Anti-rotavirus antibodies in human milk: quantification and neutralizing activity.
OBJECTIVE
To analyze anti-rotavirus antibodies in human milk in order to determine their isotypes and neutralizing activity on rotavirus strains representing different viral serotypes.


METHODS
One hundred seventy-three milk samples (65 colostrum, 55 transitional milk and 53 mature milk) obtained from 65 mothers were analyzed along with 49 serum samples collected just before delivery. Total immunoglobulin A (IgA) and rotavirus-specific IgA and immunoglobulins G (IgG) antibodies were determined in milk and serum by enzyme-linked immunosorbent assay. Neutralizing activity was evaluated by an immunoperoxidase focus reduction assay. Milk IgA was purified by binding to the lectin jacalin, elution and ultrafiltration.


RESULTS
Total IgA antibodies were detected in all serum and milk samples analyzed. IgA levels decreased sharply during the replacement of colostrum by transitional milk, and more gradually from transitional to mature milk. These differences in IgA concentration during the 3 periods were statistically significant. Anti-rotavirus antibodies detected in human milk were exclusively of the IgA type, whereas both IgA and IgG anti-rotavirus antibodies were present in serum samples. Both milk and serum samples showed in vitro neutralization of the infectivity of rotavirus strains SA11, Wa and VA70, this activity being stronger toward the human rotavirus strain Wa. No correlation was however found between the inhibitory effect on rotavirus and the concentrations of IgA in human milk and serum samples.


CONCLUSIONS
Anti-rotavirus antibodies are only partly responsible for the neutralizing activity detected in milk and serum. This result suggests that other components possessing suppressive activity against rotavirus must also be present.
Asensi
María Teresa
MT
Department of Pediatrics, School of Medicine and Hospital Clínico Universitario, University of Valencia, Avenida Blasco Ibáñez, 17, 46010 Valencia, Spain.
Martínez-Costa
Cecilia
C
Buesa
Javier
J
D000328:Adult; D000914:Antibodies, Viral / Q000032:analysis / Q000276:immunology*; D003126:Colostrum / Q000737:chemistry / Q000276:immunology*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007231:Infant, Newborn; D008895:Milk, Human / Q000737:chemistry / Q000276:immunology*; D009500:Neutralization Tests; D011247:Pregnancy; D012401:Rotavirus / Q000276:immunology* / Q000302:isolation & purification; D012703:Serotyping
D000914:Antibodies, Viral; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes