Endotracheal aerosolization of atropine sulfate protects against soman-induced acute respiratory toxicity in guinea pigs

The efficacy of endotracheal aerosolization of atropine sulfate for protection against soman (GD)-induced respiratory toxicity was investigated using microinstillation technique in guinea pigs. GD (841?mg/m³, 1.3 LCt₅₀ or 1121?mg/m³, 1.7 LCt₅₀) was aerosolized endotracheally to anesthetized male guinea pigs that were treated with atropine sulfate (5.0?mg/kg) 30 s postexposure by endotracheal microinstillation. Animals exposed to 841?mg/m³ and 1121?mg/m³GD resulted in 31 and 13% while treatment with atropine sulfate resulted in 100 and 50% survival, respectively. Cholinergic symptoms and increased body weight loss were reduced in atropine-treated animals compared to GD controls. Diminished pulse rate and blood O₂ saturation in GD-exposed animals returned to normal levels after atropine treatment. Increased cell death, total cell count and protein in the bronchoalveolar fluid (BALF) in GD-exposed animals returned to normal levels following atropine treatment. GD exposure increased glutathione and superoxide dismutase levels in BALF and that were reduced in animals treated with atropine. Respiratory parameters measured by whole-body barometric plethysmography revealed that treatment with atropine sulfate resulted in normalization of respiratory frequency, tidal volume, time of expiration, time of inspiration, end expiratory pause, pseudo lung resistance (Penh) and pause at 4 and 24?h post 841?mg/m³ GD exposure. Lung histopathology showed that atropine treatment reduced bronchial epithelial subepithelial inflammation and multifocal alveolar septal edema. These results suggest that endotracheal aerosolization of atropine sulfate protects against respiratory toxicity and lung injury induced by microinstillation inhalation exposure to lethal doses of GD.     

Protective effects of aerosolized scopolamine against soman-induced acute respiratory toxicity in guinea pigs

The protective efficacy of the antimuscarinic agent scopolamine was evaluated against soman (o-pinacolyl methylphosphonofluoridate [GD])-induced respiratory toxicity in guinea pigs. Anesthetized animals were exposed to GD (841 mg/m(3)) by microinstillation inhalation exposure and treated 30 seconds later with endotracheally aerosolized scopolamine (0.25 mg/kg) and allowed to recover for 24 hours. Treatment with scopolamine significantly increased survival and reduced clinical signs of toxicity and body weight loss in GD-exposed animals. Analysis of bronchoalveolar lavage (BAL) fluid showed normalization of GD-induced increased cell death, total cell count, and protein following scopolamine treatment. The BAL fluid acetylcholinesterase and butyrylcholinesterase levels were also increased by scopolamine treatment. Respiratory dynamics parameters were normalized at 4 and 24 hours post-GD exposure in scopolamine-treated animals. Lung histology showed that scopolamine treatment reduced bronchial epithelial and subepithelial inflammation and multifocal alveolar septal edema. These results suggest that aerosolized scopolamine considerably protects against GD-induced respiratory toxicity.     

Aerosolized delivery of oxime MMB-4 in combination with atropine sulfate protects against soman exposure in guinea pigs

We evaluated the efficacy of aerosolized acetylcholinesterase (AChE) reactivator oxime MMB-4 in combination with the anticholinergic atropine sulfate for protection against respiratory toxicity and lung injury following microinstillation inhalation exposure to nerve agent soman (GD) in guinea pigs. Anesthetized animals were exposed to GD (841?mg/m³, 1.2 LCt₅₀) and treated with endotracheally aerosolized MMB-4 (50 µmol/kg) plus atropine sulfate (0.25?mg/kg) at 30?sec post-exposure. Treatment with MMB-4 plus atropine increased survival to 100% compared to 38% in animals exposed to GD. Decreases in the pulse rate and blood O₂ saturation following exposure to GD returned to normal levels in the treatment group. The body-weight loss and lung edema was significantly reduced in the treatment group. Similarly, bronchoalveolar cell death was significantly reduced in the treatment group while GD-induced increase in total cell count was decreased consistently but was not significant. GD-induced increase in bronchoalveolar protein was diminished after treatment with MMB-4 plus atropine. Bronchoalveolar lavage AChE and BChE activity were significantly increased in animals treated with MMB-4 plus atropine at 24?h. Lung and diaphragm tissue also showed a significant increase in AChE activity in the treatment group. Treatment with MMB-4 plus atropine sulfate normalized various respiratory dynamics parameters including respiratory frequency, tidal volume, peak inspiratory and expiratory flow, time of inspiration and expiration, enhanced pause and pause post-exposure to GD. Collectively, these results suggest that aerosolization of MMB-4 plus atropine increased survival, decreased respiratory toxicity and lung injury following GD inhalation exposure.     

