Use of a live attenuated Salmonella typhimurium vaccine to protect hens against Salmonella enteritidis infection while undergoing molt

Previous studies demonstrated that Salmonella enteritidis infections in hens undergoing molt via feed withdrawal were more severe than in full fed hens. We conducted two trials to determine if immunizing specific-pathogen-free, Salmonella-culture-negative hens via aerosol exposure to MeganVacl, a commercially available attenuated Salmonella typhimurium vaccine, would reduce transmission of S. enteritidis from infected hens to uninfected but contact-exposed hens during a molt. In trial 1, one group of hens received two aerosol doses of vaccine 2 wk apart whereas a second group of hens remained nonvaccinated. In trial 2, the vaccinated group received only one dose of vaccine. Two weeks after the final immunization, feed was removed from all the hens, and on day 4, the center hen in rows of 11 hens received a dose of 3 x 10(5) (trial 1) or 1.3 x 10(6) (trial 2). Transmission to the unchallenged hens was followed 3, 10, 17, and 24 days later. Vaccination reduced the horizontal spread of S. enteritidis in vaccinated hens compared with their nonvaccinated counterparts, with vaccinated hens shedding significantly less S. enteritidis on day 10 postchallenge in trial 1 and on days 3, 10, 17, and 24 in trial 2. Recovery of S. enteritidis from ovaries was significantly reduced in the vaccinated hens in trial 1 and from livers/spleens, ovaries, and cecum in trial 2. These studies indicate that immunization of hens with a live S. typhimurium vaccine could help reduce S. enteritidis problems during a molt situation.     

Evaluation of efficacy of a new live Salmonella Typhimurium vaccine candidate in a murine model

Efficacy of a new live Salmonella Typhimurium vaccine candidate attenuated by two virulence gene deletions was evaluated in this study. Live form of the vaccine was orally administered and formalin-inactivated form was intramuscularly (IM) administered. 105 female BALB/c mice were used and divided into 5 groups, A to E, containing 21 mice per group. Serum IgG and secretory IgA titers and levels of serum IFN-γ, IL-4, TNF-α, IL-12 of the immunized groups, especially group C (oral prime-oral booster) significantly increased. In addition, all animals in groups C showed no clinical symptoms and survived the virulent challenges, whereas all or some of mice from the other groups died of the challenge. These indicate that the vaccine candidate can be an effective tool for prevention of Salmonella infections by inducing robustly protective immune responses and leading to the production of inflammatory cytokines. Booster immunization, especially via oral administration, is necessary to optimize its protection.     

Duration of immunity induced in chickens by an attenuated live Salmonella enteritidis vaccine and an inactivated Salmonella enteritidis/typhimurium vaccine

The aim of this study was to examine the duration of immunity of different vaccination schemes using the S. enteritidis live vaccine Gallivac Se and the S. enteritidis-S. typhimurium inactivated vaccine Gallimune Se+St. Three groups of Lohman Brown chickens were used. Group one was vaccinated three times orally with Gallivac Se at weeks one, seven and 13 of age. Group two was vaccinated twice orally with Gallivac Se in weeks one and seven and once i.m. with Gallimune Se+St in week 14 of age. A third group was not vaccinated and served as the control group. Eight randomly selected chickens from each of the three groups were challenged with a nalidixic acid resistant S. enteritidis PT4 strain in weeks 24, 51 and 71 of age and the same number of animals were challenged with a S. typhimurium DT 104 strain in weeks 26, 54 and 73 (75) of age.The chickens were euthanised seven days post challenge and the number of challenge strain organisms (log10 cfu) in the liver and on caecal mucosa was determined.The quantitative investigation of the challenge strain in the liver and caecal mucosa revealed a statistically significant (p < 0.05) lower challenge strain burden in the vaccinated groups compared with the non-vaccinated control group up to week 71 (73) of age. The protective effects were demonstrated for both challenge strains.     

