Aquired opsisns: specific immunoglobulin and complement
What are the three complement pathways?
aquaired- molecules are recognised on the bacteria surface
lectin- mannose binding protien
What are the three outcomes to complement pathways?
The pathogen is killed, opsonisation or inflamatory cells are recruted
What are the main characteristics of bacteria that the immune responce are triggered by?
Lipid A, peptidoglycan, bacteria lipoprotiens and bacteria DNA
What is the inflamatory responce?
Macropharges are activated and release TNF- (alpha) (Tumor necrosis factor), this causes increase release of plasma proteins into the tissue though bigger pores in the blood vessels and the lymph vessels become more active
What do T cell 1 and T cell 2 do?
T helper cell 1 activates macrophages and attack them.
T helper cells 2 activates and secretes antibody and B cells
What are the four main jobs of an antibody during an infection?
Produce anti toxins, stop the bacteria getting nutrients, stoping adhesion and invasion as well as allowing for opsonisation
What does IgA do?
It nutralises anti toxin, causes agglutination and anti-adhesion
How does T helper cell 4 activate macrophages?
Interferon gamma and CD4 liganand attacth to the macrophage causesing the bacteria to be oxidised and the bacteria to be pagocytosed, as well as causing increased nitric oxide
How do T helper 1 and T helper 2 cells inhibit each other?
T helper 1 produces interferon gamma and T helper 2 cells produce IL-4
What are the three main types of pathogen?
Oppertunistic pathogen- this is when the pathogen will only create an infection when the immune system has been compromised
secondary pathogens- these are ones which cause infection when room has been made for them i.e. infection to the rispiratory tract after a cold
Primary pathogen- this will cause disease even if the host is not compromised
The mechanism of disease development
The measure of the virus to damage or kill the host
Define virulnce factor
Componant of bacteria which is involved in pathogenesis, infectivity or virulence
The ability of the bacteria to enter, colonise and survive within a host
what is the general life cycle of a bacteria?
It is taken up by a host, it attaches to a specific cell with its fimbrae, it multiplies (for this to happen it requires nutrients and to fight off the hosts defences) and then needs to be redistrabuted
Describe the 4 steps to Kochs postules
1- The organism should be found in each diseased individual
2- The organism should be isolated and cultured outside of the organism (this can be a downfall)
3- The pure cultured organisms should be innoculated into an individual
4- The organism should be re isolated and cultured
What three ways ar used to detect virulence factors?
Molecular- by putting the virulence gene into an a virulent organism
Epidemiology- corrolation between the suspected virulence factor and disease
Biomolecular- analysis of the virulence factor (i.e. toxin) both invitro and invivo
What is K88 another name for
The gene which is a common virulance factor as it coads for fimbrae which adhear to cells
What are the two most commonly used methods to detect a virulence factor?
Random mutanogenesis- this is where UV is fired at the organisms to create a mutant (worry about healthy genes also being affected
Site directed mutanogenesis means that the virulence gene is removed and placed in an a virulent bacteria. they are then compared invitro and invivo.
What are bacterias adheasion techniques?
commersial bacteria adhear to mucous
some bacteria bind to carbohdrates for example those with K88
binding to surface proteins ie invasin proteins
binding to matrix proteins i.e. gram positive bacteria
whats the difference between extracellular and intracellular pathogens?
extracellular pathogens resist complement and phagocytes (i.e. clostridia or staphloccos aureus)
intracellular pathogens resist intracellular destruction (i.e. salmonella or brucella)
How do bacteria survive when extracellular?
They repel complement by haveing capsules containg salicic acid, the capsule also repelse phagocytes by being charged they also try to be none immunogenic by resembling the host.
how do bacteria gain iron?
sidephore which collect iron, or transferrin/lactoferrin binding protein
What methods do intracellular pathogens use?
escaping the phagosome, preventing acidification, preventing lysosome excretion and only coxielle burnetii