Abstract
Нuman bocaviruses (hBoVs) are often associated with acute respiratory infections (ARIs). Information on the distribution and molecular epidemiology of hBoVs in Bulgaria is currently limited. The objectives of this study were to investigate the prevalence and genetic characteristics of hBoVs detected in patients with ARIs in Bulgaria. From October 2016 to September 2019, nasopharyngeal/oropharyngeal swabs were prospectively collected from 1842 patients of all ages and tested for 12 common respiratory viruses using a real-time RT-PCR. Phylogenetic and amino acid analyses of the hBoV VP1/VP2 gene/protein were performed. HBoV was identified in 98 (5.3%) patients and was the 6th most prevalent virus after respiratory-syncytial virus (20.4%), influenza A(H1N1)pdm09 (11.1%), A(H3N2) (10.5%), rhinoviruses (9.9%), and adenoviruses (6.8%). Coinfections with other respiratory viruses were detected in 51% of the hBoV-positive patients. Significant differences in the prevalence of hBoVs were found during the different study periods and in patients of different age groups. The detection rate of hBoV was the highest in patients aged 0–4 years (6.9%). In this age group, hBoV was the only identified virus in 9.7%, 5.8%, and 1.1% of the children diagnosed with laryngotracheitis, bronchiolitis, and pneumonia, respectively. Among patients aged ≥5 years, hBoV was detected as a single agent in 2.2% of cases of pneumonia. Phylogenetic analysis showed that all Bulgarian hBoV strains belonged to the hBoV1 genotype. A few amino acid substitutions were identified compared to the St1 prototype strain. This first study amongst an all-age population in Bulgaria showed a significant rate of hBoV detection in some serious respiratory illnesses in early childhood, year-to-year changes in the hBoV prevalence, and low genetic variability in the circulating strains.
Highlights
Acute respiratory infections (ARIs) are associated with a huge number of disease cases, outpatient visits, and hospitalizations and significant medical and social costs, representing a significant burden on healthcare systems and society as a whole
Reinfections occur throughout life, which explains the high seroprevalence in older individuals. e detection rate of Human bocaviruses (hBoVs)-DNA in patients with ARI varies from 1.5% to 33% in different countries and studies [3, 7]
Previous studies examining the prevalence of respiratory viruses in the country have focused on children less than 5 years old, and data are absent for the prevalence of hBoVs among patients over the entire age range. ere were no data on the genetic characteristics of these viruses [12, 13]. e objectives of this study were to investigate the prevalence and circulation pattern of hBoVs among patients of all ages presenting with ARI symptoms and to perform genetic/ amino acid sequence analyses of the VP1/VP2 gene/protein of hBoV strains
Summary
Acute respiratory infections (ARIs) are associated with a huge number of disease cases, outpatient visits, and hospitalizations and significant medical and social costs, representing a significant burden on healthcare systems and society as a whole. Despite the fact that hBoV1 is detected in asymptomatic individuals and is a frequent participant in coinfections, this virus has been accepted in a large number of studies as a true cause of upper and lower respiratory tract infections, including infections among hospitalized patients [7, 10, 11]. Previous studies examining the prevalence of respiratory viruses in the country have focused on children less than 5 years old, and data are absent for the prevalence of hBoVs among patients over the entire age range. E objectives of this study were to investigate the prevalence and circulation pattern of hBoVs among patients of all ages presenting with ARI symptoms and to perform genetic/ amino acid sequence analyses of the VP1/VP2 gene/protein of hBoV strains Previous studies examining the prevalence of respiratory viruses in the country have focused on children less than 5 years old, and data are absent for the prevalence of hBoVs among patients over the entire age range. ere were no data on the genetic characteristics of these viruses [12, 13]. e objectives of this study were to investigate the prevalence and circulation pattern of hBoVs among patients of all ages presenting with ARI symptoms and to perform genetic/ amino acid sequence analyses of the VP1/VP2 gene/protein of hBoV strains
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