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Scientific result | Vaccine | Bacteria
In an article published in PLoS Neglected Tropical Diseases, SPI researchers show for the first time, in a mouse model, the induction of cross-protection against Salmonella and Shigella infections, two pathogenic bacteria responsible for gastrointestinal diseases (typhoid, dysentery among others) one of the main causes of morbidity and mortality, particularly in children under 5 years old, in several regions of Africa and Asia.
With a view to developing broad-spectrum vaccines capable of simultaneously protecting against these two bacterial pathogens, researchers at SPI/LERI have focused on the system that allows Salmonella and Shigella to inject their virulence factors through the plasma membrane of host cells. Their XXS-size "syringe", called type III secretion system or injectisome, is very similar. In particular, the injection needle cap proteins (SipD for Salmonella and IpaD for Shigella) have quite similar assembly mechanisms and three-dimensional structures, despite relatively weak sequence identity (38%). Moreover, their protective efficacy against each of the bacterial genera has already been demonstrated in rodents. These elements led the researchers to consider the possibility of obtaining cross-protection against Salmonella and Shigella using SipD or IpaD as immunogens. The team administered each of the two proteins, alone, by intranasal or intragastric routes in a mouse model of intestinal infection. Strong humoral responses (production of immunoglobulins G and A) were induced against both proteins regardless of the route of administration. In addition, mice immunized with SipD or IpaD were protected against infection by Salmonella enterica (serovar Typhimurium) or Shigella flexneri. The study thus shows that cross-protection against Salmonella - Shigella is possible and paves the way for the development of broad-spectrum therapeutic molecules.
Stéphanie Simon (firstname.lastname@example.org)
Bakhos Jneid, Audrey Rouaix, Cécile Féraudet-Tarisse, Stéphanie Simon. SipD and IpaD induce a cross-protection against Shigella and Salmonella infections. | PLoS Neglected Tropical Diseases, May 2020.
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