Virulence Factors In Bacterial Pathogenicity

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Virulence factors are part of an important concept in bacterial pathogenicity (Henderson, Poole & Wilson, 1996). According to Cross (2008), Dubey and Maheshwari (2013), virulence factors enable the bacteria to produce a variety of molecules in order to adhere, invade and evade host defences and cause tissue damage. these molecules have been grouped into adhesins, invasins, impedins, aggressins and modulins (Dubey & Maheshwari, 2013: Henderson, Poole & Wilson, 1996).

Adhesins
Adhesins are bacterial proteins that responsible for adhesion to host cells which allow the bacterium to bind to a variety of cells, mainly epithelia, as the first step to entering the host (Dubey & Maheshwari, 2013: Henderson, Poole & Wilson, 1996). Bacteria must adhere
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Invasion of the cells commonly the process comes after the adhesion of bacteria. Mainly, the host cell invaded by bacteria are epithelial and endothelial cells. Most of invasive bacteria gain entry into epithelial cells by inducing the rearrangement of the microfilaments which known as ‘actin filaments’ of the cytoskeleton. It will form a network throughout the cell and particularly dense just beneath the cytoplasmic membrane. They are also involved in maintaining the shape of the cell and play a key role in enabling cellular movement and division. Meanwhile, the invasion of endothelial cells. Many organisms are able to spread troughout the body, hence causing pathology at sites distant from the entry site by entering the bloodstream and its entails crossing another cellular barrier - the endothelium (Wilson, McNab & Henderson,…show more content…
The term ‘modulin’ is analogous to impedin and aggressin (Dubey & Maheshwari, 2013: Henderson, Poole & Wilson, 1996). According to Wilson, McNab and Henderson (2002), they stated that modulins divided into two categories. Firstly, non-proteinaceous components of bacteria associated with the cell wall which included lipopolysaccharide (LPS) in Gram-negative bacteria, peptidoglycan in both Gram-positive and Gram-negative bacteria, lipoteichoic acid (LTA) in Gram-positive bacteria and lipoarabinomannan (LAM) and lipoproteins of Mycobacterium spp. These molecules bind to the CD14-TLR membrane receptor system in order to stimulate the cells. Besides that, the other category of cytokine-inducing bacterial molecules are mainly proteins and peptides that may bind to cell via CD14-TLR receptor system or act via other known, or unknown receptors (Casadevall & Pirofski, 2009; Wilson, McNab & Henderson, 2002). The action of modulins started with the secretion of modulins from bacteria or their direct interaction with host cells, activates the transcription of host cell cytokines. These cytokines can act in an autocrine manner, hence activating the host cell. It will either can be protective or cause pathology in infection (Wilson, McNab & Henderson,

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