The effect of probiotic Bifidobacterium lactis Bl-04 on innate antiviral responses invitro.

Consumption of certain probiotic strains may be beneficial for reducing the risk of acute upper respiratory tract infections (URTIs), however, underlying immunological mechanisms are elusive. Bifidobacterium lactis Bl-04™ has been reported in humans to significantly reduce the risk of URTIs, affect the innate immunity in the nasal mucosa, and reduce nasal lavage virus titer after a rhinovirus (RV) challenge. To study the immunological mechanisms, we investigated the effect of Bl-04 on cytokine production and transcriptomes of human monocyte-derived macrophages (Mfs) and dendritic cells (DCs), and further on RV replication and cytokine production in MRC-5 fibroblasts. The results showed that Bl-04 modulates antiviral immune responses and potentiates cytokine production during viral challenge mimic in immune cells. However, effect of Bl-04 on RV replication and cytokine production in fibroblasts was negligible. Overall, the findings suggest that Bl-04 mildly stimulates antiviral immunity in Mfs and DCs, and potentially influences viral replication in fibroblasts that however warrants further investigations.

Bos taurus genome sequence reveals the assortment of immunoglobulin and surrogate light chain genes in domestic cattle.

BACKGROUND: The assortment of cattle immunoglobulin and surrogate light chain genes has been extracted from the version 3.1 of Bos taurus genome sequence as a part of an international effort to sequence and annotate the bovine genome. RESULTS: 63 variable lambda chain and 22 variable kappa chain genes were identified and phylogenetically assigned to 8 and 4 subgroups, respectively. The specified phylogenetic relationships are compatible with the established ruminant light chain variable gene families or subgroups. Because of gaps and uncertainties in the assembled genome sequence, the number of genes might change in the future versions of the genome sequence. In addition, three bovine surrogate light chain genes were identified. The corresponding cDNAs were cloned and the expression of the surrogate light chain genes was demonstrated from fetal material. CONCLUSION: The bovine kappa gene locus is compact and simple which may reflect the preferential use of the lambda chain in cattle. The relative orientation of variable and joining genes in both loci are consistent with a deletion mechanism in VJ joining. The orientation of some variable genes cannot be determined from the data available. The number of functional variable genes is moderate when compared to man or mouse. Thus, post-recombinatorial mechanisms might contribute to the generation of the bovine pre-immune antibody repertoire. The heavy chains probably contribute more to recombinational immunoglobulin repertoire diversity than the light chains but the heavy chain locus could not be annotated from the version 3.1 of Bos taurus genome.

Effect of Phytase on in Vitro Hydrolysis of Phytate and the Formation of myo-Inositol Phosphate Esters in Various Feed Materials.

Phytase is commonly used as a feed enzyme in monogastric animals to increase the bioavailability of phytate phosphorus and other nutrients. The accumulation of myo-inositol phosphate intermediates during phytate degradation in various segments of the gastrointestinal tract (GIT) is poorly understood. The aim of this study was to determine the efficacy of Buttiauxella spp. phytase in degrading the phytate in corn, soybean meal, and complete corn-soybean meal diet to myo-inositol phosphate esters (IP1-IP5) and completely dephosphorylated myo-inositol rings using an in vitro model of the poultry upper GIT. Our results show that the phytase hydrolyzes phytate efficiently to small IP esters, whereas the myo-inositol level remains constant between control and phytase treatments. Although the in vitro digestion model does not incorporate all factors that govern phytate hydrolysis, it is a valuable tool for evaluating phytase efficacy at various enzyme doses and with different feed ingredients.

Expansion of the preimmune antibody repertoire by junctional diversity in Bos taurus.

Cattle have a limited range of immunoglobulin genes which are further diversified by antigen independent somatic hypermutation in fetuses. Junctional diversity generated during somatic recombination contributes to antibody diversity but its relative significance has not been comprehensively studied. We have investigated the importance of terminal deoxynucleotidyl transferase (TdT) -mediated junctional diversity to the bovine immunoglobulin repertoire. We also searched for new bovine heavy chain diversity (IGHD) genes as the information of the germline sequences is essential to define the junctional boundaries between gene segments. New heavy chain variable genes (IGHV) were explored to address the gene usage in the fetal recombinations. Our bioinformatics search revealed five new IGHD genes, which included the longest IGHD reported so far, 154 bp. By genomic sequencing we found 26 new IGHV sequences that represent potentially new IGHV genes or allelic variants. Sequence analysis of immunoglobulin heavy chain cDNA libraries of fetal bone marrow, ileum and spleen showed 0 to 36 nontemplated N-nucleotide additions between variable, diversity and joining genes. A maximum of 8 N nucleotides were also identified in the light chains. The junctional base profile was biased towards A and T nucleotide additions (64% in heavy chain VD, 52% in heavy chain DJ and 61% in light chain VJ junctions) in contrast to the high G/C content which is usually observed in mice. Sequence analysis also revealed extensive exonuclease activity, providing additional diversity. B-lymphocyte specific TdT expression was detected in bovine fetal bone marrow by reverse transcription-qPCR and immunofluorescence. These results suggest that TdT-mediated junctional diversity and exonuclease activity contribute significantly to the size of the cattle preimmune antibody repertoire already in the fetal period.

The bovine genomic DNA sequence data reveal three IGHV subgroups, only one of which is functionally expressed.

A comprehensive analysis of cattle shotgun sequencing data reveals 36 immunoglobulin heavy chain variable genes. The previously described bovine subgroup IGHV1 contains 10 functional genes with a conserved promoter including the consensus octamer and several other transcription factor binding sites, intact exons and matching cDNA sequences. Subgroups IGHV2 and IGHV3 consist entirely of pseudogenes. Thus, the bovine germline IGHV repertoire is very limited. The IGHV genes are distributed in mammalian clans I and II, while no clan III genes were detected. Clan-specific PCR of genomic DNA from cattle, sheep, Eurasian elk, white-tailed deer, pig and dolphin indicates highly dynamic evolution of IGHV gene usage within Cetartiodactyla. The bovine germline IGHV repertoire was probably generated by recent duplications of an IGHV1-IGHV2 homology unit. Immunoglobulin heavy chain genes are largely incorrectly assembled in the current cattle genome versions Btau_4.2 and UMD_3.1. FISH experiments confirm an IGHV locus close to terminus of BTA21.

B-cell development in bovine fetuses proceeds via a pre-B like cell in bone marrow and lymph nodes.

The production of B cells and the primary antibody repertoire in mammalian species other than rodents or man appears to depend on gut-associated lymphoid tissue. Bovine B cells are generated in ileal Peyer's patch from late gestational to juvenile age. However, little is known about where and when the bona fide B lymphopoiesis takes place. We analyzed bovine fetuses for signs of ongoing B lymphopoiesis using a combination of immunohistochemistry, flow cytometry, real-time quantitative PCR and RNA in situ hybridization. In fetal bone marrow and lymph node, we could demonstrate pre-B like cells positive for intracellular Ig mu but negative for membrane IgM. Strong expression of immunoglobulin lambda-like polypeptide 1 and recombination activating genes was also detected in the same tissues. Similar analyses did not reveal pre-B like cells in the corresponding adult tissues. These results suggest that bovine fetal bone marrow and lymph node support B lymphopoiesis via a pre-B cell like stage before and in parallel to the development of the ileal Peyer's patch.