med micro chapter 18

How did Jenner’s vaccine for smallpox differ from variolation?

Variolation used material from smallpox sores and sometimes caused severe disease; Jenner’s vaccine used cowpox to give immunity safely.

What is herd immunity and how does it prevent epidemics?

When most people in a population are immune (from vaccination or infection), disease spread declines because there are few susceptible hosts.

What are the 4 hurdles to creating an effective vaccine?

Identifying effective antigens, understanding the microbe’s lifecycle, finding good animal models, and securing research funding/coordination.

Why are vaccines the only feasible way to control viral diseases?

Few antiviral drugs exist, so prevention by vaccination stops infection before it occurs and limits spread.

What is attenuation?

Deliberately weakening a live pathogen to reduce virulence for use in vaccines.

Why do attenuated vaccines often provide lifelong immunity?

The weakened pathogen replicates in the body, giving repeated exposure that boosts cellular and humoral immunity.

What is the risk associated with attenuated vaccines?

The pathogen can mutate back to a more dangerous form, and immunocompromised people may still become infected.

Give an example of an attenuated vaccine.

Ty21a typhoid vaccine.

What is an inactivated (killed) vaccine? Give an example

Uses microbes killed by chemicals so they cannot replicate but still trigger immune response. Examples: Rabies, influenza, Salk polio.

What is a subunit vaccine?

Uses only specific antigen fragments of a microorganism to generate immune response; contains no live or killed pathogen.

What is a recombinant vaccine? What is a well-known example?

Genetically modified microbes produce a pathogen fragment. Example: Hepatitis B vaccine.

What is a toxoid vaccine? Give an example.

Uses inactivated toxins to induce antibodies against the toxin. Examples: Tetanus, diphtheria, acellular pertussis.

Which vaccine type uses an empty viral capsid without nucleic acid?

Virus-like particle (VLP) vaccines (e.g., HPV vaccine).

How are polysaccharide and conjugated vaccines similar and different?

Both use capsule molecules. Polysaccharide vaccines use only capsule sugars and are weak in young children; conjugated vaccines link polysaccharides to proteins to make a stronger immune response.

What is the advantage of conjugated vaccines?

They produce a strong immune response effective in young children; enabled the Hib vaccine.

What is a DNA vaccine and how is it delivered?

Naked/encapsulated DNA encodes antigens; cells express the proteins, stimulating immunity. Delivered by needle or gene gun.

Which vaccine type uses an avirulent virus as a carrier to deliver a viral antigen?

Recombinant vector vaccines.

Which type of vaccine does NOT require a booster?

Attenuated vaccines.

List two advantages of the NanoPatch vaccine delivery method.

Targets skin rich in antigen-presenting cells; uses dry vaccine that does not require refrigeration.

What is an adjuvant and what does it do?

A chemical additive that boosts vaccine effectiveness by activating innate immune pathways.

Why do we need the influenza vaccine every year?

The virus frequently changes antigens, so the vaccine must be updated annually to match circulating strains.

Is there a link between the MMR vaccine and autism?

No. The 1998 study claiming a link was fraudulent; MMR is safe and supported by extensive research.