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

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 (20 - 400nm)

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

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

Complex viruses Helical-shaped Enveloped viruses

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.

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

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

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

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

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

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

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

Viral infection

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

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

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.

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

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

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.

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

Production of vaccines

Vaccines controversies