Phosphorylation of the Autographa californica multiple nucleopolyhedrovirus polyhedron envelope protein plays an important role in the formation of the occlusion body envelope

During the life cycle of a baculovirus, a crystallized protein matrix, formed by polyhedrin (POLH), is produced. The protein matrix is surrounded by a multilayered protein/carbohydrate envelope, and matrix and envelope together form a mature occlusion body (OB). The polyhedron envelope plays an important role in resistance against adverse external environments. The polyhedron envelope protein (PEP) is the main protein that forms the polyhedron envelope, but the mechanism of formation of the polyhedron envelope is unclear. Here, through immunofluorescence localization observations, we found that PEP interacted with both POLH and P10 during formation of the polyhedron envelope in the late stages of infection, and PEP was also required for P10 incorporation on the surface of OBs. In this process, the phosphorylation of PEP played an important role. PEP was determined to be a phosphorylated protein using the Phos-tag technique, and PK1 was determined to be the phosphokinase of PEP by co-immunoprecipitation and in vitro phosphorylation. Immunofluorescence localization revealed that PEP was continuously phosphorylated by PK1 after PEP entered the nucleus until PEP was correctly packaged on the OB surface. Multi-point mutations of PEP conservative potential phosphorylation sites showed that the simultaneous mutation of S85, T86 and Y92 caused changes in the location of PEP and P10 in the late stages of infection, and resulted in an OB surface that lacked the polyhedron envelope. These data suggested that the phosphorylation of PEP at particular sites, i.e. S85, T86 and Y92, plays an important role in the formation of the polyhedron envelope.

Synergistic effect of two antimicrobial peptides, Nisin and P10 with conventional antibiotics against extensively drug-resistant Acinetobacter baumannii and colistin-resistant Pseudomonas aeruginosa isolates

BACKGROUND

Infections caused by drug-resistant strains of Acinetobacter baumannii and Pseudomonas aeruginosa are now a global problem that requires the immediate development of new antimicrobial drugs. Combination therapy and using antimicrobial peptides are two strategies with high potential to solve this issue. By these strategies, this study aimed to determine the antimicrobial effect of Nisin and P10 antimicrobial peptides on extensively drug-resistant Acinetobacter baumannii and colistin-resistant Pseudomonas aeruginosa isolates, and investigate the most effective combination of an antimicrobial peptide with an antibiotic.

MATERIAL AND METHODS

This study was performed on five resistant clinical isolates and one standard strain for each kind of bacterium. First, the minimum inhibitory concentrations of two antimicrobial peptides (Nisin and P10) and five common antibiotics for the treatment of Gram-negative bacteria (ceftazidime, tobramycin, ciprofloxacin, doripenem, and colistin) was determined using Scanner-Assisted Colorimetric MIC Method. Then, the combination effect of P10+Nisin, P10+antibiotics, Nisin + antibiotics was investigated using checkerboard method.

RESULTS

The MIC value of Nisin and P10 against studied pathogens were 64-256 and 8-32 μg/ml, respectively. P10+Nisin combination showed synergistic effect against standard strains and additive effect against drug-resistant clinical isolates. It was also found that the combination effect of P10+ceftazidim, P10+doripenem, and Nisin + colistin was synergistic in most cases. Nisin + tobramycin combination showed synergistic effect in exposure to standard strains, while the synergy is strain-dependent against drug-resistant clinical isolates.

CONCLUSION

In conclusion, the synergism of Nisin + colistin and P10+ceftazidime/doripenem could be of great therapeutic value as antimicrobial drugs against infections caused by colistin-resistant P.aeruginosa and XDR A. baumannii.

Major capsid protein of Autographa californica multiple nucleopolyhedrovirus contributes to the promoter activity of the very late viral genes

The baculovirus expression vector system (BEVS) is one of the most powerful eukaryotic expression systems. Recombinant protein expression is usually controlled by promoters of the baculovirus very late genes (i.e., polyhedrin and p10); therefore, identifying novel regulatory factors for these promoters is key to increasing BEVS productivity. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the viral vector most frequently used in BEVS. VP39 is the major nucleocapsid protein of AcMNPV and plays a pivotal role in nucleocapsid assembly in the nucleus. In this study, we found that knocking out vp39 from the AcMNPV genome resulted in decreased protein abundance of polyhedrin and P10. Further assays revealed that the mRNA transcripts and the promoter activities of polyhedrin and p10 were decreased in the absence of vp39, suggesting that VP39 contributes to the activity of the very late viral gene promoters and may represent a means of optimizing the current BEVS.

