The Broad-Spectrum Endolysin LySP2 Improves Chick Survival after Pullorum Infection.

pullorum causes typical "Bacillary White Diarrhea" and loss of appetite in chicks, which leads to the death of chicks in severe cases; thus, it is still a critical issue in China. Antibiotics are conventional medicines used for infections; however, due to the extensive long-term use and even abuse of antibiotics, drug resistance becomes increasingly severe, making treating pullorum disease more difficult. Most of the endolysins are hydrolytic enzymes produced by bacteriophages to cleave the host's cell wall during the final stage of the lytic cycle. A virulent bacteriophage, YSP2, of was isolated in a previous study. A expression strain that can express the bacteriophage endolysin was constructed efficiently, and the Gram-negative bacteriophage endolysin, LySP2, was obtained in this study. Compared with the parental phage YSP2, which can only lyse , LySP2 can lyse and . The survival rate of -infected chicks treated with LySP2 can reach up to 70% and reduce abundance in the liver and intestine. The treatment group showed that LySP2 significantly improved the health of infected chicks and alleviated organ damage caused by infection. In this study, the bacteriophage endolysin was expressed efficiently by , and the endolysin LySP2 showed good potential for the treatment of pullorum disease caused by pullorum.