The protective properties of different Legionella antigens in experimental Legionella infection

The protective properties of Legionella antigenic preparations were studied on guinea pigs with experimental Legionella infection. Preliminary immunization of guinea pigs with serotypic antigen, cytolysin, as well as live or formalin-treated Legionella cells, did not protect the animals from the subsequent aerogenic infection with 10(5) colony-forming units of virulent L. pneumophila. Immunization with the main outer membrane protein ensured the survival of 70% of the animals and inhibited the proliferation of the infective agent in the lungs of guinea pigs subjected to aerogenic infection with 10(5) colony-forming units of virulent L. pneumophila. The data obtained in this study indicate that the main outer membrane protein of L. pneumophila is capable of stimulating protective immunity.     

Protective activity of glycolipid antigen against infection by Leptospira interrogans serovar canicola

A protective glycolipid antigen (PAg) was extracted from Leptospira interrogans serovar canicola with chloroform/methanol/water (1:2:0.8, by vol.) and partially purified by silica gel column chromatography. The PAg elicited a protective response in hamsters and in cyclophosphamide-treated mice subsequently challenged with homologous Leptospira. The PAg band was detected as a single smear-like band, corresponding to a protein of 23-30 kDa, by silver-staining in SDS-PAGE. In immunoblots, this band reacted with a monoclonal antibody, A5, which agglutinated serovar canicola and recognized a serovar-specific antigen. Furthermore, the PAg did not migrate on silica gel TLC, but was detected at the origin as a ninhydrin- and naphthol-positive spot. This suggests that PAg is a hydrophilic molecule with a carbohydrate chain that contains amino groups, possibly as amino sugars.     

Identification of protective pneumococcal t(h)17 antigens from the soluble fraction of a killed whole cell vaccine

Mucosal or parenteral immunization with a killed unencapsulated pneumococcal whole cell antigen (WCA) with an adjuvant protects mice from colonization by a T(H)17 CD4+ cell-mediated mechanism. Using preparative SDS gels, we separated the soluble proteins that compose the WCA in order to identify fractions that were immunogenic and protective. We screened these fractions for their ability to stimulate IL-17A secretion from splenocytes obtained from mice immunized with WCA and adjuvant. We identified 12 proteins within the stimulatory fractions by mass spectrometry; these proteins were then cloned, recombinantly expressed and purified using an Escherichia coli expression system. The ability of these proteins to induce IL-17A secretion was then evaluated by stimulation of mouse splenocytes. Of the four most stimulatory proteins, three were protective in a mouse pneumococcal serotype 6B colonization model. This work thus describes a method for identifying immunogenic proteins from the soluble fraction of pneumococcus and shows that several of the proteins identified protect mice from colonization when used as mucosal vaccines. We propose that, by providing protection against pneumococcal colonization, one or more of these proteins may serve as components of a multivalent pneumococcal vaccine.     

The susceptibility of five species of wild animals to experimental infection with Leptospira grippotyphosa

Five species of wild animals including opossums, Didelphis marsupialis, striped skunks, Mephitis mephitis, red, Vulpes vulpes, and gray foxes, Urocyon cinereoargenteus and raccoons, Procyon lotor, were inoculated intraperitoneally with varying numbers of Leptospira grippotyphosa, organisms. Clinical signs were not detected, however, leptospiremia, leptospiruria and antibodies for the homologous organism, were demonstrated. Lesions attributed to leptospirosis were observed in liver and kidney tissue of infected animals. Infections were demonstrated in 5 of 9 opossums, 3 of 9 striped skunks, 3 of 9 red foxes, none of the gray foxes, and 9 of 9 raccoons. Therefore, it would appear that under conditions of this experiment that raccoons were most, opossums moderately, and skunks and red foxes least susceptible; gray foxes were not susceptible.     

