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Cross-reactive immune response elicited by parenteral Vi polysaccharide typhoid vaccine against non-typhoid Salmonellae

2013; Elsevier BV; Volume: 32; Issue: 5 Linguagem: Inglês

10.1016/j.vaccine.2013.12.001

1873-2518

Sari H. Pakkanen, Jussi M. Kantele, Christian Herzog, Anu Kantele,

Hepatitis Viruses Studies and Epidemiology

Despite 155 000 deaths and over 90 million cases – and the current emergence of antimicrobial resistance – no vaccines are available against non-typhoid Salmonellae (NTS). We recently presented immunological arguments for using the oral Salmonella Typhi Ty21a as surrogate vaccine against NTS strains: Ty21a elicits intestinal antibodies against typhoidal O-9,12 antigen, and numerous NTS strains share one or both of these structures with S. Typhi. The Vi polysaccharide vaccine can, presumably because of contaminating typhoidal lipopolysaccharide, also elicit a humoral response to O-9,12, although a lower one in magnitude than the Ty21a. In this study, the Vi vaccine was explored for cross-reactive immune response to various NTS strains, and compared to that elicited by the Ty21a vaccine. Volunteers immunized with the Vi polysaccharide (Typherix®; n = 25) were investigated for circulating plasmablasts secreting antibodies reactive with six NTS serotypes. The results were compared to those for 25 age- and gender-matched volunteers vaccinated with Ty21a (Vivotif®), as partly presented in our previous study. The cross-reactive plasmablasts elicited by the Vi vaccine were also analyzed for homing receptor expressions. 49 out of 50 vaccinees showed a cross-reactive plasmablast response against S. Enteritidis sharing both O-9 and O-12 antigens with S. Typhi (mean: 95%CI 37: 19–55 and 363: 234–493 plasmablasts/106 PBMC in the Vi and the Ty21a group, respectively). The response against strains only sharing O-12 was weaker (22: 8–38 and 222: 105–338 against S. Typhimurium). Strains without typhoidal O-antigens generated no significant reactivity. The cross-reactive plasmablasts elicited by the Vi vaccine had systemic homing properties. The Vi vaccine elicited an immune response cross-reactive with several NTS strains. This response was lower than that in Ty21a-vaccinated volunteers. The clinical significance of these responses deserves further research with respect to both gastrointestinal and invasive NTS (iNTS) disease.