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Immune response to respiratory syncytial virus in young Brazilian children
D A O Queiróz1, E L Durigon, V F Botosso
1Departamento de Imunologia, Microbiologia e Parasitologia, Instituto de Ci ncias Biom dicas, Universidade Federal de Uberl ndia, Uberl ndia, MG, Brasil. dqueiroz@icbim.ufu.br
Insights
Infants under 3 months show a weak immune response to respiratory syncytial virus (RSV). Older infants (over 3 months) mount a stronger humoral and cellular immune response to RSV infection.
Area of Science:
- Immunology
- Pediatrics
- Virology
Background:
- Primary respiratory syncytial virus (RSV) infection is a significant cause of lower respiratory tract illness in infants.
- Understanding the infant immune response to RSV is crucial for developing effective prevention and treatment strategies.
Purpose of the Study:
- To evaluate the cellular and humoral immune responses to primary RSV infection in infants.
- To investigate the influence of age on the infant immune response to RSV.
Main Methods:
- Serum samples from 65 infants (<=12 months) were analyzed for anti-RSV IgG and IgG subclass antibodies using enzyme immunoassay (EIA).
- Peripheral blood mononuclear cells (PBMC) from 29 RSV-infected children were analyzed for cell surface markers using flow cytometry.
- PBMC were stimulated with RSV to assess cytokine production.
Main Results:
- Infants <3 months old had a low seroconversion rate, with predominantly T lymphocytes in their PBMC.
- Infants >3 months old exhibited a higher seroconversion rate, with a predominance of B lymphocytes.
- RSV stimulation of PBMC did not significantly increase intracellular or secreted cytokines in most infants.
Conclusions:
- Infant age is a critical factor influencing the development of an immune response to RSV.
- Younger infants (<3 months) have a less robust immune response to RSV compared to older infants.
- Further research is needed to understand the mechanisms behind age-dependent immune responses to RSV in infants.
Abstract:
We have evaluated the cellular and humoral immune response to primary respiratory syncytial virus (RSV) infection in young infants. Serum specimens from 65 patients <=12 months of age (39 males and 26 females, 28 cases <3 months and 37 cases > or = 3 months; median 3 3.9 months) were tested for anti-RSV IgG and IgG subclass antibodies by EIA. Flow cytometry was used to characterize cell surface markers expressed on peripheral blood mononuclear cells (PBMC) from 29 RSV-infected children. There was a low rate of seroconversion in children <3 months of age, whose acute-phase PBMC were mostly T lymphocytes (63.0 +/- 9.0%). In contrast, a higher rate of seroconversion was observed in children >3 months of age, with predominance of B lymphocytes (71.0 +/- 17.7%). Stimulation of PBMC with RSV (2 x 10(5) TCID50) for 48 h did not induce a detectable increase in intracellular cytokines and only a few showed a detectable increase in RSV-specific secreted cytokines. These data suggest that age is an important factor affecting the infants' ability to develop an immune response to RSV.