host parasite relationship

host and parasite relationship

1. Host parasite relationship submitted to SUBMITTED BY: Prashant sharma Dr. Monika Asthana Pukhrambam Priya devi In-charge M.SC Biotechnology Department of biotechnology, 1 st semester School of Life Sciences, khandari campus DR . B. R. A. UNIVERSITY, AGRA.

2. The term host & parasite relationship is also known as SYMBIOSIS means the coexistence of two organisms , in which one extracts the nutrition from other. PARASITOLOGY is a branch of microbiology, refers to the scientific study of parasitism. A HOST is any organism that allows another organism/bacteria to live in or on it. The PARASITE is the organism living on or in the host. Foundation Definitions

3. WHAT IS SYMBIOSIS? Symbiosis refers to the “living together” of organisms and includes commensalism, mutualism, and parasitism. TYPES OF SYMBIOSIS RELATIONSHIPS: Commensalism: The relationship in which parasite driving nourishment from a host without causing any harms or benefit to the host. EXAMPLE: Orchids: Some orchids grow on trees and that does not harm the tree.   MUTUALISM: Association between organisms of two different species in which both organisms get benefits.

4. TYPES OF MUTUALISM: Obligate mutualism Facultative mutualism In obligate mutualism, the survival of one or both of the organisms involved is dependent upon the relationship. And in facultative mutualism, both organisms benefit from but are not dependent upon their relationship for survival.

5. EXAMPLE OF MUTUATISM :

6. PARASITISM: Parasitism is type of symbiotic relationship, or long-term relationship between two species, where one member, the parasite, gain benefits that come at the expense of the host member. The word parasite comes from the Latin form of the Greek word (parasitos), “meaning one eats at the table of another”. TYPES OF PARASITES. 1. Ectoparasites 2. Endoparasites

7. ECTOPARASITISM and ENDOPARASITISM:     Ectoparasites are parasites that live on the outside of the host’s body, such as lice and ticks. Endoparasites are parasites that present inside the host’s body, such as nematodes and hookworms.

8. EXAMPLE OF PARASITISM;

9. Normal Flora Normal flora are the microorganisms that live on another living organism (human or animal) or inanimate object without causing disease. DISTRIBUTION OF NORMAL MICROFLORA ON THE SKIN: The microflora of the skin consists primarily of gram positive bacteria. For example staphylococcus epidermilis (gram positive cocci) and propionibacterium acne (gram positive bacilli).

10. NORMAL MICROFLORA OF THE ORAL CAVITY: The normal microflora of the oral cavity (mouth) consists of microorganisms that possess ability to resist mechanical removal and firmly adhere to surface like gums and teeth.

11. NORMAL MICROFLORA OF THE GASTROINSTESTINAL TRACT: Human gastrointestinal tract, the site of food digestion, consists of the stomach, small intestine, and large intestine. The composition of the gastrointestinal flora in humans varies considerably and is somewhat depend on diet.

12. HUMAN GASTROINTESTINAL TRACT SHOWING NORMAL MICROBIAL FLORA FOUND IN DIFFERENT PARTS OF IT:

13. VIRULENCE AND ITS DETERMINANTS The term virulence (Latin virulentia, from virus, poison) refers to the degree or intensity of pathogenicity. P athogenic bacteria are able to produce disease because they possess certain biochemical   or   genetic  traits that makes them pathogenic or virulent . The total of the characteristics that allow a given bacterium to produce disease are the pathogen's  determinants of virulence

14. WHAT IS BACTERIAL PATHOGENESIS Pathogenicity  is the ability of a microorganism to cause disease in another organism and this process is known as bacterial pathogenesis. Potential pathogen that lives in a commensal or parasitic relationship without producing disease. Some pathogens do not associate with their host except in the case of disease. These bacteria may be thought of as  obligate pathogens. Some Bacteria cause disease in a immuno -compromised host which typically would not occur in a healthy (noncompromised) host are acting as  opportunistic pathogens.

