Yehle C O, Doi R H
J Virol. 1967 Oct;1(5):935-47. doi: 10.1128/JVI.1.5.935-947.1967.
Two antigenically distinct bacteriophages, beta3 and beta22, have been isolated and characterized with Bacillus subtilis strain W23 as a host. They differ in plaque morphology, single-step growth characteristics, host range, and thermal stability. The deoxyribonucleic acids isolated from beta3 and beta22 differ in base composition, density in CsCl and Cs(2)SO(4), sedimentation coefficient, molecular weight, and thermal denaturation temperature. These phages have been used to analyze the ability of B. subtilis to sporulate despite infection by virulent phages. When development of phages beta3 and beta22 in sporulating cultures was compared with that in log cultures, an increase in the latent periods of infection and a decrease in the burst sizes for the two phages were observed. Sporulating cultures infected with beta3 yielded the usual percentage (85%) of mature spores; 80% of these contained phage determinants and 20% were uninfected. However, cultures infected with beta22 lysed. Of the small fraction (0.01%) which sporulated, 83% were uninfected and 17% were infected. Phage beta3-infected and uninfected spores were examined to distinguish any chemical or physical differences. Preparations of both types of spore contained 81.4 mug of dipicolinic acid per mg (dry weight), and examination by phase-contrast microscopy gave no evidence of any difference in outward appearance. A 20% decrease in infected spore count was observed upon heating at 80 C for 10 min. Differences in the infection processes of the two phages prompted an analysis of the transcription process after infection. Deoxyribonucleic acid-ribonucleic acid hybrid analysis of relative amounts of phage-specific and host-specific messenger ribonucleic acid (mRNA) present in infected cells suggested that beta3 was unable to repress the synthesis of host mRNA and that beta3-specific mRNA synthesis was repressed in sporulation-phase cultures. Phage beta22, in contrast, was able to repress host-specific mRNA synthesis in both log-infected and sporulation-infected cells. The results suggest that the differential expression of the phage genomes is due to the relative ability of the phages to repress the host genome.
已分离出两种抗原性不同的噬菌体β3和β22，并以枯草芽孢杆菌W23菌株作为宿主对其进行了特性鉴定。它们在噬菌斑形态、一步生长特性、宿主范围和热稳定性方面存在差异。从β3和β22中分离出的脱氧核糖核酸在碱基组成、在CsCl和Cs₂SO₄中的密度、沉降系数、分子量以及热变性温度方面均有所不同。这些噬菌体已被用于分析枯草芽孢杆菌在受到烈性噬菌体感染时形成芽孢的能力。当将噬菌体β3和β22在芽孢形成培养物中的生长情况与对数期培养物中的生长情况进行比较时，观察到这两种噬菌体的感染潜伏期延长，裂解量减少。感染β3的芽孢形成培养物产生了通常比例（85%）的成熟芽孢；其中80%含有噬菌体决定簇，20%未被感染。然而，感染β22的培养物发生了裂解。在少量（0.01%）形成芽孢的培养物中，83%未被感染，17%被感染。对噬菌体β3感染和未感染的芽孢进行了检查，以区分任何化学或物理差异。两种类型芽孢的制剂每毫克（干重）均含有81.4微克吡啶二羧酸，相差显微镜检查未发现外观上有任何差异。在80℃加热10分钟后，观察到感染芽孢的数量减少了20%。两种噬菌体感染过程的差异促使对感染后的转录过程进行分析。对感染细胞中噬菌体特异性和宿主特异性信使核糖核酸（mRNA）相对含量的脱氧核糖核酸-核糖核酸杂交分析表明，β3无法抑制宿主mRNA的合成，并且在芽孢形成期培养物中β3特异性mRNA的合成受到抑制。相比之下，噬菌体β22在对数期感染和芽孢形成期感染的细胞中均能够抑制宿主特异性mRNA的合成。结果表明，噬菌体基因组的差异表达是由于噬菌体抑制宿主基因组的相对能力不同所致。
