Post-inoculation Treatment Research Articles

Assessment of fungal and bacterial bioagents against Bipolaris sorokiniana inciting spot blotch on barley (Hordeum vulgare)

In India, spot blotch disease caused by Bipolaris sorokiniana is one of the major constraints in barley (Hordeum vulgare L.) production. The present study was carried out during 2022–23 at ICAR-Indian Agriculture Research Institute, New Delhi to identify promising biocontrol agents, which can act as eco-friendly alternatives to chemicals against Bipolaris sorokiniana inciting spot blotch on barley (Hordeum vulgare L.). In this study, 18 isolates of Trichoderma asperellum, 15 isolates of Trichoderma harzianum and 5 bacterial species were tested against B. sorokiniana under in vitro and in planta conditions. In the dual culture assays, Trichoderma asperellum 8686 and Trichoderma asperellum 8687 showed significantly highest per cent disease inhibition of 71.73% and 71.37% respectively. Among bacterial strains, Pseudomonas fluorescens and Bacillus amyloliquefaciens showed significantly good per cent disease inhibition of 64.09% and 57.09% respectively. B. subtilis and Pantoea spp. did not show any pathogen inhibition. In addition, the superior bioagents were also screened out. In the studies on in planta assays, Bacillus amyloliquefaciens (per cent disease control-55.19%) was found most effective for seed treatment against B. sorokiniana. Post-inoculation with biocontrol agents revealed that Bacillus amyloliquefaciens was at par with Trichoderma asperellum and Pseudomonas fluorescens against B. sorokiniana. Additionally, a combination of seed treatment, pre and post-inoculation treatment of biocontrol agents revealed that Bacillus amyloliquefaciens and Trichoderma asperellum 8686 were at par with Trichoderma harzianum (Pusa Th3) against B. sorokiniana. Overall, Bacillus amyloliquefaciens was more effective and consistent to manage spot blotch disease.

A preliminary investigation into Aureobasidium pullulans as a potential biocontrol agent against Phytophthora infestans of tomato

Two biological control agents (BCAs), Aureobasidium pullulans L1 and L8 strains, were evaluated for their efficacy against Phytophthora infestans, the casual agent of tomato late blight. Yeast strains were applied (108 CFU/mL) on tomato plants, grown under greenhouse conditions, 24h before or 16h after inoculation with P. infestans (1×104 sporangia/mL). The BCAs applied 24h before the pathogen inoculation were significantly more effective (43.9%) than those applied after pathogen inoculation. L8 reduced AUDPC more (60%) than L1 (37%), while both strains reduced the disease in a similar way (average 32.2%) in the post-inoculation treatment. Dynamic population assay revealed that L1 and L8 were able to survive and colonize the tomato leaf surface during the ten days of experiments. In vitro experiments showed that both strains enhanced plant defence response by increasing leaf β-1,3-glucanase activity (>30% than the control). BCAs also produced bioactive volatile and non-volatile metabolites able to inhibit pathogen colony growth and to cause morphological alterations of hyphae. Overall, volatile metabolites were more effective than non-volatiles in reducing pathogen growth. In addition, 2-phenyl, 1-butanol-3-methyl, 1-butanol-2-methyl and 1-propanol-2-methyl synthetic volatile compounds produced by both strains showed EC50 values for pathogen mycelial growth of 3.9µLL−1 on average. This study showed that L1 and L8 strains could be considered part of a control strategy against P. infestans on tomato.