Aerosolized delivery of oxime MMB-4 in combination with atropine sulfate protects against soman exposure in guinea pigs

We evaluated the efficacy of aerosolized acetylcholinesterase (AChE) reactivator oxime MMB-4 in combination with the anticholinergic atropine sulfate for protection against respiratory toxicity and lung injury following microinstillation inhalation exposure to nerve agent soman (GD) in guinea pigs. Anesthetized animals were exposed to GD (841?mg/m(3), 1.2 LCt(50)) and treated with endotracheally aerosolized MMB-4 (50 μmol/kg) plus atropine sulfate (0.25?mg/kg) at 30?sec post-exposure. Treatment with MMB-4 plus atropine increased survival to 100% compared to 38% in animals exposed to GD. Decreases in the pulse rate and blood O(2) saturation following exposure to GD returned to normal levels in the treatment group. The body-weight loss and lung edema was significantly reduced in the treatment group. Similarly, bronchoalveolar cell death was significantly reduced in the treatment group while GD-induced increase in total cell count was decreased consistently but was not significant. GD-induced increase in bronchoalveolar protein was diminished after treatment with MMB-4 plus atropine. Bronchoalveolar lavage AChE and BChE activity were significantly increased in animals treated with MMB-4 plus atropine at 24?h. Lung and diaphragm tissue also showed a significant increase in AChE activity in the treatment group. Treatment with MMB-4 plus atropine sulfate normalized various respiratory dynamics parameters including respiratory frequency, tidal volume, peak inspiratory and expiratory flow, time of inspiration and expiration, enhanced pause and pause post-exposure to GD. Collectively, these results suggest that aerosolization of MMB-4 plus atropine increased survival, decreased respiratory toxicity and lung injury following GD inhalation exposure.     

Aerosolized scopolamine protects against microinstillation inhalation toxicity to sarin in guinea pigs

Sarin is a volatile nerve agent that has been used in the Tokyo subway attack. Inhalation is predicted to be the major route of exposure if sarin is used in war or terrorism. Currently available treatments are limited for effective postexposure protection against sarin under mass casualty scenario. Nasal drug delivery is a potential treatment option for mass casualty under field conditions. We evaluated the efficacy of endotracheal administration of muscarinic antagonist scopolamine, a secretion blocker which effectively crosses the blood-brain barrier for protection against sarin inhalation toxicity. Age and weight matched male Hartley guinea pigs were exposed to 677.4 mg/m3 or 846.5?mg/?m3 (1.2?×?LCt??) sarin by microinstillation inhalation exposure for 4?min. One minute later, the animals exposed to 846.5?mg/?m3 sarin were treated with endotracheally aerosolized scopolamine (0.25?mg/kg) and allowed to recover for 24?h for efficacy evaluation. The results showed that treatment with scopolamine increased the survival rate from 20% to 100% observed in untreated sarin-exposed animals. Behavioral symptoms of nerve agent toxicity including, convulsions and muscular tremors were reduced in sarin-exposed animals treated with scopolamine. Sarin-induced body weight loss, decreased blood O? saturation and pulse rate were returned to basal levels in scopolamine-treated animals. Increased bronchoalveolar lavage (BAL) cell death due to sarin exposure was returned to normal levels after treatment with scopolamine. Taken together, these data indicate that postexposure treatment with aerosolized scopolamine prevents respiratory toxicity and protects against lethal inhalation exposure to sarin in guinea pigs.     

