BABS1202 – Vaccines Lecture Review

These flashcards cover definitions, historical milestones, virus biology, SARS-CoV-2 specifics, immune responses, vaccine components and types, and vaccine development stages discussed in the lecture.

What is a vaccine?

A product that stimulates a person’s immune system to produce immunity to a specific disease without causing the disease itself.

What is the primary purpose of vaccination?

To induce an immune response that creates memory cells and antibodies, protecting the host from future infection by the pathogen.

Who introduced variolation to Europe and in what century?

Lady Mary Wortley Montagu brought variolation to Europe in the early 18th century (1720s).

Which scientist used cowpox to protect against smallpox and in what year?

Edward Jenner in 1798.

Why did infection with cowpox protect milkmaids from smallpox?

Cowpox is antigenically similar to smallpox but far less virulent, so exposure generated cross-protective immunity.

How did Peter Medawar describe a virus?

"A piece of bad news wrapped up in protein."

Name the two basic structural components common to all viruses.

A core of genetic material (DNA or RNA) and a protective protein coat called a capsid.

What distinguishes an enveloped virus from a naked virus?

Enveloped viruses have a lipid membrane surrounding the capsid; naked viruses do not.

List four common viral shapes.

Helical, polyhedral (icosahedral), spherical (enveloped), and complex (e.g., bacteriophage).

Approximate size range of SARS-CoV-2 particles.

60–140 nanometres in diameter.

What does it mean when an RNA virus is "positive-sense"?

Its RNA can serve directly as mRNA for protein translation.

Which genome type has NOT been observed in nature?

Double-stranded circular RNA viruses.

How many known human coronaviruses exist, and how many cause severe disease?

Seven are known; three (SARS-CoV, MERS-CoV, SARS-CoV-2) cause severe disease.

Explain the names "SARS-CoV-2" and "COVID-19".

SARS-CoV-2: Severe Acute Respiratory Syndrome Coronavirus 2 (the virus). COVID-19: Coronavirus Disease identified in 2019 (the illness).

What is notable about the SARS-CoV-2 genome?

It is one of the largest RNA genomes (~30 kb) and encodes 29 proteins, including four structural proteins.

Why does SARS-CoV-2 mutate more slowly than many RNA viruses?

It possesses an RNA proofreading exonuclease (NSP14/ExoN) that corrects replication errors.

Why are enveloped viruses like SARS-CoV-2 generally easier to inactivate with disinfectants?

Disrupting their lipid envelope with alcohol or detergents destroys infectivity.

Which host receptor and protease are essential for SARS-CoV-2 entry?

ACE2 receptor and the serine protease TMPRSS2.

Name the body’s three lines of defence against pathogens.

1) Physical/chemical barriers (skin, mucus), 2) Innate immune cells and inflammation, 3) Adaptive immunity (B and T lymphocytes).

What role do dendritic cells play in adaptive immunity?

They ingest pathogens, process antigens, and present them on MHC II to activate helper T cells.

Differentiate humoral from cell-mediated immunity.

Humoral immunity involves B cells producing antibodies against extracellular antigens; cell-mediated immunity involves T cells destroying infected or abnormal host cells.

What do plasma B cells and memory B cells do?

Plasma cells secrete large quantities of antibodies; memory B cells persist to mount faster responses upon re-exposure.

List the main non-antigen ingredients commonly found in vaccines.

Adjuvants, preservatives, stabilisers, surfactants, residual processing substances, and diluent (usually water).

Give an example of a widely used vaccine adjuvant.

Aluminium salts (e.g., aluminium hydroxide).

How do mRNA vaccines work?

They deliver synthetic mRNA encoding a viral antigen (e.g., spike protein) so host cells transiently produce the protein, triggering an immune response.

What is a viral vector vaccine?

A harmless carrier virus delivers genetic instructions for an antigen (e.g., spike protein) into host cells to elicit immunity.

Define a live attenuated (whole-virus) vaccine.

A vaccine using a weakened form of the virus that replicates poorly and does not cause disease but provokes strong immunity.

What is a protein subunit vaccine?

A vaccine containing purified viral proteins (often combined with an adjuvant) to safely induce immunity.

List the sequential stages of vaccine development before market approval.

Preclinical studies, Phase 1, Phase 2, Phase 3 clinical trials, regulatory approval, followed by Phase 4 post-marketing surveillance.

Primary focus of Phase 1 clinical trials?

Safety in a small group of healthy adults and preliminary evidence of an immune response.

Primary focus of Phase 2 clinical trials?

Determining optimal dose, continued safety, and immunogenicity in hundreds of volunteers, including target sub-populations.

Primary focus of Phase 3 clinical trials?

Demonstrating vaccine efficacy in preventing disease and detecting rarer side effects in thousands of participants.

State two reasons vaccine development is typically slow.

Ensuring long-term safety/efficacy and securing adequate funding for large trials and manufacturing.

How did the COVID-19 pandemic accelerate vaccine development?

Massive global funding and collaboration allowed overlapping trial phases and rapid scale-up of manufacturing.

Why are smallpox virus samples still kept in high-security labs?

For ongoing research, potential future vaccine development, and (controversially) biodefence purposes.

Which viral disease is closest to global eradication after smallpox?

Polio.

How can we measure whether a vaccine has generated an immune response in a person?

By detecting and quantifying specific antibodies in the bloodstream (serological titres).

What is the immunological function of an adjuvant?

It enhances the magnitude and durability of the immune response to the vaccine antigen by providing "danger" signals.

What specific role does TMPRSS2 play in SARS-CoV-2 infection?

It cleaves (primes) the spike protein, enabling fusion of viral and host membranes for entry.

Name four key criteria used to classify viruses.

Type of nucleic acid (DNA/RNA), strandedness (single/double), capsid shape/size, presence or absence of an envelope, and replication strategy.