Vaccination of domestic pig with recombinant paramyosin. against Schistosoma japonicum in China

Paramyosin (PM), a myosin-like protein is a major antigen on Schistosoma japonicum (Sj). We reported that passive transfer of a monoclonal IgE SjE18varepsilon.1 which recognizes PM of Sj (SJPM), partially protected mice from challenge infection. In the present study, we developed an experimental model system of schistosomiasis japonica with domestic pigs in China and used it for the evaluation of vaccination with recombinant SJPM (rSJPM). Sixteen-week-old pigs were successfully infected by dermal penetration of 120 cercariae of a domestic strain of Sj (50-60% worm recovery 11 weeks after challenge). The pigs vaccinated with 400 UV attenuated cercariae showed a reduction of worm recovery (53%, p<0.001). The experimental groups were immunized intradermally with rSJPM and alum or TiterMax and were partially protected against the challenge infection (32-35% reduction).     

Human phase I vaccine trials of 3 recombinant asexual stage malaria antigens with Montanide ISA720 adjuvant

Two phase I vaccine trials were conducted to test the immunogenicity and safety of a vaccine containing three recombinant malaria antigens from the asexual stage of Plasmodium falciparum. The three antigens are a fragment of MSP1 (190LCS.T3); MSP2 and a portion of RESA and were formulated in Montanide ISA720 adjuvant. These trials investigated the dose response of each antigen for eliciting both antibody and T-cell responses and the immunogenicity of a mixture of the antigens compared with the antigens injected separately. All three antigens elicited both antibody and T-cell responses. Strong T-cell responses were observed with 190LCS.T3 and RESA with stimulation indices exceeding 100 for peripheral blood leucocytes in some individuals. The antibody responses were generally weak. The human antibody responses observed with MSP2 in Montanide ISA720 were not significantly different from those obtained in an earlier trial which used MSP2 with alum as the adjuvant. No antigenic competition was observed: volunteers receiving a mixture of antigens had similar responses to those receiving the three antigens at separate sites. Tenderness and pain at the injection site were common over the first few days following immunization. In some volunteers, especially those receiving the highest doses tested, there was a delayed reaction at the injection site with pain and swelling occurring approximately 10 days after injection.     

Vaccination with recombinant adhesins from the RgpA-Kgp proteinase-adhesin complex protects against Porphyromonas gingivalis infection

Porphyromonas gingivalis is a pathogen associated with chronic periodontitis, an inflammatory disease of the supporting tissues of the teeth. A major virulence factor for P. gingivalis is the RgpA-Kgp proteinase-adhesin complex. We have prepared the following recombinant proteins corresponding to domains/regions of the RgpA-Kgp complex; rRgpA(cat), rRgpA(A1), rRgpA(A2), rRgpA(A4), rRgpA(A1)(784-1009), rRgpA(A1)(911-1009), rKgp(A1) and rKgp(A1)(759-989). The ability of each recombinant protein to attenuate P. gingivalis infection, when used as a vaccine, in the murine lesion model was determined. All of the recombinant adhesin domains were found to significantly attenuate P. gingivalis infection with the most effective being rKgp(A1) and rKgp(A1)(759-989) followed by rRgpA(A1), rRgpA(A1)(784-1009) and rRgpA(A1)(911-1009). The predominant antibody isotype was IgG1. The A1 adhesins, which gave the best protection, contain specific motifs implicated in binding to host tissue. Immunisation with rRgpA(cat) had no effect on P. gingivalis infection. As well as detecting the Kgp(A1) adhesin in a Western blot, the rKgp(A1) and rKgp(A1)(759-989) antisera were also immunoreactive with the A1 and A3 adhesins of RgpA and HagA. Flow cytometric analysis indicated that rKgp(A1) and rRgpA(A1) antisera recognised native antigen on P. gingivalis whole cells. Furthermore, the rKgp(A1) and rKgp(A1)(759-989) antisera exhibited a similar immunoreactive profile with outer membrane preparations of all P. gingivalis serotypes and clinical isolates tested. The recombinant A1 adhesin therefore has potential in the development of a P. gingivalis vaccine.     

