Periostin and IFN-γ levels in serum and nasopharyngeal aspirate in infants with viral-induced wheezing - 2 year follow-up.

BACKGROUND: The present study assesses the immune response in children with viral-induced wheezing by examining the two factors-interferon-gamma (IFN-γ) and periostin in serum and nasopharyngeal aspirate (NPA). The aim was to find a pattern with the severity and frequency of wheezing episodes. METHODS: Sixty-nine infants (40 boys and 29 girls), with a mean age of 11.4±6 (2 - 23) months, hospitalized with a first or recurrent episode of bronchial obstruction were enrolled in this study. The serum and NPA concentrations of IFN-γ and periostin were assessed by ELISA methodology. Fifty of the children (72%) were followed for 2 years. RESULTS: We detected lower NPA IFN-γ production in boys, infants with atopic status, family history of asthma, and respiratory syncytial virus infection. Recurrent wheezing in children was associated with a twice lower concentration of IFN-γ in NPA compared to those with the first episode (7.1 vs. 14.8 pg/ml, p=0.05). Higher serum periostin level was established in children over 12 mo in the group of recurrent wheezers with persistent manifestations compared to those without symptoms during the follow-up (410.5 vs. 269.7 ng/ml, p = 0.03). Multivariate logistical regression model assessed high level of serum periostin, male gender, atopy, family history of asthma, and severity of the attack as significant risk factors for persistent compared to intermittent wheezing (r < sup > 2 < /sup > = 0.87, p = 0.04). CONCLUSIONS: Our results demonstrated that recurrent viral-induced wheezing is associated with decreased IFN-γ production and increased periostin response and their correlation with severity and persistence of symptoms were the main outcome measures.

The Prevalence and Genetic Characterization of Human Metapneumovirus in Bulgaria, 2016-2019.

INTRODUCTION: We investigated the prevalence of human metapneumovirus (hMPV) among patients with acute respiratory infections in Bulgaria, and performed genetic characterization of the F gene of these strains. METHODS: Nasopharyngeal swabs collected from patients of a range of ages were tested by using real-time PCR for 12 respiratory viruses. The F gene was sequenced, and phylogenetic and amino acid analyses of the F gene/protein were performed. RESULTS: A total of 1,842 patients were examined during a 3-year period; 1,229 patients (66.7%) were positive for at least one respiratory virus. hMPV was identified in 83 (4.5%) patient samples. Eleven (13%) of hMPV-positive patients were coinfected with another respiratory virus. The hMPV incidence rate in the 2016/2017, 2017/2018, and 2018/2019 winter seasons was 5.4, 5.4, and 3.1%, respectively. hMPV was mainly detected in specimens collected between January and May (89.2% of cases). The incidence of hMPV infection was highest (5.1%) among the youngest age-group (0-4 years), where hMPV was a causative agent in 8.1 and 4.8% of bronchiolitis and pneumonia cases, respectively. Among the patients aged ≥5 years, hMPV was detected in 2.2 and 3.2% of cases of pneumonia and central nervous system infections, respectively. Phylogenetic analysis of the F gene showed that the sequenced hMPV strains belonged to the A2b, B1, and B2 genotypes. Numerous amino acid substitutions were identified compared with the NL00/1 prototype strain. CONCLUSION: This study revealed the significant role of hMPV as a causative agent of serious respiratory illnesses in early childhood, and also demonstrated year-to-year changes in hMPV prevalence and genetic diversity in circulating strains.