Salmonella enterica Typhi vaccine protects against H. pylori infection.

2002 NOV 6 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Protection against Helicobacter pylori was provided by a vaccination regimen that combined a primary intranasal inoculation with a strain of Salmonella enterica serovar Typhi expressing an H. pylori urease followed by a parenteral boost.

Patricia Londono-Arcila and colleagues at Acambis, Ltd., in Cambridge, England, used a plasmid containing ureAB genes to generate CVD908 and CVD908-htrA strains of S. enterica serovar Typhi that expressed an H. pylori urease. These vaccine strains were able to replicate, infect human monocytes, and colonize mouse lungs.

Intranasal vaccination stimulated an antiurease Th1 immune response in mice. Urease stimulation of vaccinated mice generated immunoglobulin G2a (IgG2a) antibodies specific for the urease, and caused the proliferation of splenocytes and the release of interferon-gamma (IFN-gamma). These immune responses were enhanced by administering a subcutaneous booster injection of the urease and alum, which increased levels of specific antiurease IgG1 and IgG2a antibodies, as well as levels of interleukin-4 (IL-4), IL-5, and IL-10.

The investigators found that neither the intranasal vaccination nor the urease plus alum injection alone protected mice against an H. pylori challenge. However, combining the two did confer protection against H. pylori infection.

"This is the first report of effective vaccination against H. pylori with a combined mucosal prime-parenteral boost regimen in which serovar Typhi ...