Neurophysiological concomitants of soman-induced respiratory depression in awake, behaving guinea pigs

Soman-induced respiratory failure was investigated in awake, behaving guinea pigs chronically instrumented to allow concurrent recordings of medullary respiratory-related unit (RRU) activity, diaphragm electromyogram (DEMG), and electrocorticogram. Responses to soman typically began with hyperpnea. Loss of consciousness, as indicated by the development of seizure activities, took place shortly after the onset of hyperpnea. This was followed by dyspnea, hypopnea, and finally, respiratory failure. The most profound respiratory dysfunctions were seen during the development of dyspnea characterized by a progressively degenerative RRU-DEMG phase relationship (phase anomalies) and mixed patterns of ataxic breathing. Electrophysiographic records indicated that the anomalous RRU-DEMG phase phenomenon is attributable to a state of functional dissociation in some brainstem mechanisms that are normally involved in the orchestration of a synchronous respiratory drive. The failure of bulbar rhythmogenic mechanisms to maintain an orderly and synchronous recruitment of respiratory drive, which led to untimely and chaotic activations of respiratory muscles, was apparently the underlying cause of various ataxic breathing patterns and a reduced ventilatory efficiency. Spectral analyses of DEMG activities showed that, despite episodic muscle fasciculations and signs of fatigue, the functional integrity of the diaphragm was not significantly compromised by soman at a dose sufficient to produce respiratory failure. These findings not only support the notion of a relatively more important involvement of central respiratory mechanisms in soman-induced respiratory failure, but also identify a state of functional dissociation of central respiratory timing mechanisms as being a significant component in soman intoxication.     

Aerosolized scopolamine protects against microinstillation inhalation toxicity to sarin in guinea pigs

Sarin is a volatile nerve agent that has been used in the Tokyo subway attack. Inhalation is predicted to be the major route of exposure if sarin is used in war or terrorism. Currently available treatments are limited for effective postexposure protection against sarin under mass casualty scenario. Nasal drug delivery is a potential treatment option for mass casualty under field conditions. We evaluated the efficacy of endotracheal administration of muscarinic antagonist scopolamine, a secretion blocker which effectively crosses the blood-brain barrier for protection against sarin inhalation toxicity. Age and weight matched male Hartley guinea pigs were exposed to 677.4?mg/m³ or 846.5?mg/?m³ (1.2?×?LCt₅₀) sarin by microinstillation inhalation exposure for 4?min. One minute later, the animals exposed to 846.5?mg/?m³ sarin were treated with endotracheally aerosolized scopolamine (0.25?mg/kg) and allowed to recover for 24?h for efficacy evaluation. The results showed that treatment with scopolamine increased the survival rate from 20% to 100% observed in untreated sarin-exposed animals. Behavioral symptoms of nerve agent toxicity including, convulsions and muscular tremors were reduced in sarin-exposed animals treated with scopolamine. Sarin-induced body weight loss, decreased blood O₂ saturation and pulse rate were returned to basal levels in scopolamine-treated animals. Increased bronchoalveolar lavage (BAL) cell death due to sarin exposure was returned to normal levels after treatment with scopolamine. Taken together, these data indicate that postexposure treatment with aerosolized scopolamine prevents respiratory toxicity and protects against lethal inhalation exposure to sarin in guinea pigs.     

Post-exposure treatment with nasal atropine methyl bromide protects against microinstillation inhalation exposure to sarin in guinea pigs

We evaluated the protective efficacy of nasal atropine methyl bromide (AMB) which does not cross the blood-brain barrier against sarin inhalation exposure. Age and weight matched male guinea pigs were exposed to 846.5 mg/m³ sarin using a microinstillation inhalation exposure technique for 4 min. The survival rate at this dose was 20%. Post-exposure treatment with nasal AMB (2.5 mg/kg, 1 min) completely protected against sarin induced toxicity (100% survival). Development of muscular tremors was decreased in animals treated with nasal AMB. Post-exposure treatment with nasal AMB also normalized acute decrease in blood oxygen saturation and heart rate following sarin exposure. Inhibition of blood AChE and BChE activities following sarin exposure was reduced in animals treated with nasal AMB, indicating that survival increases the metabolism of sarin or expression of AChE. The body weight loss of animals exposed to sarin and treated with nasal AMB was similar to saline controls. No differences were observed in lung accessory lobe or tracheal edema following exposure to sarin and subsequent treatment with nasal AMB. Total bronchoalveolar lavage fluid (BALF) protein, a biomarker of lung injury, showed trends similar to saline controls. Surfactant levels post-exposure treatment with nasal AMB returned to normal, similar to saline controls. Alkaline phosphatase levels post-exposure treatment with nasal AMB were decreased. Taken together, these data suggest that nasal AMB blocks the copious airway secretion and peripheral cholinergic effects and protects against lethal inhalation exposure to sarin thus increasing survival.     

