Evaluation of a hypervariable octameric oligonucleotide fingerprints assay for identification of and discrimination between wild-type and vaccine strains of Brucella melitensis

OBJECTIVE To evaluate a hypervariable octameric oligonucleotide fingerprints (HOOF-Prints) assay for identification of and discrimination between wild-type and vaccine strains of Brucella melitensis. SAMPLE Brucella melitensis vaccine strain M5 and wild-type strain M43. PROCEDURES 8 pairs of primers (alterable, octameric nucleotides) were designed on the basis of a biological analysis of 8 flanking sequences in the DNA of B melitensis. The HOOF-Prints technique was used to identify wild-type and vaccine strains of B melitensis. Phylogenetic analysis of short, polymorphic fragments of DNA from B melitensis strains M5 and M43 was performed. RESULTS Variable-number tandem repeat DNA segments of B melitensis vaccine strain M5 and wild-type strain M43 were successfully amplified by means of PCR assay. All target gene fragments ranged in size from 100 to 300 bp. Separate phylogenetic analysis of each Brucella strain revealed considerable differences between the vaccine and wild-type strains. CONCLUSIONS AND CLINICAL RELEVANCE The results of this study suggested the HOOF-Prints assay may be useful for discriminating vaccine strains of B melitensis from wild-type strains. This ability could allow discrimination between animals that are seropositive because of vaccination against B melitensis and those that are seropositive because of B melitensis infection and could decrease the likelihood of importing Brucella-infected animals.

[Experimental evaluation of the brucellosis therapeutic vaccine efficacy]

Use of antibiotics can't completely solve the problem of brucellosis treatment, especially its chronic forms, because antibacterial preparations do not eliminate main pathogenetic factor of the disease--sensibilization of the macroorganism. It makes actual the question about complex immuno- and antibacterial therapy. Long-term clinical experience proved high effectiveness of a therapeutic brucellosis vaccine. Earlier this preparation was manufactured in Research Institute of Vaccines and Sera in Tbilisi (Georgia). To date new composition of components of the vaccine has been developed, and manufacturing and control methods have been improved. Marked desensitizing effect of the vaccine and its stimulatory action on cellular and humoral immunity has been observed. In 2002 technological normative documentation for manufacturing and use of the vaccine was developed in the Research Institute of Microbiology (Kirov) and production of the vaccine began.

Increases of efficacy as vaccine against Brucella abortus infection in mice by simultaneous inoculation with avirulent smooth bvrS/bvrR and rough wbkA mutants

The Brucella abortus S19 and RB51 strains are the most widely used live vaccines against bovine brucellosis. However, both can induce abortion and milk excretion, S19 vaccination interferes in serological tests, and RB51 is less effective. We have shown previously that a rough wbkAB. abortus mutant is attenuated and a better vaccine than RB51 in BALB/c mice, and that mutants in the two-component regulatory system bvrS/bvrR are markedly attenuated while keeping a smooth lipopolysaccharide (S-LPS). In this work, we tested whether simultaneous inoculation with live bvrS increases wbkA vaccine efficacy in mice. Even at high doses, the bvrS mutant was cleared much faster from spleens than the wbkA mutant. The splenic persistence of the wbkA mutant increased when inoculated along with the bvrS mutant, but also with inactivated bvrS cells or with purified B. abortus S-LPS, strongly suggesting that S-LPS in the bvrS mutant played a determinant role in the wbkA persistence. When inoculated alone, both mutants protected against virulent B. abortus but less than when inoculated simultaneously, and the protection afforded by the combination was better than that obtained with B. abortus S19. Increased protection was also obtained after simultaneous inoculation of the wbkA mutant and inactivated bvrS cells or purified S-LPS, showing again the role played by the S-LPS in the bvrS cells. In mice, the bvrS-wbkA combination induced an antibody response reduced with respect to B. abortus S19 vaccination. Thus, the simultaneous use of live bvrS and wbkA B. abortus mutants seems a promising approach to overcome the problems of the S19 andRB51 vaccines.

Protection of BALB/c mice against Brucella abortus 544 challenge by vaccination with bacterioferritin or P39 recombinant proteins with CpG oligodeoxynucleotides as adjuvant

