title: Molecular characteristics of the ompA gene of serotype B Chlamydia trachomatis in Qinghai Tibetan primary school students.
abstract: To study the molecular characteristics of Chlamydia trachomatis, the major outer membrane protein gene (ompA) of C. trachomatis from primary school students with trachoma residing in the Qinghai Tibetan area was sequenced and compared with the same serotype in GenBank. In Jianshetang Primary School and Galeng Central Primary School in the Galeng Tibetan Township of Qinghai Haidong Sala Autonomous County, scraped samples were collected from the upper tarsal conjunctiva and lower conjunctival sac of both eyes of 45 students with trachoma, stored at 4°C, and transported to Beijing Tongren Hospital by air within 24 h. The samples were screened for C. trachomatis by real-time PCR. The ompA gene from the C. trachomatis-positive samples was amplified by nested PCR. The serotype was confirmed by National Center for Biotechnology Information (NCBI) BLAST search and homology analysis. The entire ompA gene sequence was compared with the corresponding gene sequences of serotype B strains available in GenBank. Of the 45 students aged 6-13 years with trachoma, 26 C. trachomatis-positive students were identified by the initial real-time PCR screening (average age, (9.09±1.63) years; sex ratio, 1.0), accounting for 57.78% (26/45). The cycle threshold values for real-time PCR were 16.79-37.77. Half (13/26) of C. trachomatis-positive students had a bacterial copy number of >10(5). The compliance rate of the ompA gene sequences with the C. trachomatis serotype B strains in GenBank was up to 99%. Two novel genetic mutations were found when the ompA gene was compared with those of the 11 serotype B strains in GenBank. The two non-synonymous mutations were located at (i) position 271 in the second constant domain, an adenine (A) to guanine (G) substitution (ACT→GCT), changing the amino acid at position 91 from threonine to alanine (Thr→Ala) in all 26 strains; and (ii) position 887 in the fourth variable domain, a cytosine (C) to thymine (T) substitution (GCA→GTA), changing the amino acid at residue 296 from alanine to valine (Ala→Val) in four of the 26 strains. Six mutations were identified relative to ATCC VR-573. The strains could be divided into two gene clusters according to the mutation at nucleotide position 887: CQZ-1 (China Qinghai Tibetan-1) and CQZ-2 (China Qinghai Tibetan-2). We thus detected two novel serotype B mutant strains of C. trachomatis among study subjects with trachoma.
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Shaoya
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Liang
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China.
authors.forename: Ailian
authors.initials: A
authors.lastname: Hu
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Xiuyuan
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Benshan
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Mingxin
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China.
authors.forename: Ningli
authors.initials: N
authors.lastname: Wang
authors.affiliation: Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Lu
mesh_terms: D000293:Adolescent; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D002648:Child; D002692:Chlamydia trachomatis / Q000145:classification / Q000235:genetics*; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D008297:Male; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D012574:Schools; D013334:Students; D018609:Tibet
chemical_list: D001425:Bacterial Outer Membrane Proteins; C078167:OMPA outer membrane proteins
keywords: Chlamydia trachomatis; homology analysis; major outer membrane protein gene; sequencing