1. Medical Biotechnology, BIOL456 Fall 2016
Lecture 8 Vaccines
Medical Biotechnology, BIOL456
Fall 2016
Sulaiman Al-Hashmi

2. Introduction
A virus is basically a small organism that cannot be seen by the naked eye
Study of virus science is called virology
The elements of virus, known as virions
Mainly contain about two or three parts
Include the genetic material present in the form of DNA or RNA
Average size of virus is about one 100th the size of an average bacterium ( nm)

4. Type of viruses (shape)
Helical-shaped
Composed of a single type of capsomer to form a helical structure
Can have a hollow tube
This arrangement results in rod-shaped
Generally composed of a single-stranded RNA
Icosahedral-shaped viruses (ذوات الوجوه)
Most of the animal viruses are icosahedral in shape
Generally has 12 identical capsomeres

5. Enveloped viruses Complex viruses
Create an envelope from the outside by modifying cell membranes.
Cell membranes studded with proteins coded by the viral genome and host genome
Influenza virus
Human immunodeficiency virus (HIV)
Complex viruses
It is a capsid that is neither completely helical nor completely icosahedral
Can possess extra structures such as protein tails
Bacteriophages
Capsid قفيصة

6. Complex viruses
Helical-shaped
Enveloped viruses

7. Internal organization of viruses
Internal organization of viruses is simple and accessible for any kind of manipulation
Anatomically
Viruses can have either DNA or RNA
Called a DNA virus or an RNA virus
Vast majority of viruses have RNA genomes.
Plant viruses tend to have single-stranded RNA genomes
Bacteriophages tend to have double-stranded DNA genomes
Polyomaviruses, the viral genome is circular, whereas in the case of adenoviruses, the viral genome is linear in shape.

8. Human diseases caused by viruses
The most common type of diseases caused by viruses in humans is the common cold, influenza, chickenpox,…
Other series viral diseases:
Avian influenza, severe acute respiratory syndrome (SARS), Ebola, acquired immunodeficiency syndrome (AIDS)
Disease cause infection by different mechanisms largely depends on viral types

9. Diagnosis of viral infection
Cell culture of patient sample
Viral culture allows detection of multiple viruses
Capable of providing a viable isolate that can be used for further characterization
Serology
Detection of virus-specific antibodies in the blood.
Detection of virus antigens
Include fluorescent antibody staining
Useful for viruses that grow slowly or are labile, making recovery in culture difficult

10. Detection of virus nucleic acids
Detection of specific viral nucleic acids
Any virus can potentially be detected in this way
Gene sequencing to characterize viral strains
Observation of virus particles by electron microscope

11. Prevention of viral infections
Viruses use vital metabolic pathways within host cells to replicate
Immune defense system is composed of cells and other mechanisms that defend the host from infection
Innate immune system
Refers to nonspecific defense mechanisms that work immediately or within hours of an antigen's appearance in the body
It does not provide protective immunity to the host
Provide a first line of defense against many common microorganisms
Essential for the control of common bacterial infections

12. Adaptive (acquired) immune system
Carried out by white blood (lymphocytes)
There are two broad classes of such responses
Antibody responses
B-Cells
Cell-mediated immune responses
T-Cells
Is not present at birth. It is learned as a person's immune system encounters foreign substances (antigens)
Takes time to develop after first exposure to a new antigen. Afterward, the antigen is remembered, and subsequent responses to that antigen are quicker and more effective than those that occurred after the first exposure

13. Upon viral infection, adaptive immune system produces specific antibodies that bind to the virus and make viruses noninfectious
IgM
highly effective at neutralizing the virus’s effects, but only produced by the cells for a few weeks
IgG
Produced indefinitely in the body
Interferon
A hormone produced by the body when viruses are attacked or invade the host body
Stops the viruses from reproducing/replicating by killing the infected cell

14. Vaccination is the most effective medical approaches to viral diseases
Some virus are capable to escape from the immune system
HIV
Evades the immune system by constantly changing the structure of the amino acid sequence of the proteins.
Viruses use vital metabolic pathways within host cells to replicate
It is difficult to get rid of the from the human body
Generally most antiviral drugs are known to cause toxic effects to host cells
Vaccination is the most effective medical approaches to viral diseases

15. Viral infection

16. Antiviral drugs
Most antiviral drugs do not destroy their target pathogen
Instead they inhibit their development activity and growth
Drugs that bind to the virus-associated protein
Block the entry of the viruses into the host cells
A number of entries-blocking drugs are being developed to fight HIV

17. Drugs that interfere with viral synthesis
Blocking RNA or DNA replication
Deactivate the enzymes that synthesize the RNA or DNA of the virus
Target integrase, which splices the synthesized DNA into the host cell genome
Block the attachment of transcription factors to viral DNA
Anti- sense-antiviral drugs
Protease inhibitors drugs
Cut viral protein chains apart so they can be assembled into their final configuration

18. Type of Vaccines
Vaccines produced to improves human immunity to a particular disease
An agent that resembles a disease-causing microorganism
Often made from weakened or killed forms of the microorganism or its toxins.
Upon injection of these vaccines, the vaccine molecules stimulate the body’s immune system to recognize the agent as foreign, destroy it, and memorize it
The immune system get familiarize with it and destroy any of these microorganisms that it later encounters.

19. Type of Vaccines Live attenuated vaccines
Weakened vaccines, created from the naturally occurring microorganisms
Can still infect people, but they rarely cause severe disease
Viruses are weakened by growing them over and over again in cell culture conditions
Examples:
Measles (الحصبة) vaccine (as found in the MMR vaccine), rubella (German measles, الحصبة الالمانية) vaccine (MMR vaccine), oral polio (شلل الأطفال ) vaccine (OPV), and varicella (chickenpox) vaccine

20. Type of Vaccines Inactivated vaccines Toxoid vaccines
Cannot cause an infection, but they still can stimulate a protective immune response
Viruses can be inactivated with chemicals such as formaldehyde
Examples:
Inactivated polio vaccine
Shot form of the polio vaccine
inactivated influenza vaccine
Toxoid vaccines
Made by treating them with toxins (formalin) produced by microorganisms, to destroy their ability to cause illness

21. Type of Vaccines Component vaccines
Made by using only parts of the viruses
Cannot cause disease
Can stimulate the body to create an immune response that protects against viral infection with the whole germ
Examples:
hemophilic influenza type b (Hib) vaccine, hepatitis B (Hep B) vaccine, hepatitis A (Hep A) vaccine, and pneumococcal conjugate vaccine.

22. Type of Vaccines
Introducing a protein subunit rather than introducing an inactivated or attenuated microorganism
Subunit vaccine against hepatitis B virus that is composed of only the surface proteins of the virus
Previously extracted from the blood serum of chronically infected patients
Now produced by recombination of the viral genes into yeast

23. Production of vaccines

25. Vaccines controversies