Comprehensive Study Guide to Virology: Morphology, Replication, Genetics, and Clinical Dynamics

Comprehensive vocabulary flashcards covering basic viral characteristics, structure, taxonomy, bacteriophage cycles, transduction, multiplication mechanisms, growth kinetics, and clinical infection types.

Obligate Intracellular Parasite

An entity, such as a virus, that is incapable of reproducing or multiplying outside of a host cell and relies entirely on host cellular machinery.

Viral Genome

The genetic material of a virus, composed of either DNA or RNA (never both), which can be single-stranded or double-stranded, linear or circular, and arranged in one or several segments.

Capsid

The protein coat or shell that encloses and protects the viral genome, present in all viruses.

Envelope

An outer protective layer surrounding the capsid found in some viruses, composed of lipids, proteins, and carbohydrates, often acquired from a piece of the host cell plasma membrane when exiting.

Antigenic Drift

Mutations or changes to the sequence of a viral genome that alter the composition of its outermost surface, preventing recognition and destruction by the host immune system.

Host Range

The spectrum or range of host cells that a specific virus is capable of attaching to, entering, and infecting.

Spillover

An event where a virus that typically infects non-human animals acquires the ability to infect humans, often as a consequence of antigenic drift or shift.

Bacteriophage (Phage)

A specific type of virus that infects and replicates inside bacterial cells.

Lytic Phage

A bacteriophage that strictly undergoes the lytic cycle, resulting in the assembly of new virions and the destruction (lysis) of the host bacterial cell.

Lysogenic Phage

A bacteriophage capable of both the lysogenic and lytic cycles, integrating its viral genome into the host chromosome to replicate silently alongside the bacterial DNA during binary fission.

Prophage

The latent form of a bacteriophage genome that has been inserted and integrated into the circular bacterial host chromosome.

Generalized Transduction

A random horizontal gene transfer process occurring during the lytic cycle in which degraded fragments of bacterial host DNA are mistakenly packaged into viral capsids and delivered to a recipient bacterium.

Specialized Transduction

A non-random process at the conclusion of the lysogenic cycle where specific host DNA sequences immediately adjacent to an integrated prophage are excised incorrectly and packaged into new virions.

Phage Therapy

The therapeutic administration of lytic bacteriophages to selectively target and destroy bacteria causing an infection, particularly in multi-drug-resistant and pan-resistant cases.

RNA-dependent RNA Polymerase

A viral enzyme encoded in the genome of non-retroviral RNA viruses that uses viral RNA as a template to synthesize complementary viral RNA within the host cytoplasm.

Influenza Virus

An atypical enveloped RNA virus exception that transports its viral RNA into the host cell nucleus for replication before newly assembled virions are released via budding.

Retrovirus

A type of RNA virus, such as HIV, that reverses the central dogma by using reverse transcriptase to synthesize viral DNA from an RNA template before integrating into the host genome.

Reverse Transcriptase

A viral enzyme that catalyzes reverse transcription, creating double-stranded viral DNA from an RNA template ($\text{RNA} \rightarrow \text{DNA}$).

Provirus

The viral DNA state formed when retroviral genetic material integrates stably into a eukaryotic host cell's nuclear chromosome.

Oncogenic Virus

A cancer-causing virus, such as human papillomavirus (HPV), that induces cellular transformations leading to malignancy.

Oncolytic Virus

A virus that preferentially infects, replicates within, and lyses cancer cells, currently investigated for therapeutic oncology treatments.

Eclipse Period

The interval in a viral one-step growth curve following host cell penetration and uncoating during which infectious, intact extracellular virions cannot be detected.

Burst Size

The total number of newly synthesized, mature virions released from a single lysed bacterial host cell.

Latent Viral Infection

A persistent infection pattern characterized by an acute phase followed by viral levels dropping to near-baseline, where the virus remains dormant until periodic reactivations produce recurrent acute flare-ups.