A review of respiratory syncytial virus infection in infants and children

[Pre and postnatal tobacco exposure and bronchiolitis]

OBJECTIVES

To determine the influence of pre- and postnatal tobacco exposure in the development of bronchiolitis.

PATIENTS AND METHODS

A questionnaire was given to the parents of children hospitalized between August 2001 and August 2002. It included items on parental smoking habits and maternal smoking during pregnancy. Clinical, analytical and radiological criteria were used to diagnose bronchiolitis.

RESULTS

Of 450 children, 123 (27.3 %) were diagnosed with bronchiolitis. The control group was composed of 327 children. A total of 61.6 % of the children had at least one parent who smoked and 32.9 % of these children developed bronchiolitis; 39.1 % had non-smoking parents and 18.2 % were hospitalized with bronchiolitis (OR 2.20 [1.39-3.47]). Of the entire group of children studied, 35.3 % had mothers who smoked and 37.7 % of these children had bronchiolitis compared with 21.4 % of children whose mothers were non-smokers (OR 2.22 [1.45-3.39]). A total of 49.6 % had fathers who smoked, and 32.3 % of these children were diagnosed with bronchiolitis compared with 22 % of children whose fathers were non-smokers (OR 1.65 [1.10-2.57]). Forty-four percent of children whose mothers smoked during pregnancy were hospitalized with bronchiolitis compared with only 20.9 % of non-exposed children (OR 2.96 [1.90-4.62]). The large number of mothers who smoked during pregnancy (27.8 %) was notable. Multivariant analysis with logistic regression was performed and the only variable that remained statistically significant was smoking during pregnancy (p < 0.00001; OR 3.27 [1.39-7.71]).

CONCLUSIONS

Maternal smoking during pregnancy seems to be the main risk factor for the subsequent development of bronchiolitis

Respiratory syncytial virus infection results in activation of multiple protein kinase C isoforms leading to activation of mitogen-activated protein kinase

Respiratory syncytial virus (RSV) is an important respiratory pathogen that preferentially infects epithelial cells in the airway and causes a local inflammatory response. Very little is known about the second messenger pathways involved in this response. To characterize some of the acute response pathways involved in RSV infection, we used cultured human epithelial cells (A549) and optimal tissue culture-infective doses (TCID(50)) of RSV. We have previously shown that RSV-induced IL-8 release is linked to activation of the extracellular signal-related kinase (ERK) mitogen-activated protein kinase pathway. In this study, we evaluated the upstream events involved in ERK activation by RSV. RSV activated ERK at two time points, an early time point consistent with viral binding and a later sustained activation consistent with viral replication. We next evaluated the role of protein kinase C (PKC) isoforms in RSV-induced ERK kinase activity. We found that A549 cells contain the Ca(2+)-dependent isoforms alpha and beta1, and the Ca(2+)-independent isoforms delta, epsilon, eta, mu, theta, and zeta. Western analysis showed that RSV caused no change in the amounts of these isoforms. However, kinase activity assays demonstrated activation of isoform zeta within 10 min of infection, followed by a sustained activation of isoforms beta1, delta, epsilon, and mu 24-48 h postinfection. A cell-permeable peptide inhibitor specific for the zeta isoform decreased early ERK kinase activation by RSV. Down-regulation of the other PKC isoforms with PMA blocked the late sustained activation of ERK by RSV. These studies suggest that RSV activates multiple PKC isoforms with subsequent downstream activation of ERK kinase.

Palivizumab: an overview

Respiratory syncytial virus (RSV) affects almost all children in their first 2 years of life and can cause severe or even life-threatening disease in some at-risk infants. Treatment is limited and there is currently no safe or effective vaccine. However, a new monoclonal antibody, palivizumab, reduces RSV hospitalization by 55% in at-risk groups if given prophylactically throughout the RSV season.