Effects of mother’s log-antibody concentrations against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> at delivery on infant’s log-antibody concentrations and difference in infant’s antibody concentrations between carriers and non-carriers at birth, 4 and 8 weeks.

<p>Effects of mother’s log-antibody concentrations against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> at delivery on infant’s log-antibody concentrations and difference in infant’s antibody concentrations between carriers and non-carriers at birth, 4 and 8 weeks.</p

Kinetics of antibodies against pneumococcal proteins and their relationship to nasopharyngeal carriage in the first two months of life

<div><p>Introduction</p><p>The currently used <i>Streptococcus pneumoniae</i> vaccines have had a significant impact on the pneumococcal diseases caused by the serotypes they cover. Their limitations have stimulated a search for alternate vaccines that will cover all serotypes, be affordable and effective in young children. Pneumococcal protein antigens are potential vaccine candidates that may meet some of the shortfalls of the current vaccines. Thus, this study aimed to determine the relationship between antibodies against pneumococcal protein antigens and nasopharyngeal carriage in infants.</p><p>Methods</p><p>One hundred and twenty mother-infant pairs were enrolled into the study. They had nasopharyngeal swabs(NPS) taken at birth and every two weeks for the first eight weeks after delivery, and blood samples were obtained at birth and every four weeks for the first eight weeks after delivery. Nasopharyngeal carriage of <i>S</i>. <i>pneumoniae</i> was determined from the NPS and antibodies against the pneumococcal proteins CbpA, PspA and rPly were measured in the blood samples.</p><p>Results</p><p>The <i>S</i>. <i>pneumoniae</i> carriage rate in infants increased to that of mothers by eight weeks of age. The odds of carriage in infants was 6.2 times (95% CI: 2.0–18.9) higher when their mothers were also carriers. Bacterial density in infants was lower at birth compared to their mothers (p = 0.004), but increased with age and became higher than that of their mothers at weeks 4 (p = 0.009), 6 (p = 0.002) and 8 (p<0.0001). At birth, the infants’ antibodies against <i>CbpA</i>, and <i>rPly</i> pneumococcal protein antigens were similar, but that of <i>PspA</i> was lower (p<0.0001), compared to their mothers. Higher antibody concentrations to <i>CbpA</i> [OR (95% CI): 0.49 (0.26–0.92, p = 0.03)], but not <i>PspA</i> and <i>rPly</i>, were associated with protection against carriage in the infants.</p><p>Conclusion</p><p>Naturally induced antibodies against the three pneumococcal protein antigens were transferred from mother to child. The proportion of infants with nasopharyngeal carriage and the bacterial density of <i>S</i>. <i>pneumoniae</i> increased with age within the first eight weeks of life. Higher concentrations of antibodies against <i>CbpA</i>, but not <i>PspA</i> and <i>rPly</i>, were associated with reduced risk of nasopharyngeal carriage of <i>S</i>. <i>pneumoniae</i> in infants.</p></div

Dynamic of nasopharyngeal carriage and influence of concentration of antibodies against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> in infants.

<p>Dynamic of nasopharyngeal carriage and influence of concentration of antibodies against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> in infants.</p

Effects of mother’s log-antibody concentrations against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> at delivery on infant’s log-antibody concentrations and difference in infant’s antibody concentrations between carriers and non-carriers at birth, 4 and 8 weeks.

<p>Effects of mother’s log-antibody concentrations against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> at delivery on infant’s log-antibody concentrations and difference in infant’s antibody concentrations between carriers and non-carriers at birth, 4 and 8 weeks.</p

The density of <i>S</i>.<i>pneumoniae</i> in the nasopharynx in the first eight weeks after birth in infants (A) and the first eight weeks after delivery in mothers (B).

<p>The horizontal black lines represent the average Real-time Ct value, which is inversely correlated with the density. The p value indicates the evidence of variation of the density over the eight week period.</p

Dynamic relationship between concentration of antibodies against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> and nasopharyngeal carriage in infants.

<p>Dynamic relationship between concentration of antibodies against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> and nasopharyngeal carriage in infants.</p

Concentration of antibodies against <i>CbpA</i>, <i>PspA</i> and <i>rPly</i> in mothers’ (closed circles) and cord blood (open circles) at birth.

<p>The horizontal black lines represent the average log-plasma antibody concentrations. The p values indicate the difference between the average antibody concentration for the specific pneumococcal antigen between mothers’ venous blood and infants’ cord blood at birth.</p

Multivariable analysis of BD TBc ID conversion time to positivity using interval-censored failure time regression using Weibull distribution.

<p>Each individual regression was adjusted for all other variables.</p

Flowchart describing sample collection and processing.

<p>Flowchart describing sample collection and processing.</p

Clinical and demographic characteristics of study participants.

<p>Clinical and demographic characteristics of study participants.</p