The level and duration of RSV-specific maternal IgG in infants in Kilifi Kenya.
BACKGROUND
Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants. The rate of decay of RSV-specific maternal antibodies (RSV-matAb), the factors affecting cord blood levels, and the relationship between these levels and protection from infection are poorly defined.


METHODS
A birth cohort (n = 635) in rural Kenya, was studied intensively to monitor infections and describe age-related serological characteristics. RSV specific IgG antibody (Ab) in serum was measured by the enzyme linked immunosorbent assay (ELISA) in cord blood, consecutive samples taken 3 monthly, and in paired acute and convalescent samples. A linear regression model was used to calculate the rate of RSV-matAb decline. The effect of risk factors on cord blood titres was investigated.


RESULTS
The half-life of matAb in the Kenyan cohort was calculated to be 79 days (95% confidence limits (CL): 76-81 days). Ninety seven percent of infants were born with RSV-matAb. Infants who subsequently experienced an infection in early life had significantly lower cord titres of anti-RSV Ab in comparison to infants who did not have any incident infection in the first 6 months (P = 0.011). RSV infections were shown to have no effect on the rate of decay of RSV-matAb.


CONCLUSIONS
Maternal-specific RSV Ab decline rapidly following birth. However, we provide evidence of protection against severe disease by RSV-matAb during the first 6-7 months. This suggests that boosting maternal-specific Ab by RSV vaccination may be a useful strategy to consider.
Ochola
Rachel
R
Kenya Medical Research Institute, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. rachel.opiyo@gmail.com
Sande
Charles
C
Fegan
Gregory
G
Scott
Paul D
PD
Medley
Graham F
GF
Cane
Patricia A
PA
Nokes
D James
DJ
D000375:Aging; D000918:Antibody Specificity / Q000276:immunology*; D001800:Blood Specimen Collection; D015331:Cohort Studies; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology*; D007223:Infant; D007231:Infant, Newborn; D007630:Kenya; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D018448:Models, Immunological; D011247:Pregnancy; D012136:Respiratory Syncytial Viruses / Q000276:immunology*; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D017186:Titrimetry
D007074:Immunoglobulin G