Deleting the C84L Gene from the Virulent African Swine Fever Virus SY18 Does Not Affect Its Replication in Porcine Primary Macrophages but Reduces Its Virulence in Swine

(1) Background: African swine fever (ASF) is a highly contagious disease that causes high pig mortality. Due to the absence of vaccines, prevention and control are relatively challenging. The pathogenic African swine fever virus (ASFV) has a complex structure and encodes over 160 proteins, many of which still need to be studied and verified for their functions. In this study, we identified one of the unknown functional genes, C84L. (2) Methods: A gene deficient strain was obtained through homologous recombination and several rounds of purification, and its replication characteristics and virulence were studied through in vitro and in vivo experiments, respectively. (3) Results: Deleting this gene from the wild-type virulent strain SY18 did not affect its replication in porcine primary macrophages but reduced its virulence in pigs. In animal experiments, we injected pigs with a 102 TCID50, 105 TCID50 deletion virus, and a 102 TCID50 wild-type strain SY18 intramuscularly. The control group pigs reached the humane endpoint on the ninth day (0/5) and were euthanized. Two pigs in the 102 TCID50(2/5) deletion virus group survived on the twenty-first day, and one in the 105 TCID50(1/5) deletion virus group survived. On the twenty-first day, the surviving pigs were euthanized, which was the end of the experiment. The necropsies of the survival group and control groups' necropsies showed that the surviving pigs' liver, spleen, lungs, kidneys, and submaxillary lymph nodes did not show significant lesions associated with the ASFV. ASFV-specific antibodies were first detected on the seventh day after immunization; (4) Conclusions: This is the first study to complete the replication and virulence functional exploration of the C84L gene of SY18. In this study, C84L gene was preliminarily found not a necessary gene for replication, gene deletion strain SY18ΔC84L has similar growth characteristics to SY18 in porcine primary alveolar macrophages. The C84L gene affects the virulence of the SY18 strain.

A novel "prime and pull" strategy mediated by the combination of two dendritic cell-targeting designs induced protective lung tissue-resident memory T cells against H1N1 influenza virus challenge

Vaccination is still the most promising strategy for combating influenza virus pandemics. However, the highly variable characteristics of influenza virus make it difficult to develop antibody-based universal vaccines, until now. Lung tissue-resident memory T cells (TRM), which actively survey tissues for signs of infection and react rapidly to eliminate infected cells without the need for a systemic immune reaction, have recently drawn increasing attention towards the development of a universal influenza vaccine. We previously designed a sequential immunization strategy based on orally administered Salmonella vectored vaccine candidates. To further improve our vaccine design, in this study, we used two different dendritic cell (DC)-targeting strategies, including a single chain variable fragment (scFv) targeting the surface marker DC-CD11c and DC targeting peptide 3 (DCpep3). Oral immunization with Salmonella harboring plasmid pYL230 (S230), which displayed scFv-CD11c on the bacterial surface, induced dramatic production of spleen effector memory T cells (TEM). On the other hand, intranasal boost immunization using purified DCpep3-decorated 3M2e-ferritin nanoparticles in mice orally immunized twice with S230 (S230inDC) significantly stimulated the differentiation of lung CD11b+ DCs, increased intracellular IL-17 production in lung CD4+ T cells and elevated chemokine production in lung sections, such as CXCL13 and CXCL15, as determined by RNAseq and qRT‒PCR assays, resulting in significantly increased percentages of lung TRMs, which could provide efficient protection against influenza virus challenge. The dual DC targeting strategy, together with the sequential immunization approach described in this study, provides us with a novel "prime and pull" strategy for addressing the production of protective TRM cells in vaccine design.

SY18ΔL60L: a new recombinant live attenuated African swine fever virus with protection against homologous challenge

Introduction

African swine fever (ASF) is an acute and highly contagious disease and its pathogen, the African swine fever virus (ASFV), threatens the global pig industry. At present, management of ASF epidemic mainly relies on biological prevention and control methods. Moreover, due to the large genome of ASFV, only half of its genes have been characterized in terms of function.

Methods

Here, we evaluated a previously uncharacterized viral gene, L60L. To assess the function of this gene, we constructed a deletion strain (SY18ΔL60L) by knocking out the L60L gene of the SY18 strain. To evaluate the growth characteristics and safety of the SY18ΔL60L, experiments were conducted on primary macrophages and pigs, respectively.

Results

The results revealed that the growth trend of the recombinant strain was slower than that of the parent strain in vitro. Additionally, 3/5 (60%) pigs intramuscularly immunized with a 105 50% tissue culture infectious dose (TCID50) of SY18ΔL60L survived the 21-day observation period. The surviving pigs were able to protect against the homologous lethal strain SY18 and survive. Importantly, there were no obvious clinical symptoms or viremia.

Discussion

These results suggest that L60L could serve as a virulence- and replication-related gene. Moreover, the SY18ΔL60L strain represents a new recombinant live-attenuated ASFV that can be employed in the development of additional candidate vaccine strains and in the elucidation of the mechanisms associated with ASF infection.

Homologous Sequential Immunization Using Salmonella Oral Administration Followed by an Intranasal Boost with Ferritin-Based Nanoparticles Enhanced the Humoral Immune Response against H1N1 Influenza Virus

The influenza virus continues to pose a great threat to public health due to the frequent variations in RNA viruses. Vaccines targeting conserved epitopes, such as the extracellular domain of the transmembrane protein M2 (M2e), a nucleoprotein, and the stem region of hemagglutinin proteins, have been developed, but more efficient strategies, such as nanoparticle-based vaccines, are still urgently needed. However, the labor-intensive in vitro purification of nanoparticles is still necessary, which could hinder the application of nanoparticles in the veterinary field in the future. To overcome this limitation, we used regulated lysis Salmonella as an oral vector with which to deliver three copies of M2e (3M2e-H1N1)-ferritin nanoparticles in situ and evaluated the immune response. Then, sequential immunization using Salmonella-delivered nanoparticles followed by an intranasal boost with purified nanoparticles was performed to further improve the efficiency. Compared with 3M2e monomer administration, Salmonella-delivered in situ nanoparticles significantly increased the cellular immune response. Additionally, the results of sequential immunization showed that the intranasal boost with purified nanoparticles dramatically stimulated the activation of lung CD11b dendritic cells (DCs) and elevated the levels of effector memory T (TEM) cells in both spleen and lung tissues as well as those of CD4 and CD8 tissue-resident memory T (TRM) cells in the lungs. The increased production of mucosal IgG and IgA antibody titers was also observed, resulting in further improvements to protection against a virus challenge, compared with the pure oral immunization group. Salmonella-delivered in situ nanoparticles efficiently increased the cellular immune response, compared with the monomer, and sequential immunization further improved the systemic immune response, as shown by the activation of DCs, the production of TEM cells and TRM cells, and the mucosal immune response, thereby providing us with a novel strategy by which to apply nanoparticle-based vaccines in the future. IMPORTANCE Salmonella-delivered in situ nanoparticle platforms may provide novel nanoparticle vaccines for oral administration, which would be beneficial for veterinary applications. The combination of administering Salmonella-vectored, self-assembled nanoparticles and an intranasal boost with purified nanoparticles significantly increased the production of effector memory T cells and lung resident memory T cells, thereby providing partial protection against an influenza virus challenge. This novel strategy could open a novel avenue for the application of nanoparticle vaccines for veterinary purposes.