Safety of a live attenuated Erysipelothrix rhusiopathiae vaccine for swine

The porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus. Virions of PRRSV contain six membrane proteins: the major proteins GP5 and M and the minor proteins GP2, GP3, GP4, and E. The GP5 is the major envelope proteins, which was involved in the formation and infectivity of PRRSV by coaction with other membrane proteins. Here, to determine the function of alone GP5 envelope protein in viral entry, we investigated the formation and infectivity of GP5-pseudotyped virus particles. By co-transfection of GP5 expression plasmids with murine leukemia virus (MuLV) based retroviral vectors (pHIT60, encoding MuLV Gag-Pol; pHIT111, encoding an MuLV genome with a β-galactosidase reporter gene) into 293 T cells and analysis of the culture medium using ultracentrifugation, Western blot, and infection assay. We observed that the GP5 envelope protein was incorporated into the MuLV retroviral vectors to generate an pseudotyped murine leukemia virus, which was infectious to PAM and Mack-145 target cells and displayed the same host range with wild-type PRRSV. The infection of the pseudotyped virus on PAM target cells is effectively neutralized by polyclonal antibodies specific for PRRSV or GP5. The results suggested that the GP5 protein may play a key role in the viral entry by interacting with the host cell receptor. The GP5-pseudotyped virus will be useful in the identification of the cellular receptor binding with GP5 protein.     

Aromatic-dependent Salmonella typhimurium as modified live vaccines for calves

Strains of Salmonella sp with complete nonreverting aromatic biosynthesis (aro) defects are expected to be nonvirulent, in respect to invasive infection, because they need the aromatic metabolites paraaminobenzoate (for making folate) and dihydroxybenzoate (for making enterochelin) which are not available in host tissues. Derivatives with transposon-generated complete nonreverting aro-defects were prepared from 3 mouse-virulent strains of S typhimurium, namely, FIRN, WRAY, and UCD. The latter 2 parent strains originally were isolated from calves and are known to be calf-virulent. The resultant aromatic-dependent (aro-) strains were used to vaccinate 27 calves (2 to 3 weeks old), usually giving 2 doses by the IM route (10(9) bacteria) or orally (1.5 X 10(11)). Vaccination did not cause severe ill effects in any calf. Thus aro- defects cause loss of virulence for calves, as previously shown for mice. Vaccinated and control calves were challenge exposed, usually at 5 weeks of age, by feeding 1.5 X 10(11) cells of 1 of 2 calf-virulent S typhimurium strains, either UCD 108-11 or SL1323. Of the 16 challenge-exposed control calves, all became anorectic and depressed (CNS), and 15 had diarrhea. Fourteen of the 16 died; all tested tissues were bacteriologically culture-positive for Salmonella at necropsy. Vaccination with the live UCD aro- vaccine strain, SL1479 by either of 2 schedules (IM or orally) appeared effective.(ABSTRACT TRUNCATED AT 250 WORDS)     

A new live Salmonella enteritidis vaccine for chickens--experimental evidence of its safety and efficacy

Within the works for the registration of a new live Salmonella Enteritidis vaccine for layers, safety and efficacy of the vaccine strain were tested by experimental studies. After oral administration of the single and the tenfold dose, no incompatibility reactions were seen in day-old chicks. The laying performance and the egg weight were not affected by the vaccination of the chickens during the laying period. There was only a limited period in which the excretion of the vaccine strain and its persistency in organs were seen. Even after the threefold oral vaccination the vaccine strain could not be isolated from eggs and internal organs of slaughtered chickens. Moreover, a high safety for non-target animals (cattle, pigs) could be established. Studies with BALB/c mice proved that a cell-mediated immunity and the development of complement-fixing antibodies is induced by the vaccine. Efficacy studies in target animals were carried out by a proved dependable oral challenge system that reproduces a latent infection with marked S. Enteritidis strains and by means of the seeder-bird method. The test results demonstrate that the vaccination is capable to avert or to reduce an infection significantly.     

鸡滑液囊支原体活疫苗(MS-H株)同时免疫对新支二联活疫苗免疫效力影响的调查

为了解新支二联活疫苗和鸡滑液囊支原体活疫苗之间有无相互影响,选用70只1日龄SPF鸡随机分为4组进行比对试验,其中:G1组20只,联合免疫新支二联苗活疫苗和鸡滑液囊支原体活疫苗(MS-H株);G2组20只,为新支二联活疫苗单独免疫组;G3组20只,为传染性支气管炎病毒(IBV)攻毒组;G4组10只,为空白对照组.免疫后...     

Production and application of a live Salmonella gallinarum vaccine

The production and application of a freeze-dried Salmonella gallinarum vaccine are described in this report. The vaccine is stable when kept at 4 degrees C and a single injection elicits a good immunity for 2 months, though its effect gradually diminishes. Immunity is neither enhanced nor depressed by repeated injections of the live vaccine, and no interference effect was observed in experimentally infected chickens. Furazolidone therapy jeopardizes the immunogenicity of a live vaccine, but its effect can be countered by the administration of either an inactivated or a live vaccine when medication is commenced and this is followed by the application of live vaccine 6 days after cessation of medication.     

