| ObjectiveIn this study, in order to provide basic data and scientific evidence for the prevention and control of acute respiratory tract infection (ARTI), we investigated the common and potential viral etiological agent of ARTI among children in Lanzhou area. Meanwhile, we identified the pathogenesis of HBoV-2 in the respiratory tract infection.Subjects and Methods510 Nasopharyngea aspirates (NPAs) and throat swabs specimens were collected from children with acute respiratory infections and 290 specimes from healthy children from November 2008 to October 2009 in Lanzhou area of china.RSV, Influenza A and B, Parainflurnzal-3, HRV, HMPV, HCoV-NL63, HCoV-HKU1, HCoV-229E, HCoV-NL63, WUPyV and KIPyV were detected by RT-PCR and nest-PCR methods, and amplicons were identified by sequencing. Clinical and epidemiological analysis on acute respiratory tract infections among children which cause by diverse viruses were performed.The establishment of a case-control investigation:HBoV-1 and HBoV-2 were also tested by nested-PCR methods. The amplicons were identified by sequencing and the sequences were then used to search against those in the NCBI databases using Blast program. Meanwhile, The relatedness of HBoV-2 and newly identified Bocavirus to respiratory tract infection was also investigated in this study.Results1.382 samples were detected positive in 510 NPAs samples which were collected in 2008-2009 year and the total rate was 74.9%. Respectively, the rate of RSV was 31.4% (160/510), IFVA was 10.4%(53/510), IFVB was 4.9%(625/510), PIV3 was 16.1%(83/510), HRV was 9.4%(48/510), HMPV was 0.4%(16/510), HCoV-NL63 was 0.6%(3/510), HCoV-HKUl was 0.4%(2/510), WUPyV was 1.4%(7/510), KIPyV was 2.9%(15/510). PIV-1/-2 and HCoV-229E/OC43 were not detected. Among the 510 NPAs samples, the positive rate of samples collected from male patients was 58.3%(216/314) while that of samples from female cases was 55.5%(166/196). The ratio of male to female patients was 1.3:1. The median ages of the viruses infected patients was 28 months (range from 10 days to 14 years old).54.5%(208/510) children with viruses infection were under 1 year of age,18.1%(84/510) children were at age from 1 to 3 years,14.1%(54/510) children were at age from 3 to 5 years and 9.4%(36/510) children were older than 5 years old. The positive rate of virus detection decreased in accordance with the increasing of age. The detected rate had no significant difference among the age groups (P=0.989>0.05). There were remarkable seasonal distributions of viral respiratory tract infections in Lanzhou area, viral respiratory tract infections predominated in spring and winter.2. The detection rate of HBoV-2 was 1.4%(7/510). The positive amplicons were sequenced and then analyzed by using Blast program. The results showed that the sequences shared 98%～100% homology with Human bocavirus 2 strain HBOV2B-NI-213 in the NCBI nucleotide database except single insertions and mutations. It indicated that there was few diversity in the HBoV-2 Lanzhou isolates. The median ages of the viruses infected children was 8.5 months (range from 4 months to 65 months). All infected children except one were under 2 years old and interestingly all of them were male. The detected cases of viral respiratory tract infections were mainly during spring and winter, especially in December (3 cases). The cases of HBoV-2 usually coinfected with other viruses, mostly with RSV. Clinical symptoms included asthmatic bronchial pneumonia, acute bronchial pneumonia and acute bronchitis, especially asthmatic bronchial pneumonia (5 cases). The detection rate of HBOV-2 among the control children was 1.4%(4/290). The infected children of HBOV-2 were=6 months old. The samples detected positive were in March, May, June and August and the ratio of male to female were 3:1. The detection rate of HBOV-1 among the infected children was 14.3%(73/510) while it was 3.2% of healthy children.ConclusionsViral infection is the main reason of ALRTI of children in Lanzhou area and 74.9% of infected children were detected positive. RSV, PIV-3, HRV and IFVA are major causes of respiratory tract infections among children in this area. But there was a slightly different spectrum of respiratory tract infection representing the increasing of IFVA and PIV-3 infections comparing with that 2007-2008 year, and obvious seasonal distribution, especially in winter and spring.The relatedness of HBoV2 to respiratory tract infection:there was no significance in statistics (P>0.005, Fisher's Exact Test). It indicated that HBoV-2 has no relationship with respiratory tract infection. Whereas, The HBoV-1 is related to respiratory tract infection according to analysis in statistics (p<0.005, Pearson Chi-Square). The detection rate of infected children was higher than that of control cases. And HBoV-1 can cause respiratory tract infection.
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