Structures of SARS-CoV-2 spike protein alert noteworthy sites for the potential approaching variants

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Deletion of residues 156–157 warps the neighboring beta-sheet and leads NTD and RBD to shift.

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T859N stabilizes the packing of the 630 loop motif to make RBD standing transition more difficult.

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The overall structures of the closed state S complex from different variants resemble each other.

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Mutations in FPPR may affect the overall structure of the trimeric spike protein.

Clopidogrel monotherapy following dual antiplatelet therapy in patients with acute coronary syndrome post-drug-eluting stent implantation: a systematic review and direct/indirect treatment comparison

Background

In patients with acute coronary syndromes (ACS) receiving a drug-eluting stent (DES), treatment with dual antiplatelet therapy (DAPT) reduces the risk of recurrent ischemic events. Optimal duration of DAPT depends on patient characteristics and switching to single antiplatelet therapy (SAPT) is recommended after the course of DAPT.

Purpose

The aim of this study was to evaluate the comparative efficacy and safety of switching to clopidogrel SAPT following DAPT in patients with ACS post DES-implantation.

Methods

A systematic literature review (SLR) was conducted by searching MEDLINE®, Embase, and CENTRAL up to July 27, 2021. Randomized controlled trials (RCTs) and observational studies that evaluated clopidogrel SAPT following DAPT in adults with ACS post-DES implantation were included. Heterogeneity of included studies was vetted in a feasibility assessment. Random effects meta-analyses were conducted using the metafor package for R. Direct comparisons were conducted for clopidogrel vs. aspirin and clopidogrel vs. DAPT. Using the Bucher method, aspirin vs. DAPT was indirectly compared by taking the difference between their respective pooled treatment effects vs. clopidogrel. A sensitivity analysis was conducted by including studies with a follow-up of 12 months.

Results

Of 5,349 records identified, seven unique studies (four RCTs and three observational studies) were eligible to be included in the SLR and quantitative treatment comparison. Risk of major adverse cardiovascular events (MACE) was lower in patients who switched to clopidogrel SAPT after DAPT compared with those who switched to aspirin monotherapy (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.54, 0.98), and this difference was significant. No significant difference in risk of MACE was found between switching to clopidogrel SAPT after DAPT and continuation of DAPT (HR: 0.90; 95% CI: 0.65, 1.25). This finding was consistent with the sensitivity analysis representing studies with follow-up of 12 months (HR: 0.95; 95% CI: 0.69, 1.31). Risk of bleeding was not analysed due to insufficient data across included studies for patients with ACS. However, within-study findings from one RCT of 4,136 patients demonstrated a significantly lower risk of bleeding, defined as thrombolysis in myocardial infarction (major and/or minor, for switching to clopidogrel SAPT following DAPT compared with continuation of DAPT (0.54% vs. 1.17% of patients had bleeding [HR: 0.46; 95% CI: 0.23, 0.94]).

Conclusion

Findings from this SLR suggest switching to clopidogrel SAPT after DAPT in ACS post-DES implantation has a lower risk of MACE compared with switching to aspirin monotherapy, and no difference in the risk of MACE compared with continuation of DAPT. There was insufficient data across the included studies to evaluate the bleeding risk, however, a single study indicated a lower bleeding risk with switching to clopidogrel SAPT.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Sanofi

Essential role of ascO for virulence of Aeromonas veronii and inducing apoptosis

Aeromonas veronii is a significant pathogen that is capable of infecting humans, animals, and aquatic animals. The type III secretion system (T3SS) is intimately associated with bacterial pathogenicity. The ascO gene is an important core component of T3SS in A. veronii, but its function is still unclear. The ascO gene of A. veronii TH0426 was deleted by using the pRE112 suicide plasmid to study its function. The study results showed that the ability of ∆ascO to adhere and invade EPC cells was significantly reduced by 1.28 times. The toxicity of the mutant strain ΔascO to EPC cells was consistently significantly lower than wild-type strain TH0426 at 1, 2, and 4 h. The LD50 values of ∆ascO against zebrafish and Carassius auratus (C. auratus) were 53 and 15 times that of the wild-type strain. In addition, the bacterial load of the mutant strain ΔascO in blood, heart, liver, and spleen was lower than wild-type strain TH0426. The Hoechst staining showed that the apoptotic degree of EPC cells induced by the mutant strain ΔascO was lower than that of the wild-type strain TH0426. Furthermore, real-time quantitative PCR (RT-qPCR) analysis revealed lower expression levels of pro-apoptotic genes (including cytC, cas3, cas9, TNF-α, and IL-1β) in C. auratus tissues infected with the mutant strain ΔascO compared to the wild-type strain TH0426. The results of in vivo and in vitro experiments have shown that ascO gene mutation can reduce the adhesion and toxicity of A. veronii to EPC and reduce the level of apoptosis induced by A. veronii. As a result, these insights will help further elucidate the function of the ascO gene and thus contribute to understanding the pathogenesis of A. veronii.

Immune enhancement effects of inactivated vaccine against extracellular products of Aeromonas caviae AC-CY on crucian carp

Aeromonas caviae is a zoonotic pathogen that can cause disease in aquatic organisms and mammals, including humans, and it is widespread in nature, especially in freshwater environments. Previous research has reported that extracellular products (ECPs) secreted by pathogens during growth are effective protective antigens that can induce the host immune response and protect the host from pathogens. However, little is known about how ECPs enhance immunity. Here, we prepared extracellular products by the cellophane plate method, determined the total protein concentration, and analysed the protein composition of the extracellular products by SDS-PAGE. Subsequently, their enzyme activity and pathogenicity were evaluated separately. Crucian carp were randomly divided into four groups to receive formalin-inactivated A. caviae vaccine (FKC), ECPs mixed with the same amount of Freund's complete adjuvant, the same amount of ECPs mixed with an equal volume of A. caviae inactivated vaccine (FKC + ECPs), sterile PBS alone via intraperitoneal injection. On Days 7, 14, 21, and 28 after immunization, the expression levels of IgM, SOD, and CAT and the lysozyme (LYS) activity in the serum were detected by ELISA, and the relative expression levels of the TNF-α, IFN-γ, IL-1β, and IL-10 genes in the liver, kidney, spleen, intestine, and gills were measured by qPCR. The extracellular products generated five clearly visible protein bands and exhibited lipase, protease, amylase, DNase and lysozyme but no urease or lecithinase activities. In addition, the median lethal doses of A. caviae and ECPs to crucian carp were 411.64 μg/fish and 1.6 × 105 CFU/mL, respectively. Compared with those of the control group, the IgM, SOD, and CAT contents and serum LYS activity were significantly increased in the experimental groups, and the qRT-PCR results showed that the relative expression levels of TNF-α, IFN-γ, IL-1β, and IL-10 genes in the liver, kidney, spleen, and intestine were significantly increased after injection immunization. In addition, the relative immune protection rates of the three experimental groups were 60%, 65%, and 45%, all of which were significantly higher than those of the control group. Collectively, our findings show that the extracellular products of A. caviae can be used as a vaccine to significantly improve the immune level of crucian carp and have obvious anti-infection ability. This may represent a promising approach to prevent and control infection by A. caviae and provides strong theoretical support for the development of new inactivated vaccines.