Respiratory syncytial virus (RSV) entry is inhibited by serine protease inhibitor AEBSF when present during an early stage of infection

BackgroundHost proteases have been shown to play important roles in many viral activities such as entry, uncoating, viral protein production and disease induction. Therefore, these cellular proteases are putative targets for the development of antivirals that inhibit their activity. Host proteases have been described to play essential roles in Ebola, HCV, HIV and influenza, such that specific protease inhibitors are able to reduce infection. RSV utilizes a host protease in its replication cycle but its potential as antiviral target is unknown. Therefore, we evaluated the effect of protease inhibitors on RSV infection.MethodsTo measure the sensitivity of RSV infection to protease inhibitors, cells were infected with RSV and incubated for 18 h in the presence or absence of the inhibitors. Cells were fixed, stained and studied using fluorescence microscopy.ResultsSeveral protease inhibitors, representing different classes of proteases (AEBSF, Pepstatin A, E-64, TPCK, PMSF and aprotinin), were tested for inhibitory effects on an RSV A2 infection of HEp-2 cells. Different treatment durations, ranging from 1 h prior to inoculation and continuing for 18 h during the assay, were evaluated. Of all the inhibitors tested, AEBSF and TPCK significantly decreased RSV infection. To ascertain that the observed effect of AEBSF was not a specific feature related to HEp-2 cells, A549 and BEAS-2B cells were also used. Similar to HEp-2, an almost complete block in the number of RSV infected cells after 18 h of incubation was observed and the effect was dose-dependent. To gain insight into the mechanism of this inhibition, AEBSF treatment was applied during different phases of an infection cycle (pre-, peri- and post-inoculation treatment). The results from these experiments indicate that AEBSF is mainly active during the early entry phase of RSV. The inhibitory effect was also observed with other RSV isolates A1998/3–2 and A2000/3–4, suggesting that this is a general feature of RSV.ConclusionRSV infection can be inhibited by broad serine protease inhibitors, AEBSF and TPCK. We confirmed that AEBSF inhibition is independent of the cell line used or RSV strain. The time point at which treatment with the inhibitor was most potent, was found to coincide with the expected moment of entry of the virion with the host cell.

Suppression of bacterial infection in rice by treatment with a sulfated peptide.

The rice XA21 receptor kinase confers robust resistance to bacterial blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo). A tyrosine-sulfated peptide from Xoo, called RaxX, triggers XA21-mediated immune responses, including the production of ethylene and reactive oxygen species and the induction of defence gene expression. It has not been tested previously whether these responses confer effective resistance to Xoo. Here, we describe a newly established post-inoculation treatment assay that facilitates investigations into the effect of the sulfated RaxX peptide in planta. In this assay, rice plants were inoculated with a virulent strain of Xoo and then treated with the RaxX peptide 2 days after inoculation. We found that post-inoculation treatment of XA21 plants with the sulfated RaxX peptide suppresses the development of Xoo infection in XA21 rice plants. The treated plants display restricted lesion development and reduced bacterial growth. Our findings demonstrate that exogenous application of sulfated RaxX activates XA21-mediated immunity in planta, and provides a potential strategy for the control of bacterial disease in the field.

Evaluation of some Chemical Substances as Inducers forTomato Resistance Against Root-Knot Nematode, Meloidogyne incognita

The potency of the some chemicals from different groups known as inducersof systemic acquired resistance (SAR) viz., acetylsalicylic acid (ASA), DL-3-aminobutyric acid (BABA), 2,6-dichloroisonicotinic acid (INA), 5-chlorosalicylic acid(CSA), nitrosalicylic acid (NSA),salicylic acid (SA),ascorbic acid (AS), and selenium(SE) in reducing reproduction Meloidogyne incognita in tomato plants cv. Castelrock was investigated under greenhouse conditions. Supplying chemicals threedays-before nematode inoculation showed maximum efficacy in reducing nematodegalls, egg-masses and eggs numbers followed by synchronized addition withinoculation, while post-inoculation treatment was less effective. Reiterative dosespost-inoculation were improved the efficacy of single dose, also three doses usedwere more effective than one or two, while, differences between two or three doseswere insignificant. On the other hand, plant fitness was slightly impaired with thirddose than second one. INA and SE showed pronounced effect in inhibitionnematode population after third dose compared with the rest chemicals, whichshowed mild increase in their efficacy from second to third doses. Unfortunately,three doses of SE were reduced plant fitness after enhanced by double doses,while INA was showed obvious phytotoxicity gradually increased by repeatingdoses. Gathering between the most effective application time (before inoculation)and the proper activated dose after inoculation was studies for emphasized theiraction and comparing with pre-inoculation only in suppressing M. incognitapopulation. Chemical activators showed enhancing in peroxidase andpolyphenoloxidase activities. In conclusion, CSA, NSA, BABA and SA were showedhighest efficacy as resistance inducers. This collectively showed reduction of totalpopulation with pre-inoculation time application and pre plus post-inoculationapplication, 57.6&83.8%, 56.5&81.6%, 55.4&79.2% and 54.5&78.1%, respectively.Also the fecundity of nematode was taking similar trend as total population. Theresults suggest that tested chemicals especially CSA, NSA, BABA and SA havepotential to suppress root-knot nematode infection in tomato plants through inducedsystemic resistance.