15. ENTRY OF PATHOGEN INTO HOST: Most pathogens must gain access to the host tissues, penetrate or evade host defenses and damages the host tissue. Pathogens can enter to human body or other host through several avenues called portals of entry. PORTALS OF ENTRY: MUCOUS MEMBRANES (moist mucosa) SKIN (karatinized cutaneous membrane), PARENTERAL ROUTE:

16. WHAT IS AN INFECTION? When a parasite is growing and multiplying within or on a host, the host is said to have infection. Organisms that induce infectious disease are referred as pathogenicity and the organism is called as pathogen.

17. How does the Host Defenses itself?? The host defenses may be of such a degree that infection can be prevented entirely. Or, if infection does occur, the defenses may stop the process before disease is apparent. the host defense mechanisms are divided into two groups : 1. Innate defenses . Defenses common to all healthy animals Since they are inherent to the host. 2. Inducible Defenses . Defense mechanisms that must be induced or turned on by host exposure to a pathogen The inducible defenses are synonymous with acquired or adaptive immunity and involve the immunological responses to a pathogen causing an infection.

18. WHAT IS TOXINS? Toxins are usually poisonous substance produced by microbes which tend to cause widespread damage/disease in host. They may be necessary for virulence. TYPES OF TOXINS: EXOTOXINS: Exotoxins are soluble, heat-labile, proteins (a few enzymes) that usually are released into the surroundings as the bacterial pathogens grows. In generally exotoxins are produced by gram-positive bacteria, although some gram-negative bacteria also make exotoxins.

19. Fig: Exotoxin secretion

20. There are three types of exotoxins: AB TOXINS: It is composed of two parts, where A is the enzymes that disrupts some cell activity, while B-binds surface receptors to bring A into the host cell, e.g., botolinum and tetanus toxin.

21. Action of exotoxin

22. MEMBRANE DISRUPTING TOXINS: It causes lysis of the host cell by disrupting the integrity of the plasma membrane; there are two subtypes of membrane-disrupting exotoxins. The first is protein that binds to the cholesterol portion of the host plasma membrane, inserts itself into the membrane, and form a channel (pore). This causes the cytoplasmic contents to leak out. Also because the osmolarity of the cytoplasm is higher than the extercellular fluid, this causes a sudden influx of water into the cell, causing it to swell andrupture.

23. The two specific examples of membrane-disrupting exotoxin: Example1: Leukocidines; make protein channels in phagocytic leukocytes. Example2: haemolysins; make protein channels in RBCs (haemolysis: Streptococcus pyogenes).

24. Fig: A channel-forming (pore-forming) type of exotoxin inserts itself into the normal host cell membrane and makes an open channel (pore). Formation of multiple pores causes cytoplasmic contents to leave the cell and water to move in, leading to cellular lysis and death of the host.

25. SUPER ANTIGENS: They are the bacterial proteins that cause proliferation of T-cells and release of cytokines excessive cytokines can cause fever, nausea, vomiting, diarrhoea, shock and death (septic shock), e.g., toxic shock syndrome (staphylococcus), e.g., enterotoxins: staphylococcal food poisoning. ENTEROTOXIN: An enterotoxin is a protein exotoxin released by microorganism that targets intestines. Enterotoxins are produced in or released into intestines.

26. Enterotoxins are pore-forming toxins. Hence, they create pores in the epithelial cells of the intestine wall. When the enterotoxins increase the permeability to chloride ions in the intestinal mucosal cells, it causes secretory diarrhea. Staphylococcus aureus and E. coli are two bacterial species which can create such conditions by enterotoxins. In general, enterotoxins are produced by gram negative bacteria can also produce enterotoxins. For example, Vebrio cholera is a well-known enterotoxin producer and is a gram-negative bacterim.

27. ENDOTOXINS: They are the part of the outer membrane portion of the cell wall of gram negative bacteria, e.g., Lipopolysaccharide (LPS) which is released when dead cells lyse in blood, causes macrophages to release high levels of cytokines resulting is chills, fever, weakness, aches, small blood clots, tissue necrosis, shock and death.

28. Endotoxins

29. THANK YOU