Functional insights into the role of C-terminal disordered domain of Sesbania mosaic virus RNA-dependent RNA polymerase and the coat protein in viral replication in vivo

The C-terminal disordered domain of sesbania mosaic virus (SeMV) RNA-dependent RNA polymerase (RdRp) interacts with the viral protein P10. The functional significance of this interaction in viral replication was examined by a comparative analysis of genomic and sub-genomic RNA levels (obtained by quantitative real time PCR) in the total RNA extracted from Cyamopsis plants agro-infiltrated with wild-type or mutant forms of SeMV infectious cDNA (icDNA). The sgRNA copy numbers were found to be significantly higher than those of gRNA in the wild-type icDNA transfected plants. Transfection of a mutant icDNA expressing an RdRp lacking the C-terminal disordered domain led to a drastic reduction in the copy numbers of both forms of viral RNA. This could be due to the loss of interaction between the disordered domain of RdRp and P10 and possibly other viral/host proteins that might be required for the assembly of viral replicase. The C-terminal disordered domain also harbours the motif E which is essential for the catalytic function of RdRp. Mutation of the conserved tyrosine within this motif in the full length icDNA resulted in complete inhibition of progeny RNA synthesis in the transfected plants confirming the importance of motif E in the polymerase function in vivo. The role of coat protein (CP) in viral infection was also investigated by agro-infiltration of a CP start codon mutant icDNA which suggested that CP is essential for the encapsidation of viral progeny RNAs at later stages of infection.

CD62P and P10 as predictive markers for assessing the efficacy of hemodialysis in treating end-stage renal disease

BACKGROUND

CD62P is a platelet α-granule membrane protein, and P10 is a platelet membrane glycoprotein thrombospondin. To better understand the effects of hemodialysis (HD), we have conducted this study to investigate CD62P and P10 in assessing the efficacy of HD in treating patients with end-stage renal disease (ESRD).

METHODS

The case group consisted of 111 patients suffering ESRD treated with regular HD and the control group enrolled 117 healthy subjects. Before and after HD treatment, a series of parameters were observed, based on which, CD62P and P10 levels were detected in the patients in two groups before and after HD therapy. The correlation analysis analyzed the correlations of CD62P and P10 markers with serum creatinine (Scr), blood urea nitrogen (BUN), and subjective score; and logistic regression analysis was performed to reveal factors affecting the efficacy of HD.

RESULTS

BUN, Scr, serum phosphorus, intact parathyroid hormone (iPTH), fibrinogen, and β2-microglobulin (β2-MG) decreased while hemoglobin, albumin, and activated partial thromboplastin time increased in the patients suffering ESRD; patients presented with improvements in subjective symptoms and an increase in dry weight. CD62P and P10 levels were lower in post-treatment patients. CD62P and P10 positively correlated with Scr, BUN and subjective score; post-treatment CD62P and P10 levels, BUN, hemoglobin, albumin, triglyceride, iPTH, β2-MG, and fibrinogen were correlated with the efficacy of HD.

CONCLUSION

CD62P and P10 might be correlated to the efficacy of HD in treating ESRD, in turn providing predictive markers for assessing the ability of HD in treating ESRD.

Dendritic Cells Primed with Paracoccidioides brasiliensis Peptide P10 Are Therapeutic in Immunosuppressed Mice with Paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is an endemic systemic mycosis in Latin America, with the highest prevalence in Brazil, Colombia, and Venezuela. Fungi of the Paracoccidioides genus are etiologic agents of the disease. The 15 amino acid peptide P10 is derived from gp43, the main diagnostic antigen of Paracoccidioides brasiliensis. We previously reported that P10-pulsed dendritic cells (DCs) induce a protective response against P. brasiliensis. Presently, dexamethasone-treated BALB/c mice were intratracheally infected with P. brasiliensis Pb18 to establish the therapeutic efficacy of P10-pulsed DCs. Immunosuppressed and infected animals that received DCs had a reduction in their fungal burden, and this result was most pronounced in mice receiving DCs primed with P10. The efficacy of therapeutic DCs was significantly augmented by concomitant treatment with trimethoprim-sulfamethoxazole. Additionally, primed-DCs with or without the antifungal drug induced a beneficial Th₁-biased immune response and significantly reduced tissue damage. In conclusion, these studies with immunocompromised mice demonstrate that P10-pulsed DCs with or without concomitant antifungal drugs are potently effective in combating invasive PCM. These findings support further translational studies to validate the use of P10-primed DCs for PCM in immunocompetent and immunosuppressed hosts.

