Immunization with Toscana virus N-Gc proteins protects mice against virus challenge

Toscana virus (TOSV) is an emerging virus, circulating in the Mediterranean area, that is responsible for aseptic meningitis, meningoencephalitis, and encephalitis. The development of a vaccine that could provide complete protection from TOSV infection is needed. In this study we investigated the capacity of TOSV structural proteins, nucleocapsid protein N and the two Gc and Gn glycoproteins, produced as recombinant proteins, in an animal model. In particular, we investigated their role in inducing specific and protective immune responses against virus infection. Mice were immunized intraperitoneally using TOSV antigens singly or in combination. The results show that only the N-Gc combination was able to protect 100% of animals from a lethal challenge with a neurovirulent strain of TOSV. This potential vaccine induces high serum antibody titres with neutralizing activity and it is safe for animals. Moreover, immunization induces a virus specific cell-mediated immune response, in particular a CD8+ T cell response associated with a marked expression of interferon gamma. These results indicate that the N+Gc viral antigen combination could be useful for future development of a vaccine controlling the spread of this emerging virus that could pose a new threat for humans.     

Immunization against HCG

The possibility of using the immune system to provide protectionagainst an unwanted pregnancy has been postu–lated sincethe very early days of modern immunology. During the past twodecades or more, a major goal-directed research effort, involvingseveral independent groups of investigators, has been underwaywith the objective of developing birth control vaccines suitablefor use by men and women at all stages of their reproductivelives. The most advanced work in this area is concerned withthe development of a vaccine directed against human chorionicgonadotrophin (HCG), a hormone that is produced by the peri-implantationembryo and that is essential for successful implantation andthe establishment of early pregnancy. These studies have reachedthe stage of clinical testing of a number of prototype vaccinesbased on different parts of the HCG molecule. No adverse sideeffects have been observed or reported in these clinical trialsand larger scale clinical studies are being planned to assessfurther the safety, efficacy and acceptability of these preparations.Research is also underway to develop improved versions of theseHCG vaccines that will offer 12–18 months protection followinga single injection. The stage is set for the introduction, bythe turn of this century, of the first totally new method offamily planning in four decades.     

Immunization against bacteria- and endotoxin-induced hypotension.

The characteristics of hypotension induced in rabbits by intravenous injection of viable Salmonella typhosa 0901 organisms were studied and found to be a function of the number and age of the bacterial cells. Effective neutralization of the blood pressure lowering was achieved by immunization with homologous organisms as well as heterologous endotoxins and a detoxified derivative. In addition, native endotoxins derived from a number of different genera of gram-negative bacilli, as well as lipopolysaccharides deficient in either the polysaccharide or lipid components, were tested for their ability to induce hypotension in rabbits and tolerance to the lowering of blood pressure. Hypotension was elicited by intravenous injection of all native endotoxins as well as polysaccharide-deficient endotoxins, but was absent in preparations from which the lipid was removed. On the other hand, protection against the hypotension effect could be induced after injection of either the lipid- or polysaccharide-deficient derivatives.     

Immunization of mice against Naegleria fowleri infection.

Naegleria fowleri produces fatal meningoencephalitis in humans and in experimentally infected laboratory animals. The course of the disease in mice is dependent upon the infecting dose of amoebae, route of inoculation, and prior exposure to Naegleria antigens. DUB/ICR mice were immunized by various routes and antigen preparations, held for 21 days, and, together with noninfected control mice, challenged intravenously (i.v.) or intranasally (i.n.) with 10(7) or 10(6) N. fowleri per mouse, respectively. Mice immunized with liver or formalinized N. fowleri or live N. gruberi subcutaneously, intraperitoneally, i.v., or i.n. were significantly protected against a subsequent lethal challenge with N. fowleri i.v. or i.n. In general, i.v. inoculation afforded greated protection than other routes of immunization, intact cells immunized mice better than did cell fragments, and N. gruberi appeared to be a better immunogen than N. fowleri.     

Immunization against fatal experimental Klebsiella pneumoniae pneumonia.

The ability of serospecific anti-capsular polysaccharide (CPS) antibody to prevent fatal Klebsiella pneumoniae pneumonia was evaluated in a rat lung model. Rats were immunized intramuscularly with 100 micrograms of purified serotype 2 CPS and challenged intrabronchially 14 days later with a serotype 2 strain of K. pneumoniae. Vaccination engendered high levels of serum anti-CPS antibody which afforded significant protection (P less than 0.01) against fatal pneumonia. Immunization promoted clearance of the challenge bacteria from the lungs and prevented bacteremia. Histological examination of lung tissue from infected control animals showed pronounced inflammatory cellular infiltrate in the alveolar spaces, intra- and peribronchial inflammation, and tissue necrosis. In contrast, pathological changes noted in lungs from immunized animals were restricted to infrequent intra- and peribronchial involvement.     

Immunization of mice with mycobacterial culture filtrate proteins.