Aromatic-dependent Salmonella dublin as a parenteral modified live vaccine for calves

A virulent Salmonella dublin isolate was made histidine-requiring (his-) to allow recognition. The his- derivative, SL1367 (still calf-virulent), was then given by transduction and mutation, a transposon-generated non-reverting aromatic biosynthesis (aro) defect; this defect caused loss of virulence for the mouse. The his- aro- derivative strain, SL1438, was effective as a live vaccine in mice. Twenty male Holstein calves were divided into 4 groups. Groups I, II, and III were vaccinated IM at 2 weeks and at 3 weeks of age with aromatic-dependent (aro-) S dublin strain SL1438. Groups I and III received freshly prepared vaccine and group II received lyophilized vaccine. Serious adverse reactions to the vaccination were not seen. After vaccination, the mean maximum increase in rectal temperature was 1.8 C in group I and III calves and 0.6 C in group II calves. Fewer group II calves developed diarrhea (1 of 5) or positive blood cultures (0 of 5) after vaccination compared with group I and III calves (6 of 10 and 5 of 10, respectively). Postvaccination diarrhea was mild and of short duration. Group IV was comprised of 5 nonvaccinated calves. At 5 weeks of age, all calves were challenge exposed orally. Group I, II, and IV calves were challenge exposed with 10(11) virulent S dublin SL1367. Group III was challenge exposed with 10(11) virulent S typhimurium UCD 108-11. Subsequently, fever and diarrhea (lasting 1 to 3 days), but no deaths, were observed in the vaccinated calves. Four of the 5 nonvaccinated (group IV) calves died (P less than 0.001) within 8 days after challenge exposure. Aro- S dublin SL 1438 did not cause serious adverse effects and provided protection against oral challenge exposure with either virulent S dublin or S typhimurium.     

一种猪瘟兔化弱毒活疫苗效力检验方法的研究

现有猪瘟活疫苗的效力检验多采用兔体定型热反应法(RID),但该方法存在重复性差、检验周期长、数据不精确等缺点,为克服兔体定型热反应法存在的缺陷,本研究建立了一种快速、准确、稳定的检测猪瘟病毒含量及疫苗效力的间接免疫荧光方法(IFA),该方法以出现特异性荧光作为检测标准,通过添加促细胞感染剂PB增加特异性荧光数量,可以在4d内检测出猪瘟活疫苗成品或半成品病毒含量,该方法检验周期短、数据精确、重复性好,为猪瘟活疫苗效力检验方法的完善提供了有力支持。     

Evaluation of the efficacy of immunocastration vaccine composed of gonadotrophin-releasing hormone conjugated with Salmonella typhimurium flagellin in rats

Immunocastration is an alternative method to replace surgical castration that is commonly performed in domestic and pet animals. In this study, a new immunocastration vaccine was developed, and its efficacy was evaluated in male rats. Six tandem copies of gonadotrophin-releasing hormone (GnRH) peptide were genetically fused to Salmonella typhimurium flagellin fljB (STF2) that is a ligand of toll-like receptor 5 (TLR5). The recombinant STF2-GnRH protein expressed in Escherichia coli was used as the immunocastration vaccine. Sixteen male rats were equally assigned to four groups. Excluding the control rats, three groups were immunized with 100, 200 and 400 μg of the STF2-GnRH vaccine, respectively. All of the immunized rats developed significantly higher titres of antibodies to GnRH than the control rats. The size and weight of both testes and epididymides from the immunized rats were significantly smaller than those of the control rats. Testicular tissues in the immunized rats demonstrated atrophy of seminiferous tubules and decreased numbers of both spermatogonia and spermatocytes. These data indicate that the newly developed STF2-GnRH vaccine has a potent immunogenicity to GnRH and efficiently suppresses the development of testes in rats.     

In vitro and in vivo efficacy of a live attenuated Salmonella Typhimurium vaccine at preventing intestinal colonization in chicks

