Lactobacillus rhamnosus GG Dosage Affects the Adjuvanticity and Protection Against Rotavirus Diarrhea in Gnotobiotic Pigs.

OBJECTIVES: The use of immunostimulatory strains of probiotics as adjuvants has been increasingly recognized as a promising approach in enhancing vaccine immunogenicity; however, dose effects of probiotic adjuvants are not well defined. In the present study, we examined dose effects of a commonly used probiotic strain, Lactobacillus rhamnosus GG (LGG), on immunomodulation with 2 different dosages. METHODS: Neonatal gnotobiotic pigs were inoculated with 2 oral doses of attenuated human rotavirus (AttHRV) vaccines and fed with 5 doses (LGG5X; total 2.1 × 10(6) colony-forming units) or 9 doses (LGG9X; total 3.2 × 10(6) colony-forming units) of LGG, starting at 3 days of age. RESULTS: Both LGG feeding regimens enhanced the protection rate of AttHRV vaccine against diarrhea on virulent human rotavirus challenge. LGG5X, but not LGG9X, significantly enhanced rotavirus-specific intestinal memory B-cell responses to AttHRV; LGG5X also significantly enhanced virus-specific intestinal immunoglobulin A (IgA) antibody-secreting cell responses. Both regimens significantly enhanced rotavirus-specific serum IgA antibody responses to AttHRV. They also enhanced rotavirus-specific interferon-γ-producing effector/memory T-cell responses to AttHRV vaccine, with LGG9X being more effective than LGG5X, and both regimens downregulated CD4+CD25-FoxP3+ regulatory T (Treg) cell responses in most lymphoid tissues examined prechallenge and postchallenge and maintained the CD4+CD25+FoxP3+ Treg population in the ileum and intraepithelial lymphocyte postchallenge. LGG9X, however, did not significantly reduce total CD4+CD25-FoxP3+ Treg frequencies in the intestine and transforming growth factor-ß-producing and interleukin (IL)-10-producing Treg frequencies in the blood. CONCLUSIONS: These results indicate that LGG at both dosages functioned as effective probiotic adjuvant for AttHRV vaccine, but different dosages differentially modulated immune responses to favor either the mucosal IgA response (LGG5X) or the T-cell response (LGG9X).

A DEAD-box RNA helicase produces two forms of transcript that differentially respond to cold stress in a cryophyte (Chorispora bungeana).

MAIN CONCLUSION: This work demonstrated that a cold-induced DEAD-box RNA helicase, CbDRH, is also post-transcriptionally regulated upon cold stress, and it interacts with a cold-responsive, glycine-rich, RNA-binding protein, CbGRP. Chorispora bungeana (C. bungeana) is a representative alpine subnival plant species that shows strong tolerance to multiple abiotic stresses, especially cold stress. DEAD-box RNA helicases are implicated in almost all RNA metabolic processes and participate in multiple abiotic stress responses. Here, we characterized a cold-induced DEAD-box RNA helicase gene from C. bungeana. We cloned the full-length cDNA of the gene by RACE and called it C. bungeana DEAD-box RNA Helicase (CbDRH). Structurally, CbDRH possesses all nine conserved motifs characteristic of DEAD-box protein family members in its central region, and the N- and C- terminal extensions both harbor a glycine-rich region containing several RGG-box motifs. The CbDRH gene produces two forms of transcripts, CbDRH.2 and CbDRH.1, by alternative splicing. CbDRH.2 comes from the complete excision of all the nine introns, while CbDRH.1 results from the use of an alternative 5' splice site in the eighth intron, retaining part of the intron (the first 260 bp) with an early stop codon. Semi-quantitative RT-PCR analysis showed that CbDRH.2, but not CbDRH.1, is up-regulated by cold stress. However, the abundance of CbDRH.1 transcript can be elevated by cycloheximide (an inhibitor of nonsense-mediated decay) treatment, indicating that CbDRH.1 is targeted to nonsense-mediated decay (NMD). A subcellular localization analysis showed that CbDRH.2 protein is located in the nuclei. Further investigation suggested that CbDRH.2 can interact with a cold-responsive, glycine-rich, RNA-binding protein, CbGRP (Chorispora bungeana glycine-rich, RNA-binding protein). These data suggest that the cold-induced CbDRH is also post-transcriptionally regulated under cold stress and that CbDRH.2 may function together with the glycine-rich, RNA-binding protein, CbGRP, in the cold stress response.

CD4+ CD25- FoxP3+ regulatory cells are the predominant responding regulatory T cells after human rotavirus infection or vaccination in gnotobiotic pigs.