English

The present study aimed to study influence of temperature and relative humidity on fruit rots (Alternaria alternata and Aspergillus niger) of ber (Zizyphus mauritiana Lamk.) and find appropriate management option during storage period. Maximum damage by A. alternata was observed at 25°C while A. niger showed maximum severity at 30°C. Positive relationship was observed between relative humidity (RH) and fruit rot by both pathogens which showed highest severity at 100% RH. The pre-and post-inoculation treatment of ber fruits with four vegetable oils, four plant extracts and four fungicides showed significant differences in effectiveness in controlling both pathogens. Neem oil and its leaf extracts significantly (p<0.05) reduced severity of fruit rots by both pathogens. Among chemicals, the carbendazim at 1000 ppm proved effective against Alternaria and Aspergillus fruit rot. Chemical fungicides reduced fungus growth significantly (p<0.05) better than botanicals; however, botanical also showed better response than control. The effectiveness of botanicals in post-harvest storage of ber can be used at commercial scale.   Key words: Zizyphus mauritiana, Alternaria alternata, Aspergillus niger, fruit rot, vegetable oil, botanicals.

Survival of foodborne pathogens on inshell walnuts

The survival of Salmonella enterica Enteritidis PT 30 or five-strain cocktails of S. enterica, Escherichia coli O157:H7, and Listeria monocytogenes was evaluated on inshell walnuts during storage. Inshell walnuts were separately inoculated with an aqueous preparation of the pathogens at levels of 10 to 4log CFU/nut, dried for 24h, and then stored at either 4°C or ambient conditions (23–25°C, 25–35% relative humidity) for 3weeks to more than 1year. During the initial 24-h drying period, bacterial levels declined by 0.7 to 2.4log CFU/nut. After the inoculum dried, further declines of approximately 0.1log CFU/nut per month of Salmonella Enteritidis PT 30 levels were observed on inshell walnuts stored at 4°C; at ambient conditions the rates of decline ranged from 0.55 to 2.5log CFU/nut per month. Rates of decline were generally greater during the first few weeks of storage, particularly at lower inoculum levels. The survival of the five-strain cocktails inoculated at very low levels (under 400CFU/nut) was determined during storage at ambient conditions. The pathogens could be recovered by either enumeration or enrichment from most samples throughout the 3-month storage period; reductions in bacterial levels from the beginning to end of storage were 0.7, 0.2, and 2.3log CFU/nut for Salmonella, E. coli O157:H7, and L. monocytogenes, respectively. For 6% of all nut samples (14 of 234 samples), pathogens were isolated from the second but not first 24-h enrichment, suggesting that bacterial cells were viable but not easily culturable. Salmonella-inoculated walnuts were exposed for 2min to water or a 3% solution of sodium hypochlorite (to mimic commercial brightening) either 24h or 7days after inoculation; treated nuts were dried for 24h and held at ambient conditions. Salmonella levels were reduced by less than 0.5log or 2.4 to 2.6log CFU/nut on water– or chlorine– treated walnuts, respectively, regardless of postinoculation treatment time. Additional reductions of 2.6 and 2.1log CFU/nut were observed for water- and chlorine-treated walnuts, respectively, after storage for 2weeks at ambient conditions. Bacterial foodborne pathogens are capable of long-term survival on the surface of inshell walnuts even when initial levels are low.