Lytic Bacteriophage PZL-Ah152 as Biocontrol Measures Against Lethal Aeromonas hydrophila Without Distorting Gut Microbiota

Phage therapy is an alternative approach to overcome the problem of multidrug resistance in bacteria. In this study, a bacteriophage named PZL-Ah152, which infects Aeromonas hydrophila, was isolated from sewage, and its biological characteristics and genome were studied. The genome contained 54 putative coding sequences and lacked known putative virulence factors, so it could be applied to phage therapy. Therefore, we performed a study to (i) investigate the efficacy of PZL-Ah152 in reducing the abundance of pathogenic A. hydrophila strain 152 in experimentally infected crucian carps, (ii) evaluate the safety of 12 consecutive days of intraperitoneal phage injection in crucian carps, and (iii) determine how bacteriophages impact the normal gut microbiota. The in vivo and in vitro results indicated that the phage could effectively eliminate A. hydrophila. Administering PZL-Ah152 (2 × 10⁹ PFU) could effectively protect the fish (2 × 10⁸ CFU/carp). Furthermore, a 12-day consecutive injection of PZL-Ah152 did not cause significant adverse effects in the main organs of the treated animals. We also found that members of the genus Aeromonas could enter and colonize the gut. The phage PZL-Ah152 reduced the number of colonies of the genus Aeromonas. However, no significant changes were observed in α-diversity and β-diversity parameters, which suggested that the consumed phage had little effect on the gut microbiota. All the results illustrated that PZL-Ah152 could be a new therapeutic method for infections caused by A. hydrophila.

Oral vaccination with recombinant Lactobacillus casei expressing Aha1 fused with CTB as an adjuvant against Aeromonas veronii in common carp (Cyprinus carpio)

Aeromonas veronii (A. veronii) is a pathogenic that can infect human, animal and aquatic organisms, in which poses a huge threat to the health of many aquatic organisms such as Cyprinus carpio. In this study, Lactobacillus casei (L. casei) strain CC16 was used as antigen deliver carrier and fused with cholera toxin B subunit (CTB) as an adjuvant to construct the recombinant L. casei pPG-Aha1/Lc CC16(surface-displayed) and pPG-Aha1-CTB/Lc CC16(surface-displayed) expressing Aha1 protein of A. veronii, respectively. And the immune responses in Cyprinus carpio by oral route was explored. Our results demonstrated that the recombinant strains could stimulate high serum specific antibody immunoglobulin M (IgM) and induce a stronger acid phosphatase (ACP), alkaline phosphatase (AKP), C3, C4, lysozyme (LZM), Lectin and superoxide dismutase (SOD) activity in Cyprinus carpio compared with control groups. Meanwhile, the expression of Interleukin-10 (IL-10), Interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), immunoglobulin Z1 (IgZ1) and immunoglobulin Z2 (IgZ2) in the tissues were significantly upregulated compared with Lc-pPG or PBS groups, indicating that humoral and cell immune response were triggered. Additionally, recombinant L. casei could survive and colonize in fish intestine. Significantly, recombinant L. casei provides immune protection against A. veronii infection, which Cyprinus carpio received pPG-Aha1-CTB/Lc CC16 (64.29%) and pPG-Aha1/Lc CC16 (53.57%) had higher survival rates compared with the controls. Thus, we demonstrated that recombinant pPG-Aha1/Lc CC16 and pPG-Aha1-CTB/Lc CC16 may be the promising strategy for the development of an oral vaccine against A. veronii.

Aeromonas veronii virulence and adhesion attenuation mediated by the gene aodp

Aeromonas veronii (A. veronii) is an opportunistic pathogen of fish-human-livestock, which poses a threat to the development of aquaculture. Based on our previous studies on proteomics and genomics, we found out that the aodp gene may be related to the virulence of A. veronii TH0426. However, aodp gene encodes a hypothetical protein with an unknown function, and its role in A. veronii TH0426 is not clear. Here, we first constructed a mutant strain (△-aodp) to investigate the functional role of aodp in A. veronii TH0426. Compared with the wild strain A. veronii TH0426, the growth rate of strain △-aodp was slower and was resistant to neomycin and kanamycin, but sensitive to cephalexin. The swimming and swarming ability of △-aodp strain decreased, and the pathogenicity to mice decreased by 15.84-fold. Besides, the activity of caspase-3 in EPCs infected with △-aodp strain was 1.49-fold lower than that of the wild strain. We examined 20 factors closely related to A. veronii virulence, among them 17 genes were down-regulated as a result of aodp deficiency. This study laid a foundation for further studies on the pathogenesis of A. veronii.

Effects of four different adjuvants separately combined with Aeromonas veronii inactivated vaccine on haematoimmunological state, enzymatic activity, inflammatory response and disease resistance in crucian carp

The purpose of the current study was to explore the immunomodulatory effects of different adjuvants combined with inactivated vaccines under Aeromonas veronii TH0426 infection in crucian carp. This study explored the best conditions for A. veronii as an inactivated vaccine, and included an animal safety test. Furthermore, we expressed the flagellin FlaA of the A. veronii TH0426 strain for use as an adjuvant supplemented in the diet. Crucian carp were fed 12 different experimental diets for 35 days, including the administration of 10 different adjuvants and inactivated vaccine combinations (50% aluminum hydroxide gel and inactivated vaccine combination, and inactivated vaccine with 20%, 30%, or 50% glucan, astragalus polysaccharide or flagellin), inactivated vaccine alone, and PBS control without adjuvant and inactivated vaccine. After the 42 day feeding trials, the fish were challenged with A. veronii TH0426, and the survival rate over 14 days was recorded. In addition, flagellin FlaA can be expressed normally in large amounts. All experimental groups produced higher levels of IgM serum titres than the control group in the different feeding cycles. Moreover, the activity of serum ACP, AKP, SOD, and LZM, and the expression of inflammatory factors were significantly increased in the experimental groups compared with the control group. The results of qRT-PCR analysis showed that the transcription levels of the IL-10, IL-1β, IFN-γ and TNF-α genes in heart, liver, spleen and kidney tissues were significantly enhanced by adjuvant treatment, indicating that the addition of adjuvants can significantly promote the body's inflammatory response. In addition, the phagocytic activity of leukocytes in each adjuvant treated group was significantly enhanced compared to that in the groups without adjuvant. After the A. veronii challenge, the survival rate of all adjuvant-treated groups was significantly higher than that of the control group, and the 50% flagellin adjuvant group had the highest rate of 78.37%. Overall, our findings strongly indicate that adjuvants not only significantly improve the body's immunity, but also exhibit a strong anti-infection ability. Importantly, this work provides a new perspective for the prevention and control of aquaculture diseases.

