August 14, 2015
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Infants in Papua New Guinea lack protective levels of RSV-neutralizing antibody

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Recent data published in The Journal of Infectious Diseases suggest a link between hypergammaglobulinemia and impaired transport of respiratory syncytial virus-neutralizing antibody.

Additionally, this protective antibody may not be present in one-third of infants born in Papua New Guinea, according to the researchers.

Previous research has shown that passively acquired RSV-neutralizing antibody protects infants against RSV-associated acute lower respiratory illness; however, placental malaria and maternal hypergammaglobulinemia may block transplacental immunoglobulin (IgG) transport.

To better assess the effects of placental malaria on IgG transport, Ruth A. Karron, MD, director of the Center for Immunization Research at Johns Hopkins Bloomberg School of Public Health, and colleagues analyzed 300 pairs of maternal and cord sera collected at delivery from term pregnancies in two cohorts of women in malaria-endemic Papua New Guinea. There were 157 maternal/cord pairs in the first group (2005-2008), Alexishafen; the second cohort (2011-2013), from the Fetal Immunity Study (FIS), provided 143 pairs, they wrote.

Sixty percent of mothers in the Alexishafen group had malaria vs. 8% of the FIS mothers, while the rate of hypergammaglobulinemia was 54% in the Alexishafen group and 9% in the FIS cohort.

Thirty-four percent of Alexishafen pairs and 32% of FIS pairs showed impaired transport, defined as a cord-to-maternal-titer ratio of less than 1. Furthermore, the researchers observed a link between increasing maternal IgG and impaired transport, regardless of maternal age, gravidity, placental malaria and maternal RSV plaque reduction neutralization antibody titers.

“As maternal immunization becomes an increasingly important strategy for protection of very young infants, identification of factors that could impact vaccine effectiveness by modifying the efficiency of transplacental antibody transport will be critical,” Karron and colleagues wrote. “This study shows that increasing maternal IgG, but not [placental malaria], was associated with impaired transport of RSV-neutralizing antibodies in mothers and full-term infants in Papua New Guinea, and that impaired transport occurred in approximately one-third of maternal-cord pairs.” – by Colleen Owens

Disclosure: Karron reports grants from PATH Vaccines during the conduct of the study and grants from NIH outside the study. Please see the full study for a list of all other authors’ relevant financial disclosures.