Biological potential of Pseudomonas sp. BS1 in the control of Phytophthora root rot of soybean

In this study, the biological potential of Pseudomonas sp. BS1 in the control ofPhytophthora root rot of soybean was investigated. Fermentation filtrates ofPseudomonas sp. BS1 inhibited zoosporangium formation and zoospore germination ofPhytophthora sojae (P. sojae), and the inhibitory effect gradually weakened with the increasing filtrate dilution. It had a relatively strong inhibition on hyphal growth of P. sojae, and the inhibition rate of stock solutions reach 95.9%; as dilution increased, the inhibition gradually weakened. The results indicated that Pseudomonas sp. BS1 can inhibit normal growth and development of P. sojae, and pathogen reproduction. Through investigating the controlling effect of Pseudomonas sp. BS1 fermentation filtrates on Phytophthora root rot of soybean under greenhouse conditions, we found that pre-treatment with fermentation filtrates had a preventive effect on disease caused by P. sojae, and post-inoculation treatment with fermentation filtrates had a therapeutic effect. Simultaneous treatment with fermentation filtrates and zoospore suspension had best controlling effects. These results will provide a theoretical basis for the biological control of Phytophthora root rot of soybean using Pseudomonas sp. BS1. Key words: Pseudomonas, Phytophthora, zoosporangium, zoospore, biological control.

Benzyl and naphthalene methylphosphonic acid inhibitors of autotaxin with anti-invasive and anti-metastatic activity.

Autotaxin (ATX, NPP2) is a member of the nucleotide pyrophosphate phosphodiesterase enzyme family. ATX catalyzes the hydrolytic cleavage of lysophosphatidylcholine (LPC) by lysophospholipase D activity, which leads to generation of the growth-factor-like lipid mediator lysophosphatidic acid (LPA). ATX is highly upregulated in metastatic and chemotherapy-resistant carcinomas and represents a potential target to mediate cancer invasion and metastasis. Herein we report the synthesis and pharmacological characterization of ATX inhibitors based on the 4-tetradecanoylaminobenzylphosphonic acid scaffold, which was previously found to lack sufficient stability in cellular systems. The new 4-substituted benzylphosphonic acid and 6-substituted naphthalen-2-ylmethylphosphonic acid analogues block ATX activity with K(i) values in the low micromolar to nanomolar range against FS3, LPC, and nucleotide substrates through a mixed-mode inhibition mechanism. None of the compounds tested inhibit the activity of related enzymes (NPP6 and NPP7). In addition, the compounds were evaluated as agonists or antagonists of seven LPA receptor (LPAR) subtypes. Analogues 22 and 30 b, the two most potent ATX inhibitors, inhibit the invasion of MM1 hepatoma cells across murine mesothelial and human vascular endothelial monolayers in vitro in a dose-dependent manner. The average terminal half-life for compound 22 is 10±5.4 h and it causes a long-lasting decrease in plasma LPA levels. Compounds 22 and 30 b significantly decrease lung metastasis of B16-F10 syngeneic mouse melanoma in a post-inoculation treatment paradigm. The 4-substituted benzylphosphonic acids and 6-substituted naphthalen-2-ylmethylphosphonic acids described herein represent new lead compounds that effectively inhibit the ATX-LPA-LPAR axis both in vitro and in vivo.