Vaccination with recombinant FimH fused with flagellin enhances cellular and humoral immunity against urinary tract infection in mice

Urinary tract infection (UTI) caused by Uropathogenic Escherichia coli (UPEC) is one of the most common infections in the world. Despite extensive efforts, a vaccine that confers protection against UTIs in human is currently lacking. In this study, the ability of flagellin (FliC), a Toll-like receptor 5 (TLR5) agonist of UPEC strain, and the conventional adjuvant Montanide ISA 206 to enhance the protective immune responses of FimH against urinary tract infection have been compared. Mice immunized with the fused FimH.FliC protein induced significantly higher humoral (IgG1 and IgG2a) and cellular (IFN-γ and IL-4) immune responses than with FimH alone or FimH admixed with FliC. The immune responses of Montanide formulations were comparable to that of the fusion protein and were significantly higher than that of FimH alone. Our results showed that based on the IgG1/IgG2a ratios, FliC directed the anti-FimH responses preferentially toward Th2 and Montanide toward Th1. The FimH.FliC fusion and FimH admixed with FliC and Montanide formulations gave the best results in protection of bladder colonization, compared to the control mice. The results propose new promising vaccine formulation based on the adjuvant properties of FliC and Montanide against UTI caused by UPEC strains.     

CpG oligodeoxynucleotide and montanide ISA 206 adjuvant combination augments the immune responses of a recombinant FMDV vaccine in cattle

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. To prevent the spread of FMDV, inactivated virus vaccines are used to immunize animals in developing countries. However, there are safety concerns. In addition, it is difficult to distinguish the vaccinated animals from those naturally infected ones. In our lab, we have developed a recombinant FMDV vaccine named A7. A7 contained multiple B cell and T cell epitopes, which reside in a capsid protein (VP1) of FMDV. To enhance its immunogenicity, A7 was formulated with CpG ODN RW03 in combination with Montanide ISA 206 (ISA), and the resultant vaccine (A7 + ISA + CpG ODN RW03) was used to immunize mice and cattle. It was found that CpG ODN RW03 and ISA combination could facilitate A7 to induce a vigorous and long-lasting specific antibody response in mice and cattle. After FMDV challenge, 80% (4/5) of the calves immunized with A7 + ISA + CpG ODN RW03 were protected, which was superior to those immunized with A7 + ISA (25%, 1/4) or inactivated FMDV vaccine (50%, 2/4). These findings suggest that CpG ODN RW03 could be used with Montanide ISA 206 as a potent adjuvant for recombinant FMDV in cattle.     

Recombinant paramyosin (rec-Sj-97) tested for immunogenicity and vaccine efficacy against Schistosoma japonicum in mice and water buffaloes.

A primary vaccine candidate antigen against schistosomiasis is paramyosin (pmy), a myofibrillar protein found exclusively in invertebrates. Here we report the results of vaccine trials against the Asian schistosome undertaken on inbred and outbred mice and water buffaloes using a bacterially expressed and purified form of Schistosoma japonicum pmy (rec-Sj-97). Vaccination of the mice resulted in high levels of specific anti-pmy IgG antibodies when compared with adjuvant controls and significant reduction in worm burdens and in liver eggs. Furthermore, a significant reduction in liver eggs was recorded in two of the three water buffalo vaccine trials undertaken and, in all three trials, high levels of specific anti-pmy IgG antibodies were generated. There was no evidence of any toxic effects and the vaccine preparations and Quil A adjuvant were clearly well tolerated. The development of a vaccine intended for livestock animals such as bovines would be beneficial in two ways; directly by blocking transmission of schistosomiasis to humans and economically by contributing to healthier livestock. We are encouraged by the consistent efficacy in the mouse and the buffalo vaccine trials that resulted in a significant decrease in liver eggs. Indeed, predictions from mathematical models indicate that an egg reduction effect of 42-45% in buffaloes would be sufficient when combined with human treatment to control schistosomiasis japonica in the marshes and lakes along the middle and upper reaches of the Yangtze River, the most highly endemic areas for the disease in China.     

