Peng Fan, Mi Zhiqiang, Huang Yong, Yuan Xin, Niu Wenkai, Wang Yahui, Hua Yuhui, Fan Huahao, Bai Changqing, Tong Yigang
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China.
BMC Microbiol. 2014 Jul 5;14:181. doi: 10.1186/1471-2180-14-181.
With the use of broad-spectrum antibiotics, immunosuppressive drugs, and glucocorticoids, multidrug-resistant Acinetobacter baumannii (MDR-AB) has become a major nosocomial pathogen species. The recent renaissance of bacteriophage therapy may provide new treatment strategies for combatting drug-resistant bacterial infections. In this study, we isolated a lytic bacteriophage vB_AbaM-IME-AB2 has a short latent period and a small burst size, which clear its host's suspension quickly, was selected for characterization and a complete genomic comparative study.
The isolated bacteriophage vB_AbaM-IME-AB2 has an icosahedral head and displays morphology resembling Myoviridae family. Gel separation assays showed that the phage particle contains at least nine protein bands with molecular weights ranging 15-100 kDa. vB_AbaM-IME-AB2 could adsorb its host cells in 9 min with an adsorption rate more than 99% and showed a short latent period (20 min) and a small burst size (62 pfu/cell). It could form clear plaques in the double-layer assay and clear its host's suspension in just 4 hours. Whole genome of vB_AbaM-IME-AB2 was sequenced and annotated and the results showed that its genome is a double-stranded DNA molecule consisting of 43,665 nucleotides. The genome has a G + C content of 37.5% and 82 putative coding sequences (CDSs). We compared the characteristics and complete genome sequence of all known Acinetobacter baumannii bacteriophages. There are only three that have been sequenced Acinetobacter baumannii phages AB1, AP22, and phiAC-1, which have a relatively high similarity and own a coverage of 65%, 50%, 8% respectively when compared with our phage vB_AbaM-IME-AB2. A nucleotide alignment of the four Acinetobacter baumannii phages showed that some CDSs are similar, with no significant rearrangements observed. Yet some sections of these strains of phage are nonhomologous.
vB_AbaM-IME-AB2 was a novel and unique A. baumannii bacteriophage. These findings suggest a common ancestry and microbial diversity and evolution. A clear understanding of its characteristics and genes is conducive to the treatment of multidrug-resistant A. baumannii in the future.
随着广谱抗生素、免疫抑制药物和糖皮质激素的使用，多重耐药鲍曼不动杆菌（MDR-AB）已成为主要的医院病原体。噬菌体疗法的再度兴起可能为对抗耐药细菌感染提供新的治疗策略。在本研究中，我们分离出一种裂解性噬菌体vB_AbaM-IME-AB2，其潜伏期短且裂解量小，能迅速清除宿主菌悬液，我们选择对其进行特性鉴定和全基因组比较研究。
分离出的噬菌体vB_AbaM-IME-AB2具有二十面体头部，形态类似于肌尾噬菌体科。凝胶分离分析表明，噬菌体颗粒至少包含九条分子量在15 - 100 kDa之间的蛋白带。vB_AbaM-IME-AB2能在9分钟内吸附宿主细胞，吸附率超过99%，潜伏期短（20分钟）且裂解量小（62个噬菌斑形成单位/细胞）。它能在双层平板试验中形成清晰的噬菌斑，并在仅4小时内清除宿主菌悬液。对vB_AbaM-IME-AB2的全基因组进行了测序和注释，结果表明其基因组是一个由43,665个核苷酸组成的双链DNA分子。该基因组的G + C含量为37.5%，有82个推定的编码序列（CDS）。我们比较了所有已知鲍曼不动杆菌噬菌体的特性和全基因组序列。仅有三种已测序的鲍曼不动杆菌噬菌体AB1、AP22和phiAC-1，与我们的噬菌体vB_AbaM-IME-AB2相比，它们具有相对较高的相似性，覆盖率分别为65%、50%、8%。四种鲍曼不动杆菌噬菌体的核苷酸比对显示，一些CDS相似，未观察到明显的重排。然而，这些噬菌体菌株的某些部分是非同源的。
vB_AbaM-IME-AB2是一种新型且独特的鲍曼不动杆菌噬菌体。这些发现表明了共同的祖先以及微生物的多样性和进化。清楚了解其特性和基因有助于未来治疗多重耐药鲍曼不动杆菌。
