Unemo Magnus, Olcén Per, Jonasson Jon, Fredlund Hans
National Reference Laboratory for Pathogenic Neisseria, Department of Clinical Microbiology, Orebro University Hospital, SE-701 85 Orebro, Sweden.
J Clin Microbiol. 2004 Jul;42(7):2926-34. doi: 10.1128/JCM.42.7.2926-2934.2004.
For prevention and control of gonorrhea, an objective, highly discriminating, and reproducible molecular epidemiological characterization of Neisseria gonorrhoeae is essential. In the present study, in pursuance of providing such qualities, pyrosequencing technology, a fast real-time DNA sequence analysis, was applied to six short, highly polymorphic porB gene segments, with subsequent genetic variant (genovar) determination of the bacterial isolates. The sequencing templates were obtained by real-time PCR amplification, which also included fluorescence melting curve analysis of the entire porB gene in order to determine the genogroup (porB1a or porB1b allele) prior to pyrosequencing analysis. The PSQ 96 MA system used allowed rapid (in approximately 1.5 h) determination of 96 sequences of 20 to 65 correct nucleotides each. The results were reproducible and mostly in concordance with the results of conventional Sanger dideoxy sequencing, with the exception of shorter read lengths and some uncertainty in determining the correct number of identical nucleotides in homopolymeric segments. The number of sequence variants identified in each of the six highly polymorphic segments of the porB1a and porB1b alleles (encoding surface-exposed amino acid loops of the mature PorB protein) ranged from 5 to 11 and from 8 to 39, respectively. Among porB1a isolates (n = 22) and porB1b isolates (n = 65), 22 and 64 unique genovars, respectively, were identified. All isolates were typeable. The present results provide evidence of a high discriminatory ability, practically the same as that for sequencing of the entire porB gene. In conclusion, the fast and high-throughput pyrosequencing technology can be used for molecular epidemiological characterization of N. gonorrhoeae.
为了预防和控制淋病,对淋病奈瑟菌进行客观、高度区分且可重复的分子流行病学特征分析至关重要。在本研究中,为了具备这些特性,焦磷酸测序技术这一快速实时DNA序列分析方法被应用于六个短的、高度多态性的porB基因片段,随后对细菌分离株进行基因变异(基因变种)测定。测序模板通过实时PCR扩增获得,其中还包括对整个porB基因的荧光熔解曲线分析,以便在焦磷酸测序分析之前确定基因群(porB1a或porB1b等位基因)。所使用的PSQ 96 MA系统能够快速(约1.5小时)测定96个序列,每个序列有20至65个正确核苷酸。结果具有可重复性,并且大多与传统桑格双脱氧测序结果一致,只是读取长度较短,并且在确定同聚物片段中相同核苷酸的正确数量时存在一些不确定性。在porB1a和porB1b等位基因的六个高度多态性片段中(编码成熟PorB蛋白的表面暴露氨基酸环),每个片段鉴定出的序列变异数量分别为5至11个和8至39个。在porB1a分离株(n = 22)和porB1b分离株(n = 65)中,分别鉴定出22个和64个独特的基因变种。所有分离株均可分型。目前的结果证明了该方法具有很高的区分能力,几乎与整个porB基因测序的区分能力相同。总之,快速且高通量的焦磷酸测序技术可用于淋病奈瑟菌的分子流行病学特征分析。