Immunization with lipopolysaccharide-free outer membrane complexes protects against Acinetobacter baumannii infection

Outer membrane complex (OMC) vaccines, which contain antigens from the bacterial outer membrane, have been developed for multiple Gram-negative bacteria. However, OMC vaccines demonstrate high endotoxin activity due to the presence of lipopolysaccharide in the bacterial outer membrane, thus precluding their use in humans. We isolated OMCs from an LPS-deficient strain of A. baumannii (IB010) which completely lacks LPS due to a mutation in the lpxD gene. OMCs from IB010 demonstrated a more than 10,000-fold reduction in endotoxin activity compared to OMCs from wild type A. baumannii. Vaccination with IB010 OMCs produced similar levels of antigen-specific IgG and IgM after two administrations compared to wild type OMCs, and resulted in a similar reduction in post-infection spleen bacterial loads and serum pro-inflammatory cytokine levels. Vaccination with IB010 OMCs provided significant protection against infection compared to control mice, indicating the LPS-free OMCs could contribute to vaccine strategies for preventing infection by A. baumannii.     

Vaccination with recombinant modified vaccinia virus Ankara protects against measles virus infection in the mouse and cotton rat model

Modified vaccinia virus Ankara (MVA) has been used as an experimental vaccine vector against respiratory infections. We have tested the safety and immunogenicity of a recombinant virus expressing the hemagglutinin of measles virus (MVA-MV-H) using the mouse model of measles virus induced encephalitis and the cotton rat model for respiratory infection. MVA-MV-H proved to induce a TH1 response, neutralizing antibodies and conferred protection against both encephalitis and lung infection. The cotton rat is very sensitive to infection with replication competent vaccinia virus. In these animals MVA-MV-H proved to be a very well tolerated vaccine. However, the efficiency in the presence of MV specific maternal antibodies was low (even using a prime-boost strategy) and therefore might have to be improved.     

Vaccination with a live attenuated Acinetobacter baumannii deficient in thioredoxin provides protection against systemic Acinetobacter infection

Multi-drug resistant Acinetobacter baumannii (MDR-Ab), an opportunistic pathogen associated with nosocomial and combat related infections, has a high mortality due to its virulence and limited treatment options. Deletion of the thioredoxin gene (TrxA) from a clinical isolate of MDR-Ab resulted in a 100-fold increase in 50% lethal dose (LD₅₀) in a systemic challenge murine model. Thus, we investigated the potential use of this attenuated strain as a live vaccine against MDR-Ab. Mice were vaccinated by subcutaneous (s.c.) injection of 2 × 10⁵ CFU of the ΔtrxA mutant, boosted 14 days later with an equivalent inoculum, and then challenged 30 days post-vaccination by i.p. injection with 10 LD₅₀ of the wild type (WT) Ci79 strain. Efficacy of vaccination was evaluated by monitoring MDR-Ab specific antibody titers and cytokine production, observing pathology and organ burdens after WT challenge, and measuring levels of serum pentraxin-3, a molecular correlate of A. baumannii infection severity, before and after challenge. Mice vaccinated with ΔtrxA were fully protected against the lethal challenge of WT. However, minimal immunoglobulin class switching was observed with IgM predominating. Spleens harvested from vaccinated mice exhibited negligible levels of IL-4, IFN-γ and IL-17 production when stimulated with UV-inactivated WT Ci79. Importantly, tissues obtained from vaccinated mice displayed reduced pathology and organ burden compared to challenged non-vaccinated mice. Additionally, serum pentraxin-3 concentrations were not increased 24 h after challenge in vaccinated mice, correlating with reduction of WT MDR-Ab infection in ΔtrxA immunized mice. Furthermore, passive immunization with ΔtrxA-immune sera provided protection against lethal systemic Ci79 challenge. Collectively, the defined live attenuated ΔtrxA strain is a vaccine candidate against emerging MDR Acinetobacter infection.     

