Immunoprotective effects of invasive Lactobacillus plantarum delivered nucleic acid vaccine coexpressing Trichinella spiralis CPF1 and murine interleukin-4.

Trichinellosis is a very important food-borne parasitic disease, that seriously endangers animal husbandry and food safety. Therefore, it is necessary to develop a safe and effective vaccine against Trichinella spiralis infection. In this experiment, invasive Lactobacillus plantarum carrying the FnBPA gene served as a live bacterial vector to deliver nucleic acids to the host to produce a novel oral nucleic acid vaccine. Coexpression of the T. spiralis cathepsin F-like protease 1 gene (TsCPF1) and murine IL-4 (mIL-4) by the nucleic acid vaccine was constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. Thirty-seven days after the first immunization, the experimental mice were challenged with 350 T. spiralis infective larvae by oral gavage. The results showed that mice orally immune-stimulated with invasive L. plantarum pValac-TsCPF1/pSIP409-FnBPA not only produce anti-TsCPF1-specific IgG antibodies, sIgA, Th1/Th2 cytokine distinctly increased but also intestinal damage and worm burden relieved compare to non-invasive TsCPF1 group (pValac-TsCPF1/pSIP409). Most notably, experimental mice immunized with invasive L. plantarum coexpressing TsCPF1 and mIL-4 (pValac-TsCPF1-IL-4/pSIP409-FnBPA) exhibited the highest protection efficiency against T. spiralis infection. The above results reveal that invasive L. plantarum-expressing the FnBPA protein improved mucosal and cellular immunity and enhanced resistance to T. spiralis. The nucleic acid vaccine delivered by invasive L. plantarum described in this study offers a novel idea for the prevention of T. spiralis.

[Cloning, expression and immunologic identification of Eg10 gene of Echinococcus granulosus].

OBJECTIVE: To clone and express Eg10 gene of Echinococcus granulosus, and investigate the immunological characteristic of the recombinant. METHODS: Eg10 gene was subcloned into pET28a vector. The recombinant plasmid was transformed into E. coli BL21 and induced with IPTG. The recombinant protein was purified with His-bind purification kit. Forty-eight mice were randomly divided into 4 groups. Mice in groups A and B were injected with PBS and PBS+Freund's adjuvant (100 microl) as control. Mice in groups C and D were immunized with 10 mg and 50 microg purified Eg10 antigen formulated in Freund's adjuvant, respectively. All the mice received three immunizations at 2-week intervals with the same dose of antigen. Serum samples were collected at pre-immunization and certain time after immunization. The immunological characteristics of recombinant Eg10 was analyzed by Western blotting and ELISA. RESULTS: The recombinant Eg10 protein (Mr 31 000) was expressed in E. coli BL21. The recombinant Eg10 and expression product of PET28a/Eg10 were recognized by sera from mice immunized with recombinant Eg10. ELISA showed that the titer of IgG reached a peak at the 8th week in groups C and D, the level of IgG in sera of groups C or D was higher than that of groups A or B (P < 0.05) at the 2nd, 4th, 6th, 8th, and 10th week. There was no significant difference in the level of IgG between group C and group D (P > 0.05). CONCLUSION: The Eg10 gene has been expressed with immunogenicity.

Evolutionary perspectives on innate immunity from the study of Caenorhabditis elegans.

Genetic and functional genomic approaches have begun to define the molecular determinants of pathogen resistance in Caenorhabditis elegans. Conserved signal transduction components are required for pathogen resistance, including a Toll/IL-1 receptor domain adaptor protein that functions upstream of a conserved p38 MAP kinase pathway. We suggest that this pathway is an ancestral innate immune signaling pathway present in the common ancestor of nematodes, arthropods and vertebrates, which is likely to predate the involvement of canonical Toll signaling pathways in innate immunity. We anticipate that the study of pathogen resistance in C. elegans will continue to provide evolutionary and mechanistic insights into the signal transduction and physiology of innate immunity.

The functional genomic distribution of protein divergence in two animal phyla: coevolution, genomic conflict, and constraint.