Phosphorylation Induces Structural Changes in the Autographa californica Nucleopolyhedrovirus P10 Protein

Baculoviruses encode a variety of auxiliary proteins that are not essential for viral replication but provide them with a selective advantage in nature. P10 is a 10-kDa auxiliary protein produced in the very late phase of gene transcription by Autographa californica multiple nucleopolyhedrovirus (AcMNPV). The P10 protein forms cytoskeleton-like structures in the host cell that associate with microtubules varying from filamentous forms in the cytoplasm to aggregated perinuclear tubules that form a cage-like structure around the nucleus. These P10 structures may have a role in the release of occlusion bodies (OBs) and thus mediate the horizontal transmission of the virus between insect hosts. Here, using mass spectrometric analysis, it is demonstrated that the C terminus of P10 is phosphorylated during virus infection of cells in culture. Analysis of P10 mutants encoded by recombinant baculoviruses in which putative phosphorylation residues were mutated to alanine showed that serine 93 is a site of phosphorylation. Confocal microscopy examination of the serine 93 mutant structures revealed aberrant formation of the perinuclear tubules. Thus, the phosphorylation of serine 93 may induce the aggregation of filaments to form tubules. Together, these data suggest that the phosphorylation of serine 93 affects the structural conformation of P10.IMPORTANCE The baculovirus P10 protein has been researched intensively since it was first observed in 1969, but its role during viral infection remains unclear. It is conserved in the alphabaculoviruses and expressed at high levels during virus infection. Producing large amounts of a protein is wasteful for the virus unless it is advantageous for the survival of its progeny, and therefore, P10 presents an enigma. As P10 polymerizes to form organized cytoskeletal structures that colocalize with host cell microtubules, the structural relationship of the protein with the host cell may present a key to help understand the function and importance of this protein. This study addresses the importance of the structural changes in P10 during infection and how they may be governed by phosphorylation. The P10 structures affected by phosphorylation are closely associated with the viral progeny and thus may potentially be responsible for its dissemination and survival.

Strain preservation of experimental animals: vitrification of two-cell stage embryos for multiple mouse strains

Strain preservation of experimental animals is crucial for experimental reproducibility. Maintaining complete animal strains, however, is costly and there is a risk for genetic mutations as well as complete loss due to disasters or illness. Therefore, the development of effective vitrification techniques for cryopreservation of multiple experimental animal strains is important. We examined whether a vitrification method using cryoprotectant solutions, P10 and PEPeS, is suitable for preservation of multiple inbred and outbred mouse strains. First, we investigated whether our vitrification method using cryoprotectant solutions was suitable for two-cell stage mouse embryos. In vitro development of embryos exposed to the cryoprotectant solutions was similar to that of fresh controls. Further, the survival rate of the vitrified embryos was extremely high (98.1%). Next, we collected and vitrified two-cell stage embryos of 14 mouse strains. The average number of embryos obtained from one female was 7.3-33.3. The survival rate of vitrified embryos ranged from 92.8% to 99.1%, with no significant differences among mouse strains. In vivo development did not differ significantly between fresh controls and vitrified embryos of each strain. For strain preservation using cryopreserved embryos, two offspring for inbred lines and one offspring for outbred lines must be produced from two-cell stage embryos collected from one female. The expected number of surviving fetuses obtained from embryos collected from one female of either the inbred or outbred strains ranged from 2.9 to 19.5. The findings of the present study indicated that this vitrification method is suitable for strain preservation of multiple mouse strains.