Functional analysis of fis in Aeromonas veronii TH0426 reveals a key role in the regulation of virulence

Aeromonas veronii is a comorbid pathogen that can infect humans, and animals including various aquatic organisms. In recent years, an increasing number of cases of A. veronii infection has been reported, indicating serious risks. This bacterium not only threatens public health and safety but also causes considerable economic loss in the aquaculture industry. Currently, some understanding of the pathogenic mechanism of A. veronii has been obtained. In this study, we first constructed the A. veronii TH0426 fis gene deletion strain Δfis and the complementation strain C-fis through homologous recombination technology. The results showed that the adhesion and invasion ability of the Δfis strain towards Epithelioma papulosum cyprini (EPC) cells and the cytotoxicity were 3.8-fold and 1.38-fold lower, respectively, than those of the wild-type strain. In the zebrafish infection model, the lethality of the deleted strain is 3-fold that of the wild strain. In addition, the bacterial load of the deletion strain Δfis in crucian carp was significantly lower than the wild-type strain, and the load decreased with time. In summary, deletion of the fis gene led to a decrease in the virulence of A. veronii. Our research results showed that the deletion of the fis gene significantly reduces the virulence and adhesion ability of A. veronii TH0426. Therefore, the fis gene plays a vital role in the pathogenesis of A. veronii TH0426. This preliminary study of the function of the fis gene in A. veronii will help researchers further understand the pathogenic mechanism of A. veronii.

In Vivo Production of HN Protein Increases the Protection Rates of a Minicircle DNA Vaccine against Genotype VII Newcastle Disease Virus

The Cre-recombinase mediated in vivo minicircle DNA vaccine platform (CRIM) provided a novel option to replace a traditional DNA vaccine. To further improve the immune response of our CRIM vaccine, we designed a dual promoter expression plasmid named pYL87 which could synthesize short HN protein under a prokaryotic in vivo promoter P_pagC and full length HN protein of genotype VII Newcastle disease virus (NDV) under the previous eukaryotic CMV promoter at the same time. Making use of the self-lysed Salmonella strain as a delivery vesicle, chickens immunized with the pYL87 construction showed an increased serum haemagglutination inhibition antibody response, as well as an increased cell proliferation level and cellular IL-4 and IL-18 cytokines, compared with the previous CRIM vector pYL47. After the virus challenge, the pYL87 vector could provide 80% protection compared to 50% protection against genotype VII NDV in pYL47 immunized chickens, indicating a promising dual promoter strategy used in vaccine design.

Comparative genomic analysis of different virulence strains reveals reasons for the increased virulence of Aeromonas veronii

Aeromonas veronii is an important zoonotic and aquatic agent. More and more cases have shown that it has caused huge economic losses in the aquaculture industry in addition to threatening human health. But the reasons for the increasing virulence of A. veronii are still unclear. In order to further understand the reasons for the increased virulence of A. veronii, we conducted a comparative analysis of the genomes of A. veronii with different virulence. The analysis revealed that there are multiple virulence factors, such as those related to fimbriae, flagella, toxins, iron ion uptake systems and type II, type III and type VI secretion systems in the virulent strain TH0426 genome. And comparative analysis showed that there were two complete type III secretion systems (API1 and API2), of which the API2 and iron ion transport system were unique to the TH0426 strain. In addition, TH0426 strain also has unique functional gene clusters, which may play important roles in terms of resisting infection, adapting to different environments and genetic evolution. These particular virulence factors and gene clusters may be the important reasons for the increased virulence. These insights will provide a reference for the study of the pathogenesis of A. veronii.

Genomic, Morphological and Functional Characterization of Virulent Bacteriophage IME-JL8 Targeting Citrobacter freundii

Citrobacter freundii refers to a fish pathogen extensively reported to be able to cause injury and high mortality. Phage therapy is considered a process to alternatively control bacterial infections and contaminations. In the present study, the isolation of a virulent bacteriophage IME-JL8 isolated from sewage was presented, and such bacteriophage was characterized to be able to infect Citrobacter freundii specifically. Phage IME-JL8 has been classified as the member of the Siphoviridae family, which exhibits the latent period of 30–40 min. The pH and thermal stability of phage IME-JL8 demonstrated that this bacteriophage achieved a pH range of 4–10 as well as a temperature range of 4, 25, and 37°C. As revealed from the results of whole genomic sequence analysis, IME-JL8 covers a double-stranded genome of 49,838 bp (exhibiting 47.96% G+C content), with 80 putative coding sequences contained. No bacterial virulence- or lysogenesis-related ORF was identified in the IME-JL8 genome, so it could be applicable to phage therapy. As indicated by the in vitro experiments, phage IME-JL8 is capable of effectively removing bacteria (the colony count decreased by 6.8 log units at 20 min), and biofilm can be formed in 24 h. According to the in vivo experiments, administrating IME-JL8 (1 × 10⁷ PFU) was demonstrated to effectively protect the fish exhibiting a double median lethal dose (2 × 10⁹ CFU/carp). Moreover, the phage treatment led to the decline of pro-inflammatory cytokines in carp with lethal infections. IME-JL8 was reported to induce efficient lysis of Citrobacter freundii both in vitro and in vivo, thereby demonstrating its potential as an alternative treatment strategy for infections attributed to Citrobacter freundii.

M.neoaurum infection increased the inhibitory function of Tregs and the death rate associated with Salmonella coinfection

Mycobacterium neoaurum belongs to the nontuberculous mycobacteria (NTM) and is ubiquitously present in the environment. However, the changes in Treg percentages and suppressive properties in mice infected with M. neoaurum are still not elucidated. In this study, mice were intraperitoneally injected with M. neoaurum. The change in the CD4⁺CD25⁺ Treg cell percentage in the spleen was analyzed using flow cytometry. There was a significant increase in the number of CD4⁺CD25⁺ cells by week 6 postinfection, with a peak proportion of approximately 2%. The Foxp3 and IL-10 mRNA expression in CD4⁺CD25⁺ cells from the spleens of M.neoaurum-infected mice was higher than that in CD4⁺CD25⁺ cells from the spleens of noninfected controls. Proliferation suppression assay results indicated that CD4⁺CD25⁺ cells suppressed the proliferation of CD4⁺CD25^- cells at week 6 after M.neoaurum infection, and the suppression rate reached 89.8%. However, CD4⁺CD25⁺ cells from the noninfected control group did not suppress the proliferation of CD4⁺CD25^- cells. Based on the above results, mice were subjected to oral administration of S. Typhimurium at 6 weeks postinfection with M. neoaurum, and we found that the mortality of the M.neoaurum-S. Typhimurium infection group was higher than that of the S. Typhimurium infection group. In addition, serious pathological changes appeared in the liver and cecum of the M.neoaurum-S.Typhimurium infection group compared with those of the S. Typhimurium infection group. M. neoaurum increased Treg percentages and suppressed spleen function in mice. These results revealed the possibility that persistent M.neoaurum infection could increase the occurrence of secondary infection.

