Transplacental Respiratory Syncytial Virus and Influenza Virus Antibody Transfer in Alaska Native and Seattle Mother–Infant Pairs

Abstract

Background Alaska Native (AN) infants are at risk for severe disease due to respiratory syncytial virus (RSV) and influenza. Maternal immunization protects young infants through transplacental antibody transfer. RSV- and influenza-specific transplacental antibody transfer in mother–infant pairs has not previously been evaluated in the AN population. Methods Serum samples collected during pregnancy and at birth from AN mother–infant pairs in the Yukon-Kuskokwim Delta region (YKD) of Alaska (2000–2011; n = 75) and predominantly white pairs in Seattle, Washington (2014–2016; n = 57), were tested for RSV and influenza antibody using a microneutralization and hemagglutination inhibition assay, respectively, and compared between sites. Results Mean RSV antibody concentrations in pregnant women in YKD and Seattle were similar (log2 RSV antibody 10.6 vs 10.7, P = .86), but cord blood RSV antibody concentrations were significantly lower in infants born to mothers in YKD compared with Seattle (log2 RSV antibody 11.0 vs 12.2, P < .001). Maternal and cord blood influenza antibody concentrations were lower for women and infants in YKD compared with Seattle for all 4 influenza antigens tested (all P < .05). The mean cord to maternal RSV antibody transfer ratio was 1.15 (standard deviation [SD], 0.13) in mother–infant pairs in Seattle compared with 1.04 (SD, 0.08) in YKD. Mean cord blood to maternal antibody transfer ratios for influenza antigens ranged from 1.22 to 1.42 in Seattle and from 1.05 to 1.59 in YKD. Conclusions Though the transplacental antibody transfer ratio was high (>1.0) for both groups, transfer ratios for RSV antibody were significantly lower in AN mother–infant pairs. Further studies are needed to elucidate the impact of lower transplacental antibody transfer on infant disease risk in rural Alaska. Alaska Native and continental US mother-infant pairs have high transplacental antibody transfer ratios (>1.0) for influenza and respiratory syncytial virus, but anti-respiratory syncytial virus antibody levels are significantly lower in Alaska Native pairs than in those from the continental US.

Transplacental transfer of RSV antibody in Australian First Nations infants

“…The mean log RSV Ab titre and the CMTR in Australian First Nations infants were equivalent to levels in Alaska Native infants. 17 The CMTR observed in our study was comparable to other highburden populations with similar socio-demographic risk factors 18 but there are many unique factors that are specifically linked to Fist Nations population which were not reflected in our study cohort. For example, as all the mother-infant pairs in this study were part of a vaccine trial whereby only pregnant women with uncomplicated pregnancies were recruited, all our infants were born at term and findings from our study do not represent the transfer efficiency of maternal RSV Ab in 14% of First Nations children who are born preterm (GA ≤36 weeks) 8 and are more likely to have CMTR of <1.…”

“…The mean log RSV Ab titre and the CMTR in Australian First Nations infants were equivalent to levels in Alaska Native infants. 17 Although we did not compare our results to non-Aboriginal mother-infant pairs, the study done in Alaska Native infants showed that levels of maternal RSV Ab level in Alaska Native infants was significantly lower than their comparator group who were predominantly white infants in United States (75 Alaska Native mother-infant pairs enrolled from Bethel, Alaska vs. 57 mother-infant pairs from Seattle). A similar trend could be observed in Australia and warrants exploration, based on the data from this study.…”

“…To our knowledge this is the first study describing the efficiency of transplacental transfer of maternal RSV Ab level in Australian First Nations mother‐infant pairs. The mean log RSV Ab titre and the CMTR in Australian First Nations infants were equivalent to levels in Alaska Native infants 17 . Although we did not compare our results to non‐Aboriginal mother‐infant pairs, the study done in Alaska Native infants showed that levels of maternal RSV Ab level in Alaska Native infants was significantly lower than their comparator group who were predominantly white infants in United States (75 Alaska Native mother‐infant pairs enrolled from Bethel, Alaska vs. 57 mother‐infant pairs from Seattle).…”

Biological factors that may impair transplacental transfer of RSV antibodies: Implications for maternal immunization policy and research priorities for low- and middle-income countries

“…Few published studies have evaluated this for RSV, but one study of 213 infants found that those born < 37 weeks (both preterm low birthweight and preterm adequate birthweight) had lower CMRs for RSV compared to term infants (both term-low birthweight and term-adequate birthweight) in The Gambia [53] . A more recent study assessing RSV CMR among 75 Alaska Native mother-infant pairs found that infants with CMR < 1.0 were more likely to be lower birth weight or preterm than infants with CMR > 1.0 [54] . Similar findings were noted in a recent study of pregnant women in Kenya [55] .…”

Transplacental Antibody Transfer of Respiratory Syncytial Virus Specific IgG in Non-Human Primate Mother-Infant Pairs

“…Maternally derived RSV antibodies are efficiently transferred to the foetus and have been shown to be inversely associated with acute lower respiratory tract RSV infection and disease severity [15,16]. Ensuring an abundance of high quantity, neutralizing antibodies through the first several months of life could substantially lessen the disease burden in new-borns [17]. Maternal immunization (MI), or immunization during pregnancy has been a common practice resulting in substantial global impact by providing protection against infectious disease for the mother, child, or both [18][19][20][21][22][23].…”