The lack of association between CD14 genotypes and IgE as well as atopic outcomes in this large German study population seems to indicate that CD14 genotypes may not directly be involved in the development of allergies during childhood.

The objectives of this study were to investigate the prevalence of respiratory syncytial virus (RSV) infections in Bulgaria, to characterize the genetic diversity of the RSV strains, and to perform amino acid sequence analysis of the RSV G protein. Clinical, epidemiological data and nasopharyngeal swabs were prospectively collected from children aged less than 5 years presenting with acute respiratory infections from October 2016 to September 2018. Real‐time polymerase chain reaction for 12 respiratory viruses, and sequencing, phylogenetic, and amino acid analyses of the RSV G gene/protein were performed. Of the 875 children examined, 645 (73.7%) were positive for at least one viral respiratory pathogen. RSV was the most commonly detected virus (26.2%), followed by rhinoviruses (15%), influenza A (H3N2) (9.7%), adenoviruses (9%), bocaviruses (7.2%), human metapneumovirus (6.1%), parainfluenza viruses 1/2/3 (5.8%), influenza type B (5.5%), and A(H1N1)pdm09 (3.4%). The detection rate for RSV varied across two winter seasons (36.7% vs 20.3%). RSV‐B cases outnumbered those of the RSV‐A throughout the study period. RSV was the most common virus detected in patients with bronchiolitis (45.1%) and pneumonia (24%). Phylogenetic analysis indicated that all the sequenced RSV‐A strains belonged to the ON1 genotype and the RSV‐B strains were classified as BA9 genotype. Amino acid substitutions at 15 and 22 positions of the HVR‐2 were identified compared with the ON1 and BA prototype strains, respectively. This study revealed the leading role of RSV as a causative agent of serious respiratory illnesses in early childhood, year‐on‐year fluctuations in RSV incidence, the dominance of RSV‐B, and relatively low genetic diversity in the circulating RSV strains.

Acute lower respiratory infections (ALRIs) are a leading cause of morbidity and hospital admissions in children. This study aimed to determine the viral etiology of these infections in children aged < 5 years during three successive epidemic seasons in Bulgaria. Nasopharyngeal and throat specimens were collected from children with bronchiolitis and pneumonia during the 2015/ 2016, 2016/2017, and 2017/2018 seasons. The viral etiology was determined by individual real-time PCR assays against 11 respiratory viruses. Of the 515 children examined, 402 (78.1%) were positive for at least one virus. Co-infections with two and three viruses were found in 64 (15.9%) of the infected children. Respiratory syncytial virus (RSV) was the predominant pathogen (37.5%), followed by rhinoviruses (13.8%), metapneumovirus (9.1%), adenoviruses (7%), bocaviruses (7%), influenza A(H1N1)pdm09 (4.9%), A(H3N2) (4.3%), type B (4.1%), and parainfluenza viruses 1/2/3 (2.9%). RSV-B were more prevalent than RSV-A during the three seasons. At least one respiratory virus was identified in 82.6% and 70.1% of the children with bronchiolitis and pneumonia, respectively. Respiratory viruses, especially RSV, are principal pathogens of ALRIs in children aged < 5 years. Diagnostic testing for respiratory viruses using molecular methods may lead to the reduced use of antibiotics and may assist in measures to control infection.

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The respiratory syncytial virus (RSV) is a leading cause of acute respiratory illnesses (ARI) in infants and young children. The objectives of this study were to investigate the RSV circulation among children aged <5 years in Bulgaria, to identify the RSV-A and RSV-B genotypes and to perform an amino acid sequence analysis of second hypervariable region (HVR2) of the G gene. During the 2014/15 and 2015/16 winter seasons, nasopharyngeal specimens of 610 children aged <5 years with ARI were tested using Real Time RT-PCR for influenza viruses, RSV, metapneumovirus, parainfluenza viruses, rhinoviruses and adenoviruses. Viral respiratory pathogens were detected in 429 (70%) out of 610 patients examined and RSV was the most frequently identified virus (26%) followed by influenza A(H1N1)pdm09 virus (14%) (p < .05). RSV was the most prevalent pathogen in patients with bronchiolitis (48%) and pneumonia (38%). In the 2014/15 season, RSV-A dominated slightly (53%), while in the next season RSV-B viruses prevailed more strongly (66%). The phylogenetic analysis based on the G gene indicated that all 21 studied RSV-A strains belonged to the ON1 genotype; the vast majority (96%) of the RSV-B strains were classified into BA9 genotype and only one - into BA10 genotype. All Bulgarian RSV-A and RSV-B sequences contained a 72-nt and a 60-nt duplication in the HVR2, respectively. The study showed the leading role of this pathogen as a causative agent of serious respiratory illnesses in early childhood, year-on-year fluctuations in RSV incidence, a shift from RSV-A to RSV-B subgroup dominance and relatively low genetic divergence in the circulating strains.