Evaluation of Brucella abortus DNA and RNA vaccines expressing Cu-Zn superoxide dismutase (SOD) gene in cattle

This study was conducted to evaluate the immunogenicity of a DNA or RNA vaccines encoding Brucella abortus Cu–Zn superoxide dismutase (SOD) in cattle. Intramuscular injection of plasmid DNA carrying Brucella SOD gene (pcDNA-SOD) into animals elicited both humoral and cellular immune responses. Animals injected with pcDNA-SOD developed SOD IgG antibody with predominance of immunoglobulin G1 (IgG1) isotype over IgG2. In addition, the DNA vaccine elicited a specific T-cell-proliferative response. Furthermore, intraperitoneal injection of cattle with recombinant Semliki Forest virus particles carrying recombinant RNA encoding SOD (SFV-SOD) did not lead to the induction of SOD IgG 1 or 2 antibody, but induced specific T-cell activation. Both vaccines were able to induce a non-significant secretion of gamma interferon and did not induce the secretion of IL-4 or tumor necrosis factor (TNF)-. These results suggest that SOD gene in a genetic vaccine formulation (DNA or RNA) might be of potential us as a vaccine to induce cell-mediated immunity in cattle. To our knowledge, this is the first study to evaluate a genetic vaccine against Brucella in cattle.     

Cu/Zn SOD蛋白在布鲁菌S19疫苗株中的过表达及鉴定

以Cu/Zn SOD为目的基因,通过基因工程技术分别构建了组成型过表达系统pBBR-trc-sod和诱导型过表达系统pBBR-lacPtrc-sod,在布鲁菌S19疫苗株中进行了Cu/Zn SOD的过表达。同时,以大肠杆菌为宿主表达纯化的重组Cu/Zn SOD蛋白免疫家兔制备多克隆抗体,对2种过表达系统中Cu/Zn SOD蛋白的表达量进行分析。结果显示,诱导型Cu/Zn SOD过表达系统的表达量更高,且能与所制备的多抗发生特异性反应。结果表明,构建的过表达系统能够实现Cu/Zn SOD蛋白在布鲁菌S19疫苗株中过表达;同时,该试验也提示我们这种表达系统可应用于布鲁菌S19疫苗的抗原改造。     

Epidemiology,zoonotic aspects,vaccination and control/eradication of brucellosis in India

In India, brucellosis was first recognised in 1942 and is now endemic throughout the country. The disease is reported in cattle, buffalo, sheep, goats, pigs, dogs and humans. B. abortus biotype-1 in cattle and buffaloes and B. melitensis biotype-1 in sheep, goats and man are the predominant infective biotypes. The long-term serological studies have indicated that 5% of cattle and 3% of buffaloes are infected with brucellosis. Economic losses due to brucellosis in livestock are considerable in an agrarian country like India. There is no organised and effective brucellosis control programme in the country. With the indigenous development of serum and milk based ELISA kits, the population survey of the disease has been undertaken on a large scale in several states and plans for the control of the disease through calf-hood vaccination are being worked out. An innovative approach—Bovine Brucellosis Progressive Control Programme (BBPCP) is targeted to overcome the basic problems of ban on cow slaughter, distress sale of animals following the positive serological diagnosis of brucellosis and absence of a disease control strategy. The work plan for the implementation of BBPCP is presented.     

Evaluation of the live vaccine efficacy of virulence plasmid-cured,and phoP- or aroA-deficient Salmonella enterica serovar Typhimurium in mice

We evaluated the protective efficacy of 94-kb virulence plasmid-cured, and phoP- or aroA-deficient strains of Salmonella enterica serovar Typhimurium (ΔphoP or ΔaroA S. Typhimurium) as oral vaccine candidates in BALB/c mice. Two weeks after the completion of 3 oral immunizations with 1 × 10⁸ colony-forming units (CFU) of virulence plasmid-cured, and ΔphoP or ΔaroA S. Typhimurium at 10-day intervals, S. Typhimurium lipopolysaccharide (LPS)-specific mucosal secretory immunoglobulin A (s-IgA) antibody titers were detected in the cecal homogenate, bile and lung lavage fluid, but not in the intestinal lavage fluid. In addition, the increases in S. Typhimurium LPS-specific immunoglobulin G (IgG) and IgA antibody titers in the serum were also observed 2 weeks after completing 3 oral immunizations with virulence plasmid-cured, and ΔphoP or ΔaroA S. Typhimurium. The series of 3 oral immunizations protected the mice against an oral challenge with 5 × 10⁸ CFU of the virulent strain of S. Typhimurium, suggesting that both the virulence plasmid-cured, and ΔphoP and ΔaroA S. Typhimurium strains are promising candidates for safe and effective live S. Typhimurium vaccines.