Inactivation of the T6SS inner membrane protein DotU results in severe attenuation and decreased pathogenicity of Aeromonas veronii TH0426

Background

The inner membrane protein DotU of Aeromonas veronii is an important component of the minimal core conserved membrane proteome required for the formation of an envelope-transmembrane complex. This protein functions in a type VI secretion system (T6SS), and the role of this T6SS during the pathogenic process has not been clearly described.

Results

A recombinant A. veronii with a partial disruption of the dotU gene (720 bp of the in-frame sequence) (defined as ∆dotU) was constructed by two conjugate exchanges. We found that the mutant ∆dotU allele can be stably inherited for more than 50 generations. Inactivation of the A. veronii dotU gene resulted in no significant changes in growth or resistance to various environmental changes. However, compared with the wild-type strain colony, the mutant ∆dotU colony had a rough surface morphology. In addition, the biofilm formation ability of the mutant ∆dotU was significantly enhanced by 2.1-fold. Conversely, the deletion of the dotU gene resulted in a significant decrease in pathogenicity and infectivity compared to those of the A. veronii wild-type strain.

Conclusions

Our findings indicated that the dotU gene was an essential participant in the pathogenicity and invasiveness of A. veronii TH0426, which provides a novel perspective on the pathogenesis of TH0426 and lays the foundation for discovering potential T6SS effectors.

Aeromonas veronii Infection in Commercial Freshwater Fish: A Potential Threat to Public Health

Aeromonas veronii is an important pathogen causing freshwater fish sepsis and ulcer syndrome. An increasing number of cases have demonstrated its significance as an aquatic zoonotic agent. The purpose of this study was to ensure the safety of freshwater products by evaluating the infection status of edible freshwater fish. In this experiment, we isolated A. veronii from several species of apparently healthy freshwater fish, including Carassius auratus, Cyprinus carpio, Ctenopharyngodon idella, and Silurus asotus. A. veronii was identified through bacterial staining, culture characteristics, and 16S rDNA gene sequence. In addition, polymerase chain reaction (PCR) was used to investigate the distribution of seven major virulence genes, including aerolysin (aer: 88.51%), cytotoxic enterotoxin (act: 71.26%), serine proteinase (ser: 54.02%), adhesin (Aha: 40.23%), phospholipase (lip: 45.98%), nuclease (exu: 51.72%), and quorum sensing-controlled virulence factor (LuxS: 59.77%). In total, 496 strains of Aeromonas were isolated, including 87 strains of A. veronii. The isolates of A. veronii were Gram-negative, rod-shaped bacteria, and the colonies are yellow on Rimler-Shotts (RS) medium and showed greater than 99% homology with A. veronii ATCC35624 according to analyses of the 16S rDNA sequence. Nearly 50% of the A. veronii isolates carried at least four or more virulence genes, 25% of the isolates carried at least five types of virulence genes, and 59.77% isolates carried the LuxS gene, and the isolates carrying more virulence genes were found to be more virulent. These results are of great significance for further improving the food safety assessment of freshwater aquatic products.

An iTRAQ-Based Comparative Proteomics Analysis of the Biofilm and Planktonic States of Aeromonas veronii TH0426

Aeromonas veronii is a virulent fish pathogen that causes extensive economic losses in the aquaculture industry worldwide. In this study, a virulent strain of A. veronii TH0426 was used to establish an in vitro biofilm model. The results show that the biofilm-forming abilities of A. veronii TH0426 were similar in different media, peaking under conditions of 20 °C and pH 6. Further, isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics methods were used to compare the differential expression of A. veronii between the biofilm and planktonic cells. The results show alterations in 277 proteins, with 130 being upregulated and 147 downregulated. Pathway analysis and GO (Gene Ontology) annotations indicated that these proteins are mainly involved in metabolic pathways and the biosynthesis of secondary metabolites and antibiotics. These proteins are the main factors affecting the adaptability of A. veronii to its external environment. MRM (multiple reaction 27 monitoring) and qPCR (qPCR) were used to verify the differential proteins of the selected A. veronii. This is the first report on the biofilm and planktonic cells of A. veronii, thus contributing to studying the infection and pathogenesis of A. veronii.

Cadaverine reverse transporter (CadB protein) contributes to the virulence of Aeromonas veronii TH0426

Aeromonas veronii is one of the main pathogens causing sepsis and ulcer syndrome in freshwater fish. Analysis of the results of epidemiological investigations in recent years has revealed that the virulence of A. veronii and its tolerance to drugs have been increasing year by year. Currently, most of the research on A. veronii focuses on its isolation, identification, and drug susceptibility, whereas research on its virulence factors and pathogenesis mechanisms is relatively rare. In this study, we identified and obtained the highly expressed TH0426 cadaverine reverse transporter (CadB) of A. veronii. We used efficient suicide plasmid-mediated homologous recombination to delete the cadB gene in TH0426 and constructed a cadB deletion strain. The LD50 of ΔcadB was 93.2 times higher than that of TH0426 in zebrafish, the toxicity of ΔcadB was 9.5 times less than that of TH0426 in EPC cells, and the biofilm formation ability of ΔcadB was 5.6-fold greater than that of TH0426. In addition, motility detection results indicated that ΔcadB had lost its swimming ability. The results of flagellar staining and TEM demonstrated that ΔcadB shed the flagella. In summary, the virulence and adhesion of A. veronii TH0426 were significantly decreased by the deletion of cadB, which might provide a theoretical basis for research into A. veronii virulence factors.

Functional Analysis of preA in Aeromonas veronii TH0426 Reveals a Key Role in the Regulation of Virulence and Resistance to Oxidative Stress

Aeromonas veronii is one of the main pathogens causing freshwater fish sepsis and ulcer syndrome. This bacterium has caused serious economic losses in the aquaculture industry worldwide, and it has become an important zoonotic and aquatic agent. However, little is known about the molecular mechanism of pathogenesis of A. veronii. In this study, we first constructed an unmarked mutant strain (ΔpreA) by generating an in-frame deletion of the preA gene, which encodes a periplasmic binding protein, to investigate its role in A. veronii TH0426. Our results showed that the motility and biofilm formation ability of ΔpreA were similar to those of the wild-type strain. However, the adhesion and invasion ability in epithelioma papulosum cyprini (EPC) cells were significantly enhanced (2.0-fold). Furthermore, the median lethal dose (LD₅₀) of ΔpreA was 7.6-fold higher than that of the wild-type strain, which illustrates that the virulence of the mutant was significantly enhanced. This finding is also supported by the cytotoxicity test results, which showed that the toxicity of ΔpreA to EPC cells was enhanced 1.3-fold relative to the wild type. Conversely, tolerance test results showed that oxidative stress resistance of ΔpreA decreased 5.9-fold compared to with the wild-type strain. The results suggest that preA may negatively regulate the virulence of A. veronii TH0426 through the regulation of resistance to oxidative stress. These insights will help to further elucidate the function of preA and understand the pathogenesis of A. veronii.