A study on cryoprotectant solution suitable for vitrification of rat two-cell stage embryos

The present study was performed to develop a suitable cryoprotectant solution for cryopreservation of rat two-cell stage embryos. First, we examined the cell permeability of several cryoprotectants; propylene glycol had the fastest permeability compared to dimethyl sulfoxide, ethylene glycol, and glycerol. Embryos were then exposed to a solution containing propylene glycol to evaluate its effects on fetal development. As the development was similar to that of fresh embryos, P10 (10% v/v propylene glycol in PB1) was used as a pretreatment solution. Next, the effects of the vitrification solution components (sucrose, propylene glycol, ethylene glycol, and Percoll) were examined by observing the vitrification status; 10% v/v propylene glycol, 30% v/v ethylene glycol, 0.3 mol sucrose, and 20% v/v Percoll in PB1 (PEPeS) was the minimum essential concentration for effective vitrification without the formation of ice crystals or freeze fractures. A new vitrification method using P10 and PEPeS was tested using rat embryos. The survival rate of vitrified embryos after exposure to P10 for 120, 300, or 600 s ranged from 95.9% to 98.3%. The fetal developmental rate ranged from 57.7% to 65.2%, which was not significantly different from that of fresh embryos. The experimental results indicated that vitrification using a combination of P10 and PEPeS was suitable for cryopreservation of rat early stage embryos.

Knockout of vascular early response gene worsens chronic stroke outcomes in neonatal mice

Vascular early response gene (Verge) is a novel immediate early gene that is highly expressed during developmental angiogenesis and after ischemic insults in adult brain. However, the role of Verge after neonatal injury is not known. In the present study, we investigated the hypothesis that Verge contributes to vascular remodeling and tissue repair after neonatal ischemic injury. The Rice-Vanucci model (RVM) was employed to induce neonatal stroke in both Verge knockout (KO) and wild-type (WT) postnatal day 10 (P10) mice. Histological and behavioral outcomes at acute (24h), subacute (7 days) and chronic (30 days) phases were evaluated. Angiogenesis, neurogenesis, and glial scar formation were also examined in the ischemic brain. No significant differences in outcomes were found between WT and Verge mice at 24h or 7 days after stroke. However genetic deletion of Verge led to pronounced cystic cavitation, decreased angiogenensis and glial scar formation in the ischemic hemisphere compared to WT mice at 30 days. Verge KO mice also had significantly worse functional outcomes at 30 days which was accompanied by decreased neurogenesis and angiogenesis in the ischemic hemisphere. Our study suggests that Verge plays an important role in the induction of neurogenesis and angiogenesis after ischemia, contributes to improved tissue repair, and enhances chronic functional recovery.

The role of adjuvants in therapeutic protection against paracoccidioidomycosis after immunization with the P10 peptide

Paracoccidioidomycosis (PCM), a common chronic mycosis in Latin America, is a granulomatous systemic disease caused by the thermo-dimorphic fungus Paracoccidioides brasiliensis. The glycoprotein gp43 is the main antigen target of P. brasiliensis and a 15-mer internal peptide (QTLIAIHTLAIRYAN), known as P10, defines a major CD4(+)-specific T cell epitope. Previous results have indicated that, besides having a preventive role in conventional immunizations prior to challenge with the fungus, protective anti-fungal effects can be induced in P. brasiliensis-infected mice treated with P10 administered with complete Freund's adjuvant (CFA). The peptide elicits an IFN-γ-dependent Th1 immune response and is the main candidate for effective immunotherapy of patients with PCM, as an adjunctive approach to conventional chemotherapy. In the present study we tested the therapeutic effects of P10 combined with different adjuvants [aluminum hydroxide, CFA, flagellin, and the cationic lipid dioctadecyl-dimethylammonium bromide (DODAB)] in BALB/c mice previously infected with the P. brasiliensis Pb18 strain. Significant reductions in the number of colony forming units of the fungus were detected in lungs of mice immunized with P10 associated with the different adjuvants 52 days after infection. Mice treated with DODAB and P10, followed by mice treated with P10 and flagellin, showed the most prominent effects as demonstrated by the lowest numbers of viable yeast cells as well as reductions in granuloma formation and fibrosis. Concomitantly, secretion of IFN-γ and TNF-α, in contrast to interleukin (IL)-4 and IL-10, was enhanced in the lungs of mice immunized with P10 in combination with the tested adjuvants, with the best results observed in mice treated with P10 and DODAB. In conclusion, the present results demonstrate that the co-administration of the synthetic P10 peptide with several adjuvants, particularly DODAB, have significant therapeutic effects in experimental PCM.