A detached fruit study on the post-inoculation activity of lime sulfur against brown rot of peach (Monilinia fructicola)

Fungicides with curative activity are important tools for disease management in stone fruits. Lime sulfur (LS) is the only fungicide registered for organic fruit production with demonstrated curative activity against apple scab, but such activity against Monilinia fructicola is unknown. In this study, the 6, 12, and 24 h post-infection activity of 1.5% lime sulfur (LS) against M. fructicola was investigated on two peach fruit cultivars (early- and mid-season cultivars, Coronet and Contender, respectively) at two maturity stages (commercially mature and immature fruit) in a wound-inoculation detached fruit study. Brown rot incidence, sporulating area, and production of conidia per fruit were higher on commercially mature fruit in all treatments as compared with immature fruit, and LS treatments showed consistent results for both cultivars tested. All three disease measurements were significantly lower (P=0.05) for the 6 and 12 h post-inoculation applications of LS compared with either the untreated or 24 h post-inoculation applications of LS, irrespective of fruit maturity stages or cultivar. Disease incidence was reduced from 98.5–100% in the control treatment to 9–12% in the 6 h post-inoculation application. Both the 6 and 12 h post-inoculation applications reduced sporulating area from 64–72% in the control treatment to 0.0–1.3%. Disease incidence was not significantly (P=0.05) different between the water-treated control and the 24 h post-inoculation treatment with LS, while percent sporulating area and number of conidia per fruit were significantly different (P=0.05). Our results show up to 12 h post-inoculation activity of LS on M. fructicola in controlled environment studies and indicate that LS has potential for post-infection brown rot control in organic stone fruit production. Additional keywords: disease management, organic fruit production, stone fruits.

Biological and integrated control of postharvest blue mold (Penicillium expansum) of apples by Pseudomonas syringae and cyprodinil

In an attempt to develop fungicide (thiabendazole)-resistance management strategies, experiments were carried out to determine if the control of blue mold (Penicillium expansum) in ‘Empire’ and ‘McIntosh’ apples could be achieved by a biocontrol agent, Pseudomonas syringae and enhanced by integrating a biocontrol agent and a reduced-risk fungicide, cyprodinil, in a cold storage, and in a subsequent shelf-life study. The Ps. syringae at a concentration of 1.4 × 108 CFU ml−1, or cyprodinil at a concentration of 20 μg ml−1 were effective against blue mold caused by thiabendazole (fungicide)-sensitive and -resistant P. expansum in cold storage for 30 days and in the subsequent shelf-life study at 20 °C for 6 days in Empire’ and ‘McIntosh’ apples. Cyprodinil was effective in both the co-treatment, where fungicide or biocontrol agent and pathogen inoculum were applied together, and the post-inoculation treatment, where fungicide or biocontrol agent applied 20 h after inoculation. Ps. syringae was more effective as a co-treatment than as a post-inoculation treatment. All of the eight combinations, two concentrations of the biocontrol agent (3.0 × 107 and 6.0 × 107 CFU ml−1) and four concentrations of the fungicide (5, 10, 20, and 40 μg ml−1) were more effective than either the Ps. syringae or cyprodinil alone on blue mold caused by the isolates of P. expansum collected from Ontario. Integrated control was efficient in controlling blue mold of apple and could be considered for disease control strategies to manage thiabendazole-resistant P. expansum and also for reducing fungicide residues on fruit.

Control of blue mold (Penicillium expansum) by fludioxonil in apples (cv Empire) under controlled atmosphere and cold storage conditions

A reduced risk fungicide, fludioxonil, was tested for its efficacy against blue mold caused by thiabendazole-resistant and -sensitive Penicillium expansum (Link) Thom in apples under three storage conditions. In a co-treatment, fludioxonil and inoculum were applied together to test the protective activity of the fungicide on wounds that had been aged for 1 or 2 days. The fungicide was also tested for its curative activity in post-inoculation treatment on apples that had been inoculated for 1 or 2 days. Fludioxonil was very effective as co-treatment and as post-inoculation treatment. At a concentration of 300 mg litre(-1), fludioxonil gave complete control of post-harvest blue mold caused by the thiabendazole-resistant and -sensitive P expansum for 105 days in controlled atmosphere (CA) storage at 2 (+/-1) degrees C, for 42 days in common cold storage at 4 (+/-1) degrees C and also in a shelf-life study for 6 days at 20 (+/-1) degrees C. Comparison on the effect of fludioxonil in CA storage and common cold storage showed that higher concentrations of fungicide were needed in cold storage than in CA storage. Fludioxonil at a concentration of 450 mg litre(-1), gave 98 and 92% control of blue mold of apples in the simulated shelf-life studies after CA and common cold storages, respectively. Fludioxonil has a potential to be incorporated in the fungicide resistance management strategies for control of blue mold in apples stored for 105 days.