Role of Myeloperoxidase of northern snakehead (Channa argus) in Aeromonas veronii infection

Myeloperoxidase (MPO) is a ferrous lysosomal protein with many immune functions that belongs to the heme peroxidase enzyme. In this study, the functions of MPO in the northern snakehead (Channa argus) were investigated by cloning an MPO cDNA sequence with a full length of 3181 bp. Homology analysis showed that northern snakehead MPO gene had the highest (81%) homology with mandarin fish (Siniperca chuatsi). In healthy northern snakehead, the MPO gene was expressed in the head-kidney, kidney, heart, gill, spleen, liver, and muscles but not midgut. After the northern snakehead was infected with Aeromonas veronii, the MPO gene expression varied in different tissues with low level in spleen, liver, gill and muscle, fluctuated in kidney and head-kidney and showed high level in heart. The result indicated that MPO might play an important role in the antimicrobial immune response of the northern snakehead.

OmpW expressed by recombinant Lactobacillus casei elicits protective immunity against Aeromonas veronii in common carp

Aeromonas veronii is an opportunistic pathogen that is capable of infecting both aquatic livestock and mammals. Natural infection in fishes results in irreparable damage to the aquaculture industry. In this study, we sought to investigate whether recombinant Lactobacillus casei expressing the outer membrane protein W (OmpW) of A.veronii could elicit protective immunity against A.veronii infections. We generated two recombinant Lactobacillus casei (L.casei) strains expressing the OmpW of A.veronii (surface-displayed or secreted) and evaluated the effect on immune responses in a fish model. A 600-bp gene fragment was subcloned into the L.casei expression plasmids pPG-1 (surface-displayed) and pPG-2 (secreted). Expression of the recombinant OmpW protein was also confirmed by Western blot and immunofluorescence assays. Common carp immunized with Lc-pPG-1- OmpW and Lc-pPG-2- OmpW via oral administration elicited high serum specific antibody titers and high LZM, ACP, and SOD activities. High levels of the IL-10, IL-β, IFN-γ, and TNF-α genes in different organs indicated that the inflammatory response and cell immune response were triggered. Additionally, when immunized fish were challenged with A.veronii, Lc-pPG1-OmpW and Lc-pPG2-OmpW demonstrated 40% and 50% protective efficacy. These data indicate that the combination of OmpW delivery and the lactic acid bacteria (LAB) approach may be a promising mucosal therapeutic strategy for treatment of A.veronii.

Maltoporin (LamB protein) contributes to the virulence and adhesion of Aeromonas veronii TH0426

Aeromonas veronii is one of the main pathogens causing freshwater fish sepsis and ulcer syndrome. More and more cases have shown that it has become an important zoonotic and aquatic agent. In this study, a A. veronii TH0426 mutant strain (ΔlamB) with an in-frame deletion removed nucleotides 10-1,296 of the lamB gene was firstly constructed to investigate its functions. The results showed that the LD₅₀ value of the mutant ΔlamB to zebrafish and mice was 13.7-fold and 5.6-fold higher than those of the wild-type strain, respectively. The toxicity of wild-type strain to EPC cells was 2.1-fold and threefold higher than those of ∆lamB when infected for 1 and 2 hr. Furthermore, the ability of biofilm formation and the adhesion and invasion to EPC cells of ∆lamB significantly decreased for 5.6-fold and 1.8-fold separately. In addition, motility detection result indicated that ∆lamB lost the swimming ability. The results of flagellar staining and TEM demonstrated that the flagella of ∆lamB were shed. In general, the deletion of lamB gene caused a significant decrease in the virulence and adhesion of A. veronii TH0426, and it can be known that the lamB gene of A. veronii plays a crucial role in the pathogenesis.

Genetic variation analysis of PCV1 strains isolated from Guangxi Province of China in 2015

Background

Porcine circovirus type 1 (PCV1) was discovered in 1974 as a contaminant of a porcine kidney (PK-15) cell line and was generally accepted to be nonpathogenic. But recently it was shown to cause lesions in experimentally infected pig fetuses. Serological evidence and genetic studies suggested that PCV1 was widespread in domestic pigs. Thus, the molecular epidemiology and genetic variation of PCV1 are still necessary to understand.

Results

Here 247 tissue samples were collected from piglets in Guangxi Province, China and performed whole-genome sequencing of the PCV1 genome. Thirteen PCV1 strains were sequenced from the samples. Similarity analysis showed that there were 97.8% to 99.6% nucleotide similarity to each other and 97.1% to 99.8% nucleotide similarity to the 40 reference strains. Besides, based on sequence analysis, we found one putative recombinant virus named GXdx84 strain contained the open-reading frame 1 (ORF1) of PCV1 and the ORF2 of PCV2d-2, which was consistent with the results of phylogenetic analysis that compared PCV1 and PCV2 strains. Variation analysis of the amino acids of the capsid protein revealed that the GXyl224 strain, which encoded 235 amino acids, had two amino acids more than other strains. This is the first study to report that a cap gene mutation resulted in lengthening of in the gene sequence.

Conclusions

These data contribute to the understanding of PCV1 evolution and molecular epidemiology that will facilitate programs for its control and prevention.

Seroprevalence and risk factors of hepatitis E virus infection among the Korean, Manchu, Mongol, and Han ethnic groups in Eastern and Northeastern China

Hepatitis E virus (HEV) infection is a serious public health concern in developing countries. China is regarded as an HEV-endemic area, but epidemiological data for HEV among different nationalities is limited. This study was conducted to estimate the seroprevalence and risk factors of HEV infection in Koreans (n = 520), Manchus (n = 303), Mongols (n = 217), and Hans (n = 802) in Eastern and Northeastern China between 2013 and 2015. A total of 366 (19.87%) out of 1842 samples were seropositive for IgG or IgM HEV-antibodies detected by enzyme-linked immunoassays. Among these groups, the Mongols had the highest seroprevalence of HEV infection (25.35%, 55/217), followed by the Koreans (23.65%, 123/520), the Manchus (19.80%, 60/303), and the Hans (15.96%, 128/802). Multiple analysis showed that the gender, consumption of raw/undercooked meat, source of drinking water, residence area, and age were significantly associated with HEV infection in four ethnic groups. The present results indicated that HEV infection was prevalent in Mongols, Koreans, Manchus, and Hans in the surveyed regions, which demonstrated the higher risk of transmitting HEV in multiple nationalities in Eastern and Northeastern China.

