Oahs gene deleted strain and application thereof in prevention of streptococcus suis type 2 infection

The invention is applicable to the technical field of gene engineering, and provides an oahs gene deletion strain and application thereof in prevention of streptococcus suis type 2 infection, the oahs gene deletion strain prepared by the invention, namely SC19-delta OAHS, has very low toxicity and is basically a non-toxic strain; when a large dose of the mutant strain viable bacteria is used for immunizing mice, the mice are basically not infected and damaged, and the titer of antibodies in the mice is obviously increased under the assistance of an adjuvant, so that targeted immune protection can be successfully established; after a normal immune procedure, the established immune protection can help the mouse to effectively resist infection of streptococcus suis type 2, and the death rate and in-vivo bacterial colonization are reduced; the preparation method of the SC19-delta OAHS is simple, the SC19-delta OAHS can be prepared in a short time, the culture is simple, the SC19-delta OAHS serving as a vaccine do