The role of neutralizing antibodies in protection of American Indian infants against respiratory syncytial virus disease.
BACKGROUND
Navajo and White Mountain Apache infants have respiratory syncytial virus (RSV) hospitalization rates 2-5 times that of the general U.S. infant population. To evaluate whether these high rates can be attributable to low concentrations of maternally derived RSV neutralizing antibodies, we conducted a case-control study.


METHODS
Study subjects enrolled in a prospective, hospital-based surveillance study of RSV disease and a group randomized clinical trial of a 7-valent pneumococcal conjugate vaccine. Cord blood specimens were assayed for neutralizing RSV antibody titers. Infants hospitalized with a respiratory illness had a nasal aspirate obtained to determine whether RSV was present. Infants with an RSV respiratory hospitalization were matched by date of birth and geographic location to infants who did not have an RSV hospitalization before 6 months of age.


RESULTS
For every 1 log2 increase in titer of cord blood RSV neutralizing antibodies there was a 30% reduced risk of hospitalization with RSV (OR = 0.69, P = 0.003). However, among infants hospitalized with RSV, there was no association between cord blood RSV neutralizing antibody and the severity of the RSV illness.


CONCLUSIONS
These findings indicate that American Indian infants with high concentrations of maternally derived RSV neutralizing antibodies are protected from RSV hospitalization before 6 months of age. However, these antibodies do not modify the severity of illness once disease has occurred. The basis for elevated rates of RSV disease among American Indian infants cannot be attributed to a failure of maternal RSV neutralizing antibodies to confer protection.
Eick
Angelia
A
Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. angie.eick@us.army.mil
Karron
Ruth
R
Shaw
Jana
J
Thumar
Bhagvanji
B
Reid
Raymond
R
Santosham
Mathuram
M
O'Brien
Katherine L
KL
D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006760:Hospitalization; D006801:Humans; D007198:Indians, North American; D007223:Infant; D008297:Male; D009296:Nasal Cavity / Q000821:virology; D009500:Neutralization Tests; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification; D012307:Risk Factors; D012720:Severity of Illness Index; D014481:United States
D000914:Antibodies, Viral