Immunostimulating and protective effects of terrilytin preparations in staphylococcal infection

In mice infected with staphylococci there was observed less pronounced development of the immune response to sheep red blood cells (SRBC) than in intact animals subjected only to immunization. Administration of free terrilytin to the infected mice increased the immune response development induced by SRBC while the use of immobilized terrilytin normalized it. The supernatant liquid of the spleen cells (SLSC) from the mice treated with the free of immobilized terrilytins stimulated development of the immune response to SRBC in the infected animals and inhibited the function of the suppressor cells in the spleen. The immunomodulating and protective effects of the SLSC fractions isolated with column chromatography on Sephadex G-150 were investigated. Substances of the low molecular fraction of the SLSC proteins (molecular weight of 10-15 kD) from the mice treated with the terrilytins showed immunostimulating and protective properties. The factors inducing both the activity types included peptides and the ribonucleotide component playing a significant role in realization of the immunostimulating and protective effects of the free and immobilized proteases.     

Induction of protective immunity to experimental hepatic amoebic infection in hamsters

Immunisation of hamsters with the Sephadex G-200 chromatographed Fraction-I of the crude amoebic extract afforded protection in 58% of the animals against an intrahepatic challenge with a virulent subline of axenic Entamoeba histolytica NIH-200 (V). The protected animals had variable levels of anti-FI antiamoebic antibodies, while none of the infected controls had such antibodies. Findings suggest that chromatographed FI of crude amoebic extract might function as a potent immunogen affording protection in amoebic infection.     

The protective action of interferon type I in experimental Salmonella infection

The effect of interferon, type 1, on the course of Salmonella infection in mice has been studied. The study has shown that the injection of homologous interferon of type 1 leads to the rapid elimination of the infective agent from the blood and organs of infected mice. Morphological study has shown that the injection of the preparations of interferon of type 1 may diminish pathological changes in the organs of the infected animals and the coagulation system of their blood.     

Glucuronic acid- and branched sugar-containing glycolipid antigens of Mycobacterium avium

The pentasaccharide hapten of the dominant glycopeptidolipid antigen of serovariant 19 of the Mycobacterium avium complex is noteworthy because of the uniqueness of its distal glycobiose, the presumed antigen determinant, which contains a 3,4-di-O-methyl glucuronic acid and a novel branched sugar. The detailed structure of the entire pentasaccharide has been established by high field 1H and 13C NMR, fast atom bombardment/mass spectrometry, and various specific degradations as 3,4-di-O-Me-beta-D-GlcAp-(1----3)-2,4-di-O-Me-3-C-Me-3,6-dideox yhexosyl-(1----3)-alpha-L-Rhap-(1----3)-alpha-L-Rhap-( 1----2)-6-dT al; the extreme acid lability of the novel penultimate sugar presented special structural challenges. Thus, the task of defining the variable epitopes of M. avium serovariants in order to charter the epidemiology of opportunistic mycobacterial diseases continues to reveal an unexpected order of sugar diversity and complexity.     

Deoxycholate-treated, nontoxic, whole-cell vaccine protective against experimental salmonellosis of mice

A vaccine prepared from the residue after extraction of whole cells of Salmonella typhimurium with 2% sodium deoxycholate proved to be nontoxic and highly immunogenic. The material was not lethal for mice at 6.0 mg and was essentially nontoxic in rabbit skin, whereas endotoxic activity was found in the dialyzed extract. A high dosage, above 2.0 mg, was less protective than lower doses, indicating a degree of "immunologic paralysis." Three inoculations of low doses, 0.25 mg each, induced protection against death and tissue infection in animals challenged with 2,000 ld(50) of virulent homologous S. typhimurium and against death, but not against tissue infection, after heterologous challenge with S. enteritidis. Residues of purified cell walls were as effective as residues of whole cells, indicating that the immunizing antigen(s) resided in the cell wall.     

