Infection and Response Study Guide

Infection and Response: Exotic Pathogens and Disease

  • Types of Pathogens

    • Viruses

    • Bacteria

    • Protists

    • Fungi

  • Definition of Pathogen

    • A pathogen is defined as

    • A microorganism that causes infectious disease.

  • Disease Transmission Methods

    • Direct contact

    • Airborne transmission

    • Waterborne transmission

  • Mechanism of Disease Symptoms from Bacteria

    • Bacteria proliferate rapidly within the body and secrete toxins that damage bodily tissues.

  • Mechanism of Disease Symptoms from Viruses

    • Viruses reproduce swiftly inside host cells, leading to cellular damage.

  • Types of Pathogens for Specific Diseases

    • Measles: Virus

    • HIV (Human Immunodeficiency Virus): Virus

    • Salmonella: Bacteria

    • Gonorrhoea: Bacteria

    • Rose Black Spot: Fungus

    • Malaria: Protist

  • Symptoms and Transmission of Measles

    • Symptoms include fever and red skin rash.

    • Transmission occurs through inhalation of droplets expelled from sneezes and coughs.

  • Pathogen Attack on the Immune System

    • The pathogen HIV specifically attacks the immune system, which can lead to Acquired Immunodeficiency Syndrome (AIDS).

  • Treatment for HIV

    • Antiretroviral drugs can be utilized to treat HIV infections.

  • Transmission of HIV

    • Transmission occurs through:

    • Sexual contact or exchange of bodily fluids (e.g., shared needles among drug users).

  • Plant Pathogen: Tobacco Mosaic Virus

    • Causes a mosaic pattern of discoloration on leaves, affecting photosynthesis and plant growth.

  • Prevention of Salmonella in Chickens

    • Chickens are vaccinated against Salmonella to prevent food poisoning in humans.

  • Symptoms of Salmonella Food Poisoning

    • Symptoms include fever, abdominal cramps, diarrhea, and vomiting.

    • Caused by toxins secreted by Salmonella bacteria.

  • Gonorrhoea

    • A sexually transmitted disease characterized by a thick yellow or green discharge from the penis or vagina and pain during urination.

    • Previously treated easily with penicillin antibiotics, but now many strains are resistant.

    • Prevention methods include the use of barrier methods of contraception, such as condoms.

Non-Specific Body Defenses and Immune Response

  • Physical Barrier to Infection

    • The skin serves as a primary physical barrier against pathogen entry.

  • Non-Specific Defenses Against Disease

    • Skin

    • Ciliated cells / mucus

    • Hydrochloric acid in the stomach

    • Blood clotting at wounds

  • Ciliated Cells

    • These are the cells that move mucus out of the airways, preventing infections in the lungs and respiratory system.

  • Hydrochloric Acid

    • A chemical in the stomach that kills bacteria entering via food.

  • Immune System

    • The immune system is responsible for combating infections by pathogens.

  • Defensive Mechanisms of White Blood Cells

    • Antibody production

    • Antitoxin production

    • Phagocytosis: the process where white blood cells engulf and destroy pathogens.

  • Vaccination

    • Vaccines are made from dead or inactive forms of a pathogen.

    • In response to a vaccination, white blood cells produce antibodies.

    • Vaccination stimulates the body to produce antibodies for quicker response upon re-exposure to the same pathogen.

    • For diseases such as measles, a specific antibody is produced, which would not work for other diseases such as chickenpox.

  • Herd Immunity

    • It is crucial to immunize a significant portion of the population to reduce pathogen spread through herd immunity, where fewer individuals are available for the pathogen to infect.

  • Efficacy of Antibiotics

    • Antibiotics are effective against bacteria but do not target viruses.

    • Penicillin is categorized as an antibiotic.

    • Concern arises over antibiotic over-prescription due to the emergence of antibiotic-resistant strains of bacteria.

  • Viral Disease Symptom Management

    • Painkillers may be prescribed to alleviate symptoms of viral diseases; these medications do not cure the viral infection.

Drug Development and Testing

  • Challenges in Developing Antiviral Drugs

    • The difficulty in developing drugs to kill viruses stems from the fact that viruses replicate within host cells, making it challenging to eliminate them without harming body tissues.

  • Preclinical Testing

    • Involves:

    • Animal testing

    • Testing on cells/tissues outside the body

    • Computer modeling

  • Digitalis

    • Originating from the foxglove plant, used to treat heart problems.

  • Source of Aspirin

    • Aspirin is derived from the willow plant.

  • Discovery of Penicillin

    • Discovered by Alexander Fleming from Penicillium mould (fungus).

  • Pharmaceutical Industry

    • New drugs are synthesized by chemists within the pharmaceutical industry, often using chemicals extracted from plants.

  • Drug Testing Requirements

    • All new drugs must be evaluated for:

    • Toxicity

    • Efficacy

    • Optimal dosage

  • Clinical Trials

    • In clinical trials, a double-blind trial is conducted, where neither the patient nor the physician knows if the treatment is the active medication or a placebo.

  • Placebo

    • A placebo is defined as a "fake" treatment that appears similar in appearance or taste to the real therapeutic treatment but contains no active ingredients.

Monoclonal Antibodies: Production and Uses

  • Monoclonal Antibody Definition

    • An antibody produced from a single clone of cells.

  • Target Protein

    • The protein that a monoclonal antibody binds to is known as an antigen.

  • Production

    • The specific type of cell in mice stimulated to produce monoclonal antibodies is a lymphocyte.

    • Monoclonal antibodies are produced by fusing a lymphocyte with a tumor cell to create a hybridoma cell.

  • Uses of Monoclonal Antibodies

    • Diagnosis (e.g., pregnancy testing)

    • Laboratory measurements of hormone levels in blood

    • Detection of specific pathogens

    • Identification of specific molecules in cells using fluorescent dye

    • Treatment of diseases by targeting specific cells with therapeutic drugs

  • Concerns about Monoclonal Antibodies

    • They have not been utilized as widely as initially anticipated due to the unexpected side effects they can cause.

Plant Diseases: Symptoms and Defense Mechanisms

  • Symptoms of Plant Diseases

    • Stunted growth

    • Spots on leaves

    • Areas of decay (rot)

    • Growths

    • Malformed stems or leaves

    • Discoloration

    • Presence of pests

  • Identification of Plant Diseases

    • Methods for identifying plant diseases include:

    • Gardening manuals/websites

    • Laboratory testing

    • Testing kits with monoclonal antibodies

  • Nutrient Deficiencies in Plants

    • Nitrate Deficiency: Leads to stunted growth due to its necessity for amino acid production, which is crucial for protein synthesis.

    • Magnesium Deficiency: Causes chlorosis (yellowing of leaves) due to insufficient chlorophyll, leading to decreased photosynthesis and growth.

  • Physical Defense Mechanisms of Plants

    • Cellulose cell walls

    • Tough waxy cuticle on leaves

    • Layers of dead cells around stems that eventually fall off

  • Chemical Defense Responses in Plants

    • Production of antibacterial chemicals

    • Synthesis of poisons to deter herbivores

  • Mechanical Adaptations for Plant Defense

    • Thorns or hairs to deter herbivores

    • Leaves that curl or droop when touched

    • Mimicry to deceive animals