The distribution and dynamic changes of CD4(+) CD25(+) FoxP3(+) and CD4(+) CD25(-) FoxP3(+) regulatory T (Treg) cells induced by human rotavirus (HRV) infection and vaccination were examined in neonatal gnotobiotic pigs infected with virulent HRV (VirHRV) or vaccinated with attenuated HRV (AttHRV). Subsets of gnotobiotic pigs in the AttHRV and control groups were challenged with VirHRV at post-inoculation day (PID) 28. We demonstrated that VirHRV infection or AttHRV vaccination reduced frequencies and numbers of tissue-residing Treg cells, and decreased the frequencies of interleukin-10 (IL-10) and transforming growth factor-ß (TGF-ß) producing CD4(+) CD25(-) Treg cells in ileum, spleen and blood at PID 28. The frequencies of IL-10 and TGF-ß producing CD4(+) CD25(-) Treg cells in all sites at PID 28 were significantly inversely correlated with the protection rate against VirHRV-caused diarrhoea (r = -1, P < 0.0001). Hence, higher frequencies of functional CD4(+) CD25(-) Treg cells can be an indicator for poorer protective immunity against rotavirus. Our results highlighted the importance of CD4(+) CD25(-) Treg cells over CD4(+) CD25(+) Treg cells in rotavirus infection and immunity. AttHRV vaccination (induction of immune effector responses) reduced the expansion of CD4(+) CD25(-) Treg cells in ileum seen in the challenged naive pigs during the acute phase of VirHRV infection and preserved normal levels of intestinal TGF-ß producing Treg cells post-challenge. The reduced suppressive effect of Treg cells in AttHRV-vaccinated pigs would unleash effector/memory T-cell activation upon challenge. Preserving TGF-ß producing CD4(+) CD25(-) Treg cells is important in maintaining homeostasis. Based on our findings, a model is proposed to depict the dynamic equilibrium course of Treg and effector T-cell responses after primary rotavirus infection/vaccination and challenge.

Probiotic as Adjuvant Significantly Improves Protection of the Lanzhou Trivalent Rotavirus Vaccine against Heterologous Challenge in a Gnotobiotic Pig Model of Human Rotavirus Infection and Disease.

This preclinical study in the gnotobiotic (Gn) pig model of human rotavirus (HRV) infection and disease evaluates the effect of probiotic Lactobacillus rhamnosus GG (LGG) as a mucosal adjuvant on the immunogenicity and cross-protective efficacy of the Lanzhou live oral trivalent (G2, G3, G4) vaccine (TLV, aka LLR3). Gn pigs were immunized with three doses of TLV with or without concurrent administration of nine doses of LGG around the time of the first dose of the TLV vaccination, and were challenged orally with the virulent heterotypic Wa G1P[8] HRV. Three doses of TLV were highly immunogenic and conferred partial protection against the heterotypic HRV infection. LGG significantly enhanced the intestinal and systemic immune responses and improved the effectiveness of protection against the heterotypic HRV challenge-induced diarrhea and virus shedding. In conclusion, we demonstrated the immune-stimulating effects of probiotic LGG as a vaccine adjuvant and generated detailed knowledge regarding the cross-reactive and type-specific antibody and effector B and T cell immune responses induced by the TLV. Due to the low cost, ease of distribution and administration, and favorable safety profiles, LGG as an adjuvant has the potential to play a critical role in improving rotavirus vaccine efficacy and making the vaccines more cost-effective.

Identification of a natural human serotype 3 parainfluenza virus.

Parainfluenza virus is an important pathogen threatening the health of animals and human, which brings human many kinds of disease, especially lower respiratory tract infection involving infants and young children. In order to control the virus, it is necessary to fully understand the molecular basis resulting in the genetic diversity of the virus. Homologous recombination is one of mechanisms for the rapid change of genetic diversity. However, as a negative-strand virus, it is unknown whether the recombination can naturally take place in human PIV. In this study, we isolated and identified a mosaic serotype 3 human PIV (HPIV3) from in China, and also provided several putative PIV mosaics from previous reports to reveal that the recombination can naturally occur in the virus. In addition, two swine PIV3 isolates transferred from cattle to pigs were found to have mosaic genomes. These results suggest that homologous recombination can promote the genetic diversity and potentially bring some novel biologic characteristics of HPIV.

Molecular cloning, functional analysis and localization of a novel gene encoding polygalacturonase-inhibiting protein in Chorispora bungeana.

Polygalacturonase-inhibiting proteins (PGIPs) are plant defense proteins. To date, no spatial distribution of PGIPs and interaction between PGIPs and nitric oxide (NO) in plant were described. Here, we first reported the full-length cDNA sequence of PGIP of Chorispora bungeana (CbPGIP1). Notably, immunofluorescence localization showed that the CbPGIP was evenly distributed in leaves but it was mainly localized in epidermis and vascular bundle in stems and roots. Further studies indicated that CbPGIP had higher abundance in roots than in stems and leaves. Conversely, the bulk PGIP of C. bungeana showed a higher activity in leaves than in stems and roots. In addition, quantitative real-time polymerase chain reaction demonstrated that CbPGIP1 expression was induced by Stemphylium solani, salicylic acid (SA), 4, -4 degrees C and NO. This is a first report attempting to predict if NO can induce the PGIP expression. Taken together, these findings showed that the gene was spatially regulated and NO and SA might take part in CbPGIP1 expression induced by biotic and abiotic stresses. This study highlighted the potential importance of CbPGIP1 and NO in plant resistance.