RNA and Sugars, Unique Properties of Bacteriophages Infecting Multidrug Resistant Acinetobacter radioresistens Strain LH6

Bacteriophages (phages) are predicted to be the most ubiquitous biological entity on earth, and yet, there are still vast knowledge gaps in our understanding of phage diversity and phage–host interactions. Approximately one hundred Acinetobacter-infecting DNA viruses have been identified, and in this report, we describe eight more. We isolated two typical dsDNA lytic podoviruses (CAP1–2), five unique dsRNA lytic cystoviruses (CAP3–7), and one dsDNA lysogenic siphovirus (SLAP1), all capable of infecting the multidrug resistant isolate Acinetobacter radioresistens LH6. Using transmission electron microscopy, bacterial mutagenesis, phage infectivity assays, carbohydrate staining, mass-spectrometry, genomic sequencing, and comparative studies, we further characterized these phages. Mutation of the LH6 initiating glycosyltransferase homolog, PglC, necessary for both O-linked glycoprotein and capsular polysaccharide (CPS) biosynthesis, prevented infection by the lytic podovirus CAP1, while mutation of the pilin protein, PilA, prevented infection by CAP3, representing the lytic cystoviruses. Genome sequencing of the three dsRNA segments of the isolated cystoviruses revealed low levels of homology, but conserved synteny with the only other reported cystoviruses that infect Pseudomonas species. In Pseudomonas, the cystoviruses are known to be enveloped phages surrounding their capsids with the inner membrane from the infected host. To characterize any membrane-associated glycoconjugates in the CAP3 cystovirus, carbohydrate staining was used to identify a low molecular weight lipid-linked glycoconjugate subsequently identified by mutagenesis and mass-spectrometry as bacterial lipooligosaccharide. Together, this study demonstrates the isolation of new Acinetobacter-infecting phages and the determination of their cell receptors. Further, we describe the genomes of a new genus of Cystoviruses and perform an initial characterization of membrane-associated glycoconjugates.

НОВЫЙ ПАТОГЕН ACINETOBACTER RADIORESISTENS - ПРИЧИНА МАССОВОГО ПАДЕЖА БРОЙЛЕРОВ Йылдырым Е.А., Лаптев Г.Ю., Новикова Н.И., Тюрина Д.Г., Ильина Л.А., Дубровин А.В., Тарлавин Н.В., Филиппова В.А.

КЛЮЧЕВЫЕ СЛОВА: БРОЙЛЕРЫ, ИНФЕКЦИОННЫЕ БАКТЕРИАЛЬНЫЕ БОЛЕЗНИ ПТИЦ, МОЛЕКУЛЯРНО-ГЕНЕТИЧЕСКИЕ МЕТОДЫ АНАЛИЗА, ACINETOBACTER RADIORESISTENS, АНТИБИОТИКОРЕЗИСТЕНТНОСТЬ АННОТАЦИЯ: В ООО «БИОТРОФ» обратились специалисты одной из птицефабрик для помощи в идентификации возбудителя вторичной бактериальной инфекции бройлеров, возникшей на фоне ослабления иммунитета вирусной этиологии. Заболевание достигло масштабов эпизоотии, приведя к массовому падежу птицы. При патологоанатомическом вскрытии павших цыплят на птицефабрике отмечали поражения печени, сердца, яйцеводов, которые были симптомами острой фазы заболевания, более поздними симптомами были аэросаккулиты. Причиной заболевания явилась вторичная бактериальная инфекция, протекающая по типу септицемии. Системная инфекция была связана с иммуносупрессивным состоянием. В молекулярно-биологической лаборатории компании был проведен анализ патологического материала от птиц и образцов кормов, а также кормовых добавок методом NGS-секвенирования; выявлен патоген, которым оказался Acinetobacter radioresistens. Приводится характеристика патогена и его распространенности, возможные пути заражения им птицы и птицепродуктов; предлагаются возможные стратегии борьбы с ним.

Intestinal Microbiota of Grass Carp Fed Faba Beans: A Comparative Study

Many reports of the intestinal microbiota of grass carp have addressed the microbial response to diet or starvation or the effect of microbes on metabolism; however, the intestinal microbiota of crisp grass carp has yet to be elucidated. Moreover, the specific bacteria that play a role in the crispiness of grass carp fed faba beans have not been elucidated. In the present study, 16S sequencing was carried out to compare the intestinal microbiota in the fore-, mid- and hind-intestine segments of grass carp following feeding with either faba beans or formula feed. Our results showed that (1) the hind-intestine presented significant differences in diversity relative to the fore- or midintestine and (2) faba beans significantly increased the diversity of intestinal microbiota, changed the intestinal microbiota structure (Fusobacteria was reduced from 64.26% to 18.24%, while Proteobacteria was significantly increased from 17.75% to 51.99%), and decreased the metabolism of energy, cofactors and vitamins in grass carp. Furthermore, at the genus and species levels, Acinetobacter accounted for 15.09% of the microbiota, and Acinetobacter johnsonii and Acinetobacter radioresistens constituted 3.41% and 2.99%, respectively, which indicated that Acinetobacter of the family Moraxellaceae contributed to changes in the intestinal microbiota structure and could be used as a potential biomarker. These results may provide clues at the intestinal microbiota level to understanding the mechanism underlying the crispiness of grass carp fed faba beans.