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Immunity to infectious disease

ا . م . د وفاق محمود علي الوتار

Infection could be:

Viral Bacterial Parasitic Fungal

Types of immune response:

Non-specific immune response Mechanical: as Skin ,saliva ,tears, ciliary movement, mucus , Cellular :NK, macrophages ,complement lysis,commensals Specific immune response.

The types of immune response

Cellular: Mediated by the lymphocytes and cytokines. Th-1,Th-2,Th-Del
Humoral Mediated by antibodies like IgG ,IgM, IgE, IgA, IgD.

Immune response against bacteria

Cellular or humeral The function of ab could be Opsonizing Complement fixing Haemolysing Agglutinating Surface receptors as IgD Secretory IgA

Immunity to viruses

Obligate IC pathogen Invasion ,replication, evasion of immune system. Antiviral response is a complex process Alpha ,beta, gamma INF,as 1ST two interfere with viral replication ,stimulate the MHC -1 to make it recognizable to T-LC ,and activate NK cells to kill infected cells By ADCC NK produce gamma INF----act macrophage Complement damage the envelope of some viruses

Role of humoral immunity

Neutralizing antibodies IgG the most active combine with viral antigen on cell surface leading to ------attachment of NK,Macr,PMNs --- damage to viral infected cells ADCC IgA protect epithelial & mucosal surfaces Agglutination of viral particles IgM complement activation, promoting phagocytosis by macrophage Opsonization Inhibition of viral enzymes

TYPES OF HOST INFECTION

Or locally as rhinovirus If there is entry local invasion---- followed by haematogenic spread----- target organ infection e.g measles ,poliomylitis hepatitis. Or local entry-----neurological spread e.g rabies. Some others remaine dorminant as HSV Some are latent as HIV ,CMV,EBV.

Cellular immune response

After infection cell mediated immunity is the main eliminator of virally infected cells CD4+,CD8+. CD4+--------effective antibody Cytokine production Excess macrophage activation CD8+ are generated early ,can recognize the virally infected cells +MHC 1

Immunity to bacteria

G+ve Thick peptidoglycan Teichoic acid,CHO,protiens Resist cell lysis by complement IR: spesific Ab,opsonine,phagcytosis by PNC IgG,IgM, & OR C3b Cell wall stimulate alternative pathway---opsonine--- inflamatry IR
G-ve Thin inner &outer cell membrane. LPS endotxines can directly activate the ulternative pathway C3aC5a--chemotactic C3b Spesific antibody Phagositic cells

Special bacteria

mycobacteria
spirochets

Immunity to parasites

Immunity to fungi

Bacterial evasion of immune response
Capsule Toxins Antigenic variation IC survival Immune system suppression Extacellular enzymes Expression of antibody binding protiens

Viral escape

Parasitic escape site, size, migration,





رفعت المحاضرة من قبل: Abdalmalik Abdullateef
المشاهدات: لقد قام 7 أعضاء و 161 زائراً بقراءة هذه المحاضرة








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