Preparation and Application on the Inactivated Bacterins of Yellow and White Scour of Piglets

Pathogenic Escherichia coli strains were isolated from yellow and white scour samples in pig farms. The strains were used to make autologous inactivated bacterins,and the bacterins were applied to multiple infected farms. The results showed that in the group of inactivated bacterins,the infected piglet number was less,the course of disease was shorter and the symptoms was milder. The piglet E. coli inactivated bacterins could significantly reduced morbidity of yellow and white scour of piglets,the preventive effects of E. coli autologous inactivated bacterins against yellow and white scour of piglets were much better than that of genetically engineered vaccines.

Observation of the Immune Effect of Fusion Protein VP4-STI

The aim of the study was to investigate the immune effect of fusion protein VP4-STI. 40 mouse were randomly divided into 4 groups of test bacterin group （30 μg VP4-STI ＋0.6 μg LTB）, aluminiumhydroxide vaccine group （30 μg VP4-STI ＋Al（OH）3 gel ） , pure protein VP4- STI vaccine group （30μg VP4-STI ） and PBS control group were immunized by rhinal dripping. And then, the antibody levels of the mouse were determined. The protection effects of mouse in all immune groups were observed after the toxicity test with strong virulent strain C83902 of E. coli. Anti-VP4-STI antibodies were produced in other groups with the highest at the 6th week, except PBS control group. The antibody level in aluminiumhydroxide bactetin group was higher than that in test vaccine group. The antibody level in pure protein VP4-STI bacterin group was lower, being extremely significantly different from that in test vaccine group （ P 〈0. 001 ）. Mouse in test vaccine group and aluminium hydroxide bacterin group had better immuno-protection effect on strong virulent strain C83902 of E. coli, obviously different from that in PBS control group. The research provided basis for further improving the immunogeneticity of STI.

Live and Inactivated Salmonella Enteritidis Vaccines:Immune Mechanisms in Broiler Breeders

Salmonella is a ubiquitous pathogen which, in addition to causing poultry diseases, has a growing zoonotic impact. It has demanded the implementation of diverse control strategies, in which vaccines play a major role. The understanding of the immune pathways elicited by the different vaccines is important, contributing for the establishment of strong immune correlates of protection, for instance. With the purpose of determining the dynamics of the humoral and cellular immune responses to vaccination, broiler breeders (Cobb Slow) were immunized with live or inactivated vaccines against Salmonella Enteritidis. Lymphocyte and macrophage subsets were analyzed in the peripheral blood by flow cytometry and antigen-specific circulating IgY and mucosal IgA were quantified. The markers analyzed by flow cytometry were CD8/CD28, CD4/TCRVβ1, Kul/ MHC II and Bu-1. Both live and inactivated vaccines induced an increase in the proportion of circulating monocytes (Kul+MHCII+) in some time points compared to non-vaccinated controls. However, whereas the live vaccine leads to an increase in CD8-CD28+ and Bu-1+ lymphocytescompared to the control group, the inactivated vaccine prompteda reduction in the percentage of severalleucocyte subsets (Kul-MHCII+, Bu-1+, CD8+CD28+, CD8-CD28+, CD4+TCRVβ1-, CD4+TCRVβ1+, CD4-TCRVβ1+) after the boost dose. Both vaccines induced specific serum IgY and mucosal IgA production;however, the inactivated vaccine stimulated higher titers in a shorter period. These results contribute to the understanding of mechanisms of action of live and inactivated Salmonella vaccines in chickens.