Abstract
Invasive nontyphoidal Salmonella (iNTS) disease is a major cause of deaths among children and HIV-infected individuals in sub-Saharan Africa. Acquisition of IgG to iNTS lipopolysaccharide (LPS) O-antigen in Malawi in early childhood corresponds with a fall in cases of iNTS disease suggesting that vaccines able to induce such antibodies could confer protection. To better understand the acquisition of IgG to iNTS in other African settings, we performed a cross-sectional seroepidemiological study using sera from 1090 Ugandan individuals aged from infancy to old age. Sera were analysed for IgG to LPS O-antigen of S. Typhimurium and S. Enteritidis using an in-house ELISA. Below 18 months of age, most children lacked IgG to both serovars. Thereafter, specific IgG levels increased with age, peaking in adulthood, and did not wane noticeably in old age. There was no clear difference in antibody levels between the sexes and the few HIV-infected individuals in the study did not have obviously different levels from uninfected subjects. While IgG to iNTS is acquired at a younger age in Malawian compared with Ugandan children, it is not clear whether this is due to differences in the populations themselves, their exposure to iNTS, or variations between assays used. In conclusion, there is a need to develop a harmonised method and standards for measuring antibodies to iNTS across studies and to investigate acquisition of such antibodies with age across different sites in sub-Saharan Africa.
Highlights
Invasive non-typhoidal Salmonella disease is principally caused by serovars S
Typhimurium antibodies, notably IgG to O-antigen of LPS and flagellin, and serum bactericidal activity rises rapidly with age in the first few years of life corresponding with a fall in cases of Invasive non-typhoidal Salmonella (iNTS) disease[4,5]
Given that incidence of iNTS disease drops in children over 2 years, it has been suggested that a rise in specific antibodies and bactericidal activity correlates with protection
Summary
Invasive non-typhoidal Salmonella (iNTS) disease is principally caused by serovars S. Enteritidis and is thought to be responsible for up to 680,000 deaths annually, with Africa accounting for more than half of cases[1] Much of this burden is in children under 5 years and HIV-infected adults. Given that incidence of iNTS disease drops in children over 2 years, it has been suggested that a rise in specific antibodies and bactericidal activity correlates with protection. This hypothesis is complicated by the observation that among HIV-infected Malawian adults, high LPS-specific IgG was associated with a lack of in vitro bacterial killing[6]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have