Pasteurella multocida(Pm)type A is an important pathogen responsible for respiratory diseases,such as bovine pneumonia,which seriously restricts the development of cattle industry in China.Currently,the prevention of Pm infection-related diseases primarily relies on vaccination in production.However,the diverse Pm serotypes result in inadequate cross-immunological protection from vaccines.Therefore,it is of great significance to develop vaccines with cross-protection for the prevention and control of Pm infectious diseases.The previous studies conducted by our team have demonstrated that PmCQ2△cra exhibits a strong immune protective effect against Pm type A(PmA),Pm type B(PmB),and Pm type F(PmF).Transcriptomic sequencing results suggest that the cross-immunoprotective effect of PmCQ2△cra may be attributed to high expression levels of bacterial surface protective antigens.Consequently,four putative immune protective antigens,namely PmCQ2-5175,PmCQ2-6290,PmCQ2-0275 and PmCQ2-2640,were screened through bioin-formatics analysis in this study.Subunit vaccines formulated with these potential antigenic proteins exhibited protective efficacy of 62.5％,25％,12.5％and 10％against PmA-infected mice,respectively.Importantly,PmCQ2-5175,one of the most protective single-component antigen vac-cines,demonstrating a 75％cross-protection against PmB infection in mice.Furthermore,the pro-tective efficacy of the PmCQ2-5175 protein screened in this study was superior to that of the previ-ously reported Pm antigen protein plpE.Moreover,the fusion expression protein PmCQ2-5175-PLPE exhibited better protective effects against PmA compared to a single protein.The findings of this study will establish a theoretical foundation for the advancement of Pm subunit vaccines with broad-spectrum immune protection.

Pasteurella multocida(Pm)type A is an important pathogen responsible for respiratory diseases,such as bovine pneumonia,which seriously restricts the development of cattle industry in China.Currently,the prevention of Pm infection-related diseases primarily relies on vaccination in production.However,the diverse Pm serotypes result in inadequate cross-immunological protection from vaccines.Therefore,it is of great significance to develop vaccines with cross-protection for the prevention and control of Pm infectious diseases.The previous studies conducted by our team have demonstrated that PmCQ2△cra exhibits a strong immune protective effect against Pm type A(PmA),Pm type B(PmB),and Pm type F(PmF).Transcriptomic sequencing results suggest that the cross-immunoprotective effect of PmCQ2△cra may be attributed to high expression levels of bacterial surface protective antigens.Consequently,four putative immune protective antigens,namely PmCQ2-5175,PmCQ2-6290,PmCQ2-0275 and PmCQ2-2640,were screened through bioin-formatics analysis in this study.Subunit vaccines formulated with these potential antigenic proteins exhibited protective efficacy of 62.5％,25％,12.5％and 10％against PmA-infected mice,respectively.Importantly,PmCQ2-5175,one of the most protective single-component antigen vac-cines,demonstrating a 75％cross-protection against PmB infection in mice.Furthermore,the pro-tective efficacy of the PmCQ2-5175 protein screened in this study was superior to that of the previ-ously reported Pm antigen protein plpE.Moreover,the fusion expression protein PmCQ2-5175-PLPE exhibited better protective effects against PmA compared to a single protein.The findings of this study will establish a theoretical foundation for the advancement of Pm subunit vaccines with broad-spectrum immune protection.

Trueperella pyogenes(TP),an important livestock and poultry pathogen,can cause vari-ous diseases such as suppurative pneumonia,arthritis,and mastitis in animals.The newly brought calves of one cattle farm occurred respiratory diseases and accompanied death in Yunyang,Chongqing,based on post-mortem examination,suppuration nodules were found in the lungs,and microscopic observation of tissue smears with staining showed that a lot of short rod shape bacteri-a were in tissue.The bacteria were isolated and purified from the clinic lung tissue and analyzed by 16S rRNA sequence,the result showed the infectious bacteria was Rueperella pyogenes,and it was nominated as TpCQ-yy1.TpCQ-yy1 cultured on rabbit blood agar plates could form double-zone hemolysis,and can utilize glucose and lysine.Interestingly,the drug-resistance characteristics of TpCQ-yy1 partially changed along with the variation of the culture medium.Pathogenicity analysis showed that TpCQ-yy1 could make suppurative lesions in the lungs of mice infected via the thorac-ic and intraperitioneal route,and later led mice to death,while the subcutaneous and intramuscular routes of infection had only suppurative foci at the site of injection and were dose-dependent and non-lethal.The genome size of TpCQ-yy1 is 2.335 Mb,which encoding 2 107 proteins,and the phy-logenetic analysis showed TpCQ-yy1 is close to Trueperella pyogenes TP1 strain but away from other strains.TpCQ-yy1 infection could promote the secretion of inflammatory factors of macro-phage.TpCQ-yy1 inactivated bacterial vaccine and recombinant hemolysin(rPLO)subunit vaccine could induce high levels of antibodies production in mice immunized via subcutaneous and muscle route,but only provided 33.3％-66.7％protection to the immunized mice against TpCQ-yyl infec-tion via intraperitioneal route.This research provides a fundamental basis for the understanding of the biological characteristics,pathogenicity,and prevention and control of Trueperella pyogenes.

infC gene encodes the translation initiation factor IF3 in bovine Pasteuella multocida,but it whether or not regulation to the virulence and cross-protection in P.multocida is still not well understood.In this study,the infC gene mutant(△infC)derived from bovine P.multocida type A strain CQ2 was constructed using by homologous recombination method.Compared with wild strain,the △infC showed significant increasing in biofilm formation,but the capsule produc-tion,virulence and bacterial loading in organs were significant decreased,and the IL-1β secretion of mouse peritoneal macrophage increased.Along with the infC gene deletion,the expression of genes related to capsule synthesis and LPS synthesis and transport were significantly down-regulated,while that of genes related to biofilm synthesis and outer membrane protein were significantly up-regulated.The inactivated vaccines of wild type and mutant were prepared and mice were immu-nized twice then challenged with wild type strains,respectively.The immuno-protection rate of△in fC inactivated vaccine against bovine P.multocida type A,B and F were 100.0％,83.3％and 0.0％,respectively,and the immuno-protection rate that against rabbit type P.multocida was 33.3％.The results indicated that infC gene could affect the virulence of P.multocida by regula-ting the production of capsule and the expressions of virulence related factors,and the deletion of infC gene conferred a certain cross-protection property of strains.This study provided a certain foundation for the development of P.multocida vaccine.