Microbiology: Viral Biology, Bacteriophage Life Cycles, and Diagnostic Assays

Comprehensive vocabulary flashcards covering the plague, horizontal gene transfer, viral structure and classification, bacteriophage life cycles, HIV pathogenesis, and molecular diagnostic assays (hemagglutination, PCR, and RT-PCR).

Yersinia pestis

The bacterial pathogen responsible for the plague, which can infect the lymphatic system via flea bites or the lungs causing pneumonia.

Bubo

A severely swollen lymph node that serves as a characteristic sign and symptom of bubonic plague, capable of bursting through the skin.

Pneumonic plague

A form of plague infecting the lungs that causes pneumonia and spreads directly from person to person through respiratory droplets.

CCR5 delta 32

A 32-base deletion mutation in the CCR5 gene that produces an abnormally short CCR5 receptor, preventing HIV fusion and infection.

Conjugation

A form of horizontal gene transfer in bacteria where a donor cell uses a pilus to connect to a recipient cell and transfer a replicated plasmid.

F+ donor cell

A bacterial cell containing a plasmid that uses a pilus to transfer a copy of that plasmid to an F- recipient cell during conjugation.

F- recipient cell

A bacterial cell lacking a plasmid that, upon receiving a plasmid copy from an F+ cell during conjugation, becomes an F+ cell.

Acellular

A biological classification referring to entities, such as viral particles, that do not consist of cells and are not considered living.

Virion

A newly formed, complete viral particle produced inside a host cell.

Obligate intracellular parasite

An agent, such as a virus, that must enter and utilize a host cell's resources and machinery to replicate, harming the host cell in the process.

Host range

The collection of specific hosts that a virus is capable of infecting.

Bacteriophage

A virus that infects bacteria exclusively and contains only DNA as its genome.

Capsid

A viral protein shell that surrounds and protects the genetic material (genome).

Sheath

A tube-like protein structure on a bacteriophage used to pierce the bacterial cell wall and plasma membrane to inject the viral DNA.

Tail fibers

Protein structures on a bacteriophage used for attachment to specific receptors on the surface of a bacterial host cell.

Viral envelope

A phospholipid bilayer surrounding certain viruses, acquired from the host cell's plasma membrane when the virus buds off.

Positive single-stranded RNA (+ssRNA)

Viral single-stranded RNA that is functionally equivalent to messenger RNA (mRNA) and can be directly translated into protein by host ribosomes.

Negative single-stranded RNA (-ssRNA)

Viral single-stranded RNA that is complementary to +ssRNA and cannot be directly translated into viral proteins until copied into +ssRNA.

RNA-dependent RNA polymerase (RdRp)

A viral-specific enzyme that synthesizes RNA from an RNA template, converting +ssRNA into -ssRNA and vice versa.

Virulent phage

A bacteriophage that reproduces exclusively via the lytic cycle, immediately causing host bacterial death and cell lysis.

Temperate phage

A bacteriophage that can enter either the lysogenic cycle to integrate into the host DNA or the lytic cycle when host survival is compromised.

Lytic cycle

A viral replication pathway in which a phage commandeers host machinery, produces new virions, and causes the bacterial cell to lyse to release them.

Lysogenic cycle

A phage lifecycle in which viral DNA integrates into the host bacterial chromosome, replicating harmlessly with each round of binary fission until triggered to excise.

Prophage

The viral DNA of a temperate phage that has integrated into the bacterial host chromosome during the lysogenic cycle.

Generalized transduction

A process carried out by virulent phages where fragments of degraded bacterial host DNA are accidentally packaged into a new phage and transferred to a subsequent host.

Specialized transduction

A process mediated by temperate phages where an excising prophage accidentally takes adjacent host bacterial DNA with it, transferring it to another bacterium.

GP120

The specific glycoprotein spike found on the surface of HIV that mediates attachment to host CD4 receptors and co-receptors.

Reverse transcriptase

An enzyme unique to retroviruses like HIV that transcribes viral positive single-stranded RNA into double-stranded DNA.

Integrase

An HIV enzyme that incorporates the synthesized double-stranded viral DNA directly into the host cell's nuclear chromosome.

PrEP (Pre-Exposure Prophylaxis)

Preventative drugs for HIV that function by inhibiting reverse transcriptase, preventing the virus from synthesizing DNA or integrating into host chromosomes.

Opsonization

The process where antibodies coat a pathogen, providing a biochemical handle that facilitates recognition and phagocytosis by macrophages.

Hemagglutination

The visible clumping together of red blood cells caused by viral glycoprotein spikes adhering to erythrocytes in vitro.

Hemagglutination assay

A diagnostic laboratory test where the inhibition of red blood cell clumping by specific antibodies is used to detect and identify a virus.

Taq polymerase

A heat-stable DNA polymerase isolated from Thermus aquaticus that carries out primer extension at $72^\circ\text{C}$ during PCR.

Reverse transcription PCR (RT-PCR)

A highly sensitive diagnostic method where viral RNA is converted into complementary DNA (cDNA) by reverse transcriptase prior to amplification by standard PCR.

cDNA (Complementary DNA)

A strand of DNA synthesized directly from an RNA template using the enzyme reverse transcriptase.