HMM101 Introduction to Medical Biotechnology - Vaccines and Emerging Infections

Target and treat infections after identification.
Examples: RNAi (e.g., siRNA), Interferon, Viral reverse transcriptase inhibitors, Viral integrase inhibitors, Viral helicase inhibitors, Viral protease inhibitors, Splicing inhibitors, Human monoclonal antibodies.
Block viral reproductive cycle by:
- Preventing attachment to host cell.
- Blocking release of viral genes and enzymes.
- Stopping replication of viral components.
- Disrupting assembly of viral components.
- Preventing release of viral particles.

Imitate infection to develop immunity without causing illness.
Stimulate the immune system to produce T cells, B cells, and antibodies.
May cause minor symptoms like fever as the body builds immunity.
Body is left with “memory” T-lymphocytes and B-lymphocytes for future defense.
Takes a few weeks for the body to produce T-cells and B-cells after vaccination.

Live, Attenuated Vaccines:
- Weakened version of the living virus.
- Example: MMR vaccine.
- Pros: Good for the immune system.
- Cons: Not suitable for individuals with weakened immune systems.
Inactivated Vaccines:
- Made by inactivating or killing the virus.
- Example: Inactivated polio vaccine.
- Pros: Stable, some can be taken orally.
- Cons: Multiple doses often needed.
Toxoid Vaccines:
- Prevent diseases caused by bacteria that produce toxins.
- Example: DTaP vaccine (diphtheria and tetanus toxoids).
- Pros: Immune system learns to fight off the natural toxin.
- Cons: Doesn’t protect against non-toxicgenic strains.
Subunit Vaccines:
- Include only parts of the virus or bacteria.
- Example: Pertussis component of the DTaP vaccine.
- Pros: Fewer side effects.
- Cons: Ineffective if the germ evolves to display different antigens.
Conjugate Vaccines:
- Fight bacteria with polysaccharide coatings.
- Example: Haemophilus influenzae type B (Hib) vaccine.
- Pros: Effective for bacteria with polysaccharide coatings.
- Cons: Cannot be used if the antigen is also found in humans.

Reasons for needing more than one dose:
- First dose may not provide enough immunity.
- Immunity wears off over time, requiring booster doses.
- Multiple doses needed for everyone to develop the best immune response.
- Annual flu shots are needed due to antigenic drift and shift.

Infectious diseases whose incidence has increased in the past 35 years.
Caused by:
- Newly identified species or strains.
- Spread to a new population or area.
- Re-emerging infections.
Contributing factors:
- Microbial adaptation.
- Changing human susceptibility.
- Climate and weather.
- Changes in human demographics and trade.
- Economic development.
- Breakdown of public health.
- Poverty and social inequality.
- War and famine.
- Bioterrorism.
- Dam and irrigation system construction.

Reappearance of and increase in infections from a disease formerly not considered a public health problem.
Examples: Dengue fever, Yellow fever, Diphtheria, Rift valley fever.

Infectious diseases transmitted between humans and animals.
30% increase in newly emerging zoonotic diseases in the last 30 years of the 20th century.
Examples: HIV, Ebola, Marburg, Zaire, West Nile, SARS