Child Salivary SIgA and Its Relationship to Enteric Infections and EED Biomarkers in Maputo, Mozambique

Abstract

Characterizing child immunological responses to enteric infections with antibody detection in serum can be challenging in resource-constrained field settings, because sample collection requires trained individuals and its invasive procedure may lead to low response rates, especially among children. Saliva may present a promising non-invasive alternative. The objectives of this research were to compare salivary antibody levels in children to enteric infections and biomarkers of environmental enteric dysfunction (EED). We collected saliva samples from children aged one to six years enrolled in a sanitation trial in Maputo, Mozambique, and characterized salivary secretory immunoglobulin A (SIgA) concentrations with enzyme-linked immunosorbent assays. We used multilevel linear models to analyze cross-sectional associations between salivary SIgA and the number of concurrent enteric pathogen infections, as well as EED biomarkers in matched stool samples. Median salivary SIgA concentrations in this study population were 54 μg/mL (inter-quartile range (IQR): 34, 85 μg/mL), and SIgA levels were similar between children of different ages. SIgA was lower in children experiencing a higher number of concurrent infections −0.04 log μg/mL (95% confidence interval (CI): −0.08 to −0.005 log μg/mL), but was not associated with any of the included EED biomarkers. Contrary to evidence from high-income countries that suggests salivary SIgA increases rapidly with age in young children, the high prevalence of enteric infections may have led to a suppression of immunological development in this study sample and could in part explain the similar SIgA levels between children of different ages.

Complementary measurement of nontyphoidal Salmonella-specific IgG and IgA antibodies in oral fluid and serum

“…As an orally acquired pathogen [ 48 ], the buccal cavity it the first port of entry for Salmonella. Oral IgA derived from both serum and secretory IgA [ 19 ], may play an important role in protection or control of oropharyngeal carriage as with other enteric infections [ 49 , 50 , 51 , 52 ], and may correlate directly with gut immunity [ 18 , 20 ]. This is important, as gut mucosal immunity is difficult to measure beyond the mouth.…”

Norovirus-Associated Gastroenteritis Vesikari Score and Pre-Existing Salivary IgA in Young Children from Rural South Africa

“…In this survey, only the VLP of the worldwide circulating and predominant genotype GII.4 [71,72] was used as an antigen for ELISA assays though the ongoing vaccine trials that are using GII.4c and GI.1 genotypes [73]. Children aged less than 12 months in our sample collection as previously described were not excluded in this study [26,74]. Several conflicting findings have been reported on the effect of breastfeeding in childhood NoV-associated AGE.…”

“…The study samples were randomly collected by the trained research assistants and qualified nurses. Cotton swabs were used to collect saliva and epithelial cells, by rubbing them inside of the cheek for around 1 min, from each study participant [26].…”

Salivary sIgA as a predictor of caries risk in stunting children

“…EED arises as a result of intestinal inflammation, which results in impaired nutritional absorption. Numerous studies have established a link between intestinal inflammation and stunting (16) .…”