Quantifying maternally derived respiratory syncytial virus specific neutralising antibodies in a birth cohort from coastal Kenya.
BACKGROUND
Severe respiratory syncytial virus (RSV) disease occurs predominantly in children under 6 months of age. There is no licensed RSV vaccine. Protection of young infants could be achieved by a maternal vaccine to boost titres of passively transferred protective antibodies. Data on the level and kinetics of functional RSV-specific antibody at birth and over the early infant period would inform vaccine product design.


METHODS
From a birth cohort study (2002-2007) in Kilifi, Kenya, 100 participants were randomly selected for whom cord blood and 2 subsequent 3-monthly blood samples within the first year of life, were available. RSV antibodies against the A2 strain of RSV were assayed and recorded as the logarithm (base 2) plaque reduction neutralisation test (PRNT) titre. Analysis by linear regression accounted for within-person clustering.


RESULTS
The geometric mean neutralisation antibody titre was 10.6 (SD: 1.13) at birth with a log-linear decay over the first 6 months of life. The estimated rate of decay was -0.58 (SD: 0.20) log2PRNT titre per month and a half-life of 36 days. There was no significant interaction between cord titre and rate of decay with age. Mean cord titres rose and fell in a pattern temporally tracking community virus transmission.


CONCLUSIONS
In this study population, RSV neutralising antibody titres decay approximately two-fold every one month. The rate of decay varies widely by individual but is not related to titre at birth. RSV specific cord titres vary seasonally, presumably due to maternal boosting.
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. Electronic address: jnyiro@kemri-wellcome.org.
Joyce U
JU
Nyiro
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. Electronic address: csande@kemri-wellcome.org.
Charles
C
Sande
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. Electronic address: mmutunga@kemri-wellcome.org.
Martin
M
Mutunga
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. Electronic address: pkiyuka@kemri-wellcome.org.
Patience K
PK
Kiyuka
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya. Electronic address: pmunywoki@kemri-wellcome.org.
Patrick K
PK
Munywoki
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya; London School of Hygiene and Tropical Medicine, London, UK. Electronic address: Ascott@kemri-wellcome.org.
J Anthony G
JA
Scott
Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya; School of Life Sciences, University of Warwick and WIDER, Coventry, UK. Electronic address: jnokes@kemri-wellcome.org.
D James
DJ
Nokes
D057134:Antibodies, Neutralizing / Q000097:blood* / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D006207:Half-Life; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007223:Infant; D007630:Kenya / Q000453:epidemiology; D009500:Neutralization Tests; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology*; D018113:Respiratory Syncytial Virus, Human / Q000276:immunology*; D012621:Seasons; D013997:Time Factors
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
Birth cohort; Maternal antibody; Neutralisation; Rate of decay; Respiratory syncytial virus; Vaccine design