Recombinant paraoxonase 1 protects against sarin and soman toxicity following microinstillation inhalation exposure in guinea pigs

To explore the efficacy of paraoxonase 1 (PON1) as a catalytic bioscavenger, we evaluated human recombinant PON1 (rePON1) expressed in Trichoplusia ni larvae against sarin and soman toxicity using microinstillation inhalation exposure in guinea pigs. Animals were pretreated intravenously with catalytically active rePON1, followed by exposure to 1.2 X LCt₅₀ sarin or soman. Administration of 5 units of rePON1 showed mild increase in the blood activity of the enzyme after 30 min, but protected the animals with a significant increase in survival rate along with minimal signs of nerve agent toxicity. Recombinant PON1 pretreated animals exposed to sarin or soman prevented the reduction of blood O₂ saturation and pulse rate observed after nerve agent exposure. In addition, rePON1 pretreated animals showed significantly higher blood PON1, acetylcholinesterase (AChE), and butyrylcholinesterase activity after nerve agent exposure compared to the respective controls without treatments. AChE activity in different brain regions of rePON1 pretreated animals exposed to sarin or soman were also significantly higher than respective controls. The remaining activity of blood PON1, cholinesterases and brain AChE in PON1 pretreated animals after nerve agent exposure correlated with the survival rate. In summary, these data suggest that human rePON1 protects against sarin and soman exposure in guinea pigs.     

Diazepam protects against the enhanced toxicity of cocaine adulterated with atropine

We examined the toxicity of cocatropine (cocaine/atropine mixture) and the therapeutic potential of diazepam on some behavioral and physiological parameters in rats. Atropine (20 and 60 mg/kg) or cocaine (40 mg/kg) alone did not induce any seizure or death, but the combination significantly increased both, after both acute and binge treatment. There was a significant increase of EEG mean total spectral power in cocatropine- in comparison with cocaine-treated animals. Hyperlocomotion was observed in non-seizuring rats treated with cocaine or cocatropine. Cocaine, atropine 60, and cocatropine (40 + 20 and 40 + 60) all induced hyperthermic effects in non-seizuring rats, while cocatropine (40 + 60)-seizuring animals had hypothermia. An initial hypertensive and tachycardiac effect within 15 min was followed by a secondary fall in the cocatropine (40 + 60) group. Cocatropine toxicity was partially or fully reversed by diazepam (5 mg/kg), given intraperitoneally after the first seizure. The present findings provide, for the first time, details of a synergistic toxic effect of the cocaine/atropine mixture and of the potential of diazepam for treating cocatropine-related hospital emergencies.     

Acute respiratory toxicity following inhalation exposure to soman in guinea pigs

Respiratory toxicity and lung injury following inhalation exposure to chemical warfare nerve agent soman was examined in guinea pigs without therapeutics to improve survival. A microinstillation inhalation exposure technique that aerosolizes the agent in the trachea was used to administer soman to anesthetized age and weight matched male guinea pigs. Animals were exposed to 280, 561, 841, and 1121 mg/m³ concentrations of soman for 4 min. Survival data showed that all saline controls and animals exposed to 280 and 561 mg/m³ soman survived, while animals exposed to 841, and 1121 mg/m³ resulted in 38% and 13% survival, respectively. The microinstillation inhalation exposure LCt₅₀ for soman determined by probit analysis was 827.2 mg/m³. A majority of the animals that died at 1121 mg/m³ developed seizures and died within 15-30 min post-exposure. There was a dose-dependent decrease in pulse rate and blood oxygen saturation of animals exposed to soman at 5-6.5 min post-exposure. Body weight loss increased with the dose of soman exposure. Bronchoalveolar lavage (BAL) fluid and blood acetylcholinesterase and butyrylcholinesterase activity was inhibited dose-dependently in soman treated groups at 24 h. BAL cells showed a dose-dependent increase in cell death and total cell counts following soman exposure. Edema by wet/dry weight ratio of the accessory lung lobe and trachea was increased slightly in soman exposed animals. An increase in total bronchoalveolar lavage fluid protein was observed in soman exposed animals at all doses. Differential cell counts of BAL and blood showed an increase in total lymphocyte counts and percentage of neutrophils. These results indicate that microinstillation inhalation exposure to soman causes respiratory toxicity and acute lung injury in guinea pigs.     

Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: influence of atropine dose

This investigation compared the efficacy of diazepam and the water-soluble prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD(50) of sarin (s.c. route) and 1 min after intoxication treated by intramuscular injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiological parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were observed in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were observed. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not observed but 62.5% of the animals displayed respiratory difficulties. These symptoms were not observed when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concentration of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.     

The combination of donepezil and procyclidine protects against soman-induced seizures in rats

Current treatment of nerve agent poisoning consists of prophylactic administration of pyridostigmine and therapy using atropine, an oxime and a benzodiazepine. Pyridostigmine does however not readily penetrate the blood-brain barrier giving ineffective protection of the brain against centrally mediated seizure activity. In this study, we have evaluated donepezil hydrochloride, a partial reversible inhibitor of acetylcholinesterase (AChE) clinically used for treating Alzheimer's disease, in combination with procyclidine, used in treatment of Parkinson's disease and schizophrenia, as prophylaxis against intoxication by the nerve agent soman. The results demonstrated significant protective efficacy of donepezil (2.5 mg/kg) combined with procyclidine (3 or 6 mg/kg) when given prophylactically against a lethal dose of soman (1.6 x LD(50)) in Wistar rats. No neuropathological changes were found in rats treated with this combination 48 h after soman intoxication. Six hours after soman exposure cerebral AChE activity and acetylcholine (ACh) concentration was 5% and 188% of control, respectively. The ACh concentration had returned to basal levels 24 h after soman intoxication, while AChE activity had recovered to 20% of control. Loss of functioning muscarinic ACh receptors (17%) but not nicotinic receptors was evident at this time point. The recovery in brain AChE activity seen in our study may be due to the reversible binding of donepezil to the enzyme. Donepezil is well tolerated in humans, and a combination of donepezil and procyclidine may prove useful as an alternative to the currently used prophylaxis against nerve agent intoxication.     

Protective effects of dextran sulfate and polyvinyl sulfate against acute toxicity of paraquat in mice

The protective effects of sodium dextran sulfate (SDS) and potassium polyvinyl sulfate (PPS) against the acute toxicity of paraquat (PQ) in mice were studied. The survival rates of mice treated with SDS (2000 mg/kg) or PPS (2000 mg/kg) immediately after PQ ingestion (200 mg/kg) were 100% or 100%, respectively. When treated with SDS (2000 mg/kg) or PPS (2000 mg/kg) 15 or 30 min after PQ ingestion (200 mg/kg), the survival rates were 83% or 67% for SDS-treated groups and 67% or 33% for PPS-treated groups, respectively. Treatment with SDS (2000 mg/kg) or PPS (2000 mg/kg) immediately after oral administration of PQ (200 mg/kg) increased the fecal excretion of PQ, decreased the urinary excretion of PQ and decreased the contents of PQ in the lung, liver and kidney. Such effects of SDS and PPS were reduced in the treatment with these drugs at 15 min after PQ. The in situ small intestinal absorption of PQ was significantly reduced in the presence of SDS or PPS. The binding of PQ to SDS or PPS was determined by an ultrafiltration method. These results indicate that SDS and PPS inhibit the gastrointestinal absorption of PQ on the basis of the increased intestinal transit of PQ and the binding of PQ to the drugs resulting in the protective effectiveness of SDS and PPS on the acute toxicity of PQ.     

Protection against soman-induced neuropathology and respiratory failure: a comparison of the efficacy of diazepam and avizafone in guinea pig

The purpose of this study was to compare the efficacy of diazepam and the pro-diazepam avizafone in preventing the severity of soman-induced pathology in guinea pig. Survival, respiration and seizures of experimental animals were investigated with on-line monitoring of respiratory and EEG parameters. Guinea pigs were pretreated with pyridostigmine (0.1mg/kg i.m.) and 30 min later challenged with 1 or 2 LD50 soman. One minute after intoxication they were treated with atropine (3 or 33.8 mg/kg), pralidoxime chloride (32 mg/kg) and either diazepam (2 mg/kg), avizafone (3.5 mg/kg) or saline solution. The highest dose of atropine (33.8 mg/kg) gave a protective effect in groups treated without anticonvulsants by reducing the severity of clinical signs and death within 24 h but also by decreasing seizure occurrence and brain injuries. When injected at the similar molar dose of 7 micromoles/kg, the protection of anticonvulsants against soman neurotoxicity was higher with the atropine/pralidoxime/avizafone combination than with atropine/pralidoxime/diazepam. Indeed, when atropine was used at the lowest dose, avizafone was found to prevent early mortality and seizures occurrence with better efficacy than diazepam. On the other hand, when added to the therapy, the both anticonvulsants did not prevent the moderate EEG depression (reduction of amplitude by 30-52%) observed under 2 LD50 soman. Moreover, the number of animals suffering from respiratory distress (defined as a decrease of minute ventilation of more than 20% from the baseline value) was enhanced when diazepam or avizafone were used in the therapy. This effect was dependent on the atropine dose and the nature of the anticonvulsant. The beneficial effects of the different therapeutics tested were assessed and compared to the previous data obtained with the same therapies against sarin and from the pharmacokinetics properties of the atropine/diazepam mixture.     