Mycobacterium vaccae induces a strong Th1 response that subsequently declines in C57BL/6 mice

Mycobacterium (M.) vaccae is a fast-growing species of saprophytic bacteria that is widely distributed. To understand the host immune responses induced by M. vaccae isolated from bovine submaxillary lymph nodes, C57BL/6 mice were infected with reference strain M. bovis Bacillus Calmette-Guérin (BCG) and isolated M. vaccae using intraperitoneal injections. Comparison of the bacterial replication and organ pathology between M. vaccae and M. bovis BCG revealed that M. vaccae was more malignant than M. bovis in mice. We also demonstrated that serum from the M. vaccae-infected mice contained a higher expression level of gamma-interferon (IFN-γ), tumor necrosis factor alpha, monocyte chemoattractant protein-1, interleukin (IL)-4, IL-12, IL-10 and transforming growth factor beta than did the other groups, especially after week 4. Furthermore, when the numbers of CD3⁺CD4⁺IFN-γ⁺ and CD3⁺CD4⁺IL4⁺cells in the infected mice were observed by flow cytometry, we found that a powerful T helper 1 (Th1) response was induced by M. vaccae infection, which was associated with the emergence of CD3⁺CD4⁺IFN-γ⁺cells. However, the Th1 response declined over time, which was associated with appearance of the CD4⁺CD25⁺FoxP3⁺ and CD4⁺CD25⁺CD152⁺Treg cell reaction. In addition, a strong Th2 response was found. Finally, we found that M. vaccae infection increased the production of type I IFNs, which was associated with a reduced Th1 response.

Cepharanthine, an alkaloid from Stephania cepharantha Hayata, inhibits the inflammatory response in the RAW264.7 cell and mouse models

The aim of this study was to investigate the protective effects of cepharanthine (CEP) on inflammation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells in vitro and a LPS-induced lung injury model in vivo. RAW264.7 cells were treated with various concentrations of CEP for 1 h followed by incubation with or without 1 μg/ml LPS for 18 h. TNF-α, IL-6, and IL-1β in the supernatants were measured by ELISA. Nuclear factor-κB (NF-κB) and mitogen-activated protein kinase pathways were analyzed by Western blot. Mice were randomly divided into control group, LPS group, CEP + LPS group, and dexamethasone + LPS group. A male BALB/c mouse model of acute lung injury was induced by LPS. Bronchoalveolar lavage fluid was collected for inflammatory cell count and cytokine assays. Histopathologic examination was performed on mice that were not subjected to bronchoalveolar lavage fluid collection. CEP dose-dependently inhibited the release of TNF-α, IL-6, and IL-1β in LPS-stimulated RAW264.7 cells. Significantly, CEP dose-dependently suppressed NF-κB activation, IκBα degradation, and phosphorylation of ERK, JNK, and p38 induced by LPS. In vivo, it was also observed that CEP attenuated lung histopathologic changes and down-regulated the level of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, in the mouse acute lung injury model. These results suggest that CEP potentially decreases inflammation in vitro and in vivo and might be a therapeutic agent against inflammatory diseases.

Comparison of gene expression profiles between Peyronie's disease and Dupuytren's contracture

OBJECTIVES

To compare the gene expression alterations in human Peyronie's disease (PD) and Dupuytren's disease (DD) to determine whether they share a common pathophysiology. Multiple mRNA expression profiles of human PD have previously shown that genes that regulate fibroblast replication, myofibroblast differentiation, collagen metabolism, tissue repair, and ossification are involved. DD, a palmar fascia fibrosis, may be associated with PD.

METHODS

Total RNA samples from PD plaques, normal tunica albuginea, Dupuytren's nodules, and normal palmar fascia (nine samples per group) were subjected to differential gene expression profile analysis (Clontech Atlas DNA microarray) comparing PD with tunica albuginea and DD with normal palmar fascia. Changes of more than 2.0 in PD and DD compared with tunica albuginea and normal palmar fascia, respectively, were recorded. Reverse transcriptase-polymerase chain reactions were performed for some genes whose expression was altered in PD.

RESULTS

Some of the gene families upregulated in both PD and DD were (a) collagen degradation: matrix metalloproteinase (MMP), with MMP2 and MMP9, and thymosins (MMP activators), with TMbeta10 and TMbeta4; (b) ossification: osteoblast-specific factors (OSFs) OSF-1 and OSF-2 (DD only); and (c) myofibroblast differentiation: RhoGDP dissociation inhibitor 1. The genes upregulated in PD only were decorin (an inhibitor of transforming growth factor-beta1 and a part of fibroblast replication/collagen synthesis) and early growth response protein. Reverse transcriptase-polymerase chain reaction confirmed these changes.

CONCLUSIONS

These data demonstrate that the pattern of alterations in the expression of certain gene families in PD and DD is similar, suggesting that they share a common pathophysiology and may be amenable to the same therapeutic regimens.

Gene expression in Peyronie's disease

Currently, surgical intervention is the only efficacious treatment for Peyronie's disease (PD), a fibromatosis of the tunica albuginea of the penis. Therapies based on the molecular pathways for this disease could provide alternatives to surgical treatment but only recently has the pathophysiology of the Peyronie's disease plaque been investigated at the molecular level. In this review, we examine the current knowledge of gene expression in the PD plaque and the relationship of PD with other fibrotic conditions such as Dupytren's disease. TGFbeta1, along with other growth factors, pro-fibrotic genes, and collagen, are expressed in fibroblasts and myofibroblasts. Myofibroblasts are normally involved in wound contracture and largely eliminated via apoptosis during the late stages of wound remodeling. In the PD plaque, however, these cells persist and may play an important role in the PD plaque fibrosis. The expression levels of TGFbeta1 and pro- and anti-fibrotic gene products, along with the nitric oxide/reactive oxygen species (NO/ROS) ratio in the tunica albuginea, appear to be essential for the formation and progression of the PD plaque and effect the expression of multiple genes. This can be assessed with the recently developed DNA-based chip arrays and results with the PD plaque have been encouraging. OSF-1 (osteoblast recruitment), MCP-1 (macrophage recruitment), procollagenase IV (collagenase degradation), and other fibrotic genes have been identified as being possible candidate regulatory genes. Finally, possible therapeutic avenues for gene-based therapy in the treatment of PD are discussed that may eventually reduce the need for surgical intervention.

Antifibrotic role of inducible nitric oxide synthase

Long-term treatment in rats with l-NAME, an isoform-non-specific inhibitor of nitric oxide synthase (NOS), leads to fibrosis of the heart and kidney, suggesting that nitric oxide (NO) may play a role in preventing tissue fibrosis. In this process, a likely target of NO is the quenching of reactive oxygen species (ROS) through peroxynitrite formation, and one possible source for this NO is inducible NOS (iNOS). Using Peyronie's disease (PD) tissue from both human specimens and from a rat model of PD as the source of fibrotic tissue, we investigated if NO derived from iNOS could act as such an antifibrogenic defense mechanism by determining whether: (a) tunical ROS and iNOS are increased in PD; and (b) the long-term inhibition of iNOS activity decreases the NO/ROS balance in the tunica albuginea thereby promoting collagen deposition. It was determined that in the human PD plaque, iNOS mRNA and protein, ROS, collagen, and the peroxynitrite marker, nitrotyrosine, were all increased in comparison to the normal tunica. In the rat model of PD, the fibrotic plaque also showed significant increases in iNOS mRNA and protein, nitrotyrosine, ROS as measured by heme oxygenase-1, and collagen when compared with the normal control tunica. When a selective inhibitor of iNOS, L-NIL, was given to rats with the PD-like plaque, this resulted in a decrease in nitrotyrosine levels but intensified ROS levels and collagen deposition. These data demonstrate that: (a) iNOS induction occurs in both the human and rat PD fibrotic plaque; and (b) that the NO derived from iNOS appears to counteract ROS formation and collagen deposition. Because the inhibition of iNOS activity leads to a decrease in the NO/ROS ratio, thereby favoring the development of fibrosis, it is proposed that iNOS induction in this tissue may be a protective mechanism against fibrosis and abnormal wound healing.

