Placental transfer and decay of maternally acquired antimeasles antibodiesin Nigerian children

Background. In developing countries vaccination against measles virus (MV) is generally administered at 9 months of age, although it is well-documente d that protection of most infants by passively acquired maternal MV antibod ies is waning before immunization is given. The purpose of this study was t o investigate the decay of maternally derived MV antibodies in Nigerian inf ants as well as to compare a German and Nigerian cohort of paired mothers a nd newborns regarding the placental transfer efficiency of MV-specific IgG and total IgG antibodies. Methods. MV-specific IgG antibodies were measured with a commercially avail able MV-enzyme-linked immunosorbent assay, a recombinant hemagglutinin enzy me-linked immunosorbent assay as well as a neutralization assay. Total IgG values were determined with a standard immunoturbidimetric test. Results. Anti-MV IgG titers were twice as high in German newborns as in Nig erian newborns. An increased concentration of immunoglobulins transferred v ia the placenta was found only in the German cohort. High concentrations of total maternal IgG reduced the concentration of MV-specific as well as tot al IgG that crossed the placenta. Furthermore only 17% of the 4-month-old N igerian infants were still protected against measles. Antibodies had a biol ogic half-life of 33 days and a biochemical half-life of 48 days. Conclusions. Our findings demonstrate that the decay of passively acquired MV antibodies occurred even more rapidly than expected resulting in suscept ibility to MV in most of the 4-month-old infants in Nigeria. Furthermore tr ansfer of maternal anti-MV IgG and total IgG antibodies to the newborn was more efficient in the German cohort compared with the Nigerian group. These findings suggest the use of alternative vaccination strategies in developi ng countries to possibly reduce the window of susceptibility against measle s.