Intranasal immunisation with recombinant adenovirus vaccines protects against a lethal challenge with pneumonia virus of mice

Pneumonia virus of mice (PVM) infection of BALB/c mice induces bronchiolitis leading to a fatal pneumonia in a dose-dependent manner, closely paralleling the development of severe disease during human respiratory syncytial virus infection in man, and is thus a recognised model in which to study the pathogenesis of pneumoviruses. This model system was used to investigate delivery of the internal structural proteins of PVM as a potential vaccination strategy to protect against pneumovirus disease. Replication-deficient recombinant human adenovirus serotype 5 (rAd5) vectors were constructed that expressed the M or N gene of PVM pathogenic strain J3666. Intranasal delivery of these rAd5 vectors gave protection against a lethal challenge dose of PVM in three different mouse strains, and protection lasted for at least 20 weeks post-immunisation. Whilst the PVM-specific antibody response in such animals was weak and inconsistent, rAd5N primed a strong PVM-specific CD8⁺ T cell response and, to a lesser extent, a CD4⁺ T cell response. These findings suggest that T-cell responses may be more important than serum IgG in the observed protection induced by rAd5N.     

Vaccination of mice with a cocktail DNA vaccine induces a Th1-type immune response and partial protection against Schistosoma japonicum infection.

Several defined vaccine candidate antigens of Schistosoma japonicum have shown promise in large animal vaccination experiments. However, vaccination of mice in the laboratory with either single recombinant antigens or DNA encoding forms of the individual antigens has so far failed to induce significant protection against S. japonicum cercarial challenge infection as judged by worm reduction, although specific antibodies were generated. This is in contrast to the results achieved using radiation-attenuated vaccines which are highly protective. Even in large animal vaccination experiments, the protection levels obtained with single defined antigens were far below those achieved using the attenuated vaccines. One possible interpretation is that the immune responses induced by single antigen vaccination may not be strong enough to combat the challenging infection. We, therefore, carried out mouse vaccination experiments using a cocktail DNA vaccine comprising four DNA plasmids encoding four different S. japonicum antigens, Sj62, Sj28, Sj23 and Sj14-3-3, respectively. We, also investigated whether co-injection of the mouse IL-12 encoding plasmid with the cocktail DNA vaccine was able to enhance the Th1 responses and hence the protective immunity. Three intramuscular injections of the cocktail DNA vaccine induced a significant Th1-type cellular response with high level of IFN-gamma production by splenocytes upon in vitro stimulation with recombinant antigens. Importantly, significant IgG antibody responses were also induced against crude worm antigens. In two out of three experiments, significant resistance (34-37 and 44-45%, respectively) was demonstrated while another experiment did not show any protection against S. japonicum cercarial challenge infection. Co-injection of the IL-12 encoding DNA did not further enhance these responses, nor the level of resistance, compared with the cocktail DNA alone.     

Immunization with a peptide mimicking Lipoteichoic acid protects mice against Staphylococcus aureus infection

Lipoteichoic acid (LTA), a major component of the cell wall of Staphylococcus aureus (S. aureus), is not generally considered as an ideal vaccine candidate since it is a thymus-independent antigen. In this study, we screened a 12-mer phage peptide library and identified a series of peptide sequences that can mimic the epitope of LTA. A tetra-branched multiple antigenic peptide, named MAP2-3, comprising one of the positive peptide sequences (GHKEDRQWCQHS), was synthesized. Immunization with MAP2-3 induced LTA-specific IgG antibodies, prolonged the survival time, and decreased the bacterial burden in organs of mice infected with S. aureus. Moreover, passive immunization with polyclonal anti-MAP2-3 sera reduced bacterial load in organs of mice with bacteremia, alleviated acute lung injury in mice with pneumonia, and decreased the size of lesions in mice with skin infection. The number of LTA-specific antibody-secreting cells in the spleen of MAP2-3 immunized mice were significantly higher than that in the control mice. In summary, as a surrogate of LTA, vaccination with MAP2-3 elicited humoral immune response and protected mice from S. aureus infection. This study provides a new option to design vaccines against S. aureus.     

