requires passing through this nucleic acid intermediate.
double-stranded DNA (dsDNA)
Unlike cellular organisms that exclusively use dsDNA, viral genomes can exist in these four structural combinations of strandedness and nucleic acid type.
dsDNA, ssDNA, dsRNA, and ssRNA
According to the Baltimore classification system, all viral genomes—regardless of starting material—must ultimately synthesize this specific molecule to express proteins.
positive-sense messenger RNA
Influenza A virus attaches to host upper respiratory cells by binding its surface glycoprotein Hemagglutinin (HA) to this terminal sugar residue on host glycoproteins.
sialic acid
Poliovirus synthesizes its entire coding region as a single massive protein before cutting it into individual functional units using this strategy.
polyprotein processing
In addition to RNA-dependent DNA polymerase and DNA-dependent DNA polymerase activities, reverse transcriptase possesses this specific enzymatic activity to clear the RNA template.
Ribonuclease H (RNase H)
These three distinct physical/functional states represent the complete existence of a virus throughout its life cycle inside and outside host cells.
virion (extracellular particle), intracellular replication complex, and integrated/persistent form (provirus/prophage)
Group 1 dsDNA viruses (like HSV-1) can rely entirely on host machinery for transcription because host cell nuclei naturally possess this enzyme.
DNA-dependent RNA polymerase
This minor, gradual evolutionary process results from point mutations introduced by the error-prone viral RdRp, causing seasonal flu epidemics.
antigenic drift
Poliovirus initiates infection by attaching to this immunoglobulin-like cell surface adhesion molecule, also known as CD155.
Poliovirus Receptor (PVR)
This viral enzyme catalyzes the covalent insertion of reverse-transcribed viral dsDNA into host cell chromosomes to establish a permanent provirus.
integrase
This flexible capsid architecture spirally wraps individual capsomers around nucleic acid strands, allowing its length to scale directly with genome size.
helical capsid
In HSV-1 replication, this specific temporal wave of viral proteins acts as transcription factors to switch on early and late viral gene expression.
Immediate-Early proteins
During -ssRNA viral replication, this full-length positive-sense RNA molecule serves strictly as the template for synthesizing new negative-sense genomic strands.
antigenome
This complex secondary RNA structure in the 5' UTR allows Poliovirus to initiate protein synthesis without a 5' m7G cap or intact host eIF4F factors.
Internal Ribosome Entry Site (IRES)
Reverse transcriptase is an exceptionally effective drug target primarily because human host cells completely lack an enzyme performing this reverse flow of genetic information.
RNA-dependent DNA synthesis
Although segmented genomes present a complex packaging challenge during assembly, they offer this major evolutionary advantage during co-infection.
genetic reassortment (or antigenic shift)
Eukaryotic host cells completely lack an enzyme capable of copying RNA from an RNA template, forcing all RNA viruses to encode this essential enzyme.
RNA-dependent RNA polymerase (RdRp)
This antiviral drug class prevents influenza spread by blocking the enzyme that cleaves host sialic acid tethers during viral budding.
Neuraminidase (NA) inhibitors
If a researcher introduces a mutation that completely inactivates the viral RdRp in a Group 4 virus, this stage of the viral lifecycle will still temporarily occur.
initial translation of the viral genome
Combined antiretroviral therapy (ART) uses multiple drug classes simultaneously to overcome this major evolutionary property of reverse transcriptase.
high mutation rate (or lack of 3'-to-5' proofreading exonuclease activity)