Vaccination of chicks with Salmonella (S .) Typhimurium aroA deletion mutants has previously been shown to inhibit intestinal colonization of wild‐type S.  Typhimurium strains. In Australia, Bioproperties VaxSafe? STM1 strain is the only licensed and commercially available S . Typhimurium vaccine. This vaccine is a live attenuated aroA deletion mutant. Currently, it is recommended that the first dose of the STM1 vaccine is administered through coarse spray. It is unclear whether this mode of administration effectively permits intestinal colonization. Furthermore, it is not known whether the STM1 strain prevents or inhibits Salmonella colonization of chicks following this first dose. This study investigated both in vitro and in vivo colonization parameters. Invasiveness was assessed using an in vitro invasion assay into sections of ileum and caecum collected from day‐old chicks. The S.  Typhimurium definitive types (DT) 9 and 44 exhibited the greatest invasion into both intestinal segments. STM1 was invasive but was significantly less so than both isolates of S.  Typhimurium. In dual and triple infections, no competitive microbial interactions between STM1 and wild‐type Salmonella were observed. In vivo colonization inhibition was also tested. Vaccinated and nonvaccinated day‐old chicks were challenged with S.  Typhimurium DT9. Both STM1 and S.  Typhimurium DT9 were found in spleen, liver, ileum, caecum and caecal contents from day 2 postinfection. No significant exclusion effect was observed in vaccinated and challenged chicks.     

Testing a bivalent vaccine in sheep against experimental infection with Salmonella bovismorbificans and Salmonella typhimurium

Abstract

Extract

Increasing awareness of the threat from salmonellosis to animal and human health, and recognition of implications to the farming economy and meat marketing industry in New Zealand, have emphasized the need for effective measures for controlling this disease. As pointed out by Beckett (1967 Beckett, F. W. 1967. The use of Salmonella vaccine in outbreaks of salmonellosis in sheep. N.Z. vet. J., 15: 66–69. [Taylor &; Francis Online] , [Google Scholar]), reduction in stocking rates or use of chemotherapeutic agents is often impracticable or ineffective. Other recent publications, drawing attention to the possible role of vaccination in controlling salmonellosis, have dealt with fundamental aspects of immunity (Jonas 1967 a Jonas, W. E. 1967a. Studies of the immunological aspects of salmonellosis of mice: active immunity. N.Z. vet. J., 15: 27–30. [Taylor &; Francis Online] , [Google Scholar]; b Jonas, W. E. 1967b. Salmonellosis of sheep: use of serum from a vaccinated ewe in a mouse passive protection test. N.Z. vet. J., 15: 55–61. [Taylor &; Francis Online] , [Google Scholar]) and with evaluation of an experimental vaccine under field conditions (Wallace and Murch, 1967 Wallace, G. V. and Murch, O. 1967. Field trials to assess the value of a bivalent killed salmonella vaccine in the control of ovine salmonellosis. N.Z. vet. J., 15: 62–65. [Taylor &; Francis Online] , [Google Scholar]).     

Cross-protection against Salmonella Typhimurium infection conferred by a live attenuated Salmonella Enteritidis vaccine

In this study, a genetically engineered live attenuated Salmonella Enteritidis (SE) vaccine was evaluated for its ability to protect against Salmonella Typhimurium (ST) infection in chickens. The birds were orally primed with the vaccine on the 1st day of life and given an oral booster at 5 wk of age. Control birds were orally inoculated with phosphate-buffered saline. Both groups of birds were orally challenged with a virulent ST strain at 9 wk of age. Compared with the control chickens, the vaccinated chickens had significantly higher levels of systemic IgG and mucosal IgA against specific ST antigens and a significantly greater lymphoproliferative response to ST antigens. The excretion of ST into the feces was significantly lower in the vaccinated group than in the control group on days 9 and 13 d after challenge. In addition, the vaccinated group had significantly fewer pronounced gross lesions in the liver and spleen and lower bacterial counts in the internal organs than the control group after challenge. These data indicate that genetically engineered live attenuated SE may induce humoral and cellular immune responses against ST antigens and may confer protection against virulent ST challenge.     

Galactose epimeraseless mutants of Salmonella typhimurium as live vaccines for calves.

The purpose of the study was to evaluate the safety and efficacy of a galactose epimeraseless mutant of Salmonella typhimurium administered as an oral vaccine to one week old calves and to investigate properties of galactose epimeraseless mutants which affect their virulence and immunogenicity. The galactose epimeraseless mutant S. typhimurium strain G30D caused diarrhea and fever in three calves to which it was administered orally at a dose of 10(10) organisms; all three calves died following challenge with virulent S. typhimurium ten days postvaccination. Mild illness developed in four calves vaccinated with a dose of 9 X 10(6) organisms and one of these calves survived challenge. Three unvaccinated calves died following challenge. The vaccine organism persisted in tissues and was shed for a prolonged period by calves which received 10(10) organisms. Studies of characteristics of galactose epimeraseless mutants of S. typhimurium showed that, in the presence of galactose, there is selection for secondary mutants which are galactose resistant. The studies indicate that galactose epimeraseless mutants of S. typhimurium are not good candidate live vaccine organisms for use in calves.