Abstract:
Background:BCG immunogenicity in infants differs between populations and these differences have been
attributed to various factors. In this study, the influence of geographical location, season of birth, timing of
vaccination, micronutrient status (zinc) and inflammatory status (C-reactive protein, CRP) were assessed.
Methods:Immunogenicity was assessed by cytokine signature in culture supernatants from diluted whole blood
samples stimulated withM. tuberculosisPPD, using a multiplex bead assay. Results were correlated with the plasma
zinc and CRP concentrations at the time of sampling, and with interview and household data. BCG vaccinated
infants were recruited in Malawi, The Gambia and the UK.
Results:In Malawi, infants vaccinated within the first week after birth showed lower production of most cytokines
measured than those vaccinated later. The number of cytokines showing significant differences between Malawian
and Gambian infants decreased after adjusting for season of birth. In Malawi, a proportion of infants had zinc
deficiency and elevated plasma CRP (>10 mg/L), but neither zinc deficiency nor high CRP was associated with
production of any of the cytokines measured.
Conclusions:The cytokine/chemokine signatures observed in response toM. tuberculosisPPD in infants at
3 months post BCG vaccination were affected by geographical location, season of birth, and timing of vaccination
but not associated with the concentration of plasma zinc or inflammatory status. These factors should be
considered in future trials of new TB vaccines
