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Neonatal rotavirus infections
1Department of Paediatrics, Faculty of Medicine, University of Natal, Durban, South Africa.
Insights
Rotavirus (RV) infections in newborns are typically mild or asymptomatic, unlike in older infants. These neonatal infections may offer protection against severe RV disease later in life.
Area of Science:
- Virology
- Neonatal Immunology
- Infectious Diseases
Background:
- Rotavirus (RV) infections present differently in neonates compared to older infants.
- Most neonatal RV infections are mild or asymptomatic, with diarrhea occurring in less than one-third of cases.
Purpose of the Study:
- To describe the characteristics of Rotavirus infections in newborns.
- To explore factors contributing to the attenuated virulence of neonatal RV strains.
- To investigate the protective immune response elicited by neonatal RV infections.
Main Methods:
- Clinical observation of neonatal RV infections.
- Analysis of immune responses (mucosal and serologic antibodies).
- Characterization of RV strains, focusing on outer-capsid protein VP4.
Main Results:
- Neonatal RV infections are usually mild, occurring within the first week of life.
- Infections typically induce a mucosal antibody response but not a serologic one.
- Neonatal RV strains possess a conserved VP4 protein, contributing to lower virulence.
- Factors like immature neonatal gut enzymes and breast milk components (IgA, trypsin inhibitors) may reduce severity.
Conclusions:
- Neonatal RV infections are generally mild and may confer protection against severe RV disease later in life.
- Specific characteristics of neonatal RV strains and the neonatal host environment contribute to attenuated virulence.
- Natural 'nursery' RV strains are being explored as potential vaccine candidates.
Abstract:
Rotavirus (RV) infections in newborns differ from those in older infants; the majority of RV infections that occur in neonates are mild or asymptomatic. Generally, fewer than one-third of RV-infected neonates have diarrhea, although rates have reached 77% in some hospital nursery populations. Cases with severe diarrhea, necrotizing enterocolitis, bowel perforation, and death have been reported, but such cases are very rare. Infection usually occurs during the first week of life and generally invokes a mucosal antibody response without a concomitant serologic antibody response. Neonatal RV infections appear to incite an immune response that affords significant protection against severe RV-associated diarrhea, although not necessarily against a symptomatic RV infection later in life. Strains that cause neonatal infections differ from those that infect older infants; the outer-capsid protein VP4 is highly conserved in "nursery" RV strains, a property that probably plays a key role in their attenuated virulence. Immaturity of proteolytic enzymes in the neonatal gut and presence of secretory anti-RV IgA and trypsin inhibitors in breast milk are other factors that could account for the asymptomatic nature of RV infections in newborns. Natural "nursery" strains of RV are currently being evaluated as vaccine candidates.