The Evergreen State College, Olympia, WA, USA.
Virol J. 2011 Sep 7;8:430. doi: 10.1186/1743-422X-8-430.
Phage vB_EcoM_CBA120 (CBA120), isolated against Escherichia coli O157:H7 from a cattle feedlot, is morphologically very similar to the classic phage ViI of Salmonella enterica serovar Typhi. Until recently, little was known genetically or physiologically about the ViI-like phages, and none targeting E. coli have been described in the literature. The genome of CBA120 has been fully sequenced and is highly similar to those of both ViI and the Shigella phage AG3. The core set of structural and replication-related proteins of CBA120 are homologous to those from T-even phages, but generally are more closely related to those from T4-like phages of Vibrio, Aeromonas and cyanobacteria than those of the Enterobacteriaceae. The baseplate and method of adhesion to the host are, however, very different from those of either T4 or the cyanophages. None of the outer baseplate proteins are conserved. Instead of T4's long and short tail fibers, CBA120, like ViI, encodes tail spikes related to those normally seen on podoviruses. The 158 kb genome, like that of T4, is circularly permuted and terminally redundant, but unlike T4 CBA120 does not substitute hmdCyt for cytosine in its DNA. However, in contrast to other coliphages, CBA120 and related coliphages we have isolated cannot incorporate 3H-thymidine (3H-dThd) into their DNA. Protein sequence comparisons cluster the putative "thymidylate synthase" of CBA120, ViI and AG3 much more closely with those of Delftia phage φW-14, Bacillus subtilis phage SPO1, and Pseudomonas phage YuA, all known to produce and incorporate hydroxymethyluracil (hmdUra).
Phage vB_EcoM_CBA120 (CBA120)，分离自牛饲料场的大肠杆菌 O157:H7，在形态上与沙门氏菌肠炎血清型 Typhi 的经典噬菌体 ViI 非常相似。直到最近，人们对这种类似 ViI 的噬菌体在遗传和生理上的了解还很少，文献中也没有描述针对大肠杆菌的噬菌体。CBA120 的基因组已被完全测序，与 ViI 和志贺氏菌噬菌体 AG3 高度相似。CBA120 的核心结构和复制相关蛋白与 T-偶数噬菌体的同源，但与弧菌、气单胞菌和蓝藻的 T4 样噬菌体的同源性通常高于肠杆菌科的噬菌体。然而，基板和与宿主的粘附方式与 T4 或蓝藻噬菌体的非常不同。没有一个外基板蛋白是保守的。与 T4 不同，CBA120 像 ViI 一样，编码与通常在 Podoviruses 上看到的尾刺相关的长而短的尾纤维。与 T4 一样，158kb 的基因组是圆形排列和末端冗余的，但与 T4 不同的是，CBA120 不会在其 DNA 中用 hmdCyt 替代胞嘧啶。然而，与其他 coli 噬菌体不同，CBA120 和我们分离的相关 coli 噬菌体不能将 3H-胸腺嘧啶 (3H-dThd) 掺入其 DNA 中。蛋白序列比较将 CBA120、ViI 和 AG3 的假定“胸苷酸合酶”聚类与 Delftia 噬菌体 φW-14、枯草芽孢杆菌噬菌体 SPO1 和 Pseudomonas 噬菌体 YuA 的聚类更为接近，这些噬菌体都已知能产生并掺入羟甲基尿嘧啶 (hmdUra)。
