Monophasic Salmonella Typhimurium

Topics: Immune system, Vaccine, Antigen Pages: 3 (957 words) Published: October 31, 2012
Monophasic Salmonella Typhimurium - Efficacy of vaccine administration Since mid- 1990´s a number of reports have been published on the isolation of different Salmonella strains, similar to S. Typhimurium but a difference in the flagella antigen, in several European countries as well as in the U.S.A (EFSA Journal 2010, Andrea et al. 2008). As known, serotyping of Salmonellas is based on antigenic variability of LPS (O Antigen), flagella (H antigen) and capsule (VI antigen). Most Salmonella strains are motile by means of flagella, the flagella can be encoded by 2 genes (fljB, fljC), which expression is regulated through a mechanism called “Phase variation”. Most of the salmonella strains express both phases and are therefore called “biphasic” (Heather R et al. 2003). In S. Typhimurium strains antigen H has 2 phases, one is called “i” and the second “1,2”. Salmonella strains with antigenic structure similar to that of S. Typhimurium but lacking certain flagellar antigens phases are called ‘Salmonella Typhimurium like’. S. Typhimurium 1,4,[5],12:i strain and S. Typhimurium (1,4,[5],12:i 1,2) have the same O and Hi antigens, but 1,4,[5],12:i strain lacks expression of phase 2 flagella, it is therefore called “Monophasic S. Typhimurium”. Strains that do not express first phase antigen (1,4,[5],12:-: 1,2) or both phases (1,4,[5],12:-:-:) were also reported but seem not to be associated with significant diseases in animals or humans. 1,4,[5],12:i strain appear to have been ecologically successful, recent studies in numerous countries worldwide confirm the rapid emergence and dissemination. 1,4,[5],12:i:– strain, currently, is among the 10 most common serotypes associated with human infections in a number of countries. According to the E.U surveillance system 1,4,[5],12:i strain was the forth in its prevalence in humans in year 2006, outbreaks in human were also reported in the U.S.A, Spain, Brazil and others (Andrea et al. 2008). Last outbreak in the U.S.A affected...
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