Objective  To understand the biological characteristics of three Brucella phages A1, NMY-1 and NMY-2 isolated from Inner Mongolia autonomous region.

  Methods  The phages were purified and proliferated using double layer plate method, the characteristics of the plaques were observed, and the titers were determined, and transmission electron microscopy was used to observe the morphology of the phages. The phage host-range, optimal multiplicity of infection (MOI), one-step growth curve and physicochemical stability were determined using double layer plate method and drop method.

  Results  All three phages in this study had icosahedral structures with a head diameter of 61.0 nm–65.6 nm and a short tail of 16.5 nm–19.2 nm, which were observed by electron microscopy; At the routine test dilution (RTD) and 10⁴×RTD, bacteriophage A1 and NMY-1 could lyse smooth B. abortus, B. melitensis, B. suis and B. neotomae, NMY-2 could lyse rough B. abortus, B. melitensis and B. canis, and at high concentration (10⁴×RTD), the number of strains that could be lysed by three phages increased; the MOIs of A1, NMY-1, and NMY-2 were 0.1, 0.001, and 0.01, respectively; one-step growth curve results showed that A1 and NMY-2 had a latency of about 30–60 min, an outbreak period of 20–40 min, and an outbreak amount of 2210 PFU/cell and 6000 PFU/cell, respectively, and the latency and outbreak period of NMY-1 were longer, with 600 min and 420 min, respectively, with an outbreak amount of 1.90×10⁵ PFU/cell. The three phages maintained good activity at 40– 60 ℃, pH of 2–13 and ultraviolet irradiation for 30 min.

  Conclusion  The biological characteristics and attributes of phages A1, NMY-1 and NMY-2 were clarified, and the phage typing system of Brucella was enriched, which can provide more choice for phage therapy in the treatment of drug-resistant Brucella infection.