RESUMO
Sapoviruses (SVs) are an important cause of acute pediatric gastroenteritis. Due to the lack of appropriate diagnostic methods, the epidemiology of SV-associated illness remains poorly understood. Baculovirus and Escherichia coli expression systems were evaluated for the development of antibody detection enzyme immunoassays (EIA). Age-related antibody prevalence in children was studied using the new EIA. Because of the low yield of the baculovirus system, the E. coli-expressed SV capsid proteins were used to develop the EIA. The antigenic specificities of the E. coli-expressed SV capsid proteins were demonstrated using hyperimmune antisera raised in animals and sera collected from patients. A high prevalence (>90%) of antibodies to both SV (strain Mex340) and norovirus (strain VA387) was observed in children involved in a birth cohort at 20 to 24 months of age; however, at 1 to 3 months of age, <25% of the children possessed anti-SV antibodies versus >90% with anti-NV antibodies. The E. coli-derived SV proteins are an excellent source of antigens for the EIA. SV infection is common in the first 2 years of life. The low prevalence of maternal antibodies detected in Mexican children against SVs in this study is unique and needs to be addressed in future studies.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Caliciviridae/epidemiologia , Infecções por Caliciviridae/imunologia , Técnicas Imunoenzimáticas/métodos , Sapovirus/imunologia , Envelhecimento , Baculoviridae/metabolismo , Pré-Escolar , Escherichia coli/metabolismo , Regulação Viral da Expressão Gênica , Humanos , Lactente , México , Estudos SoroepidemiológicosRESUMO
Noroviruses (NVs) recognize human histo-blood group antigens (HBGAs) as receptors. We characterized the interaction of human milk samples with recombinant virus-like particles representing VA387, Norwalk, VA207, and MOH. Milk samples from 60 healthy women were tested for human HBGAs and for their ability to block the binding of NVs. Fifty-four women were secretors (Se+), and 6 were nonsecretors (Se-). No women had detectable A or B antigens in their milk samples. All 54 Se+ milk samples, but 0 of 6 Se- milk samples, blocked VA387 and Norwalk virus (Se+ binders) from binding to saliva samples. All 6 Lewis-positive Se- milk samples blocked binding to VA207, and variable blocking activities were exhibited by the Se+ milk samples. No milk samples blocked the binding of MOH to A and B antigens. Secretor and Lewis, but not A or B antigens, were present in human milk and were responsible for blocking NV binding to receptors and therefore are likely to be decoy receptors that protect breast-fed infants from NV infection.
Assuntos
Antígenos de Grupos Sanguíneos/metabolismo , Leite Humano/imunologia , Norovirus/fisiologia , Receptores Virais/metabolismo , Saliva/imunologia , Infecções por Caliciviridae/prevenção & controle , Feminino , Humanos , México , Saliva/virologia , Virginia , Inativação de VírusRESUMO
OBJECTIVE: To determine the association between maternal milk levels of 2-linked fucosylated oligosaccharide and prevention of diarrhea as a result of Campylobacter, caliciviruses, and diarrhea of all causes in breast-fed infants. STUDY DESIGN: Data and banked samples were analyzed from 93 breast-feeding mother-infant pairs who were prospectively studied during 1988-1991 from birth to 2 years with infant feeding and diarrhea data collected weekly; diarrhea was diagnosed by a study physician. Milk samples obtained 1 to 5 weeks postpartum were analyzed for oligosaccharide content. Data were analyzed by Poisson regression. RESULTS: Total 2-linked fucosyloligosaccharide in maternal milk ranged from 0.8 to 20.8 mmol/L (50%-92% of milk oligosaccharide). Moderate-to-severe diarrhea of all causes (n=77 cases) occurred less often (P=.001) in infants whose milk contained high levels of total 2-linked fucosyloligosaccharide as a percent of milk oligosaccharide. Campylobacter diarrhea (n=31 cases) occurred less often (P=.004) in infants whose mother's milk contained high levels of 2'-FL, a specific 2-linked fucosyloligosaccharide, and calicivirus diarrhea (n=16 cases) occurred less often (P=.012) in infants whose mother's milk contained high levels of lacto-N-difucohexaose (LDFH-I), another 2-linked fucosyloligosaccharide. CONCLUSION: This study provides novel evidence suggesting that human milk oligosaccharides are clinically relevant to protection against infant diarrhea.