Effect of fludioxonil on germination and growth of Penicillium expansum and decay in apple cvs. Empire and Gala

Penicillium expansum is the predominant fungal pathogen responsible for blue mold of apple. The sensitivity of three thiabendazole-sensitive (TBZ S) and three thiabendazole-resistant (TBZ R) isolates of P. expansum, collected from apple stores in Ontario, to fludioxonil was determined in vitro (conidial germination and colony diameter on fludioxonil amended medium) and in vivo (apples). On fungicide amended medium, the concentration of 50% inhibition (EC 50 ) of germination for the TBZ S and TBZ R isolates of P. expansum ranged from 0.079 to 0.113 μg a.i. of fludioxonil/ml and for mycelial growth from 0.013 to 0.023 μg a.i. of fludioxonil/ml. Harvested apples were wounded and co-treated with a suspension of conidia of P. expansum and the fungicides by drenching. Fludioxonil at a concentration of 100 μg a.i./ml was found effective against blue mold induced by both TBZ S and TBZ R isolates of P. expansum on apple cv. Empire. In post-inoculation treatments, wounded apples were inoculated with P. expansum and incubated for 18–20 h at 13°C, and then drenched with appropriate concentrations of fungicides and incubated at 20°C for 6 days. Fludioxonil at a concentration of 100 μg a.i./ml controlled blue mold in the co-treatment and in the post-inoculation treatment on cvs. Empire and Gala. The activity of fludioxonil on two or more stages, conidial germination and mycelial growth, of life cycle of P. expansum and on decay formation in two cultivars of apples suggests that this compound potentially can provide an alternative to TBZ in post-harvest control of blue mold of apple, where any TBZ R conidia are present.

Effects of Pyrimidine and Purine Analog Combinations in the Duck Hepatitis B Virus Infection Model

To design new strategies of antiviral therapy for chronic hepatitis B, we have evaluated the antiviral activity of the combination of amdoxovir (DAPD), emtricitabine [(-)FTC], and clevudine (L-FMAU) in the duck hepatitis B virus (DHBV) model. Using their triphosphate (TP) derivatives in a cell-free system expressing a wild-type active DHBV reverse transcriptase (RT), the three dual combinations exhibited a greater additive inhibitory effect on viral minus-strand DNA synthesis than the single drugs, according to the Bliss independence model. Both dual combinations with DAPD TP were the most efficient while the triple combination increased the inhibitory effect on the DHBV RT activity in comparison with the dual association, however, without additive effect. Postinoculation treatment of experimentally infected primary duck hepatocytes showed that dual and triple combinations potently inhibited viral DNA synthesis during treatment but did not inhibit the reinitiation of viral DNA synthesis after treatment cessation. Preinoculation treatment with the same combinations exhibited antiviral effects on intracellular viral DNA replication, but it was unable to prevent the initial covalently closed circular DNA (cccDNA) formation. Short-term in vivo treatment in acutely infected ducklings showed that the dual combinations were more-potent inhibitors of virus production than the single treatments, with the L-FMAU and FTC combination being the most potent. A longer administration of L-FMAU and FTC for 4 weeks efficiently suppressed viremia and viral replication. However, no viral clearance from the liver was observed, suggesting that the enhanced antiviral effect of this combination was not sufficient for cccDNA suppression and HBV eradication from infected cells.

