Objective       To investigate the biological characteristics of mycobacteriophage Legendre and explore its anti-drug-resistant tuberculosis potentials.       Methods       Plaque morphological properties of Legendre were observed by double-layer plating

and the ultrastructure of Legendre was obser

ved by electron microscopy. The genome of Legendre was extracted and the type of nucleic acid was identified with restriction enzyme analysis. Legendre was amplified by double-layer agar plate method in different multiplicity of infection (MOI) to find the optimal MOI and the lowest MOI. One step growth experiment was carried out to find the latent period

burst period and burst size of Legendre. The rabbits were immunized with purified Legendre particles to prepare anti-Legendre serum and cross neutralization test was performed to examine the reaction constant K values of Legendre and other 8 phages. The host range of Legendre was examined by single-spot examination. The effect of UV ray

temperature

chloroform

alcohol

pH values on Legendre survival was surveyed.       Results       The plaques of Legendre were transparent and their sizes were about 1 mm in the diameter. There was an isometric head with an average diameter of about 65 nm and a long tail with an average length of about 215 nm in Legendre. Legendre was digested by restriction endonuclease EcoRⅠ

Hind Ⅲ and BamHⅠ and the size of genome was about 65 kb. The optimal and lowest MOI of Legendre are 10

-4

and 10

-3

respectively. Legendre was extremely susceptible to Mycobacterium smegmatis. The latent period was 180 min

the burst period was 120 min

and the burst size was 13. The K value of Legendre was 697. Legendre

TM4 and D29 were affinity low. Legendre lyzed Mycobacterium smegmatis

Mycobaterium tuberculosis H

37

Rv and the majority of clinical drug-resistant strains. Legendre was unstable to UV ray

temperature

chloroform

alcohol and pH values.       Conclusion       Legendre is a suitable broad host range and low antigenicity siphoviridae phage which could be used in phage therapy to treat drug-resistant tuberculosis.