RESUMO
The purpose was to discuss the infection status of human parainfluenza virus type 3 (HPIV-3) in children with acute respiratory tract infection(ARTI) in Qingdao, Shandong province, and to analyze the gene characteristics of HPIV-3 hemagglutinin-neuraminidase protein (HN). This study was a cross-sectional study. A total of 1 674 throat swab samples were collected randomly from children with ARTI, in the three hospitals (Qingdao Women and Children's Hospital, West Coast Branch of Affiliated Hospital of Qingdao University, Laoshan Branch of Affiliated Hospital of Qingdao University) from January 2018 to December 2019. Multiplex real-time fluorescence RT-PCR was performed to screen HPIV-3 positive specimens. For HPIV-3 positive specimens, nested PCR was used to amplify the full-length HN gene of HPIV-3. The HN gene was sequenced and compared with the representative strains of HPIV-3 in GenBank, and the phylogenetic tree was established. As results, this study collected 1 674 samples, in which there were 90 HPIV-3 positive samples showed and the detection rate was 5.37%. Among positive specimens, the number of samples from children under 6 years old was 88, accounting for 97.78%. HPIV-3 positive cases were mainly distributed in spring and summer. The full-length sequences of 44 HPIV-3 HN genes were obtained by nested PCR method. Sequence alignment and evolutionary analysis showed that the HPIV-3HN gene belonged to the C3a and C3b branches of C3 genotype, with 30 strains of subtype C3a and 14 strains of subtype C3b. The nucleotide and amino acid homology of the amplified 44 strains of the HPIV-3 HN gene in Qingdao were 97.0%-100.0% and 98.5%-100.0%, respectively. In conclusion, from 2018 to 2019, the C3a and C3b branches of HPIV-3 C3 genotype were circulating prevalent in Qingdao, Shandong province. HN gene variation rate was low, but showed certain regional characteristics in evolution.