A multiple-target mRNA-LNP vaccine induces protective immunity against experimental multi-serotype DENV in mice

Dengue virus (DENV) is a mosquito-borne virus with a rapid spread to humans, causing mild to potentially fatal illness in hundreds of millions of people each year. Due to the large number of serotypes of the virus, there remains an unmet need to develop protective vaccines for a broad spectrum of the virus. Here, we constructed a modified mRNA vaccine containing envelope domain III (E-DIII) and non-structural protein 1 (NS1) coated with lipid nanoparticles. This multi-target vaccine induced a robust antiviral immune response and increased neutralizing antibody titers that blocked all four types of DENV infection in vitro without significant antibody-dependent enhancement (ADE). In addition, there was more bias for Th1 than Th2 in the exact E-DIII and NS1-specific T cell responses after a single injection. Importantly, intramuscular immunization limited DENV transmission in vivo and eliminated vascular leakage. Our findings highlight that chimeric allogeneic structural and non-structural proteins can be effective targets for DENV vaccine and that they can prevent the further development of congenital DENV syndrome.     

Cell-free Pseudomonas vaccine. III. Immunochemical analysis of purified Pseudomonas aeruginosa protein antigens and protective properties of antisera against these antigens

The immunochemical analysis of isolated and purified antigens A and B obtained from P. aeruginosa, strains 868 (serogroup O3 according to Lányi or immunotype 3/7 according to Fisher) and 170015 (serogroup O7 or immunotype 2), was carried out. Rabbit antisera to proteins A and B, as well as to the initial aqueous extracts and partially purified aqueous extracts, were obtained. Cross activity between the protein antigens of different strains was established by the methods of immunodiffusion and two-dimensional immunoelectrophoresis. Isolated proteins A and B contained both common and specific antigenic determinants detected by the method of two-dimensional immunoelectrophoresis. The immunization of rabbits with proteins A and B was found to stimulate the synthesis of protective, probably species-specific, antibodies.     

Single intranasal immunization with recombinant adenovirus-based vaccine induces protective immunity against respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract disease in infancy and early childhood. Despite its importance as a pathogen, there is no licensed vaccine against RSV. The G glycoprotein of RSV, a major attachment protein, is a potentially important target for protective antiviral immune responses. Here, a recombinant replication-deficient adenovirus-based vaccine, rAd/3xG, expressing the soluble core domain of G glycoprotein (amino acids 130 to 230) engineered by codon optimization and tandem repetition for higher-level expression, was constructed and evaluated for its potential as an RSV vaccine in a murine model. A single intranasal immunization with rAd/3xG provided potent protection against RSV challenge which lasted for more than 10 weeks. Strong mucosal immunoglobulin A responses were also induced by a single intranasal immunization but not by intramuscular or oral administration of rAd/3xG. Interestingly, neither gamma interferon- nor interleukin-4-producing CD4 T cells directed to I-E^d-restricted epitope were detected in the lungs of rAd/3xG-immune mice upon challenge, whereas priming with vaccinia virus expressing RSV G (vvG) elicited strong Th1/Th2 mixed CD4 T-cell responses. Lung eosinophilia and vaccine-induced weight loss were significantly lower in the rAd/3xG-immune group than in the vvG-primed group. Together, our data demonstrate that a single intranasal administration of rAd/3xG elicits beneficial protective immunity and represents a promising vaccine regimen against RSV infection.     

Evidence for a phosphatidylinositol anchor in glycolipid antigens of Leishmania major

The structure of the membrane anchor of three Leishmania major surface antigenic glycolipids was analyzed. Phosphatidylinositol-specific phospholipase C treatment and nitrous acid deamination indicated the presence of a phosphatidylinositol anchor linked to the glycan through a non-N-acetylated hexosamine. An ester linkage on the C-2 of glycerol was revealed by phospholipase A2 hydrolysis. This fatty acyl substitution was not found on the phosphatidylinositol anchor of the Leishmania lipophosphoglycan.