| Summary: | 碩士 === 國立臺灣海洋大學 === 生物科技研究所 === 96 === Abstract
Human bocavirus (HBoV) , a new member of the genus Bocavirus in the family Parvoviridae, was first detected in 2005 in nasopharyngeal aspirates of a children under 2-years old with respiratory tract infection. Later studies have shown that HBoV can also be found in other respiratory secretion, blood, and fecal samples. It is prevalent in children world-wide with prevalence of 1.5%~18.3%. This non-random distribution in paitent of respirtory tract and gastrointestinal suggested that HBoV is a likely causative agent of respiratory tract infection and gastroenteritis. Due to the lack of information regarding to HBoV infection in Taiwan so far, we try to investigate the epidemiology and phylogeny of HBoV in Taiwan.
Thirty were found to be HBoV positive among 531 samples (30/531; 5.62%) collected from Ping-Tong Christian Hospital. Of those positive cases 56.67% at the age less than 2 years old and the youngest HBoV positive individual was 40 days of age at the time that the respiratory specimen was obtained. HBoV was detected from Octorber, 2006 to March, 2007, the highest positive rate peaked in October (11.1%).
13 HBoV positive samples tested negative for influenza A and B viruses, parainfluenza virus type1, 2, 3, respiratory syncytial virus, adenovirus, human metapneumovirus, and 3 human coronaviruses (229E, OC43, and NL63) were selected to amplify their full genome sequences. The 5.2kb genome of HBoV contains 3 ORFs encoding NS1, NP1, and VP1/VP2 three genes. Sequences comparison showed high similarity among different isolates( similarity over 98% ).
Likelihood-mapping analysis suggested that each ORF may have some “unresolved” phylogenetic signal and VP1 is the best region to construct phylogenetic trees. Phylogenetic trees constructed by neighbor -joining, maximum likelihood, and Bayesian inference methods showed a similarity topology. There are no corelationship among geographical distribution and genotype. A monophyletic group with longer branch length consists of Taiwanese HBoV isolates implied that this virus might have circulated in Taiwan for a certain period. Furthermore, we also found some HBoV strains might have gone recombination.
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