Use of essential oil as botanical-pesticide against post harvest spoilage in Malus pumilo fruit

During antifungal screening of the essentialoils of some angiospermic plants, oil ofCymbopogon flexuosus showed potentbioactivity against dominant post harvestfungal pathogens. The minimum bioactiveconcentrations with fungicidal action of theoil was found to be 0.2 µl ml−1 for Alternaria alternata, 0.4 µlml−1 for Aspergillus flavus, A.fumigatus, A. niger, A. parasiticus,Cladosporium cladosporioides, Colletotrichumcapsici, C. falcatum, Curvularia lunata,Fusarium cerealis, F. culmorum, F. oxysporum,F. udum, Gloeosporium fructigenum, Penicilliumexpansum, P. italicum, P. implicatum, P. digitatum,P. minio-luteum, P. variable,and 0.5 µl ml−1 forBotrytis cinerea, Helminthosporium oryzae, H.maydis, Phoma violacea, Rhizopus nigricans.The oil exhibited potency against heavy doses(30 mycelial disc, each of 5 mm in diameter) ofinoculum at 1.0 µl ml−1 concentrations.The bioactivity of the oil was thermostable upto 100°C and lasted up to 48 months.The oil preparation did not exhibit anyphytotoxic effect on the fruit skins ofMalus pumilo up to 50 µlml−1 concentrations. In vivo trials of theoil as a fungicidal spray on Malus pumilofor checking the rotting of fruits, it showedthat 20 µl ml−1 concentration controls100% infection by pre-inoculation treatment,while in post-inoculation treatment, 30 µlml−1 concentration of fungicidal spraywas required for the 100% control of rotting.The fungicidal spray was found to be costeffective (INR 15/l), has long shelf life (48month) and was devoid of any adverse effects.Therefore, it can be used as a potential sourceof sustainable eco-friendly botanicalpesticide, after successfulcompletion of wide range trials.

Role of CD8(+) lymphocytes in control of simian immunodeficiency virus infection and resistance to rechallenge after transient early antiretroviral treatment.

Transient antiretroviral treatment with tenofovir, (R)-9-(2-phosphonylmethoxypropyl)adenine, begun shortly after inoculation of rhesus macaques with the highly pathogenic simian immunodeficiency virus (SIV) isolate SIVsmE660, facilitated the development of SIV-specific lymphoproliferative responses and sustained effective control of the infection following drug discontinuation. Animals that controlled plasma viremia following transient postinoculation treatment showed substantial resistance to subsequent intravenous rechallenge with homologous (SIVsmE660) and highly heterologous (SIVmac239) SIV isolates, up to more than 1 year later, despite the absence of measurable neutralizing antibody. In some instances, resistance to rechallenge was observed despite the absence of detectable SIV-specific binding antibody and in the face of SIV lymphoproliferative responses that were low or undetectable at the time of challenge. In vivo monoclonal antibody depletion experiments demonstrated a critical role for CD8(+) lymphocytes in the control of viral replication; plasma viremia rose by as much as five log units after depletion of CD8(+) cells and returned to predepletion levels (as low as <100 copy Eq/ml) as circulating CD8(+) cells were restored. The extent of host control of replication of highly pathogenic SIV strains and the level of resistance to heterologous rechallenge achieved following transient postinoculation treatment compared favorably to the results seen after SIVsmE660 and SIVmac239 challenge with many vaccine strategies. This impressive control of viral replication was observed despite comparatively modest measured immune responses, less than those often achieved with vaccination regimens. The results help establish the underlying feasibility of efforts to develop vaccines for the prevention of AIDS, although the exact nature of the protective host responses involved remains to be elucidated.

Antifungal activity of three spermidine conjugates

Three tri-substituted spermidines, di- p-coumaroyl-caffeoylspermidine, tri-caffeoylspermidine and tri- p-coumaroylspermidine, isolated from pollen of Quercus alba, were examined for antifungal activity. Both di- p-coumaroyl-caffeoylspermidine and tri- p-coumaroylspermidine reduced mycelial growth of the oat leaf stripe pathogen, Pyrenophora avenae and reduced powdery mildew ( Blumeria graminis f. sp. hordei) infection of barley seedlings when applied as a post-inoculation treatment. When used as a pre-inoculation treatment, only di- p-coumaroyl-caffeoylspermidine reduced powdery mildew infection significantly. Growth of P. avenae in the presence of 100 μM di- p-coumaroyl-caffeoylspermidine reduced activity of S-adenosylmethionine decarboxylase (AdoMetDC), and led to a reduction in the incorporation of labelled ornithine into spermidine. The other two spermidine conjugates increased AdoMetDC activity and the flux label from ornithine into spermine in P. avenae significantly.