Culture filtrate proteins were obtained from Mycobacterium tuberculosis cultures after 7 days growth in Proskauer and Beck medium. The protein yield increased substantially to peak about the time the number of viable organisms reached its maximum level (day 8). Examination of the protein concentrate by SDS-PAGE revealed the presence of at least 12 separate protein bands varying from 10 to 90 kD. Mice were injected subcutaneously with 20 micrograms of M. tuberculosis culture filtrate (MTCF) protein suspended in saline or Freund's complete or incomplete adjuvant. The vaccinated mice were subjected to an aerogenic challenge with 10(3) colony-forming unit (CFU) M. tuberculosis Erdman and a significant reduction in the number of viable organisms was observed in the spleens and lungs determined over a 21-day period compared with age-matched normal controls. Mice immunized with the same culture filtrate proteins bound to nitrocellulose particles also showed some resistance to the virulent challenge, suggesting that individual antigens present in the culture filtrate were able to induce a protective T cell-mediated immune response in appropriately immunized mice.     

Immunization against human papillomavirus infection and associated neoplasia.

BACKGROUND: Chimeric virus like particles (CVLPs) constructed by fusing human papillomavirus type 16 (HPV16) E7 sequences into the C-terminus of the viral L1 gene constitute the first generation of preventive and therapeutic HPV vaccines. Even though vaccination with DNA is highly efficient in the induction of a cytotoxic T-cell (CTL) response utilization of a DNA vaccine in the HPV context, it has been hampered by concern for the oncogenic potential of the E6 and E7 proteins encoded by the viral oncogenes. OBJECTIVE: To consider the use and impact of E7 DNA for immunization. EXPERIMENTAL: In addition to hemagglutination inhibition, a versatile assay to measure neutralization of yeast cell-derived pseudovirions carrying a green fluorescence reporter gene has now been developed. Mice immunized with the HPV16 CVLPs generate E7-specific CTLs, which kill E7 expressing or E7 peptide loaded RMA-cells, protect against tumor formation by syngeneic HPV transformed cells and also induce regression of already established tumors. Since generation of CTL response is achieved by presentation of epitopes as short peptides together with appropriate MHC class I molecules, complete proteins are not required. Instead a shuffled E7 protein has now been used successfully for generating CTL responses comparable to the CVLP responses in mice. CONCLUSIONS: Our preliminary results suggest that immunization with E7 shuffled DNA yields a response directed against the authentic E7 protein. Furthermore, booster immunization with E7 shuffled DNA would avoid inhibition by neutralizing antibodies, however, further studies are needed to guarantee that the shuffled E7 protein lacks oncogenic activity.     

Immunization against experimental murine salmonellosis with liposome-associated O-antigen.

Partially delipidated Salmonella typhimurium (O-1,4,5,12) lipopolysaccharide was incorporated into small multilamellar liposomes composed of either naturally occurring or synthetic phospholipids. Vaccination of mice with the liposome-lipopolysaccharide complexes induced a cellular response specific for O-1,4,5,12 determinants, as determined by the development of a delayed-type hypersensitivity reaction. The liposome-lipopolysaccharide vaccines were significantly more effective, compared with other nonviable vaccines tested, in protecting mice against a lethal intravenous challenge infection with virulent S. typhimurium. Protection afforded by the liposome-lipopolysaccharide vaccines was comparable to that conferred by a live S. typhimurium vaccine. Results suggest that liposome-induced modulation of the host immune response in favor of cell-mediated immunity may be more efficacious in preventing diseases in which cell-mediated immunity is of prime importance.     

Immunization against Q-fever of naturally infected dairy cows.

Dairy cows infected naturally with Coxiella burnetii as evidenced either by presence of phase II agglutinating antibodies in the blood or by shedding C. burnetii in the milk, were vaccinated subcutaneously with formalin-killed phase I C. burnetii organisms. Attempts to demonstrate C. burnetii in the milk of vaccinated dairy cows 47 days after vaccination were negative, while continuous shedding of C. burnetii in the milk of control non-vaccinated dairy cows was repeatedly demonstrated in the course of 123 days (period of investigation). No harmful systemic reaction following vaccination was observed.     

Specificity of avian serum proteins in tests against the sera of bird fanciers

Tests of the sera of fifty-eight bird fanciers, comprising eighteen pigeon faticiers, thirty-five budgerigar fanciers and five exposed to other birds, against the sera of the pigeon, budgerigar, hen, turkey, pheasant, canary and finch, showed the presence in the avian sera of antigenically related serum albumin and some β-globulin components. Pigeon serum macro- and γ-globulin components reacted specifically only with the pigeon faticiers'sera, and budgerigar γ-globulin and a β-globulin B_β2G reacted specifically only with budgerigar fanciers'sera. The pigeon fanciers'sera contained the largest amounts of precipitating and haemagglutinating antibody. Avian serum proteins are present in bird droppings, so that the common antigens may cause reactions in affected subjects on exposure to the droppings dust of different birds. The patients'sera may also be useful for characterization of the avian serum proteins.     

Immunization of mice against coccidioidomycosis with a subcellular vaccine.