The P39 and the bacterioferrin (BFR) antigens of Brucella melitensis 16M were previously identified as T dominant antigens able to induce both delayed-type hypersensivity in sensitized guinea pigs and in vitro gamma interferon (IFN-gamma) production by peripheral blood mononuclear cells from infected cattle. Here, we analyzed the potential for these antigens to function as a subunitary vaccine against Brucella abortus infection in BALB/c mice, and we characterized the humoral and cellular immune responses induced. Mice were injected with each of the recombinant proteins alone or adjuvanted with either CpG oligodeoxynucleotides (CpG ODN) or non-CpG ODN. Mice immunized with the recombinant antigens with CpG ODN were the only group demonstrating both significant IFN-gamma production and T-cell proliferation in response to either Brucella extract or to the respective antigen. The same conclusion holds true for the antibody response, which was only demonstrated in mice immunized with recombinant antigens mixed with CpG ODN. The antibody titers (both immunoglobulin G1 [IgG1] and IgG2a) induced by P39 immunization were higher than the titers induced by BFR (only IgG2a). Using a B. abortus 544 challenge, the level of protection was analyzed and compared to the protection conferred by one immunization with the vaccine strain B19. Immunization with P39 and CpG ODN gave a level of protection comparable to the one conferred by B19 at 4 weeks postchallenge, and the mice were still significantly protected at 8 weeks postchallenge, although to a lesser extent than the B19-vaccinated group. Intriguingly, no protection was detected after BFR vaccination. All other groups did not demonstrate any protection.

Brucella melitensis Rev. 1 living attenuated vaccine: stability of markers, residual virulence and immunogenicity in mice

Five commercial Brucella melitensis Rev. 1 vaccines from different sources were compared to the original Elberg Rev. 1 strain, in vitro for classic markers and in vivo in mice, for residual virulence and immunogenicity. Because colonies of several morphology types (smooth, non-smooth) were isolated from the vaccines, representative substrains were purified to study their in vitro and in vivo activities either at once (16 strains), or after storage by subculture (12 strains) and by lyophilization (eight strains) or after passage in mice (six strains). After purification, five strains had the characteristic pattern of resistance to penicillin and streptomycin of the original strain while 11 differed by a two-fold dilution or more. A few modifications only occurred after storage or passage. Residual virulence--the time taken by 50% of the subcutaneously vaccinated mice to eradicate the strain from their spleen--or recovery time 50%, and immunogenicity--the ability of the vaccinated mice to restrict the spleen count 15 days after a virulent intraperitoneal challenge--were compared on eight strains after purification, subculture and lyophilization. After purification, one smooth strain out of five had the same activities as the original strain and three were as immunogenic but less virulent. One smooth strain and the three non-smooth were neither immunogenic nor virulent. Some strains which were typically non-smooth after purification recovered a smooth phase aspect after subculture, concomitantly with an increase in immunogenicity but not in virulence.(ABSTRACT TRUNCATED AT 250 WORDS)

Temporal ELISA response of rams to Brucella ovis following experimental infection or vaccination

Sera from rams vaccinated with antigens extracted chaotropically from Brucella ovis by potassium thiocyanate treatment were used to optimise a whole-cell, enzyme-linked immunosorbent assay (CELISA) and to monitor the temporal serological response of rams which had been challenged with infected semen by the intranasal or intrapreputial route. Three patterns of CELISA response were detected. Thirteen of 15 rams intranasally challenged did not respond serologically (pattern 1 or nil response). Only one of 15 rams in the intranasal group exhibited a rise and fall response with CELISA (pattern 2), while another showed a rise and surge response (pattern 3). The numbers of rams in the intrapreputial group which displayed a pattern 1 or 2 or 3 response were four, nine and two, respectively. No ram with a pattern 2 response excreted B ovis in the semen or showed any other evidence of infection, whereas rams with a pattern 3 response excreted B ovis in the semen and developed palpable lesions. Intrapreputially challenged rams that were CELISA-positive consistently mounted an antibody response against B ovis about two to four weeks earlier than intranasally challenged rams.

Immunization by an insoluble fraction extracted from Brucella melitensis: immunological and chemical characterization of the active substances

A peptidoglycan-containing fraction called fraction P.I. (phenol insoluble), extracted from Brucella melitensis and previously described by some of us, had immunogenic and protective properties and did not produce any allergic reactions. Since it is well known that bacterial peptidoglycans studied so far have immunoadjuvant properties, the isolation of the active factor(s) of Brucella was undertaken. By successive enzymatic and chemical treatments, a new, much more purified fraction, called "4A" (approximately 5% of fraction P.I.), is obtained, retaining the same properties as P.I. and giving better protection against infection by Brucella. Immunogenicity, immunoadjuvant activity, allergizing capacity, and specific and nonspecific protective effects of fractions P.I. and 4A are compared. Chemically, fraction 4A is constituted by a lipoprotein covalently linked to peptidoglycan and by a few (lipo)proteins that could be solubilized by hot sodium dodecyl sulfate. Intrinsic properties of peptidoglycan could not be studied, but it does not seem to be essential for the activity. In conclusion, fractions P.I. and 4A are not agglutinogenic and, since fraction 4A induces better protection against infection by Brucella, it could advantageously replace fraction P.I. as a vaccine for humans.