Glycoconjugate vaccines comprising basic units of a molecular construct expressing built-in multiple epitopes for the formulation of a broad-spectrum vaccine against infections due to enteropathogenic bacteria

A conjugation process for preparing the antigenic multivalent molecular construct according to 1, which comprises the following steps:

• a) chemical activation of the at least three antigenically different carbohydrate structures selected between:
• capsular polysaccharides of Salmonella typhi, Vibrio cholerae, Escherichia coli and Clostridium difficile
• or
• lipopolysaccharides from Salmonella typhi, Escherichia coli, Vibrio cholerae, Salmonella enteritidis, Shigella jlexneri, Shigella sonnei, Salmonella paratyphi A, Salmonella dysenteriae and Salmonella cholerasuis;
• forming imine reduced bonds with an alkyl diamine spacer, then derivatized to active esters;
• b) simultaneous coupling of the at least three ester-derivative carbohydrate structures to the amino groups of the polyfunctional carrier protein Enterotoxoid A or Cytotoxoid B from Clostridium difficile, through the formation of amide bonds;
• wherein at least one mole of protein carrier is reacted with at least one mole of each, or their molar sum, of said antigenically different carbohydrate structures.