Prevalence of respiratory syncytial virus IgG antibodies in infants living in a rural area of Mozambique

Abstract

A case control study was carried out in Manhiça (Mozambique). Serum samples were collected from infants < 1 year of age in hospital to assess the effect of serum antibodies on the incidence of respiratory syncytial virus (RSV) infection. Sera were collected from a total of 31 cases of RSV infection and paired uninfected controls matched for age and sex. Anti-RSV antibodies were assessed by a membrane fluorescent antibody test (MFAT) for immunoglobulin G (IgG) antibodies and by a neutralizing antibody test. IgG RSV antibodies were of higher prevalence and at higher levels in the control group when compared to the infected case group (P < 0.001), indicating an important role for IgG antibodies in protection. To assess infection before recruitment, IgA RSV antibodies were also measured by MFAT. IgA RSV antibody prevalence was very low in patients and controls (0/31 and 4/31 respectively), suggesting that most of the detected IgG RSV antibody in both groups was of maternal origin. Re-analysis of data from the subset of 27 matched, IgA RSV antibody negative infant pairs mirrored the full analysis indicating that maternal antibody has an important role in RSV protection. Similar results were obtained when neutralizing antibodies were measured and when the measurement was done against subgroup A virus strain A2, subgroup B virus strain 8/60 and a contemporary subgroup A isolate, Moz00. No significant differences in the reactivity of maternal antibodies with the three virus strains were observed. The data described below represent the first analysis of the role of maternal antibodies in reducing the risk of pediatric infection in developing countries. The results reinforce the concept of maternal vaccination for the control of RSV in very young children in whom the risk and severity of infection are the highest.

The transmission dynamics of groups A and B human respiratory syncytial virus (hRSV) in England & Wales and Finland: seasonality and cross-protection

“…The role of maternal antibodies in the transmission of hRSV at the population level is uncertain. It has been shown that higher levels of maternal antibodies are associated with increased protection from clinical infection [24], but this association is partial and probably short term (maternal antibodies are only present for 3-6 months [25]). For the purposes of the model presented, it is assumed that maternal antibodies have negligible effect on the transmission of the virus in the whole population.…”

Group B streptococcus and respiratory syncytial virus immunisation during pregnancy: a landscape analysis

“…Maternally-derived high affinity RSV-specific serum IgG antibody is the best known correlate of protection against infection in infants (Fig 2d) and it is assumed that the relative rarity of severe RSV disease in the first weeks of life is due to virus-specific maternally derived antibody 44,45,[63][64][65][66][67] . However, some of this protection may be indirect, due to reduced rates of maternal infection in those with high levels of antibody.…”

“…Nevertheless, severe RSV infection is consistently associated with low levels of pre-existing serum or cord blood RSV antibody 44,45,[63][64][65][66][67] . Infants in the top .…”

“…The virus subtype specificity of antibody does not seem to influence the presence of infection or the viral type causing RSV LRTI 63,86,87 , and antibodies to the viral F-protein correlate better with protection in infants than anti-G antibodies 88 .…”

“…For clinical trials of vaccine efficacy there is currently little evidence that more complex assays are of additional use as correlates of protection than simple measurements of serum antibody titre 63 , however measurement of local immunity in the airways should be considered. A study in infants hospitalised with RSV found that there was an inverse correlation between infant nasal IgG and viral load, but found no correlation with serum IgG 89 .…”