Identification of retinoic acid-responsive elements on the HNF1alpha and HNF4alpha genes

Hepatocyte nuclear factor 1alpha (HNF1alpha) and HNF4alpha are liver-selective transcription factors and are essential for hepatocyte differentiation. This study demonstrates that HNF1alpha as well as HNF4alpha genes contain a direct repeat with a space of one nucleotide (DR1)-retinoic acid (RA) response element that can be bound and regulated by RA and retinoid x receptor alpha (RXRalpha) complex. Transient transfection experiments showed that RA increased the promoter activity of the HNF1alpha and HNF4alpha genes in Hep3B cells. Overexpression of RXRalpha further enhanced the activities of both genes. Two putative RXRalpha binding sites on the HNF1alpha (-295 to -276) and HNF4alpha (-418 to -399) genes have been characterized. By transient transfection, both sites positively responded to RA, and overexpression of RXRalpha in Hep3B cells increased the regulatory effect. Gel mobility shift assay demonstrated that these two DR-1 sites could be bound by RXRalpha specifically. These data suggest that the differentiation effect of RA on hepatocyte may be due to direct interaction of RXRalpha with the RA-responsive elements on the HNF1alpha and HNF4alpha genes.

Molecular mechanisms regulating the effects of oxytocin on myometrial intracellular calcium

Oxytocin stimulates an increase in intracellular calcium in uterine myometrium by several mechanisms. Several lines of evidence indicate that the oxytocin receptor is functionally coupled to GTP-binding proteins of the G alpha q/11 class which stimulate phospholipase C activity. The IP3 generated as a result of phospholipase C activation can trigger release of calcium from intracellular stores. The finding that the oxytocin-stimulated increase in intracellular calcium in myometrial cells is greater in the presence of extracellular calcium than that in its absence indicates that oxytocin also has effects on calcium entry. This action is nifedipine-insensitive but may involve indirect stimulation of calcium entry through release-operated channels. An anti-G alpha q/11 antibody inhibits both oxytocin-stimulated GTPase activity and phospholipase C activity in myometrial membranes. The stimulation by oxytocin of phosphoinositide turnover in COS cells transfected with a plasmid expressing the oxytocin receptor is enhanced by cotransfection of G alpha q. Co-transfection of intracellular domains of the oxytocin receptor causes varying degrees of interference with oxytocin-stimulated phosphoinositide turnover. The data suggest that more than one intracellular domain is involved in oxytocin receptor/G-protein coupling. Oxytocin receptor stimulation of phospholipase C is inhibited by cAMP. This occurs in myometrial cells and in COS cells transfected with a plasmid expressing the receptor. The inhibitory mechanism involves the action of protein kinase A and is probably targeted indirectly at the G alpha q/11 /phospholipase C coupling step.

Evidence for the involvement of several intracellular domains in the coupling of oxytocin receptor to G alpha(q/11)

In order to probe the nature of oxytocin receptor (OTR)/G alpha(q/11) protein coupling, we examined the effect of co-expression of OTR intracellular domains on oxytocin-stimulated phosphoinositide turnover in COSM6 cells overexpressing OTR and G alpha(q). Co-expression of G alpha(q) enhanced the oxytocin response maximally at a pOTR/pG alpha(q) plasmid transfection ratio of 1:0.16. In cells co-expressing OTR and G alpha(q/11), oxytocin stimulated phosphoinositide turnover with an EC50 of 48 nM. Co-transfection with plasmids expressing OTR intracellular domains inhibited oxytocin-stimulated phosphoinositide turnover by 23 +/- 6% (1i), 37 +/- 4% (2i), 55 +/- 6% (3i), and 40 +/- 6% (4i), respectively (P < 0.01). Expression of the 3i loop of the alpha(1B)-adrenergic receptor, which also couples to G alpha(q/11), inhibited phosphoinositide turnover by 35 +/- 2% (P < 0.01), while expression of the 3i loop of the dopamine 1A receptor, which couples to G alpha(s), had no effect. While these data indicate a functional role for the OTR 3i loop, they also suggest that interactions with more than one intracellular domain probably mediate the coupling of OTR to the G alpha(q/11) class of GTP-binding proteins.

Oxytocin stimulates myometrial guanosine triphosphatase and phospholipase-C activities via coupling to G alpha q/11

Oxytocin stimulates phosphoinositide turnover in myometrium. To elucidate whether the coupling mechanism involves the interaction of oxytocin receptor with GTP-binding proteins, we examined oxytocin stimulation of guanosine triphosphatase (GTPase) activity and phospholipase-C activity in rat and human myometrial membranes. Oxytocin consistently stimulated both GTPase and phospholipase-C activities, and both stimulations were attenuated by an antibody directed against the carboxyl-terminals of the GTP-binding proteins, G alpha q and G alpha 11. Neutralization of the antibody by preincubation with antigenic peptide reversed this inhibition. [Thr4,Gly7]oxytocin, a specific oxytocin receptor agonist, stimulated both GTPase and phospholipase-C activities, and the stimulations were also inhibited by anti-G alpha q/11 IgG. Immunoreactive GTP-binding proteins, G alpha q and G alpha 11, and phospholipase-C beta 3 isoforms were present in myometrial membranes. These results indicate that stimulation of phospholipase-C activity by oxytocin in myometrium is mediated via G alpha q, G alpha 11, or a closely related GTP-binding protein, probably coupling to phospholipase-C beta.

A comparison of microtubule assembly in brain extracts from young and old rats

Microtubule assembly was examined in the high-speed supernatant from homogenates of young (2-4 months old) and old (more than 24 months old) rat brains and significant age-related differences in microtubule assembly were found in the absence of exogenous GTP. In extracts from young brains, the increase in absorbance at 350 nm, which reflects the assembly reaction, was characterized by three phases (lag, elongation, and steady state) superimposed on a slow continuous increase due to non-specific aggregation. However, assembly in extracts from old brains, was very sluggish, in some cases barely more rapid than the non-specific aggregation reaction. Two to three times as much protein was assembled into cold-labile microtubules in extracts from young brains than from old brains. When 1 mM GTP was included in the assembly solutions the patterns of assembly in extracts from young and old brains became similar, with about the same amount of protein assembled into cold-labile microtubules. The assembly of tubulin purified from rat brains showed no differences between young and old. Results showed that extracts from old brains contained a higher GTPase activity than extracts from young brains. The sluggish assembly in extracts from old brains could be due to a deficiency in GTP or an inefficient regeneration of GTP.