Parenteral immunization with IpaB/IpaD protects mice against lethal pulmonary infection by Shigella

Shigellosis is an important diarrheal disease, especially among children in the developing world. About 90 million infections with Shigella spp are estimated to appear each year. We previously demonstrated that the type III secretion apparatus (T3SA) proteins IpaB and IpaD are protective antigens when administered intranasally using the mouse lethal pulmonary model. To simplify vaccine administration, we tested the parenteral route for IpaB and IpaD with several adjuvants and compared the immune response and protective efficacy via the intranasal route. We found that the intramuscular administration generated a response consisting of similar levels of serum IgG, a lack of IgA response and higher IL-17 secretion. Therefore, while parenteral administration yielded a unique pattern of immune responses, it retained the ability to protect mice in a lethal pulmonary challenge against S. flexneri when both proteins were used. Our results show the feasibility of generating protective parenteral vaccines against Shigella spp.     

Vaccination with recombinant Mycobacterium avium subsp. paratuberculosis proteins induces differential immune responses and protects calves against infection by oral challenge

We previously reported the in vitro cellular immune responses to recombinant antigens (rAgs) of Mycobacterium avium subsp. paratuberculosis (MAP). Here we report the differential immune responses and protective efficacy of four rAgs of MAP (85A, 85B, 85C, and superoxide dismutase (SOD)) used with two adjuvants (monophosphoryl lipid A (MPLA) containing synthetic trehalose dicorynomycolate, cell wall skeleton (MPLA) and bovine IL-12), against MAP challenge in calves. Group I was administered the four rAgs with MPLA and IL-12. Group II was administered the four rAgs and MPLA. Group III received MPLA and IL-12, and Group IV MPLA. rAgs induced significant lymphoproliferative responses in vaccinated animals (Groups I and II). All the rAgs induced significant IFN-gamma production from 11 to 23 wk after primary vaccination (APV), except for SOD. Significant increases were noted in CD3(+), CD4(+), CD8(+), CD21(+), CD25(+), and gammadelta(+) cells against all four rAgs in vaccinated animals. rAg-specific expression of IL-2, IL-12p40, IFN-gamma and TNF-alpha was significantly higher in the two vaccinated groups. Culture results found 4/8 animals in Group I, 3/8 animals in Group II, and 3/4 animals in Groups III and IV were positive for MAP in one or more tissues. Among the seven positive animals in Groups I and II, all but one had had <10CFU. Isolation was confined to one tissue in these animals, except in one animal in which MAP was isolated from two tissues. In the control groups (III and IV), MAP was cultured from up to five different tissues with >250CFU. Preliminary data from this study indicates that all four rAgs induced a good Th1 response and conferred protection against MAP infection in calves.     

Immunization with a recombinant fusion protein protects mice against Helicobacter pylori infection

More than 50% of the world's population is infected with the bacterium Helicobacter pylori. If left untreated, infection with H. pylori can cause chronic gastritis and peptic ulcer disease, which may progress into gastric cancer. Owing to the limited efficacy of anti-H. pylori antibiotic therapy in clinical practice, the development of a protective vaccine to combat this pathogen has been a tempting goal for several years. In this study, a chimeric gene coding for the antigenic parts of H. pylori FliD, UreB, VacA, and CagL was generated and expressed in bacteria and the potential of the resulting fusion protein (rFUVL) to induce humoral and cellular immune responses and to provide protection against H. pylori infection was evaluated in mice. Three different immunization adjuvants were tested along with rFUVL: CpG oligodeoxynucleotides (CpG ODN), Addavax, and Cholera toxin subunit B. Compared to the control group that had received PBS, vaccinated mice showed significantly higher cellular recall responses and antigen-specific IgG2a, IgG1, and gastric IgA antibody titers. Importantly, rFUVL immunized mice exhibited a reduction of about three orders of magnitude in their stomach bacterial loads. Thus, adjuvanted rFUVL might be considered as a promising vaccine candidate for the control of H. pylori infection.     

