Zain Arfeen expansively elaborates all aspects of pathogenesis of cholera. At first, information about enzymatic reaction and effects of cholera toxin is deliberated. Following this, virulence factors are pursued including regulation of Ctx A and B genes. After that, mechanism of pathogenesis, types of cholera enterotoxin, diphtheria toxin and rice water stool are highlighted.
This section is initiated by diagrammatic explanation of normal enzymatic reaction of adenyl cyclase and cholera toxin. Effects of toxin on enterocytes are discussed later on. Determinants of colonization process of small intestine are adhesins, neuraminidase, motility, chemotaxis and toxin production. Adherence of vibrio cholerae is mediated by long filamentous fimbriae. Two other possible adhesins are responsible for adherence of vibrio cholerae.
Transcriptional regulation of Ctx A and B genes are responsible for toxin production and fimbriae synthesis. mRNA of ctx operon contain two RBS. Their components are assembled in periplasm after translation. After that Zain Arfeen talks about their mode of entry that they enters cell by unknown translocation mechanism. Transcription of ctxAB operon is regulated by environmental signals. ToxR, ToxS, and ToxT are the proteins present in control regulon.
Mechanism of Pathogenesis
In this section mechanism of pathogenesis is delineated primarily. Cholera causes disease of small bowel, it establishes residence and multiply there. Zain Arfeen elaborates in detail how the disease progress in sqadia.com medical video lecture. Discussion continues on cholera toxin B region known as choleragenoid. Antigenically related types of cholera enterotoxin are CT-1 and CT-2. Conclusively, information about cholera toxin and diphtheria toxin is delivered along with rice water stool.