We compare the functional spectrum of protein evolution in two separate animal lineages with respect to two hypotheses: (1) rates of divergence are distributed similarly among functional classes within both lineages, indicating that selective pressure on the proteome is largely independent of organismic-level biological requirements; and (2) rates of divergence are distributed differently among functional classes within each lineage, indicating species-specific selective regimes impact genome-wide substitutional patterns. Integrating comparative genome sequence with data from tissue-specific expressed-sequence-tag (EST) libraries and detailed database annotations, we find a functional genomic signature of rapid evolution and selective constraint shared between mammalian and nematode lineages despite their extensive morphological and ecological differences and distant common ancestry. In both phyla, we find evidence of accelerated evolution among components of molecular systems involved in coevolutionary change. In mammals, lineage-specific fast evolving genes include those involved in reproduction, immunity, and possibly, maternal-fetal conflict. Likelihood ratio tests provide evidence for positive selection in these rapidly evolving functional categories in mammals. In contrast, slowly evolving genes, in terms of amino acid or insertion/deletion (indel) change, in both phyla are involved in core molecular processes such as transcription, translation, and protein transport. Thus, strong purifying selection appears to act on the same core cellular processes in both mammalian and nematode lineages, whereas positive and/or relaxed selection acts on different biological processes in each lineage.

Immune evasion genes from filarial nematodes.

Helminth parasites have large genomes (approximately 10(8) bp) which are likely to encode a spectrum of products able to block or divert the host immune response. We have employed three parallel approaches to identify the first generation of 'immune evasion genes' from parasites such as the filarial nematode Brugia malayi. The first strategy is a conventional route to characterise prominent surface or secreted antigens. In this way we have identified a 15-kDa protein, which is located on the surface of both L3 and adult B. malayi, and secreted by these parasites in vitro, as a member of the cystatin (cysteine protease inhibitor) family. This product, Bm-CPI-2, blocks conventional cysteine proteases such as papain, but also the aspariginyl endopeptidase involved in the Class II antigen processing pathway in human B cells. In parallel, we identified the major T cell-stimulating antigen from the microfilarial stage as a serpin (serine protease inhibitor), Bm-SPN-2. Microfilariae secrete this product which blocks two key proteases of the neutrophil, a key mediator of inflammation and innate immunity. The second route involves a priori hypotheses that helminth parasites encode homologues of mammalian cytokines such as TGF-beta which are members of broad, ancient metazoan gene families. We have identified two TGF-beta homologues in B. malayi, and shown that one form (Bm-TGH-2) is both secreted by adult parasites in vitro and able to bind to host TGF-beta receptors. Likewise, B. malayi expresses homologues of mammalian MIF, which are remarkably similar in both structure and function to the host protein, even though amino acid identity is only 28%. Finally, we deployed a third method of selecting critical genes, using an expression-based criterion to select abundant mRNAs taken from key points in parasite life histories. By this means, we have shown that the major transcript present in mosquito-borne infective larvae, Bm-ALT, is a credible vaccine candidate for use against lymphatic filariasis, while a second abundantly-expressed gene, Bm-VAL-1, is similar to a likely vaccine antigen being developed against hookworm parasites.

[Researches on immunogenicity identification of recombinant Sj22.6(rSj22.6) kDa antigen gene of schistosoma japonicum].

AIM: To identify the immunogenicity and the potentiality of rSj22.6 as a candidate vaccine antigen for schistosomiasis japonica. METHODS: rSj22.6 was tested by Western blot with specific antibodies to identify its immunogenicity. The rSj22.6 protein was isolated and purified by SDS-PAGE and injected twice into rabbits to raise antirSj22.6 serum that was tested by Western blot to recognize the native protein of adult S. japonicum and SEA. C57 mice were immunized with rSj22.6 and challenged with S. japonicum cercariae to identify the protective immunity raised by rSj22.6. RESULTS: rSj22.6 could be recognized by specific antibodies and could stimulate the rabbits to produce high level of anti-rSj22.6 antibodies. Anti-rSj22.6 serum could recognize an adult native protein with the same molecular weight as rSj22.6. The preliminary immune-challenge test resulted in significant reduction in adult worm burden. CONCLUSION: rSj22.6 possesses immunogenicity in stimulating rabbits to produce high level of specific antibody and has protective role as a candidate vaccine antigen against S. japonicum infection.