Isolation and identification of virulent bacteriophage to Riemerella anatipestifer.

To explore a biological therapy for Riemerella anatipestifer infection,healthy Muscovy duck feces were examined by using an enrichment method.A virulent bacteriophage to R.anatipestifer,RAP15,was isolated.The phage was only specific for two isolated strains,RAf63 and RAf71 of R.anati-pestifer,indicating its host range was narrow.Examination by transmission electron microscopy revealed that the phage had an isometric head(55 nm in diameter) and a long non-contractile tail(approximately 200 nm in length).Phage RAP15 nucleic acid could be digested with DNaseⅠbut neither with RNase A nor mung bean nuclease,indicating that its DNA was double-stranded.Studies of the morphology and molecular characteristics of phage showed that RAP15 may represent a member of the Siphoviridae family.