Factors affecting immunogenicity of BCG in infants, a study in Malawi, The Gambia and the UK.
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 with M. tuberculosis PPD, 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 to M. tuberculosis PPD 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.
Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine London WC1E 7HT, UK. hur1225@gmail.com.
Yun-Gyoung
YG
Hur
Patricia
P
Gorak-Stolinska
Maeve K
MK
Lalor
Hazzie
H
Mvula
Sian
S
Floyd
John
J
Raynes
Anne
A
Ben-Smith
Joseph R
JR
Fitchett
Katie L
KL
Flanagan
Sarah
S
Burl
Martin O
MO
Ota
Amelia C
AC
Crampin
Steven G
SG
Smith
Hazel M
HM
Dockrell
D001500:BCG Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D001942:Breast Feeding; D002097:C-Reactive Protein / Q000276:immunology; D016207:Cytokines / Q000097:blood; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008295:Malawi / Q000453:epidemiology; D008297:Male; D014376:Tuberculosis / Q000276:immunology* / Q000517:prevention & control*; D006113:United Kingdom / Q000453:epidemiology; D015032:Zinc / Q000097:blood
D001500:BCG Vaccine; D016207:Cytokines; D002097:C-Reactive Protein; D015032:Zinc