In vitro-cultivated spherules of Coccidioides immitis were disrupted in a Braun homogenizer. The resultant wall fragments were separated from cell sap and endospores by centrifugation. Extraction of the walls with phosphate-buffered saline yielded a subcellular fraction that was immunogenic in mice. This fraction, which contained polysaccharide and protein, gave substantial protection against intranasal challenge with a usually lethal dose (1,000) of arthrospores, provided that it was administered with adjuvant.     

Immunization with the biologically active lectin domain of PapGII induces strong adhesion-inhibiting antibody responses but not protection against avian pathogenic Escherichia coli.

The aim of this study was to investigate whether immunization with the sugar binding domain of PapGII (PapGII196) was able to protect chickens against avian pathogenic Escherichia coli. PapGII196 was expressed, purified by Ni-NTA column chromatography and shown to retain its biological activity, as demonstrated by binding to its receptor, globoside. PapGII196 was tested as a vaccine in specific pathogen free broilers and also by vaccinating breeders and assessing protection in their offspring, and using aerosol exposure or air sac inoculation for challenge. Notwithstanding a strong anti-PapGII196 serum IgG response in vaccinated birds in all experiments and inhibition of haemagglutination by serum from PapGII196-vaccinated birds, chickens were not protected against avian pathogenic E. coli. These findings suggest that PapGII may not be a useful candidate for inclusion in vaccines against avian pathogenic E. coli.     

Immunization with influenza A NP-expressing vaccinia virus recombinant protects mice against experimental infection with human and avian influenza viruses

Summary. Two-fold immunization of Balb/c mice with a vaccinia virus recombinant expressing the NP protein of influenza A/PR8/34 (H1N1) virus under the control of a strong synthetic promoter induced specific antibodies and protected animals against low-dose challenge by mouse-adapted heterosubtypic variants of human A/Aichi2/68 (H3N2) and avian A/Mallard/Pennsylvania/10218/84 (H5N2) influenza virus strains. The surviving immunized animals had lower anti-hemagglutinin antibody titers compared to non-immunized mice. There was no difference in viral titers in lungs of immunized and non-immunized animals that succumbed to the infection. In order to try to increase immune system presentation of NP-protein-derived peptides, and thereby increase their immunogenicity, we constructed another vaccinia-based NP-expressing recombinant containing a rapid proteolysis signal covalently bound to the NP protein. This sequence, derived from the mouse ornithine decarboxylase gene has been shown to increase degradation of various proteins. However, we found that when used as part of a recombinant NP, this signal neither increased its proteolytic degradation, nor was it more efficient in the induction of a protective response against influenza infection.     

Immunization with FimA protects against Streptococcus parasanguis endocarditis in rats.

FimA, a surface-associated protein of Streptococcus parasanguis, is associated with initial colonization of damaged heart tissue in an endocarditis model (D. Burnette-Curley, V. Wells, H. Viscount, C. Munro, J. Fenno, P. Fives-Taylor, and F. Macrina, Infect. Immun. 63:4669-4674, 1995). We have evaluated the efficacy of recombinant FimA as a vaccine in the rat model of endocarditis and investigated in vitro the mechanism for the protective role of immunization. FimA-immunized and nonimmunized control animals were catheterized to induce heart valve damage and infected intravenously with 10(7) CFU of wild-type S. parasanguis FW213 bacteria. The presence of bacteria associated with platelet-fibrin vegetations 24 h postchallenge was evaluated. Immunized rats were significantly less susceptible to endocarditis (2 cases among 34 animals) than the control group (21 cases among 33 animals) (P < 0.001). Incubation of S. parasanguis FW213 with rabbit anti-FimA immune serum decreased the mean percent adherence (0.34% of added cells) to platelet-fibrin matrix in vitro compared with that of preimmune normal serum (5.04% of added cells; P < 0.001). Adsorption of immune serum with FimA-positive S. parasanguis FW213 yielded antiserum that failed to block adherence to the platelet-fibrin matrix. We assessed the vaccine potential of FimA as a common immunogen able to provide cross-protection in streptococcal endocarditis by determining the occurrence and expression of fimA in the viridans group streptococci and enterococci. We detected the presence of fimA homologs by Southern hybridization and PCR amplification analyses and determined by immunoblotting the expression of FimA-like proteins among a variety of streptococci and enterococci that frequently cause endocarditis. Eighty-one percent (26 of 32) of streptococcal and enterococcal strains isolated from bacteremic patients expressed proteins that comigrated with FimA and were reactive with polyclonal anti-FimA serum. Streptococcal DNA from strains that were positive by Western blot (immunoblot) analysis hybridized to the full-length fimA probe. Our studies suggest that FimA immunization results in antibody-mediated inhibition of bacterial adherence, a critical early event in the pathogenesis of endocarditis. Our data demonstrate that a majority of streptococcal strains associated with endocarditis have genes that encode FimA-like proteins. Taken together, these results suggest that FimA is a promising candidate for an endocarditis vaccine.