Protection against Schistosoma haematobium infection in hamsters by immunization with Schistosoma mansoni gut-derived cysteine peptidases,SmCB1 and SmCL3

We examined the immunogenicity and protective potential of SmCB1 and SmCL3 cysteine peptidases, alone and in combination, in hamsters challenged with S. haematobium. For each of two independent experiments, eight Syrian hamsters were immunized twice with a three week-interval with 0 (controls), 20 µg SmCB1, 20 µg SmCL3, or 10 µg SmCB1 plus 10 µg SmCL3, and then percutaneously exposed eight weeks later to 100 S. haematobium cercariae. Hamsters from each group were assessed for humoral and whole blood culture cytokine responses on day 10 post challenge infection, and examined for parasitological parameters 12 weeks post infection. At day 10 post-infection we found that SmCB1 and SmCL3 elicited low antibody titres and weak but polarized cytokine type 2 responses. Nevertheless, both cysteine peptidases, alone or in combination, evoked reproducible and highly significant reduction in challenge worm burden (>70%, P < 0.02) as well as a significant reduction in worm egg counts and viability. The data support our previous findings and show that S. mansoni cysteine peptidases SmCB1 and SmCL3 are efficacious adjuvant-free vaccines that induce protection in mice and hamsters against both S. mansoni and S. haematobium.     

Protection against Fasciola gigantica infection in mice by vaccination with recombinant juvenile-specific cathepsin L

Fasciola gigantica cathepsin L1H (FgCatL1H) is one of the major cathepsin L released by juveniles of F. gigantica to aid in the invasion of host's tissues. Due to its high sequence similarity with other cathepsin L (CatL) isoforms of late stage F. gigantica, it was considered to be a good vaccine candidate that can block all CatL-mediated protease activities and affect juveniles as well as adult parasites. In this study, recombinant proFgCatL1H protein expressed in yeast, Pichia pastoris, system was mixed with Freund's adjuvants and used to subcutaneously immunize mice that were later challenged with metacercariae of F. gigantica. The percentage of worm protection in the rproFgCatL1H-vaccinated mice compared to the non-immunized and adjuvant control mice were approximately 62.7% and 66.1%, respectively. Anti-rproFgCatL1H antisera collected from vaccinated mice reacted specifically with rproFgCatL1H and other cathepsin L isoforms of F. gigantica, but the antibodies did not cross react with antigens from other trematode and nematode parasites, including Eurytrema pancreaticum, Opisthorchis viverrini, Fischoederius cobboldi, Cotylophoron cotylophorum, Gigantocotyle explanatum, Paramphistomum cervi, and Setaria labiato-papillosa. The levels of IgG1 and IgG2a in mouse sera increased significantly at two weeks after immunization and were highest during the sixth to eighth weeks after immunization. The IgG1 level was higher than IgG2a at all periods of immunization, implicating the dominance of the Th2 response. The levels of IgG1 and IgG2a in the immune sera were shown to be strongly correlated with the numbers of worm recovery, and the correlation coefficient was higher for IgG1. The levels of serum aspartate aminotransferase and alanine transaminase were significantly lower in the sera of rproFgCatL1H-vaccinated mice than in the infected control mice indicating a lower degree of liver damage. This study demonstrated a high potential of FgCatL1H vaccine, and its efficacy is currently being studied in the larger economic animals.     

Vaccination with Neospora caninum-cyclophilin and -profilin confers partial protection against experimental neosporosis-induced abortion in sheep