Skin toxicity of propranolol in guinea pigs.

The skin toxicities of propranolol were studied in guinea pigs. In the primary and cumulative skin irritation studies, the skin reactions and the histopathological changes were observed in all animals treated with propranolol, and those tended to increase with the increase of propranolol dosage. The skin reactions increased with the application times of propranolol up to 7 days in the cumulative skin irritation study. In the skin sensitization, the phototoxicity and the skin photosensitization studies, no skin reactions were observed in any animals used in the studies. These results indicate that propranolol caused skin irritation, but was negative for skin sensitization, phototoxicity and skin photosensitization in guinea pigs.     

Paraoxonase protects against chlorpyrifos toxicity in mice

Paraoxonase can hydrolyze paraoxon (PO), chlorpyrifos-oxon (CPO) and other organophosphates. Previous studies have indicated that the levels of serum paraoxonase can influence the toxicity of PO and CPO. In the present study we have investigated whether exogenous paraoxonase administered to mice would offer protection toward the acute toxicity of a phosphorothioate, chlorpyrifos (CPS). Paraoxonase was purified from rabbit serum and injected i.v., or i.v. plus i.p., in mice. Inhibition of acetylcholinesterase (AChE) in brain, diaphragm, plasma and red blood cells was measured as an index of CPS (100 mg/kg) toxicity. Administration of paraoxonase 30 min before CPS increased plasma enzyme activity toward CPO by 35-fold, and protected against its toxicity; protection was still present at 24 h, when enzyme activity was still 20-fold over basal. When paraoxonase was given 30 min after CPS, a significant protection against CPS toxicity was still observed, while after 3 h the protective effect was decreased. To mimic conditions of severe acute poisoning, a higher dose of CPS (150 mg/kg) was also administered. Administration of paraoxonase 30 min after this exposure abolished cholinergic signs and significantly protected against AChE inhibition. These results indicate that exogenous paraoxonase offers significant protection against CPS toxicity when administered both before and after the organophosphate, suggesting that it may be considered as a potential additional treatment of organophosphate poisoning.     

A single sublingual dose of an adenovirus-based vaccine protects against lethal Ebola challenge in mice and guinea pigs

Sublingual (SL) delivery, a noninvasive immunization method that bypasses the intestinal tract for direct entry into the circulation, was evaluated with an adenovirus (Ad5)-based vaccine for Ebola. Mice and guinea pigs were immunized via the intramuscular (IM), nasal (IN), oral (PO) and SL routes. SL immunization elicited strong transgene expression in and attracted CD11c(+) antigen presenting cells to the mucosa. A SL dose of 1 × 10? infectious particles induced Ebola Zaire glycoprotein (ZGP)-specific IFN-γ? T cells in spleen, bronchoalveolar lavage, mesenteric lymph nodes and submandibular lymph nodes (SMLN) of naive mice in a manner similar to the same dose given IN. Ex vivo CFSE and in vivo cytotoxic T lymphocyte (CTL) assays confirmed that SL immunization elicits a notable population of effector memory CD8+ T cells and strong CTL responses in spleen and SMLN. SL immunization induced significant ZGP-specific Th1 and Th2 type responses unaffected by pre-existing immunity (PEI) that protected mice and guinea pigs from lethal challenge. SL delivery protected more mice with PEI to Ad5 than IM injection. SL immunization also reduced systemic anti-Ad5 T and B cell responses in naive mice and those with PEI, suggesting that secondary immunizations could be highly effective for both populations.