Genetic variability human respiratory syncytial virus subgroups A and B in Turkey during six successive epidemic seasons, 2009-2015

Abstract

Human respiratory syncytial virus (HRSV) is most important viral respiratory pathogen of acute lower respiratory tract infections in infants and young children worldwide. The circulating pattern and genetic characteristics in the HRSV attachment glycoprotein gene were investigated in Turkey during six consecutive seasons from 2009 to 2015. HRSVA was dominant in the all epidemic seasons except 2011-2012 season. Partial sequences of the HVR2 region of the G gene of 479 HRSVA and 135 HRSVB were obtained. Most Turkish strains belonged to NA1, ON1, and BA9, which were the predominant genotypes circulating worldwide. Although three novel genotypes, TR-A, TR-BA1, and TR-BA2, were identified, they were not predominant. Clinical data were available for 69 HRSV-positive patients who were monitored due to acute lower respiratory tract illness. There were no significant differences in the clinical diagnosis, hospitalization rates, laboratory findings and treatment observed between the HRSVA and HRSVB groups, and co-infections in this study. The major population afflicted by HRSV infections included infants and children between 13 and 24 months of age. We detected that the CB1, GB5, and THB strains clustered in the same branch with a bootstrap value of 100%. CB-B and BA12 strains clustered in the same branch with a bootstrap value of 65%. The BA11 genotype was clustered in the BA9 genotype in our study. The present study may contribute on the molecular epidemiology of HRSV in Turkey and provide data for HRSV strains circulating in local communities and other regions worldwide.

Keywords: G gene; Turkey; acute respiratory tract illness; human respiratory syncytial virus; novel genotypes.

Figure 1

HRSV positivity year‐based (2009‐2015)

Figure 2

Age distribution of HRSV‐positive samples

Figure 3

Year‐based (2009‐2015) weekly distribution of HRSV infections in Turkey

Figure 4

HRSV positivity according to the gender

Figure 5

Unrooted phylogenetic trees of HRSVA (A) and HRSVB (B) strains from the Turkey. The phylogenetic tree of HVR2 was constructed by the neighbour‐joining method using the substitution model nucleotide p‐distance, complete deletion for gap or missing data treatment, and 1000 replicates of bootstrap probabilities within Mega 6