Antifungal activity of three spermidine conjugates.

Three tri-substituted spermidines, di-p-coumaroyl-caffeoylspermidine, tri-caffeoylspermidine and tri-p-coumaroylspermidine, isolated from pollen of Quercus alba, were examined for antifungal activity. Both di-p-coumaroyl-caffeoylspermidine and tri-p-coumaroylspermidine reduced mycelial growth of the oat leaf stripe pathogen, Pyrenophora avenae and reduced powdery mildew (Blumeria graminis f. sp. hordei) infection of barley seedlings when applied as a post-inoculation treatment. When used as a pre-inoculation treatment, only di-p-coumaroyl-caffeoylspermidine reduced powdery mildew infection significantly. Growth of P. avenae in the presence of 100 microM di-p-coumaroyl-caffeoylspermidine reduced activity of S-adenosylmethionine decarboxylase (AdoMetDC), and led to a reduction in the incorporation of labelled ornithine into spermidine. The other two spermidine conjugates increased AdoMetDC activity and the flux label from ornithine into spermine in P. avenae significantly.

Therapeutic effects of FTY720, a new immunosuppressive agent, in a murine model of acute viral myocarditis

OBJECTIVESThis study examines the efficacy of FTY720 (FTY), a new immunosuppressor, in the treatment of acute viral myocarditis in a murine model.BACKGROUNDImmunosuppressive agents have no proven therapeutic efficacy in experimental or clinical myocarditis.METHODSEncephalomyocarditis virus was inoculated i.p. in DBA/2 mice on day 0. Postinoculation treatment consisted of FTY 10 mg/kg/day p.o. (FTY group), or cyclosporine A (CsA) 40 mg/kg/day p.o. (CsA group) or distilled water p.o. only (control group). Survival until day 14, as well as cardiac histopathology, virus concentrations, cytokines (interleukin [IL]-2, IL-12, interferon [IFN]-gamma and tumor necrosis factor [TNF]-alpha) and nitric oxide (NO) on day 5 were examined.RESULTSIn the control and CsA groups, all mice died within 10 and 7 days, respectively. However, in the FTY group, 27% of the animals survived up to day 14. Compared with the control group, 1) histological scores were significantly lower in the FTY group but unchanged in the CsA group; 2) virus concentration was significantly higher in the CsA group but not in the FTY group; 3) expressions of IL-2, IL-12 and IFN-gamma in the heart were suppressed in both the FTY and CsA groups, though suppression was weaker in the FTY group; 4) TNF-alpha and NO were significantly increased in the CsA group but not in the FTY group.CONCLUSIONSFTY720 had a significant therapeutic effect in acute experimental myocarditis without inducing excessive virus replication. This report is the first to describe a beneficial effect by an immunosuppressive agent in the treatment of acute viral myocarditis.

Antifungal activity of venenatine, an indole alkaloid isolated from Alstonia venenata.

The indole alkaloid venenatine exhibited antifungal activity against some plant pathogenic and saprophytic fungi. Venenatine in an aqueous acetic acid solution inhibited spore germination of all the 10 tested fungi, Fusarium udum, Alternaria brassicicola, Ustilago cynodontis and Aspergillus flavus showed an especially high sensitivity towards this compound, exhibiting germination levels below 10%. The spore germination and colony development of the parasitic fungus Erysiphe pisi, which causes powdery mildew in pea (Pisum sativum), on excised leaves of pea was also significantly affected. Pre-inoculation rather than post inoculation treatment of the leaves was more inhibitory against spore germination and colony development.