The purpose of this study was to evaluate the protective efficacy of a vaccine consisting of recombinant Neospora caninum-cyclophilin (NcCyP) and -profilin (NcPro) in sheep. At 42 d and 21 d prior to mating, adult Dorset ewes were immunized with the rNcCyP-rNcPro vaccine (Group 1) or co-purifying non-recombinant (NR) control vaccine (Group 2). At 90 days post-mating, all immunized ewes and were challenged by intravenous injection with 10⁶ Nesopora caninum Illinois tachyzoites (NcTZ). Significant protection (P < 0.05) was observed in Group 1 with 9 out of 13 ewes giving birth to live-born lambs (69.2%), whereas all Group 2 ewes aborted (6/6). Neospora caninum was detected by PCR in both fetal and placental tissues from all Group 2 aborting ewes and in the placental tissues of Group 1 aborting ewes. In contrast, tissues and placentas of Group 1 live-born lambs were Neospora DNA-negative. Immunoreactive Neospora antigens were demonstrated in placentas associated with abortions, but not in tissues of aborted fetuses or those of the live-born lambs and their associated placentas. Anti-NcCyP and anti-NcPro titers were high in sera from Group 1 ewes and were further boosted by challenge infection, resulting in long-lasting (≥14.5 mos.) elevated titers. Lambs born to Group 1 ewes also had high NcCyP and NcPro titers in pre-colostrum sera. Immunofluorescence staining (IFA) of NcTZ with Group 1 post-immunization sera revealed both surface and internal TZ staining, a pattern consistent with that observed with rabbit sera to rNcCyP or rNcPro. Infection of NR-vaccinated ewes produced high but transient anti-NcCyP and anti-NcPro Ab titers. The results indicate that the NcCyP-NcPro vaccine elicited strong anti-N. caninum responses and conferred significant protection against abortion and transplacental transmission of N. caninum TZ in sheep.     

Immunization with a recombinant BibA surface protein confers immunity and protects mice against group B Streptococcus (GBS) vaginal colonization

Streptococcus agalactiae or group B Streptococcus (GBS) is a Gram-positive bacterium divided into ten distinct serotypes that colonizes the vaginal and rectal tracts of approximately 30% of women worldwide. GBS is the leading cause of invasive infection in newborns, causing sepsis, pneumoniae and meningitis. The main strategy to prevent GSB infection in newborns includes the use of intrapartum antibiotic therapy, which does not prevent late-onset diseases and may select resistant bacterial strains. We still do not have a vaccine formulation specific for this pathogen approved for human use. Conserved surface proteins are potential antigens that could be targets for recognition by antibodies and activation of cell opsonization. We used a serotype V GBS (GBS-V)-derived recombinant surface protein, rBibA, and evaluated the potential protective role of the induced antigen-specific antibodies after parenteral or mucosal immunizations in C57BL/6 mice. In vitro and in vivo assays demonstrated that vaccine formulations containing BibA combined with different adjuvants induced serum IgG and/or secreted IgA antibodies, leading to enhanced opsonophagocytosis of GBS-V cells and reduced invasion of epithelial cells. One BibA-based vaccine formulation adjuvanted with a nontoxic derivative of the heat-labile toxin produced by enterotoxigenic Escherichia coli (ETEC) strains was capable of inducing protection against vaginal colonization and lethal parenteral challenge with GBS-V. Serum collected from vaccinated mice conferred passive protection against vaginal colonization in naïve mice challenged with GBS-V. Taken together, the present data demonstrate that the BibA protein is a promising antigen for development of a vaccine to protect against GBS infection.     

A novel recombinant human lactoferrin augments the BCG vaccine and protects alveolar integrity upon infection with Mycobacterium tuberculosis in mice

Lactoferrin, an iron binding glycoprotein, possesses multiple immune modulatory activities, including the ability to promote antigen specific cell-mediated immunity. Previous studies showed that adding bovine lactoferrin to the BCG vaccine (an attenuated strain of Mycobacterium bovis Bacillus Calmette Guerin) resulted in increased host protective responses upon subsequent challenge with virulent Erdman Mycobacterium tuberculosis (MTB) in mice. The studies outlined here investigate utility of a novel recombinant human lactoferrin to enhance the BCG vaccine and protect against alveolar injury during experimental MTB infection in mice. Sialylated and non-sialylated forms of the recombinant human lactoferrin (rhLF), glycoengineered in yeast (Pichia pastoris) and expressing humanized N-glycosylation patterns, were examined for their ability to enhance efficacy of the BCG vaccine in a murine TB model system. Results indicated that the sialylated form of the recombinant human lactoferrin generated increased antigen specific recall responses to BCG antigens. Furthermore, augmented protection was demonstrated using the sialylated lactoferrin adjuvant with BCG, resulting in significant reduction in associated pathology following challenge with virulent organisms.