Dissecting age-stratified immunity to different dengue virus serotypes and Zika viruses among children in a highly endemic region in Sri Lanka

BackgroundDetermining serotype-specific age stratified dengue (DENV) and Zika (ZIKV) seroprevalence rates is crucial for implementing vaccines and vector control strategies. Therefore, we sought to assess age-stratified seroprevalence of monotypic or multi-typic exposure in a community cohort in Sri Lanka. MethodsThe DENV-specific serostatus was assessed in 4,161 children aged 4 to 16 years, using an in-house DENV specific IgG ELISA and compared the results with a widely used commercial assay (dengue indirect Panbio IgG ELISA). We also used a multiplexed, microsphere-based serological assay, to characterise monotypic vs multi-typic infections and to differentiate exposure rates to different DENV serotypes and ZIKV in a sub-cohort of children (n=604). ResultsBy IgG-ELISA DENV seropositivity was 72.34% (n=4,161), and the seroprevalence rate significantly increased with age (Spearmans r=1.0, p=0.003). The estimated FOI was 0.16 (95% credible interval 0.14-0.17). Of the 604 individuals tested by Luminex, 258 (42.7%) had a monotypic dengue infection, whereas 209 (34.9%) had a multi-typic response. 100 (16.5%) had evidence of a past infection to zika, while 20 (3.33%) children, only had antibodies to the ZIKV. Of the 258 individuals with evidence of a monotypic infection of DENV, DENV2 (56.83%) and DENV1 (30.57%) accounted for most infections. An inverse correlation between exposure to ZIKV and age (Spearmanss r=-0.72, 0=0.007). Conclusions72.3% of children were seropositive for dengue with 42.7% been infected with only one DENV in the past. The data suggests that prior immunity to DENV may reduce the risk of ZIKV infection, which should be further assessed.